In a paper read before the Geological Society of London in 1862,

Professor Ramsay maintained that the first formation of most existing

lakes took place during the glacial epoch, and was due, not to

elevation or subsidence, but to actual erosion of their basins by

glaciers. M. Mortillet in the same year advanced the theory that after

the Alpine lake-basins had been filled up with loose fluviatile

deposits, they were re-excavated by the great glaciers which passed

down the valleys at the time of the greatest cold, a doctrine which

would attribute to moving ice almost as great a capacity of erosion as

that which assumed that the original basins were scooped out of solid

rock by glaciers. It is impossible to deny that the mere geographical

distribution of lakes points to the intimate connection of their origin

with the abundance of ice during a former excess of cold, but how far

the erosive action of moving ice has been the sole or even the

principal cause of lake-basins, is a question still open to discussion.

The lakes of Switzerland and the north of Italy are some of them twenty

and thirty miles in length, and so deep that their bottoms are in some

cases from 1000 to 2000 feet beneath the level of the sea. It is

admitted on all hands that they were once filled with ice, and as the

existing glaciers polish and grind down, as before stated, the surface

of the rocks, we are prepared to find that every lake-basin in

countries once covered by ice should bear the marks of superficial

glaciation, and also that the ice during its advance and retreat should

have left behind it much transported matter as well as some evidence of

its having enlarged the pre-existing cavity. But much more than this is

demanded by the advocates of glacial erosion. They suggest that as the

old extinct glaciers were several thousand feet thick, they were able

in some places gradually to scoop out of the solid rock cavities twenty

or thirty miles in length, and as in the case of Lago Maggiore from a

thousand to two thousand six hundred feet below the previous level of

the river-channel, and also that the ice had the power to remove from

the cavity formed by its grinding action all the materials of the

missing rocks. A constant supply, it is argued, of fine mud issues from

the termination of every glacier in the stream which is produced by the

melting of the ice, and this result of friction is exhibited both

during winter and summer, affording evidence of the continual deepening

and widening of the valleys through which glaciers pass. As the fine

mud is carried away by a river from the deep pool which is formed from

the base of every cataract, so it seems to be imagined that lake-basins

may be gradually emptied of the mud formed by abrasion during the

glacial period.

I am by no means disposed to object to this theory on the ground of the

insufficiency of the time during which the extreme cold endured, but we

must carefully consider whether that same time is not so vast as to

make it probable that other forces, besides the motion of glaciers,

must have cooperated in converting some parts of the ancient valley

courses into lake-basins. They who have formed the most exalted

conceptions of the erosive energy of moving ice do not deny that during

the period termed “Glacial” there have been movements of the earth’s

crust sufficient to produce oscillations of level in Europe amounting

to 1000 feet or more in both directions. M. Charpentier, indeed,

attributed some of the principal changes of climate in Switzerland,

during the glacial period, to a depression of the central Alps to the

extent of 3000 feet, and Swiss geologists have long been accustomed to

attribute their lake basins, in part, to those convulsions by which the

shape and course of the valleys may have been modified. Our experience,

in the lifetime of the present generation, of the changes of level

witnessed in New Zealand during great earthquakes is entirely opposed

to the notion that the movements, whether upward or downward, are

uniform in amount or direction throughout areas of indefinite extent.

On the contrary, the land has been permanently raised in one region

several feet or yards, and the rise has been found gradually to die

out, so as to be imperceptible at a distance of twenty miles, and in

some areas is even exchanged for a simultaneous downward movement of

several feet.

But, it is asked, if such inequality of movement can have contributed

towards the production of lake basins, does it not leave unexplained

the comparative rarity of lakes in tropical and subtropical countries.

In reply to this question it may be observed that in our endeavour to

estimate the effects of subterranean movements in modifying the

superficial geography of a country we must remember that each

convulsion effects a very slight change. If it interferes with the

drainage, whether by raising the lower or sinking the higher portion of

a hydrographical basin, the upheaval or depression will only amount to

a few feet at a time, and there may be an interval of years or

centuries before any further movement takes place in the same region.

In the mean time an incipient lake if produced may be filled up with

sediment, and the recently-formed barrier will then be cut through by

the river, whereas in a country where glacial conditions prevail no

such obliteration of the temporary lake-basin would take place; for

however deep it became by repeated sinking of the upper or rising of

the lower extremity, being always filled with ice it might remain,

throughout the greater part of its extent, free from sediment or drift

until the ice melted at the close of the glacial period.

One of the most serious objections to the exclusive origin by

ice-erosion of wide and deep lake-basins arises from their capricious

distribution, as for example in Piedmont, both to the eastward and

westward of Turin, where great lakes are wanting,[6] although some of

the largest extinct glaciers descending from Mont Blanc and Monte Rosa

came down from the Alps, leaving their gigantic moraines in the low

country. Here, therefore, we might have expected to find lakes of the

first magnitude rivalling the contiguous Lago Maggiore in importance.

A still more striking illustration of the same absence of lakes where

large glaciers abound is afforded by the Caucasus, a chain more than

300 miles long, and the loftiest peaks of which attain heights from

16,000 to 18,000 feet. This greatest altitude is reached by Elbruz, a

mountain in lat. 43° N. three degrees south of Mont Blanc, but on the

other hand 3000 feet higher. The present Caucasian glaciers are equal

or superior in dimensions to those of Switzerland, and like them give

rise occasionally to temporary lakes by obstructing the course of

rivers, and causing great floods when the icy barriers give way. Mr.

Freshfield, a careful observer, writing in 1869, says:[7] “A total

absence of lakes on both sides of the chains is the most marked

feature. Not only are there no great subalpine sheets of water, like

Como or Geneva, but mountain tarns, such as the Dauben See on the

Gemmi, or the Klonthal See near Glarus, are equally wanting.” The same

author states on the authority of the eminent Swiss geologist, Mons. E.

Favre, who also explored the Caucasus in 1868, that moraines of great

height and huge erratics of granite and other rocks “justify the

assertion that the present glaciers of the Caucasus, like those of the

Alps, are only the shadows of their former selves.”

It seems safe to assume that the chain of lakes, of which the Albert

Nyanza forms one in equatorial Africa, was due to causes other than

glacial. Yet if we could imagine a glacial period to visit that region

filling the lakes with ice and scoring the rocks which form their sides

and bottoms, we should be unable to decide how much the capacity of the

basins had been enlarged and the surface modified by glacial erosion.

The same may be true of the Lago Maggiore and Lake Superior, although

the present basins of both of them afford abundant superficial markings

due to ice-action.

But to whatever combination of causes we attribute the great Alpine

lakes one thing is clear, namely, that they are, geologically speaking,

of modern origin. Every one must admit that the upper valley of the

Rhone has been chiefly caused by fluviatile denudation, and it is

obvious that the quantity of matter removed from that valley previous

to the glacial period would have been amply sufficient to fill up with

sediment the basin of the Lake of Geneva, supposing it to have been in

existence, even if its capacity had been many times greater than it is

now.[8]

On the whole, it appears to me, in accordance with the views of

Professor Ramsay, M. Mortillet, Mr. Geikie, and others, that the

abrading action of ice has formed some mountain tarns and many morainic

lakes; but when it is a question of the origin of larger and deeper

lakes, like those of Switzerland or the north of Italy, or inland

fresh-water seas, like those of Canada, it will probably be found that

ice has played a subordinate part in comparison with those movements by

which changes of level in the earth’s crust are gradually brought

about.

[1] Jamieson, Quart. Geol. Journ., 1860, vol. xvi, p. 370.

[2] Bryce, Quart. Geol. Journ., vol. xxi, p. 217, 1865.

[3] Geikie, Trans. Geol. Soc. Glasgow, vol. i, part ii, p. 68, 1863.

[4] Milne Home, Trans. Royal Soc. Edinburgh, vol. xxv, 1868-9.

[5] Quart. Geol. Journ., 1852, vol. viii, p. 372.

[6] Antiquity of Man, p. 313.

[7] Travels in Central Caucasus, 1869, p. 452.

[8] See Principles, vol. i, p. 420, 10th ed., 1867.

TERTIARY OR CAINOZOIC PERIOD

CHAPTER XIII.

PLIOCENE PERIOD

Glacial Formations of Pliocene Age. — Bridlington Beds. — Glacial

Drifts of Ireland. — Drift of Norfolk Cliffs. — Cromer Forest-bed. —

Aldeby and Chillesford Beds. — Norwich Crag. — Older Pliocene Strata. —

Red Crag of Suffolk. — Coprolitic Bed of Red Crag. — White or Coralline

Crag. — Relative Age, Origin, and Climate of the Crag Deposits. —

Antwerp Crag. — Newer Pliocene Strata of Sicily. — Newer Pliocene

Strata of the Upper Val d’Arno. — Older Pliocene of Italy. —

Subapennine Strata. — Older Pliocene Flora of Italy.

It will be seen in the description given in the last chapter of the

Post-pliocene formations of the British Isles that they comprise a

large proportion of those commonly termed glacial, characterised by

shells which, although referable to living species, usually indicate a

colder climate than that now belonging to the latitudes where they

occur fossil. But in parts of England, more especially in Yorkshire,

Norfolk, and Suffolk, there are superficial formations of clay with

glaciated boulders, and of sand and pebbles, containing occasional,

though rare, patches of shells, in which the marine fauna begins to

depart from that now inhabiting the neighbouring sea, and comprises

some species of mollusca not yet known as living, as well as extinct

varieties of others, entitling us to class them as Newer Pliocene,

although belonging to the close of that period and chronologically on

the verge of the later or Post-pliocene epoch.

Bridlington Drift.—To this era belongs the well-known locality of

Bridlington, near the mouth of the Humber, in Yorkshire, where about

seventy species or well-marked varieties of shells have been found on

the coast, near the sea-level, in a bed of sand several feet thick

resting on glacial clay with much chalk débris, and covered by a

deposit of purple clay with glaciated boulders. More than a third of

the species in this drift are now inhabitants of arctic regions, none

of them extending southward to the British seas; which is the more

remarkable as Bridlington is situated in lat. 54° north. Fifteen

species are British and Arctic, a very few belong to those species

which range south of our British seas. Five species or well-marked

varieties are not known living, namely, the variety of _Astarte

borealis_ (called _A. Withami_); _ A. mutabilis_; the sinistral form of

_Tritonium carinatum, Cardita analis,_ and _Tellina obliqua,_ Fig. 120,

p. 194. Mr. Searles Wood also inclines to consider _Nucula Cobboldiæ,_

Fig. 119, p. 194, now absent from the European seas and the Atlantic,

as specifically distinct from a closely-allied shell now living in the

seas surrounding Vancouver’s Island, which some conchologists regard as

a variety. _Tellina obliqua_ also approaches very near to a shell now

living in Japan.

Glacial Drift of Ireland.—Marine drift containing the last-mentioned

Nucula and other glacial shells reaches a height of from 1000 to 1200

feet in the county of Wexford, south of Dublin. More than eighty

species have already been obtained from this formation, of which two,

_Conovulus pyramidalis_ and _ Nassa monensis,_ are not known as living;

while _Turritella incrassata_ and _Cypræa lucida_ no longer inhabit the

British seas, but occur in the Mediterranean. The great elevation of

these shells, and the still greater height to which the surface of the

rocks in the mountainous regions of Ireland have been smoothed and

striated by ice-action, has led geologists to the opinion that that

island, like the greater part of England and Scotland, after having

been united with the continent of Europe, from whence it received the

plants and animals now inhabiting it, was in great part submerged. The

conversion of this and other parts of Great Britain into an archipelago

was followed by a re-elevation of land and a second continental period.

After all these changes the final separation of Ireland from Great

Britain took place, and this event has been supposed to have preceded

the opening of the straits of Dover.[1]

Fig. 116: Tellina balthica

Drift of Norfolk Cliffs.—There are deposits of boulder clay and till in

the Norfolk cliffs principally made up of the waste of white chalk and

flints which, in the opinion of Mr. Searles Wood, jun., and others, are

older than the Bridlington drift, and contain a larger proportion of

shells common to the Norwich and Red Crag, including a certain number

of extinct forms, but also abounding in _Tellina balthica_ (_T.

solidula,_ Fig. 116), which is found fossil at Bridlington, and living

in our British seas, but wanting in all the formations, even the

newest, afterwards to be described as Crag. As the greater part of

these drifts are barren of organic remains, their classification is at

present a matter of great uncertainty.

They can nowhere be so advantageously studied as on the coast between

Happisburgh and Cromer. Here we may see vertical cliffs, sometimes 300

feet and more in height, exposed for a distance of fifty miles, at the

base of which the chalk with flints crops out in nearly horizontal

strata. Beds of gravel and sand repose on this undisturbed chalk. They

are often strangely contorted, and envelop huge masses or erratics of

chalk with layers of vertical flint. I measured one of these fragments

in 1839 at Sherringham, and found it to be eighty feet in its longest

diameter. It has been since entirely removed by the waves of the sea.

In the floor of the chalk beneath it the layers of flint were

horizontal. Such erratics have evidently been moved bodily from their

original site, probably by the same glacial action which has polished

and striated some of the accompanying granitic and other boulders,

occasionally six feet in diameter, which are imbedded in the drift.

Cromer Forest-bed.—Intervening between these glacial formations and the

subjacent chalk lies what has been called the Cromer Forest-bed. This

buried forest has been traced from Cromer to near Kessingland, a

distance of more than forty miles, being exposed at certain seasons

between high and low water mark. It is the remains of an old land and

estuarine deposit, containing the submerged stumps of trees standing

erect with their roots in the ancient soil. Associated with the stumps

and overlying them, are lignite beds with fresh-water shells of recent

species, and laminated clay without fossils. Through the lignite and

forest-bed are scattered cones of the Scotch and spruce firs with the

seeds of recent plants, and the bones of at least twenty species of

terrestrial mammalia. Among these are two species of elephant, _E.

meridionalis,_ Nesti, and _E. antiquus,_ the former found in the Newer

Pliocene beds of the Val d’Arno, near Florence. In the same bed occur

_Hippopotamus major, Rhinoceros etruscus,_ both of them also Val d’Arno

species, many species of deer considered by Mr. Boyd Dawkins to be

characteristic of warmer countries, and also a horse, beaver, and

field-mouse. Half of these mammalia are extinct, and the rest still

survive in Europe. The vegetation taken alone does not imply a

temperature higher than that now prevailing in the British Isles. There

must have been a subsidence of the forest to the amount of 400 or 500

feet, and a re-elevation of the same to an equal extent in order to

allow the ancient surface of the chalk or covering of soil, on which

the forest grew, to be first covered with several hundred feet of

drift, and then upheaved so that the trees should reach their present

level. Although the relative antiquity of the forest-bed to the

overlying glacial till is clear, there is some difference of opinion as

to its relation to the crag presently to be described.

Fig. 117: Natica helicoides

Chillesford and Aldeby Beds.—It is in the counties of Norfolk, Suffolk,

and Essex, that we obtain our most valuable information respecting the

British Pliocene strata, whether newer or older. They have obtained in

those counties the provincial name of “Crag,” applied particularly to

masses of shelly sand which have long been used in agriculture to

fertilise soils deficient in calcareous matter. At Chillesford, between

Woodbridge and Aldborough in Suffolk, and Aldeby, near Beccles, in the

same county, there occur stratified deposits, apparently older than any

of the preceding drifts of Yorkshire, Norfolk, and Suffolk. They are

composed at Chillesford of yellow sands and clays, with much mica,

forming horizontal beds about twenty feet thick. Messrs. Prestwich and

Searles Wood, senior, who first described these beds, point out that

the shells indicate on the whole a colder climate than the Red Crag;

two-thirds of them being characteristic of high latitudes. Among these

are _Cardium Grœnlandicum, Leda limatula, Tritonium carinatum,_ and

_Scalaria Grœnlandica._ In the upper part of the laminated clays a

skeleton of a whale was found associated with casts of the

characteristic shells, _Nucula Cobboldiæ_ and _Tellina obliqua,_

already referred to as no longer inhabiting our seas, and as being

extinct varieties if not species. The same shells occur in a perfect

state in the lower part of the formation. _ Natica helicoides_ (Fig.

117) is an example of a species formerly known only as fossil, but

which has now been found living in our seas.

At Aldeby, where beds occur decidedly similar in mineral character as

well as fossil remains, Messrs. Crowfoot and Dowson have now obtained

sixty-six species of mollusca, comprising the Chillesford species and

some others. Of these about nine-tenths are recent. They are in a

perfect state, clearly indicating a cold climate; as two-thirds of them

are now met with in arctic regions. As a rule, the lamellibranchiate

molluscs have both valves united, and many of them, such as _Mya

arenaria,_ stand with the siphonal end upward, as when in a living

state. _Tellina balthica,_ before mentioned (Fig. 116) as so

characteristic of the glacial beds, including the drift of Bridlington,

has not yet been found in deposits of Chillesford and Aldeby age,

whether at Sudbourn, East Bavent, Horstead, Coltishall, Burgh, or in

the highest beds overlying the Norwich Crag proper at Bramerton and

Thorpe.

Fig. 118: <i>Mastodon arvernensis,</i> third milk molar, left side,

upper jaw: grinding surface. Norwich Crag, Postwick, also found in Red

Crag, see p. 197.

Norwich or Fluvio-marine Crag.—The beds above alluded to ought,

perhaps, to be regarded as beds of passage between the glacial

formations and those called from a provincial name “Crag,” the newest

member of which has been commonly called the “Norwich Crag.” It is

chiefly seen in the neighbourhood of Norwich, and consists of beds of

incoherent sand, loam, and gravel, which are exposed to view on both

banks of the Yare, as at Bramerton and Thorpe. As they contain a

mixture of marine, land, and fresh-water shells, with bones of fish and

mammalia, it is clear that these beds have been accumulated at the

bottom of a sea near the mouth of a river. They form patches rarely

exceeding twenty feet in thickness, resting on white chalk. At their

junction with the chalk there invariably intervenes a bed called the

“Stone-bed,” composed of unrolled chalk-flints, commonly of large size,

mingled with the remains of a land fauna comprising _ Mastodon

arvernensis, Elephas meridionalis,_ and an extinct species of deer. The

mastodon, which is a species characteristic of the Pliocene strata of

Italy and France, is the most abundant fossil, and one not found in the

Cromer forest before mentioned. When these flints, probably long

exposed in the atmosphere, became submerged, they were covered with

barnacles, and the surface of the chalk became perforated by the

_Pholas crispata,_ each fossil shell still remaining at the bottom of

its cylindrical cavity, now filled up with loose sand from the

incumbent crag. This species of Pholas still exists, and drills the

rocks between high and low water on the British coast. The name of

“Fluvio-marine” has often been given to this formation, as no less than

twenty species of land and fresh-water shells have been found in it.

They are all of living species; at least only one univalve, _Paludina

lenta,_ has any, and that a very doubtful, claim to be regarded as

extinct.

Fig. 119: Nucula Cobboldiæ; Fig. 120: Tellina obliqua.

Of the marine shells, 124 in number, about 18 per cent are extinct,

according to the latest estimate given me by Mr. Searles Wood; but, for

reasons presently to be mentioned, this percentage must be only

regarded as provisional. It must also be borne in mind that the

proportion of recent shells would be augmented if the uppermost beds at

Bramerton, near Norwich, which belong to the most modern or Chillesford

division of the Crag, had been included, as they were formerly, by Mr.

Woodward and myself, in the Norwich series. Arctic shells, which formed

so large a proportion in the Chillesford and Aldeby beds, are more rare

in the Norwich Crag, though many northern species—such as _Rhynchonella

psittacea, Scalaria Grœnlandica, Astarte borealis, Panopæa Norvegia,_

and others—still occur. The _Nucula Cobboldiæ_ and _Tellina obliqua,_

Figs. 119 and 120, before mentioned, p. 194, are frequent in these

beds, as are also _Littorina littorea, Cardium edule,_ and _Turritella

communis,_ of our seas, proving the littoral origin of the beds.

OLDER PLIOCENE STRATA.

Red Crag.—Among the English Pliocene beds the next in antiquity is the

Red Crag, which often rests immediately on the London Clay, as in the

county of Essex, illustrated in Fig. 121.

Fig. 121: Red Crag, London clay and chalk.

It is chiefly in the county of Suffolk that it is found, rarely

exceeding twenty feet in thickness, and sometimes overlying another

Pliocene deposit, the Coralline Crag, to be mentioned in the sequel. It

has yielded—exclusive of 25 species regarded by Mr. Wood as

derivative—256 species of mollusca, of which 65, or 25 per cent, are

extinct. Thus, apart from its order of superposition, its greater

antiquity than the Norwich and glacial beds, already described, is

proved by the greater departure from the fauna of our seas. It may also

be observed that in most of the deposits of this Red Crag, the northern

forms of the Norwich Crag, and of such glacial formations as

Bridlington, are less numerous, while those having a more southern

aspect begin to make their appearance. Both the quartzose sand, of

which it chiefly consists, and the included shells, are most commonly

distinguished by a deep ferruginous or ochreous colour, whence its

name. The shells are often rolled, sometimes comminuted, and the beds

have much the appearance of having been shifting sand-banks, like those

now forming on the Dogger-bank, in the sea, sixty miles east of the

coast of Northumberland. Cross stratification is almost always present,

the planes of the strata being sometimes directed towards one point of

the compass, sometimes to the opposite, in beds immediately overlying.

That such a structure is not deceptive or due to any subsequent

concretionary rearrangement of particles, or to mere bands of colour

produced by the iron, is proved by each bed being made up of flat

pieces of shell which lie parallel to the planes of the smaller strata.

It has long been suspected that the different patches of Red Crag are

not all of the same age, although their chronological relation cannot

be decided by superposition. Separate masses are characterised by

shells specifically distinct or greatly varying in relative abundance,

in a manner implying that the deposits containing them were separated

by intervals of time. At Butley, Tunstall, Sudbourn, and in the Red

Crag of Chillesford, the mollusca appear to assume their most modern

aspect when the climate was colder than when the earliest deposits of

the same period were formed. At Butley, _Nucula Cobboldiæ_, so common

in the Norwich and certain glacial beds, is found, and _Purpura

tetragona_ (Fig. 122) is very abundant. On the other hand, at

Walton-on-the-Naze, in Essex, we seem to have an exhibition of the

oldest phase of the Red Crag; and a warmer climate seems indicated, not

only by the absence of many northern forms, but also by the abundance

of some now living in the British seas and the Mediterranean. _Voluta

Lamberti_ (see Figs. 123 and 124), an extinct form, which seems to have

flourished chiefly in the antecedent Coralline Crag period, is still

represented here by individuals of every age.

Fig. 122: Purpura tetragona.

The reversed whelk (Fig. 125) is common at Walton, where the dextral

form of that shell is unknown. Here also we find most frequently

specimens of lamellibranchiate molluscs, with both the valves united,

showing that they belonged to this sea of the Upper Crag, and were not

washed in from an older bed, such as the Coralline, in which case the

ligament would not have held together the valves in strata so often

showing signs of the boisterous action of the waves. No less than forty

species of lamellibranchiate molluscs, with double valves, have been

collected by Mr. Bell from the various localities of the Red Crag.

Fig. 123: Voluta Lamberti; Fig. 124: Voluta Lamberti; Fig. 125: Trophon

antiquum.

At and near the base of the Red Crag is a loose bed of brown nodules,

first noticed by Professor Henslow as containing a large percentage of

earthy phosphates. This bed of coprolites (as it is called, because

they were originally supposed to be the fæces of animals) does not

always occur at one level, but is generally in largest quantity at the

junction of the Crag and the underlying formation. In thickness it

usually varies from six to eighteen inches, and in some rare cases

amounts to many feet. It has been much used in agriculture for manure,

as not only the nodules, but many of the separate bones associated with

them, are largely impregnated with phosphate of lime, of which there is

sometimes as much as sixty per cent. They are not unfrequently covered

with barnacles, showing that they were not formed as concretions in the

stratum where they now lie buried, but had been previously

consolidated. The phosphatic nodules often collect fossil crabs and

fishes from the London Clay, together with the teeth of gigantic

sharks. In the same bed have been found many ear-bones of whales, and

the teeth of _Mastodon arvernensis, Rhinoceros Schleiermacheri, Tapirus

priscus,_ and Hipparion (a quadruped of the horse family), and antlers

of a stag, _Cervus anoceros._ Organic remains also of the older chalk

and Lias are met with, showing how great was the denudation of previous

formations during the Pliocene period. As the older White Crag,

presently to be mentioned, contains similar phosphatic nodules near its

base, those of the Red Crag may be partly derived from this source.

White or Coralline Crag.—The lower or Coralline Crag is of very limited

extent, ranging over an area about twenty miles in length, and three or

four in breadth, between the rivers Stour and Alde, in Suffolk. It is

generally calcareous and marly—often a mass of comminuted shells, and

the remains of bryozoa[2] (or polyzoa), passing occasionally into a

soft building-stone. At Sudbourn and Gedgrave, near Orford, this

building-stone has been largely quarried. At some places in the

neighbourhood the softer mass is divided by thin flags of hard

limestone, and bryozoa placed in the upright position in which they

grew. From the abundance of these coralloid mollusca the lowest or

White Crag obtained its popular name, but true corals, as now defined,

or zoantharia, are very rare in this formation.

The Coralline Crag rarely, if ever, attains a thickness of thirty feet

in any one section. Mr. Prestwich imagines that if the beds found at

different localities were united in the probable order of their

succession, they might exceed eighty feet in thickness, but Mr. Searles

Wood does not believe in the possibility of establishing such a

chronological succession by aid of the organic remains, and questions

whether proof could be obtained of more than forty feet. I was unable

to come to any satisfactory opinion on the subject, although at Orford,

especially at Gedgrave, in the neighbourhood of that place, I saw many

sections in pits, where this crag is cut through. These pits are so

unconnected, and of such limited extent, that no continuous section of

any length can be obtained, so that speculations as to the thickness of

the whole deposit must be very vague. At the base of the formation at

Sutton a bed of phosphatic nodules, very similar to that before alluded

to in the Red Crag, with remains of mammalia, has been met with.

Fig. 126: Section near Woodbridge, in Suffolk.

Whenever the Red and Coralline Crag occur in the same district, the Red

Crag lies uppermost; and in some cases, as in the section represented

in Fig. 126, which I had an opportunity of seeing exposed to view in

1839, it is clear that the older deposit, or Coralline Crag, _b_, had

suffered denudation, before the newer formation, _a_, was thrown down

upon it. At D there was not only seen a distinct cliff, eight or ten

feet high, of Coralline Crag, running in a direction N.E. and S.W.,

against which the Red Crag abuts with its horizontal layers, but this

cliff occasionally overhangs. The rock composing it is drilled

everywhere by _ Pholades_, the holes which they perforated having been

afterwards filled with sand, and covered over when the newer beds were

thrown down. The older formation is shown by its fossils to have

accumulated in a deeper sea, and contains none of those littoral forms

such as the limpet, _Patella_, found in the Red Crag. So great an

amount of denudation could scarcely take place, in such incoherent

materials, without some of the fossils of the inferior beds becoming

mixed up with the overlying crag, so that considerable difficulty must

be occasionally experienced by the palæontologist in deciding which

species belong severally to each group.

Fig. 127: Fascicularia aurantium, from the inferior or Coralline Crag,

Suffolk. Fig. 128: Astarte Omalii, species common to Upper and Lower

Crag.

Mr. Searles Wood estimates the total number of marine testaceous

mollusca of the Coralline Crag at 350, of which 110 are not known as

living, being in the proportion of thirty-one per cent extinct. No less

than 130 species of bryozoa have been found in the Coralline Crag, and

some belong to genera unknown in the living creation, and of a very

peculiar structure; as, for example, that represented in Fig. 127,

which is one of several species having a globular form. Among the

testacea the genus _Astarte_ (see Fig. 128) is largely represented, no

less than fourteen species being known, and many of these being rich in

individuals. There is an absence of genera peculiar to hot climates,

such as _Conus, Oliva, Fasciolaria, Crassatella_, and others. The

absence also of large cowries (_Cyprea_), those found belonging

exclusively to the section _Trivia_, is remarkable. The large volute,

called _Voluta Lamberti_ (Fig. 123, p. 196), may seem an exception; but

it differs in form from the volutes of the torrid zone, and, like the

living _Voluta Magellanica_, must have been fitted for an

extra-tropical climate.

Fig. 129: Lingula Dumortieri. Fig. 130: Pyrula reticulata. Fig. 131:

Temnechinus excavatus.

The occurrence of a species of _Lingula_ at Sutton (see Fig. 129) is

worthy of remark, as these _Brachiopoda_ seem now confined to more

equatorial latitudes; and the same may be said still more decidedly of

a species of _Pyrula_, supposed by Mr. Wood to be identical with _P.

reticulata_ (Fig. 130), now living in the Indian Ocean. A genus also of

echinoderms, called by Professor Forbes _Temnechinus_ (Fig. 131),

occurs in the Red and Coralline Crag of Suffolk, and until lately was

unknown in a living state, but it has been brought to light as an

existing form by the deep-sea dredgings, both of the United States

survey, off Florida, at a depth of from 180 to 480 feet, and more

recently (1869), in the British seas, during the explorations of the

“Porcupine.”

Climate of the Crag Deposits.—One of the most interesting conclusions

deduced from a careful comparison of the shells of the British Pliocene

strata and the fauna of our present seas has been pointed out by

Professor E. Forbes. It appears that, during the Glacial period, a

period intermediate, as we have seen, between that of the Crag and our

own time, many shells, previously established in the temperate zone,

retreated southward to avoid an uncongenial climate, and they have been

found fossil in the Newer Pliocene strata of Sicily, Southern Italy,

and the Grecian Archipelago, where they may have enjoyed, during the

era of floating icebergs, a climate resembling that now prevailing in

higher European latitudes.[3] The Professor gave a list of fifty shells

which inhabited the British seas while the Coralline and Red Crag were

forming, and which, though now living in our seas, were wanting, as far

as was then known, in the glacial deposits. Some few of these species

have subsequently been found in the glacial drift, but the general

conclusion of Forbes remains unshaken.

The transport of blocks by ice, when the Red Crag was being deposited,

appears to me evident from the large size of some huge, irregular,

quite unrounded chalk flints, retaining their white coating, and 2 feet

long by 18 inches broad, in beds worked for phosphatic nodules at

Foxhall, four miles south-east of Ipswich. These must have been

tranquilly drifted to the spot by floating ice. Mr. Prestwich also

mentions the occurrence of a large block of porphyry in the base of the

Coralline Crag at Sutton, which would imply that the ice-action had

begun in our seas even in this older period. The cold seems to have

gone on increasing from the time of the Coralline to that of the

Norwich Crag, and became more and more severe, not perhaps without some

oscillations of temperature, until it reached its maximum in what has

been called the Glacial period, or at the close of the Newer Pliocene,

and in the Post-pliocene periods.

Relation of the Fauna of the Crag to that of the recent Seas.—By far

the greater number of the recent marine species occurring in the

several Crag formations are still inhabitants of the British seas; but

even these differ considerably in their relative abundance, some of the

commonest of the Crag shells being now extremely scarce—as, for

example, _Buccinum Dalei_—while others, rarely met with in a fossil

state, are now very common, as _Murex erinaceus_ and _Cardium

echinatum._ Some of the species also, the identity of which with the

living would not be disputed by any conchologist, are nevertheless

distinguishable as varieties, whether by slight deviations in form or a

difference in average dimensions. Since Mr. Searles Wood first

described the marine testacea of the Crags, the additions made to that

fossil fauna have not been considerable, whereas we have made in the

same period immense progress in our knowledge of the living testacea of

the British and arctic seas, and of the Mediterranean. By this means

the naturalist has been enabled to identify with existing species many

forms previously supposed to be extinct.

In the forthcoming supplement to the invaluable monograph communicated

by Mr. Wood to the Palæontographical Society, in which he has completed

his figures and descriptions of the British crag shells of every age,

list will be found of all the fossil shells, of which a summary is

given in the table, p. 202.

To begin with the uppermost or Chillesford beds, it will be seen that

about 9 per cent only are extinct, or not known as living, whereas in

the Norwich, which succeeds in the descending order, seventeen in a

hundred are extinct. Formerly, when the Norwich or Fluvio-marine Crag

was spoken of, both these formations were included under the same head,

for both at Bramerton and Thorpe, the chief localities where the

Norwich Crag was studied, an overlying deposit occurs referable to the

Chillesford age. If now the two were fused together as of old, their

shells would, according to Mr. Wood, yield a percentage of fifteen in a

hundred of species extinct or not known as living.

NUMBER OF KNOWN SPECIES OF MARINE TESTACEA IN THE CRAG.

CHILLESFORD AND ALDEBY BEDS Total

number Not known

as living Percentage of

Shells not known

as living Bivalves 61 4 9·5 Univalves 33 5

Brachiopods 0 0 NORWICH OR FLUVIO-MARINE CRAG Bivalves

61 10 17·5 Univalves 64 12 Brachiopods 1 0

RED CRAG

_(Exclusive to many derivative shells)_ Bivalves 128 31 25·0

Univalves 127 33 Brachiopods 1 1 CORALLINE CRAG

Bivalves 161 47 31·5 Univalves 184 60 Brachiopods

5 3

To come next to the Red Crag, the reader will observe that a percentage

of 25 is given of shells unknown as living, and this increases to 31 in

the antecedent Coralline Crag. But the gap between these two stages of

our Pliocene deposits is really wider than these numbers would

indicate, for several reasons. In the first place, the Coralline Crag

is more strictly the product of a single period, the Red Crag, as we

have seen, consisting of separate and independent patches, slightly

varying in age, of which the newest is probably not much anterior to

the Norwich Crag. Secondly, there was a great change of conditions,

both as to the depth of the sea and climate, between the periods of the

Coralline and Red Crag, causing the fauna in each to differ far more

widely than would appear from the above numerical results.

The value of the analysis given in the above table of the shells of the

Red and Coralline Crags is in no small degree enhanced by the fact that

they were all either collected by Mr. Wood himself, or obtained by him

direct from their discoverers, so that he was enabled in each case to

test their authenticity, and as far as possible to avoid those errors

which arise from confounding together shells belonging to the sea of a

newer deposit, and those washed into it from a formation of older date.

The danger of this confusion may be conceived when we remember that the

number of species rejected from the Red Crag as derivative by Mr. Wood

is no less than 25. Some geologists have held that on the same grounds

it is necessary to exclude as spurious some of the species found in the

Norwich Crag proper; but Mr. Wood does not entertain this view,

believing that the spurious shells which have sometimes found their way

into the lists of this crag have been introduced by want of care from

strata of Red Crag.

There can be no doubt, on the other hand, that conchologists have

occasionally rejected from the Red and Norwich Crags, as derivative,

shells which really belonged to the seas of those periods, because they

were extinct or unknown as living, which in their eyes afforded

sufficient ground for suspecting them to be intruders. The derivative

origin of a species may sometimes be indicated by the extreme scarcity

of the individuals, their colour, and worn condition; whereas an

opposite conclusion may be arrived at by the integrity of the shells,

especially when they are of delicate and tender structure, or their

abundance, and, in the case of the lamellibranchiata, by their being

held together by the ligament, which often happens when the shells have

been so broken that little more than the hinges of the two valves are

preserved. As to the univalves, I have seen from a pit of Red Crag,

near Woodbridge, a large individual of the extinct _Voluta Lamberti_,

seven inches in length, of which the lip, then perfect, had in former

stages of its growth been frequently broken, and as often repaired. It

had evidently lived in the sea of the Red Crag, where it had been

exposed to rough usage, and sustained injuries like those which the

reversed whelk, _Trophon antiquum_, so characteristic of the same

formation, often exhibits. Additional proofs, however, have lately been

obtained by Mr. Searles Wood that this shell had not died out in the

era of the Red Crag by the discovery of the same fossil near Southwold,

in beds of the later Norwich Crag.

Antwerp Crag.—Strata of the same age as the Red and Coralline Crag of

Suffolk have been long known in the country round Antwerp, and on the

banks of the Scheldt, below that city; and the lowest division, or

Black Crag, there found, is shown by the shells to be somewhat more

ancient than any of our British series, and probably forms the first

links of a downward passage from the strata of the Pliocene to those of

the Upper Miocene period.

Fig. 132: Murex vaginatus

Newer Pliocene Strata of Sicily.—At several points north of Catania, on

the eastern sea-coast of Sicily—as at Aci-Castello, for example,

Trezza, and Nizzeti—marine strata, associated with volcanic tuffs and

basaltic lavas, are seen, which belong to a period when the first

igneous eruptions of Mount Etna were taking place in a shallow bay of

the Mediterranean. They contain numerous fossil shells, and out of 142

species that have been collected all but eleven are identical with

species now living. Some few of these eleven shells may possibly still

linger in the depths of the Mediterranean, like _Murex vaginatus_, see

Fig. 132. The last-mentioned shell had already become rare when the

associated marine and volcanic strata above alluded to were formed. On

the whole, the modern character of the testaceous fauna under

consideration is expressed not only by the small proportion of extinct

species, but by the relative number of individuals by which most of the

other species are represented, for the proportion agrees with that

observed in the present fauna of the Mediterranean. The rarity of

individuals in the extinct species is such as to imply that they were

already on the point of dying out, having flourished chiefly in the

earlier Pliocene times, when the Subapennine strata were in progress.

Yet since the accumulation of these Newer Pliocene sands and clays, the

whole cone of Etna, 11,000 feet in height and about 90 miles in

circumference at its base, has been slowly built up; an operation

requiring many tens of thousands of years for its accomplishment, and

to estimate the magnitude of which it is necessary to study in detail

the internal structure of the mountain, and to see the proofs of its

double axis, or the evidence of the lavas of the present great centre

of eruption having gradually overwhelmed and enveloped a more ancient

cone, situated 3½ miles to the east of the present one.[4]

It appears that while Etna was increasing in bulk by a series of

eruptions, its whole mass, comprising the foundations of subaqueous

origin above alluded to, was undergoing a slow upheaval, by which those

marine strata were raised to the height of 1200 feet above the sea, as

seen at Catera, and perhaps to greater heights, for we cannot trace

their extension westward, owing to the dense and continuous covering of

modern lava under which they are buried. During the gradual rise of

these Newer Pliocene formations (consisting of clays, sands, and

basalts) other strata of Post-pliocene date, marine as well as

fluviatile, accumulated round the base of the mountain, and these, in

their turn, partook of the upward movement, so that several inland

cliffs and terraces at low levels, due partly to the action of the sea

and partly to the river Simeto, originated in succession. Fossil

remains of the elephant, and other extinct quadrupeds, have been found

in these Post-Pliocene strata, associated with recent shells.

There is probably no part of Europe where the Newer Pliocene formations

enter so largely into the structure of the earth’s crust, or rise to

such heights above the level of the sea, as Sicily. They cover nearly

half the island, and near its centre, at Castrogiovanni, reach an

elevation of 3000 feet. They consist principally of two divisions, the

upper calcareous and the lower argillaceous, both of which may be seen

at Syracuse, Girgenti, and Castrogiovanni. According to Philippi, to

whom we are indebted for the best account of the tertiary shells of

this island, thirty-five species out of one hundred and twenty-four

obtained from the beds in central Sicily are extinct.

A geologist, accustomed to see nearly all the Newer Pliocene formations

in the north of Europe occupying low grounds and very incoherent in

texture, is naturally surprised to behold formations of the same age so

solid and stony, of such thickness, and attaining so great an elevation

above the level of the sea. The upper or calcareous member of this

group in Sicily consists in some places of a yellowish-white stone,

like the Calcaire Grossier of Paris; in others, of a rock nearly as

compact as marble. Its aggregate thickness amounts sometimes to 700 or

800 feet. It usually occurs in regular horizontal beds, and is

occasionally intersected by deep valleys, such as those of Sortino and

Pentalica, in which are numerous caverns. The fossils are in every

stage of preservation, from shells retaining portions of their animal

matter and colour to others which are mere casts. The limestone passes

downward into a sandstone and conglomerate, below which is clay and

blue marl, from which perfect shells and corals may be disengaged. The

clay sometimes alternates with yellow sand.

South of the plain of Catania is a region in which the tertiary beds

are intermixed with volcanic matter, which has been for the most part

the product of submarine eruptions. It appears that, while the clay,

sand, and yellow limestone before mentioned were in course of

deposition at the bottom of the sea, volcanoes burst out beneath the

waters, like that of Graham Island, in 1831, and these explosions

recurred again and again at distant intervals of time. Volcanic ashes

and sand were showered down and spread by the waves and currents so as

to form strata of tuff, which are found intercalated between beds of

limestone and clay containing marine shells, the thickness of the whole

mass exceeding 2000 feet. The fissures through which the lava rose may

be seen in many places, forming what are called _dikes._

Fig. 133: Pecten jacobæus

No shell is more conspicuous in these Sicilian strata than the great

scallop, _Pecten jacobæus_ (Fig. 133), now so common in the

neighbouring seas. The more we reflect on the preponderating number of

this and other recent shells, the more we are surprised at the great

thickness, solidity, and height above the sea of the rocky masses in

which they are entombed, and the vast amount of geographical change

which has taken place since their origin. It must be remembered that,

before they began to emerge, the uppermost strata of the whole must

have been deposited under water. In order, therefore, to form a just

conception of their antiquity, we must first examine singly the

innumerable minute parts of which the whole is made up, the successive

beds of shells, corals, volcanic ashes, conglomerates, and sheets of

lava; and we must afterwards contemplate the time required for the

gradual upheaval of the rocks, and the excavation of the valleys. The

historical period seems scarcely to form an appreciable unit in this

computation, for we find ancient Greek temples, like those of Girgenti

(Agrigentum), built of the modern limestone of which we are speaking,

and resting on a hill composed of the same; the site having remained to

all appearances unaltered since the Greeks first colonised the island.

It follows, from the modern geological date of these rocks, that the

fauna and flora of a large part of Sicily are of higher antiquity than

the country itself. The greater part of the island has been raised

above the sea since the epoch of existing species, and the animals and

plants now inhabiting it must have migrated from adjacent countries,

with whose productions the species are now identical. The average

duration of species would seem to be so great that they are destined to

outlive many important changes in the configuration of the earth’s

surface, and hence the necessity for those innumerable contrivances by

which they are enabled to extend their range to new lands as they are

formed, and to escape from those which sink beneath the sea.

Newer Pliocene Strata of the Upper Val D’arno.—When we ascend the Arno

for about ten miles above Florence, we arrive at a deep narrow valley

called the Upper Val d’Arno, which appears once to have been a lake, at

a time when the valley below Florence was an arm of the sea. The

horizontal lacustrine strata of this upper basin are twelve miles long

and two broad. The depression which they fill has been excavated out of

Eocene and Cretaceous rocks, which form everywhere the sides of the

valley in highly inclined stratification. The thickness of the more

modern and unconformable beds is about 750 feet, of which the upper 200

feet consist of Newer Pliocene strata, while the lower are Older

Pliocene. The newer series are made up of sands and a conglomerate

called “sansino.” Among the imbedded fossil mammalia are _Mastodon

arvernensis, Elephas meridionalis, Rhinoceros etruscus, Hippopotamus

major,_ and remains of the genera bear, hyæna, and felis, nearly all of

which occur in the Cromer forest-bed (see Chap. 13, p. 191).

In the same upper strata are found, according to M. Gaudin, the leaves

and cones of _Glyptostrobus europæus_, a plant closely allied to _G.

heterophyllus_, now inhabiting the north of China and Japan. This

conifer had a wide range in time, having been traced back to the Lower

Miocene strata of Switzerland, and being common at Œningen in the Upper

Miocene, as we shall see in the sequel (p. 218).

Older Pliocene of Italy.—Subapennine Strata.—The Apennines, it is

well-known, are composed chiefly of Secondary or Mesozoic rocks,

forming a chain which branches off from the Ligurian Alps and passes

down the middle of the Italian peninsula. At the foot of these

mountains, on the side both of the Adriatic and the Mediterranean, are

found a series of tertiary strata, which form, for the most part, a

line of low hills occupying the space between the older chain and the

sea. Brocchi was the first Italian geologist who described this newer

group in detail, giving it the name of the Subapennine. Though chiefly

composed of Older Pliocene strata, it belongs, nevertheless, in part,

both to older and newer members of the tertiary series. The strata, for

example, of the Superga, near Turin, are Miocene; those of Asti and

Parma Older Pliocene, as is the blue marl of Sienna; while the shells

of the incumbent yellow sand of the same territory approach more nearly

to the recent fauna of the Mediterranean, and may be Newer Pliocene.

We have seen that most of the fossil shells of the Older Pliocene

strata of Suffolk which are of recent species are identical with

testacea now living in British seas, yet some of them belong to

Mediterranean species, and a few even of the genera are those of warmer

climates. We might therefore expect, in studying the fossils of

corresponding age in countries bordering the Mediterranean, to find

among them some species and genera of warmer latitudes. Accordingly, in

the marls belonging to this period at Asti, Parma, Sienna, and parts of

the Tuscan and Roman territories, we observe the genera _Conus, Cypræa,

Strombus, Pyrula, Mitra, Fasciolaria, Sigaretus, Delphinula,

Ancillaria, Oliva, Terebellum, Terebra, Perna, Plicatula,_ and

_Corbis_, some characteristic of tropical seas, others represented by

species more numerous or of larger size than those now proper to the

Mediterranean.

Older Pliocene Flora of Italy.—I have already alluded to the Newer

Pliocene deposits of the Upper Val d’Arno above Florence, and stated

that below those sands and conglomerates, containing the remains of the

_Elephas meridionalis_ and other associated quadrupeds, lie an older

horizontal and conformable series of beds, which may be classed as

Older Pliocene. They consist of blue clays with some subordinate layers

of lignite, and exhibit a richer flora than the overlying Newer

Pliocene beds, and one receding farther from the existing vegetation of

Europe. They also comprise more species common to the antecedent

Miocene period. Among the genera of flowering plants, M. Gaudin

enumerates pine, oak, evergreen oak, plum, plane, alder, elm, fig,

laurel, maple, walnut, birch, buckthorn, hickory, sumach, sarsaparilla,

sassafras, cinnamon, Glyptostrobus, Taxodium, Sequoia, Persea,

Oreodaphne (Fig. 134), Cassia, and Psoralea, and some others. This

assemblage of plants indicates a warm climate, but not so subtropical

an one as that of the Upper Miocene period, which will presently be

considered.

Fig. 134: Creodaphne Heerii. Fig. 135: Liquidambar europæum, var.

trilobatum Fig. 134: _Creodaphne Heerii_.

Leaf[5]

Fig. 135: _Liquidambar europæum_, var. _trilobatum_, A. Br. (sometimes

four-lobed, and more commonly five-lobed).

_a._ Leaf. _b._ Part of same. _c._ Fruit. _d._ Seed Œningen.

M. Gaudin, jointly with the Marquis Strozzi, has thrown much light on

the botany of beds of the same age in another part of Tuscany, at a

place called Montajone, between the rivers Elsa and Evola, where, among

other plants, is found the _Oreodaphne Heerii_, Gaud. (see Fig. 134),

which is probably only a variety of _Oreodaphne foetens_, or the laurel

called the Til in Madeira, where, as in the Canaries, it constitutes a

large portion of the native woods, but cannot now endure the climate of

Europe. In the fossil specimens the same glands or protuberances are

preserved[6] (see Fig. 134) as those which are seen in the axils of the

primary veins of the leaves in the recent Til. Another plant also

indicating a warmer climate is the _ Liquidambar europæum_, Brong. (see

Fig. 135), a species nearly allied to _L. styracifluum_, L., which

flourishes in most places in the Southern States of North America, on

the borders of the Gulf of Mexico.

[1] See Antiquity of Man, chap. xiv.

[2] Ehrenberg proposed in 1831 the term _ Bryozoum_, or “Moss-animal,”

for the molluscous or ascidian form of polyp, characterised by having

two openings to the digestive sack, as in _Eschara, Flustra,

Retepora,_ and other zoophytes popularly included in the corals, but

now classed by naturalists as mollusca. The term _Polyzoum,_

synonymous with _ Bryozoum,_ was, it seems, proposed in 1830, or the

year before, by Mr. J. O. Thompson.

[3] E. Forbes Mem. Geol. Survey of Gt. Brit., vol. i, p. 386.

[4] See a Memoir on the Lavas and Mode of Origin of Mount Etna by the

Author in Phil. Trans., 1858.

[5] Feuilles fossiles de la Toscane.

[6] Contributions à la Flore fossile Italienne. Gaudin and Strozzi.

Plate 11, Fig. 3. Gaudin, p. 22.

CHAPTER XIV.

MIOCENE PERIOD—UPPER MIOCENE.

Upper Miocene Strata of France—Faluns of Touraine. — Tropical Climate

implied by Testacea. — Proportion of recent Species of Shells. — faluns

more ancient than the Suffolk Crag. — Upper Miocene of Bordeaux and the

South of France. — Upper Miocene of Œningen, in Switzerland. — Plants

of the Upper Fresh-water Molasse. — Fossil Fruit and Flowers as well as

Leaves. — Insects of the Upper Molasse. — Middle or Marine Molasse of

Switzerland. — Upper Miocene Beds of the Bolderberg, in Belgium. —

Vienna Basin. — Upper Miocene of Italy and Greece. — Upper Miocene of

India; Siwalik Hills. — Older Pliocene and Miocene of the United

States.

Upper Miocene Strata of France—Faluns of Touraine.—The strata which we

meet with next in the descending order are those called by many

geologists “Middle Tertiary,” for which in 1833 I proposed the name of

Miocene, selecting the “faluns” of the valley of the Loire, in France,

as my example or type. I shall now call these falunian deposits Upper

Miocene, to distinguish them from others to which the name of Lower

Miocene will be given.

No British strata have a distinct claim to be regarded as Upper

Miocene, and as the Lower Miocene are also but feebly represented in

the British Isles, we must refer to foreign examples in illustration of

this important period in the earth’s history. The term “faluns” is

given provincially by French agriculturists to shelly sand and marl

spread over the land in Touraine, just as similar shelly deposits were

formerly much used in Suffolk to fertilise the soil, before the

coprolitic or phosphatic nodules came into use. Isolated masses of such

faluns occur from near the mouth of the Loire, in the neighbourhood of

Nantes, to as far inland as a district south of Tours. They are also

found at Pontlevoy, on the Cher, about seventy miles above the junction

of that river with the Loire, and thirty miles south-east of Tours.

Deposits of the same age also appear under new mineral conditions near

the towns of Dinan and Rennes, in Brittany. I have visited all the

localities above enumerated, and found the beds on the Loire to consist

principally of sand and marl, in which are shells and corals, some

entire, some rolled, and others in minute fragments. In certain

districts, as at Doué, in the Department of Maine and Loire, ten miles

south-west of Saumur, they form a soft building-stone, chiefly composed

of an aggregate of broken shells, bryozoa, corals, and echinoderms,

united by a calcareous cement; the whole mass being very like the

Coralline Crag near Aldborough, and Sudbourn in Suffolk. The scattered

patches of faluns are of slight thickness, rarely exceeding fifty feet;

and between the district called Sologne and the sea they repose on a

great variety of older rocks; being seen to rest successively upon

gneiss, clay-slate, various secondary formations, including the chalk;

and, lastly, upon the upper fresh-water limestone of the Parisian

tertiary series, which, as before mentioned (p. 142), stretches

continuously from the basin of the Seine to that of the Loire.

Fig. 136: Dinotherium giganteum.

At some points, as at Louans, south of Tours, the shells are stained of

a ferruginous colour, not unlike that of the Red Crag of Suffolk. The

species are, for the most part, marine, but a few of them belong to

land and fluviatile genera. Among the former, _ Helix turonensis)_

(Fig. 38) is the most abundant. Remains of terrestrial quadrupeds are

here and there intermixed, belonging to the genera Dinotherium (Fig.

136), Mastodon, Rhinoceros, Hippopotamus, Chæropotamus, Dichobune,

Deer, and others, and these are accompanied by cetacea, such as the

Lamantin, Morse, Sea-calf, and Dolphin, all of extinct species.

The fossil testacea of the faluns of the Loire imply, according to the

late Edward Forbes, that the beds were formed partly on the shore

itself at the level of low water, and partly at very moderate depths,

not exceeding ten fathoms below that level. The molluscan fauna is, on

the whole, much more littoral than that of the Pliocene Red and

Coralline Crag of Suffolk, and implies a shallower sea. It is,

moreover, contrasted with the Suffolk Crag by the indications it

affords of an extra-European climate. Thus it contains seven species of

Cypræa, some larger than any existing cowry of the Mediterranean,

several species of _Oliva, Ancillaria, Mitra, Terebra, Pyrula,

Fasciolaria,_ and _ Conus._ Of the cones there are no less than eight

species, some very large, whereas the only European cone now living is

of diminutive size. The genus _Nerita,_ and many others, are also

represented by individuals of a type now characteristic of equatorial

seas, and wholly unlike any Mediterranean forms. These proofs of a more

elevated temperature seem to imply the higher antiquity of the faluns

as compared with the Suffolk Crag, and are in perfect accordance with

the fact of the smaller proportion of testacea of recent species found

in the faluns.

Out of 290 species of shells, collected by myself in 1840 at Pontlevoy,

Louans, Bossée, and other villages twenty miles south of Tours, and at

Savigné, about fifteen miles north-west of that place, seventy-two only

could be identified with recent species, which is in the proportion of

twenty-five per cent. A large number of the 290 species are common to

all the localities, those peculiar to each not being more numerous than

we might expect to find in different bays of the same sea.

The total number of species of testaceous mollusca from the faluns in

my possession is 302, of which forty-five only, or fourteen per cent,

were found by Mr. Wood to be common to the Suffolk Crag. The number of

corals, including bryozoa and zoantharia, obtained by me at Doué and

other localities before adverted to, amounts to forty-three, as

determined by Mr. Lonsdale, of which seven (one of them a zoantharian)

agree specifically with those of the Suffolk Crag. Some of the genera

occurring fossil in Touraine, as the corals Astrea and _

Dendrophyllia_, and the bryozoan _Lunulites_, have not been found in

European seas north of the Mediterranean; nevertheless, the zoantharia

of the faluns do not seem to indicate, on the whole, so warm a climate

as would be inferred from the shells.

It was stated that, on comparing about 300 species of Touraine shells

with about 450 from the Suffolk Crag, forty-five only were found to be

common to both, which is in the proportion of only fifteen per cent.

The same small amount of agreement is found in the corals also. I

formerly endeavoured to reconcile this marked difference in species

with the supposed co-existence of the two faunas, by imagining them to

have severally belonged to distinct zoological provinces or two seas,

the one opening to the north and the other to the south, with a barrier

of land between them, like the Isthmus of Suez, now separating the Red

Sea and the Mediterranean. But I now abandon that idea for several

reasons; among others, because I succeeded in 1841 in tracing the Crag

fauna southward in Normandy to within seventy miles of the Falunian

type, near Dinan, yet found that both assemblages of fossils retained

their distinctive characters, showing no signs of any blending of

species or transition of climate.

The principal grounds, however, for referring the English Crag to the

older Pliocene and the French faluns to the Upper Miocene epochs,

consist in the predominance of fossil shells in the British strata

identifiable with species not only still living, but which are now

inhabitants of neighbouring seas, while the accompanying extinct

species are of genera such as characterise Europe. In the faluns, on

the contrary, the recent species are in a decided minority; and most of

them are now inhabitants of the Mediterranean, the coast of Africa, and

the Indian Ocean; in a word, less northern in character, and pointing

to the prevalence of a warmer climate. They indicate a state of things

receding farther from the present condition of Central Europe in

physical geography and climate, and doubtless, therefore, receding

farther from our era in time.

Fig. 137: Voluta Lamberti.

Among the conspicuous fossils common to the faluns of the Loire and the

Suffolk Crag is a variety of the _Voluta Lamberti_, a shell already

alluded to (Fig. 123). The specimens of this shell which I have myself

collected in Touraine, or have seen in museums, are thicker and heavier

than British individuals of the same species, and shorter in proportion

to their width, and have the folds on the columella less oblique, as

represented in Fig. 137.

Upper Miocene of Bordeaux and the South of France.—A great extent of

country between the Pyrenees and the Gironde is overspread by tertiary

deposits of various ages, and chiefly of Miocene date. Some of these,

near Bordeaux, coincide in age with the faluns of Touraine, already

mentioned, but many of the species of shells are peculiar to the south.

The succession of beds in the basin of the Gironde implies several

oscillations of level by which the same wide area was alternately

converted into sea and land and into brackish-water lagoons, and

finally into fresh-water ponds and lakes.

Among the fresh-water strata of this age near the base of the Pyrenees

are marls, limestones and sands, in which the eminent comparative

anatomist, M. Lartet, has obtained a great number of fossil mammalia

common to the faluns of the Loire and the Upper Miocene beds of

Switzerland, such as _Dinotherium giganteum_ and _Mastodon

angustidens_; also the bones of quadrumana, or of the ape and monkey

tribe, which were discovered in 1837, the first of that order of

quadrupeds detected in Europe. They were found near Auch, in the

Department of Gers, in latitude 43° 39′ N. About forty miles west of

Toulouse. They were referred by MM. Lartet and Blainville to a genus

closely allied to the Gibbon, to which they gave the name of

_Pliopithecus._ Subsequently, in 1856, M. Lartet described another

species of the same family of long-armed apes (_Hylobates_), which he

obtained from strata of the same age at Saint-Gaudens, in the Haute

Garonne. The fossil remains of this animal consisted of a portion of a

lower jaw with teeth and the shaft of a humerus. It is supposed to have

been a tree-climbing frugivorous ape, equalling man in stature. As the

trunks of oaks are common in the lignite beds in which it lay, it has

received the generic name of _Dryopithecus._ The angle formed by the

ascending ramus of the jaw and the alveolar border is less open, and

therefore more like the human subject, than in the Chimpanzee, and what

is still more remarkable, the fossil, a young but adult individual, had

all its milk teeth replaced by the second set, while its last true

molar (or wisdom-tooth) was still undeveloped, or only existed as a

germ in the jaw-bone. In the mode, therefore, of the succession of its

teeth (which, as in all the old-World apes, exactly agree in number

with those in man) it differed from the Gorilla and Chimpanzee, and

corresponded with the human species.

Upper Miocene Beds of Œningen, in Switzerland.—The faluns of the Loire

first served, as already stated (p. 211), as the type of the Miocene

formations in Europe. They yielded a plentiful harvest of marine fossil

shells and corals, but were entirely barren of plants and insects. In

Switzerland, on the other hand, deposits of the same age have been

discovered, remarkable for their botanical and entomological treasures.

We are indebted to Professor Heer, of Zurich, for the description,

restoration, and classification of several hundred species and

varieties of these fossil plants, the whole of which he has illustrated

by excellent figures in his “Flora Tertiaria Helvetiæ.” This great

work, and those of Adolphe Brongniart, Unger, Goppert and others, show

that this class of fossils is beginning to play the same important part

in the classification of the tertiary strata containing lignite or

brown coal as an older flora has long played in enabling us to

understand the ancient coal or carboniferous formation. No small

skepticism has always prevailed among botanists as to whether the

leaves alone and the wood of plants could ever afford sufficient data

for determining even genera and families in the vegetable kingdom. In

truth, before such remains could be rendered available a new science

had to be created. It was necessary to study the outlines, nervation,

and microscopic structure of the leaves, with a degree of care which

had never been called for in the classification of living plants, where

the flower and fruit afforded characters so much more definite and

satisfactory. As geologists, we cannot be too grateful to those who,

instead of despairing when so difficult a task was presented to them,

or being discouraged when men of the highest scientific attainments

treated the fossil leaves as worthless, entered with full faith and

enthusiasm into this new and unexplored field. That they should

frequently have fallen into errors was unavoidable, but it is

remarkable, especially if we inquire into the history of Professor

Heer’s researches, how often early conjectures as to the genus and

family founded on the leaves alone were afterwards confirmed when

fuller information was obtained. As examples to be found on comparing

Heer’s earlier and later works, I may instance the chestnut, elm,

maple, cinnamon, magnolia, buckbean or Menyanthes, vine, buckthorn

(_Rhamnus_), _Andromeda_ and _Myrica,_ and among the conifers _Sequoia_

and _ Taxodium._ In all these cases the plants were first recognised by

their leaves, and the accuracy of the determination was afterwards

confirmed when the fruit, and in some instances both fruit and flower,

were found attached to the same stem as the leaves.

But let us suppose that no fruit, seed, or flower had ever been met

with in a fossil state, we should still have been indebted to the

persevering labours of botanical palæontologists for one of the

grandest scientific discoveries for which the present century is

remarkable—namely, the proofs now established of the prevalence of a

mild climate and a rich arborescent flora in the arctic regions in that

Miocene epoch on the history of which we are now entering. It may be

useful if I endeavour to give the reader in a few words some idea of

the nature of the evidence of these important conclusions, to show how

far they may be safely based on fossil leaves alone. When we begin by

studying the fossils of the Newer Pliocene deposits, such as those of

the Upper Val d’Arno, before alluded to, we perceive that the fossil

foliage agrees almost entirely with the trees and shrubs of a modern

European forest. In the plants of the Older Pliocene strata of the same

region we observe a larger proportion of species and genera which,

although they may agree with well-known Asiatic or other foreign types,

are at present wanting in Italy. If we then examine the Miocene

formations of the same country, exotic forms become more abundant,

especially the palms, whether they belong to the European or American

fan-palms, _Chamærops_ and _Sabal_, or to the more tropical family of

the date-palms or _Phœnicites_, which last are conspicuous in the Lower

Miocene beds of Central Europe. Although we have not found the fruit or

flower of these palms in a fossil state, the leaves are so

characteristic that no one doubts the family to which they belong, or

hesitates to accept them as indications of a warm and sub-tropical

climate.

When the Miocene formations are traced to the northward of the 50th

degree of latitude, the fossil palms fail us, but the greater

proportion of the leaves, whether identical with those of existing

European trees or of forms now unknown in Europe, which had accompanied

the Miocene palms, still continue to characterise rocks of the same

age, until we meet with them not only in Iceland, but in Greenland, in

latitude 70° N., and in Spitzbergen, latitude 78° 56′, or within about

11 degrees of the pole, and under circumstances which clearly show them

to have been indigenous in those regions, and not to have been drifted

from the south (see p. 240). Not only, therefore, has the botanist

afforded the geologist much palæontological assistance in identifying

distinct tertiary formations in distant places by his power of

accurately discriminating the forms, veining, and microscopic structure

of leaves or wood, but, independently of that exact knowledge derivable

from the organs of fructification, we are indebted to him for one of

the most novel, unexpected results of modern scientific inquiry.

The Miocene formations of Switzerland have been called _ Molasse_, a

term derived from the French _mol_, and applied to a _soft_,

incoherent, greenish sandstone, occupying the country between the Alps

and the Jura. This molasse comprises three divisions, of which the

middle one is marine, and being closely related by its shells to the

faluns of Touraine, may be classed as Upper Miocene. The two others are

fresh-water, the upper of which may be also grouped with the faluns,

while the lower must be referred to the Lower Miocene, as defined in

the next chapter.

Upper Fresh-water Molasse.—This formation is best seen at Œningen, in

the valley of the Rhine, between Constance and Schaffhausen, a locality

celebrated for having produced in the year 1700 the supposed human

skeleton called by Scheuchzer “homo diluvii testis,” a fossil

afterwards demonstrated by Cuvier to be a reptile, or aquatic

salamander, of larger dimensions than even its great living

representative, the salamander of Japan.

The Œningen strata consist of a series of marls and limestones, many of

them thinly laminated, and which appear to have slowly accumulated in a

lake probably fed by springs holding carbonate of lime in solution. The

elliptical area over which this fresh-water formation has been traced

extends, according to Sir Roderick Murchison, for a distance of ten

miles east and west from Berlingen, on the right bank of the river to

Wangen, and to Œningen, near Stein, on the left bank. The organic

remains have been chiefly derived from two quarries, the lower of which

is about 550 feet above the level of the Lake of Constance, while the

upper quarry is 150 feet higher. In this last, a section thirty feet

deep displays a great succession of beds, most of them splitting into

slabs and some into very thin laminæ. Twenty-one beds are enumerated by

Professor Heer, the uppermost a bluish-grey marl seven feet thick, with

organic remains, resting on a limestone with fossil plants, including

leaves of poplar, cinnamon, and pond-weed (_Potamogeton_), together

with some insects; while in the bed No. 4, below, is a bituminous rock,

in which the _Mastodon tapiroides_, a characteristic Upper Miocene

quadruped, has been met with. The 5th bed, two or three inches thick,

contains fossil fish, e.g., _Leuciscus_ (roach), and the larvæ of

dragon-flies, with plants such as the elm (_Ulmus_), and the aquatic

Chara. Below this are other plant-beds; and then, in No. 9, the stone

in which the great salamander (Andrias Scheuchzeri) and some fish were

found. Below this other strata occur with fish, tortoises, the great

salamander before alluded to, fresh-water mussels, and plants. In No.

16 the fossil fox of Œningen, _Galecynus Œningensis,_ Owen, was

obtained by Sir R. Murchison. To this succeed other beds with mammalia

(_Lagomys_), reptiles, (_Emys_), fish, and plants, such as walnut,

maple, and poplar. In the 19th bed are numerous fish, insects, and

plants, below which are marls of a blue indigo colour.

In the lower quarry eleven beds are mentioned, in which, as in the

upper, both land and fresh-water plants and many insects occur. In the

6th, reckoning from the top, many plants have been obtained, such as

_Liquidambar, Daphnogene, Podogonium,_ and _ Ulmus_, together with

tortoises, besides the bones and teeth of a ruminant quadruped, named

by H. von Meyer _Palæomeryx eminens._ No. 9 is called the insect-bed, a

layer only a few inches thick, which, when exposed to the frost, splits

into leaves as thin as paper. In these thin laminæ plants such as _

Liquidambar, Daphnogene,_ and _Glyptostrobus_, occur, with innumerable

insects in a wonderful state of preservation, usually found singly.

Below this is an indigo-blue marl, like that at the bottom of the

higher quarry, resting on yellow marl ascertained to be at least thirty

feet thick.

Fig. 138: Cinnamomum polymorphum.

All the above fossil-bearing strata were evidently formed with extreme

slowness. Although the fossiliferous beds are, in the aggregate, no

more than a few yards in thickness, and have only been examined in the

small area comprised in the two quarries just alluded to, they give us

an insight into the state of animal and vegetable life in part of the

Upper Miocene period, such as no other region in the world has

elsewhere supplied. In the year 1859, Professor Heer had already

determined no less than 475 species of plants and more than 800 insects

from these Œningen beds. He supposes that a river entering a lake

floated into it some of the leaves and land insects, together with the

carcasses of quadrupeds, among others a great Mastodon. Occasionally,

during tempests, twigs and even boughs of trees with their leaves were

torn off and carried for some distance so as to reach the lake.

Springs, containing carbonate of lime, seem at some points to have

supplied calcareous matter in solution, giving origin locally to a kind

of travertin, in which organic bodies sinking to the bottom became

hermetically sealed up. The laminæ, says Heer, which immediately

succeed each other were not all formed at the same season, for it can

be shown that, when some of them originated, certain plants were in

flower, whereas, when the next of these layers was produced, the same

plants had ripened their fruit. This inference is confirmed by

independent proofs derived from insects. The principal insect-bed is

rarely two inches thick, and is composed, says Heer, of about 250

leaf-like laminæ, some of which were deposited in the spring, when the

_Cinnamomum polymorphum_ (Fig. 138) was in flower, others in summer,

when winged ants were numerous, and when the poplar and willow had

matured their seed; others, again, in autumn, when the same _

Cinnamomum polymorphum_ (Fig. 138) was in fruit, as well as the

liquidambar, oak, clematis, and many other plants. The ancient lake

seems to have had a belt of poplars and willows round its borders,

countless leaves of which were imbedded in mud, and together with them,

at some points, a species of reed, _Arundo_, which was very common.

One of the most characteristic shrubs is a papilionaceous and

leguminous plant of an extinct genus, called by Heer _ Podogonium_, of

which two species are known. Entire twigs have been found with flowers,

and always without leaves, as the flowers evidently came out, as in the

poplar and willow tribe, before any leaves made their appearance. Other

specimens have been obtained with ripe fruits accompanied by leaves,

which resemble those of the tamarind, to which it was evidently allied,

being of the family Cæsalpineæ, now proper to warmer regions.

Fig. 138: Acer trilobatum.

The Upper Miocene flora of Œningen is peculiarly important, in

consequence of the number of genera of which not merely the leaves,

but, as in the case of the _Podogonium_ just mentioned, the fruit also

and even the flower are known. Thus there are nineteen species of

maple, ten of which have already been found with fruit. Although in no

one region of the globe do so many maples now flourish, we need not

suspect Professor Heer of having made too many species in this genus

when we consider the manner in which he has dealt with one of them,

_Acer trilobatum_, Figs. 139 and 140. Of this plant the number of

marked varieties figured and named is very great, and no less than

three of them had been considered as distinct species by other

botanists, while six of the others might have laid claim, with nearly

equal propriety, to a like distinction. The common form, called _Acer

trilobatum_, Fig. 139, may be taken as a normal representative of the

Œningen fossil, and Fig. 140, as one of the most divergent varieties,

having almost four lobes in the leaf instead of three.

Fig. 140: Acer trilobatum.

Among the conspicuous genera which abounded in the Miocene period in

Europe is the plane-tree, _Platanus,_ the fossil species being

considered by Heer to come nearer to the American _ P. occidentalis_

than to _P. orientalis_ of Greece and Asia Minor. In some of the fossil

specimens the male flowers are preserved. Among other points of

resemblance with the living plane-trees, as we see them in the parks

and squares of London, fossil fragments of the trunk are met with,

having pieces of their bark peeling off.

Platanus aceroides.

The vine of Œningen, _Vitis teutonica_, Ad. Brong, is of a North

American type. Both the leaves and seeds have been found at Œningen,

and bunches of compressed grapes of the same species have been met with

in the brown coal of Wetteravia in Germany. No less than eight species

of smilax, a monocotyledonous genus, occur at Œningen and in other

Upper Miocene localities, the flowers of some of them, as well as the

leaves, being preserved; as in the case of the very common fossil, _S.

sagittifera_, Fig. 142, _a._

Leaves of plants supposed to belong to the order Proteaceæ have been

obtained partly from Œningen and partly from the lacustrine formation

of the same age at Locle in the Jura. They have been referred to the

genera _Banksia, Grevillea, Hakea,_ and _Persoonia._ Of Hakea there is

the impression of a supposed seed-vessel, with its characteristic thick

stalk and seeds, but as the fruit is without structure, and has not yet

been found attached to the same stem as the leaf, the proof is

incomplete.

Fig. 142: Smilax sagittifera.

To whatever family the foliage hitherto regarded as proteaceous by many

able palæontologists may eventually be shown to belong, we must be

careful not to question their affinity to that order of plants on those

geographical considerations which have influenced some botanists. The

nearest living Proteaceæ now feel the in Abyssinia in lat. 20° N., but

the greatest number are confined to the Cape and Australia. The

ancestors, however, of the Œningen fossils ought not to be looked for

in such distant regions, but from that European land which in Lower

Miocene times bore trees with similar foliage, and these had doubtless

an Eocene source, for cones admitted by all botanists to be proteaceous

have been met with in one division of that older Tertiary group (see

Fig. 206). The source of these last, again, must not be sought in the

antipodes, for in the white chalk of Aix-la-Chapelle leaves like those

of Grevillea and other proteaceous genera have been found in abundance,

and, as we shall see (p. 304) in a most perfect state of preservation.

All geologists agree that the distribution of the Cretaceous land and

sea had scarcely any connection with the present geography of the

globe.

Fig. 143: Fruit of the fossil and recent species of Hakea, a genus of

Proteaceæ.

In the same beds with the supposed Proteaceæ there occurs at Locle a

fan-palm of the American type Sabal (for genus see Fig. 151), a genus

which ranges throughout the low country near the sea from the Carolinas

to Florida and Louisiana. Among the Coniferæ of Upper Miocene age is

found a deciduous cypress nearly allied to the _Taxodium distichum_ of

North America, and a _Glyptostrobus_ (Fig. 144), very like the Japanese

_G. heterophyllus,_ now common in our shrubberies.

Fig. 144: Glyptostrobus Europæus.

Before the appearance of Heer’s work on the Miocene Flora of

Switzerland, Unger and Goppert had already pointed out the large

proportion of living North American genera which distinguished the

vegetation of the Miocene period in Central Europe. Next in number,

says Heer, to these American forms at Œningen the European genera

preponderate, the Asiatic ranking in the third, the African in the

fourth, and the Australian in the fifth degree. The American forms are

more numerous than in the Italian Pliocene flora, and the whole

vegetation indicates a warmer climate than the Pliocene, though not so

high a temperature as that of the older or Lower Miocene period.

The conclusions drawn from the insects are for the most part in perfect

harmony with those derived from the plants, but they have a somewhat

less tropical and less American aspect, the South European types being

more numerous. On the whole, the insect fauna is richer than that now

inhabiting any part of Europe. No less than 844 species are reckoned by

Heer from the Œningen beds alone, the number of specimens which he has

examined being 5080. The entire list of Swiss species from the Upper

and Lower Miocene together amount to 1322. Almost all the living

families of Coleoptera are represented, but, as we might have

anticipated from the preponderance of arborescent and ligneous plants,

the wood-eating beetles play the most conspicuous part, the Buprestidæ

and other long-horned beetles being particularly abundant.

The patterns and some remains of the colours both of _ Coleoptera_ and

_Hemiptera_ are preserved at Œningen, as, for example in _Harpactor_

(Fig. 145), in which the antennæ, one of the eyes, and the legs and

wings are retained. The characters, indeed, of many of the insects are

so well defined as to incline us to believe that if this class of the

invertebrata were not so rare and local, they might be more useful than

even the plants and shells in settling chronological points in geology.

Middle or Marine Molasse (Upper Miocene) of Switzerland.—It was before

stated that the Miocene formation of Switzerland consisted of, first,

the upper fresh-water molasse, comprising the lacustrine marls of

Œningen; secondly, the marine molasse, corresponding in age to the

faluns of Touraine; and thirdly, the lower fresh-water molasse. Some of

the beds of the marine or middle series reach a height of 2470 feet

above the sea. A large number of the shells are common to the faluns of

Touraine, the Vienna basin, and other Upper Miocene localities. The

terrestrial plants play a subordinate part in the fossiliferous beds,

yet more than ninety of them are enumerated by Heer as belonging to

this falunian division, and of these more than half are common to

subjacent Lower Miocene beds, while a proportion of about forty-five in

one hundred are common to the overlying Œningen flora. Twenty-six of

the ninety-two species are peculiar.

Fig. 145: Harpactor maculipes.

Fig. 146: Olica Dufresnii.

Upper Miocene of the Bolderberg, in Belgium.—In a small hill or ridge

called the Bolderberg, which I visited in 1851, situated near Hasselt,

about forty miles E.N.E. of Brussels, strata of sand and gravel occur,

to which M. Dumont first called attention as appearing to constitute a

northern representative of the faluns of Touraine. On the whole, they

are very distinct in their fossils from the two upper divisions of the

Antwerp Crag before mentioned (p. 204), and contain shells of the

genera _Oliva, Conus, Ancillaria, Pleurotoma,_ and _ Cancellaria_ in

abundance. The most common shell is an Olive (Fig. 146), called by Nyst

_Oliva Dufresnii_; and constituting, as M. Bosquet observes, a smaller

and shorter variety of the Bordeaux species.

So far as the shells of the Bolderberg are known, the proportion of

recent species agrees with that in the faluns of Touraine, and the

climate must have been warmer than that of the Coralline Crag of

England.

Upper Miocene Beds of the Vienna Basin.—In South Germany the general

resemblance of the shells of the Vienna tertiary basin with those of

the faluns of Touraine has long been acknowledged. In the late Dr.

Hörnes’s excellent work on the fossil mollusca of that formation, we

see accurate figures of many shells, clearly of the same species as

those found in the falunian sands of Touraine.

According to Professor Suess, the most ancient and purely marine of the

Miocene strata in this basin consist of sands, conglomerates,

limestones, and clays, and they are inclined inward, or from the

borders of the trough towards the centre, their outcropping edges

rising much higher than the newer beds, whether Miocene or Pliocene,

which overlie them, and which occupy a smaller area at an inferior

elevation above the sea. M. Hornes has described no less than 500

species of gasteropods, of which he identifies one-fifth with living

species of the Mediterranean, Indian, or African seas, but the

proportion of existing species among the lamellibranchiate bivalves

exceeds this average. Among many univalves agreeing with those of

Africa on the eastern side of the Atlantic are _Cypræa sanguinolenta,

Buccinum lyratum,_ and _Oliva flammulata._ In the lowest marine beds of

the Vienna basin the remains of several mammalia have been found, and

among them a species of _Dinotherium_, a Mastodon of the _Trilophodon_

family, a Rhinoceros (allied to _R. megarhinus_, Christol), also an

animal of the hog tribe, _ Listriodon_, von Meyer, and a carnivorous

animal of the canine family. The _Helix turonensis_ (Fig. 38), the

most common land shell of the French faluns, accompanies the above land

animals. In a higher member of the Vienna Miocene series are found

_Dinotherium giganteum_ (Fig. 136), _Mastodon longirostris, Rhinoceros

Schleiermacheri, Acerotherium incisivum,_ and _ Hippotherium gracile,_

all of them equally characteristic of an Upper Miocene deposit

occurring at Eppelsheim, in Hesse Darmstadt; a locality also remarkable

as having furnished in latitude 49° 50′ N. the bone of a large ape of

the Gibbon kind, the most northerly example yet discovered of a

quadrumanous animal.

Fig. 147: Amphistegina Hauerina.

M. Alcide d’Orbigny has shown that the foraminifera of the Vienna basin

differ alike from the Eocene and Pliocene species, and agree with those

of the faluns, so far as the latter are known. Among the Vienna

foraminifera, the genus _Amphistegina_ (Fig. 147) is very

characteristic, and is supposed by d’Archiac to take the same place

among the Rhizopods of the Upper Miocene era which the Nummulites

occupy in the Eocene period.

The flora of the Vienna basin exhibits some species which have a

general range through the whole Miocene period, such as _Cinnamomum

polymorphum_ (Fig. 138), and _C. Scheuchzeri,_ also Planera Richardi,

Mich., _Liquidambar europæum_ (Fig. 135) _Juglans bilinica, Cassia

ambigua,_ and _C. lignitum._ Among the plants common to the Upper

Miocene beds of Œningen, in Switzerland, are _Platanus aceroides_ (Fig.

141), _Myrica vindobonensis,_ and others.

Upper Miocene Strata of Italy.—We are indebted to Signor Michelotti for

a valuable work on the Miocene shells of Northern Italy. Those found in

the hill called the Superga, near Turin, have long been known to

correspond in age with the faluns of Touraine, and they contain so many

species common to the Upper Miocene strata of Bordeaux as to lead to

the conclusion that there was a free communication between the northern

part of the Mediterranean and the Bay of Biscay in the Upper Miocene

period.

Upper Miocene Formations of Greece.—At Pikermé, near Athens, MM. Wagner

and Roth have described a deposit in which they found the remains of

the genera _Mastodon, Dinotherium, Hipparion,_ two species of _Giraffe,

Antelope,_ and others, some living and some extinct. With them were

also associated fossil bones of the _Semnopithecus,_ showing that here,

as in the south of France, the quadrumana were characteristic of this

period. The whole fauna attests the former extension of a vast expanse

of grassy plains where we have now the broken and mountainous country

of Greece; plains, which were probably united with Asia Minor,

spreading over the area where the deep Ægean Sea and its numerous

islands are now situated. We are indebted to M. Gaudry, who visited

Pikermé, for a treatise on these fossil bones, showing how many data

they contribute to the theory of a transition from the mammalia of the

Upper Miocene through the Pliocene and Post-pliocene forms to those of

living genera and species.

Upper Miocene of India. Siwâlik Hills.—The Siwâlik Hills lie at the

southern foot of the Himalayan chain, rising to the height of 2000 and

3000 feet. Between the Jumna and the Ganges they consist of inclined

strata of sandstone, shingle, clay, and marl. We are indebted to the

indefatigable researches of Dr. Falconer and Sir Proby Cautley,

continued for fifteen years, for the discovery in these marls and

sandstones of a great variety of fossil mammalia and reptiles, together

with many fresh-water shells. Out of fifteen species of shells of the

genera _Paludina, Melania, Ampullaria,_ and _Unio,_ all are extinct or

unknown species with the exception of four, which are still inhabitants

of Indian rivers. Such a proportion of living to extinct mollusca

agrees well with the usual character of an Upper Miocene or Falunian

fauna, as observed in Touraine, or in the basin of Vienna and

elsewhere.

The genera of mammalia point in the same direction. One of them, of the

genus _Chalicotherium_ (or _Anisodon_ of Lartet), is a pachyderm

intermediate between the _Rhinoceros_ and _ Anoplothere,_ and

characteristic of the Upper Miocene strata of Eppelsheim, and of the

south of France. With it occurs also an extinct form of Hippopotamus,

called Hexaprotodon, and a species of Hippotherium and pig, also two

species of _Mastodon_, two of elephant, and three other elephantine

proboscidians; none of them agreeing with any fossil forms of Europe,

and being intermediate between the genera Elephas and Mastodon,

constituting the sub-genus _Stegodon_ of Falconer. With these are

associated a monkey, allied to the _Semnopithecus entellus_, now living

in the Himalaya, and many ruminants. Among these last, besides the

giraffe, camel, antelope, stag, and others, we find a remarkable new

type, the _Sivatherium,_ like a gigantic four-horned deer. There are

also new forms of carnivora, both feline and canine, the _Machairodus_

among the former, also hyænas, and a subursine form called the

Hyænarctos, and a genus allied to the otter (_Enhydriodon_), of

formidable size.

The giraffe, camel, and a large ostrich may be cited as proofs that

there were formerly extensive plains where now a steep chain of hills,

with deep ravines, runs for many hundred miles east and west. Among the

accompanying reptiles are several crocodiles, some of huge dimensions,

and one not distinguishable, says Dr. Falconer, from a species now

living in the Ganges (_C. Gangeticus_); and there is still another

saurian which the same anatomist has identified with a species now

inhabiting India. There was also an extinct species of tortoise of

gigantic proportions (_Colossochelys Atlas_), the curved shell of which

was twelve feet three inches long and eight feet in diameter, the

entire length of the animal being estimated at eighteen feet, and its

probable height seven feet.

Numerous fossils of the Siwâlik type have also been found in Perim

Island, in the Gulf of Cambay, and among these a species of

_Dinotherium,_ a genus so characteristic of the Upper Miocene period in

Europe.

Older Pliocene and Miocene Formations in the United States.—Between the

Alleghany Mountains, formed of older rocks, and the Atlantic, there

intervenes, in the United States, a low region occupied principally by

beds of marl, clay, and sand, consisting of the cretaceous and tertiary

formations, and chiefly of the latter. The general elevation of this

plain bordering the Atlantic does not exceed 100 feet, although it is

sometimes several hundred feet high. Its width in the middle and

southern states is very commonly from 100 to 150 miles. It consists, in

the South, as in Georgia, Alabama, and South Carolina, almost

exclusively of Eocene deposits; but in North Carolina, Maryland,

Virginia, Delaware, more modern strata predominate, of the age of the

English Crag and faluns of Touraine.[1]

Fig. 148: Fulgur canaliculatus. Fig. 149: Fusus quadricostatus.

In the Virginian sands, we find in great abundance a species of Astarte

(_A. undulata,_ Conrad), which resembles closely, and may possibly be a

variety of, one of the commonest fossils of the Suffolk Crag (_A.

Omalii_); the other shells also, of the genera _Natica, Fissurella,

Artemis, Lucina, Chama, Pectunculus,_ and _Pecten,_ are analagous to

shells both of the English Crag and French faluns, although the species

are almost all distinct. Out of 147 of these American fossils I could

only find thirteen species common to Europe, and these occur partly in

the Suffolk Crag, and partly in the faluns of Touraine; but it is an

important characteristic of the American group, that it not only

contains many peculiar extinct forms, such as _Fusus quadricostatus,_

Say (see Fig. 149), and _Venus tridacnoides,_ abundant in these same

formations, but also some shells which, like _Fulgur carica_ of Say and

_F. canaliculatus_ (see Fig. 148), _Calyptræa costata, Venus

mercenaria,_ Lam., _Modiola glandula,_ Totten, and _ Pecten

magellanicus,_ Lam., are recent species, yet of forms now confined to

the western side of the Atlantic—a fact implying that some traces of

the beginning of the present geographical distribution of mollusca date

back to a period as remote as that of the Miocene strata.

Fig. 150: Astrangia lineata.

Of ten species of corals which I procured on the banks of the James

River, one agrees generically with a coral now living on the coast of

the United States. Mr. Lonsdale regarded these corals as indicating a

temperature exceeding that of the Mediterranean, and the shells would

lead to similar conclusions. Those occurring on the James River are in

the 37th degree of N. latitude, while the French faluns are in the

47th; yet the forms of the American fossils would scarcely imply so

warm a climate as must have prevailed in France when the Miocene strata

of Touraine originated.

Among the remains of fish in these post-eocene strata of the United

States are several large teeth of the shark family, not distinguishable

specifically from fossils of the faluns of Touraine.

[1] Proceedings of the Geol. Soc., vol. iv, pt. iii, 1845, p. 547.

CHAPTER XV.

LOWER MIOCENE (OLIGOCENE OF BEYRICH).

Lower Miocene Strata of France. — Line between Miocene and Eocene. —

Lacustrine Strata of Auvergne. — Fossil mammalia of the Limagne

d’Auvergne. — Lower Molasse of Switzerland. — Dense Conglomerates and

Proofs of Subsidence. — Flora of the Lower Molasse. — American

Character of the Flora. — Theory of a Miocene Atlantis. — Lower Miocene

of Belgium. — Rupelian Clay of Hermsdorf near Berlin. — Mayence Basin.

— Lower Miocene of Croatia. — Oligocene Strata of Beyrich. — Lower

Miocene of Italy. — Lower Miocene of England. — Hempstead Beds. — Bovey

Tracey Lignites in Devonshire. — Isle of Mull Leaf-Beds. — Arctic

Miocene Flora. — Disco Island. — Lower Miocene of United States. —

Fossils of Nebraska.

Line between Miocene and Eocene Formations.—The marine faluns of the

valley of the Loire have been already described as resting in some

places on a fresh-water tertiary limestone, fragments of which have

been broken off and rolled on the shores and in the bed of the Miocene

sea. Such pebbles are frequent at Pontlevoy on the Cher, with hollows

drilled in them in which the perforating marine shells of the Falunian

period still remain. Such a mode of superposition implies an interval

of time between the origin of the fresh-water limestone and its

submergence beneath the waters of the Upper Miocene sea. The limestone

in question forms a part of the formation called the Calcaire de la

Beauce, which constitutes a large table-land between the basins of the

Loire and the Seine. It is associated with marls and other deposits,

such as may have been formed in marshes and shallow lakes in the newest

part of a great delta. Beds of flint, continuous or in nodules,

accumulated in these lakes, and aquatic plants called Charae, left

their stems and seed-vessels imbedded both in the marl and flint,

together with fresh-water and land shells. Some of the siliceous rocks

of this formation are used extensively for mill-stones. The flat

summits or platforms of the hills round Paris, and large areas in the

forest of Fontainebleau, as well as the Plateau de la Beauce, already

alluded to, are chiefly composed of these fresh-water strata. Next to

these in the descending order are marine sands and sandstone, commonly

called the Gres de Fontainebleau, from which a considerable number of

shells, very distinct from those of the faluns, have been obtained at

Etampes, south of Paris, and at Montmartre and other hills in Paris

itself, or in its suburbs. At the bottom of these sands a green clay

occurs, containing a small oyster, _Ostrea cyathula,_ Lam., which,

although of slight thickness, is spread over a wide area. This clay

rests immediately on the Paris gypsum, or that series of beds of gypsum

and gypseous marl from which Cuvier first obtained several species of

Palæotherium and other extinct mammalia.[1]

At this junction of the clay and the gypsum the majority of French

geologists have always drawn the line between the Middle and Lower

Tertiary, or between the Miocene and Eocene formations, regarding the

Fontainebleau sands and the _Ostrea cyathula_ clay as the base of the

Miocene, and the gypsum, with its mammalia, as the top of the Eocene

group. I formerly dissented from this division, but I now find that I

must admit it to be the only one which will agree with the distribution

of the Miocene mammalia, while even the mollusca of the Fontainebleau

sands, which were formerly supposed to present at preponderance of

affinities to an Eocene fauna, have since been shown to agree more

closely with the fossils of certain deposits always regarded as Middle

Tertiary at Mayence and in Belgium. In fact, we are now arriving at

that stage of progress when the line, wherever it be drawn between

Miocene and Eocene, will be an arbitrary one, or one of mere

convenience, as I shall have an opportunity of showing when the Upper

Eocene formations in the Isle of Wight are described in the sixteenth

chapter.

Lower Miocene of Central France.—Lacustrine strata, belonging, for the

most part, to the same Miocene system as the Calcaire de la Beauce, are

again met with farther south in Auvergne, Cantal, and Vélay. They

appear to be the monuments of ancient lakes, which, like some of those

now existing in Switzerland, once occupied the depressions in a

mountainous region, and have been each fed by one or more rivers and

torrents. The country where they occur is almost entirely composed of

granite and different varieties of granitic schist, with here and there

a few patches of Secondary strata, much dislocated, and which have

suffered great denudation. There are also some vast piles of volcanic

matter, the greater part of which is newer than the fresh-water strata,

and is sometimes seen to rest upon them, while a small part has

evidently been of contemporaneous origin. Of these igneous rocks I

shall treat more particularly in the sequel.

The study of these regions possesses a peculiar interest very distinct

in kind from that derivable from the investigation either of the

Parisian or English Tertiary areas. For we are presented in Auvergne

with the evidence of a series of events of astonishing magnitude and

grandeur, by which the original form and features of the country have

been greatly changed, yet never so far obliterated but that they may

still, in part at least, be restored in imagination. Great lakes have

disappeared—lofty mountains have been formed, by the reiterated

emission of lava, preceded and followed by showers of sand and

scoriæ—deep valleys have been subsequently furrowed out through masses

of lacustrine and volcanic origin—at a still later date, new cones have

been thrown up in these valleys—new lakes have been formed by the

damming up of rivers—and more than one assemblage of quadrupeds, birds,

and plants, Eocene, Miocene, and Pliocene, have followed in succession;

yet the region has preserved from first to last its geographical

identity; and we can still recall to our thoughts its external

condition and physical structure before these wonderful vicissitudes

began, or while a part only of the whole had been completed. There was

first a period when the spacious lakes, of which we still may trace the

boundaries, lay at the foot of mountains of moderate elevation,

unbroken by the bold peaks and precipices of Mont Dor, and unadorned by

the picturesque outline of the Puy de Dome, or of the volcanic cones

and craters now covering the granitic platform. During this earlier

scene of repose deltas were slowly formed; beds of marl and sand,

several hundred feet thick, deposited; siliceous and calcareous rocks

precipitated from the waters of mineral springs; shells and insects

imbedded, together with the remains of the crocodile and tortoise, the

eggs and bones of water-birds, and the skeletons of quadrupeds, most of

them of genera and species characteristic of the Miocene period. To

this tranquil condition of the surface succeeded the era of volcanic

eruptions, when the lakes were drained, and when the fertility of the

mountainous district was probably enhanced by the igneous matter

ejected from below, and poured down upon the more sterile granite.

During these eruptions, which appear to have taken place towards the

close of the Miocene epoch, and which continued during the Pliocene,

various assemblages of quadrupeds successively inhabited the district,

among which are found the genera mastodon, rhinoceros, elephant, tapir,

hippopotamus, together with the ox, various kinds of deer, the bear,

hyæna, and many beasts of prey which ranged the forest or pastured on

the plain, and were occasionally overtaken by a fall of burning

cinders, or buried in flows of mud, such as accompany volcanic

eruptions. Lastly, these quadrupeds became extinct, and gave place in

their turn to the species now existing. There are no signs, during the

whole time required for this series of events, of the sea having

intervened, nor of any denudation which may not have been accomplished

by currents in the different lakes, or by rivers and floods

accompanying repeated earthquakes, or subterranean movements, during

which the levels of the district have in some places been materially

modified, and perhaps the whole upraised relatively to the surrounding

parts of France.

_Auvergne._—The most northern of the fresh-water groups is situated in

the valley-plain of the Allier, which lies within the department of the

Puy de Dome, being the tract which went formerly by the name of the

Limagne d’Auvergne. The average breadth of this tract is about twenty

miles; and it is for the most part composed of nearly horizontal strata

of sand, sandstone, calcareous marl, clay, and limestone, none of which

observe a fixed and invariable order of superposition. The ancient

borders of the lake wherein the fresh-water strata were accumulated may

generally be traced with precision, the granite and other ancient rocks

rising up boldly from the level country. The actual junction, however,

of the lacustrine beds and the granite is rarely seen, as a small

valley usually intervenes between them. The fresh-water strata may

sometimes be seen to retain their horizontality within a very slight

distance of the border-rocks, while in some places they are inclined,

and in few instances vertical. The principal divisions into which the

lacustrine series may be separated are the following:—first, Sandstone,

grit, and conglomerate, including red marl and red sandstone; secondly,

Green and white foliated marls; thirdly, Limestone, or travertin, often

oolitic in structure; fourthly, Gypseous marls.

The relations of these different groups cannot be learnt by the study

of any one section; and the geologist who sets out with the expectation

of finding a fixed order of succession may perhaps complain that the

different parts of the basin give contradictory results. The arenaceous

division, the marls, and the limestone may all be seen in some places

to alternate with each other; yet it can by no means be affirmed that

there is no order of arrangement. The sands, sandstone, and

conglomerate constitute in general a littoral group; the foliated white

and green marl, a contemporaneous central deposit more than 700 feet

thick, and thinly foliated, a character which often arises from the

innumerable thin shells or carapace valves shed by the small crustacean

called _Cypris_ in the ancient lakes of Auvergne; and lastly the

limestone is for the most part subordinate to the newer portions of

both the above formations.

It seems that, when the ancient lake of the Limagne first began to be

filled with sediment, no volcanic action had yet produced lava and

scoriæ on any part of the surface of Auvergne. No pebbles, therefore,

of lava were transported into the lake—no fragments of volcanic rocks

imbedded in the conglomerate. But at a later period, when a

considerable thickness of sandstone and marl had accumulated, eruptions

broke out, and lava and tuff were deposited, at some spots, alternately

with the lacustrine strata. It is not improbable that cold and thermal

springs, holding different mineral ingredients in solution, became more

numerous during the successive convulsions attending this development

of volcanic agency, and thus deposits of carbonate and sulphate of

lime, silex, and other minerals were produced. Hence these minerals

predominate in the uppermost strata. The subterranean movements may

then have continued until they altered the relative levels of the

country, and caused the waters of the lakes to be drained off, and the

further accumulation of regular fresh-water strata to cease.

Lower Miocene Mammalia of the Limagne.—It is scarcely possible to

determine the age of the oldest part of the fresh-water series of the

Limagne, large masses both of the sandy and marly strata being devoid

of fossils. Some of the lowest beds may be of Upper Eocene date,

although, according to M. Pomel, only one bone of a _Palæotherium_ has

been discovered in Auvergne. But in Vélay, in strata containing some

species of fossil mammalia common to the Limagne, no less than four

species of Palæothere have been found by M. Aymard, and one of these is

generally supposed to be identical with _Palæotherium magnum,_ an

undoubted Upper Eocene fossil, of the Paris gypsum, the other three

being peculiar.

Not a few of the other mammalia of the Limagne belong undoubtedly to

genera and species elsewhere proper to the Lower Miocene. Thus, for

example, the Cainotherium of Bravard, a genus not far removed from the

Anoplotherium, is represented by several species, one of which, as I

learn from Mr. Waterhouse, agrees with _Microtherium Renggeri_ of the

Mayence basin. In like manner, the _Amphitragulus elegans_ of Pomel, an

Auvergne fossil, is identified by Waterhouse with _Dorcatherium nanum_

of Kaup, a Rhenish species from Weissenau, near Mayence. A small

species, also, of rodent, of the genus Titanomys of H. von Meyer, is

common to the Lower Miocene of Mayence and the Limagne d’Auvergne, and

there are many other points of agreement which the discordance of

nomenclature tends to conceal. A remarkable carnivorous genus, the

Hyænodon of Laizer, is represented by more than one species. The same

genus has also been found in the Upper Eocene marls of Hordwell Cliff,

Hampshire, just below the level of the Bembridge Limestone, and

therefore a formation older than the Gypsum of Paris. Several species

of opossum (_Didelphis_) are met with in the same strata of the

Limagne. The total number of mammalia enumerated by M. Pomel as

appertaining to the Lower Miocene fauna of the Limagne and Velay falls

little short of a hundred, and with them are associated some large

crocodiles and tortoises, and some Ophidian and Batrachian reptiles.

Lower Molasse of Switzerland.—The two upper divisions of the Swiss

Molasse—the one fresh-water, the other marine—have already been

described in the preceding chapter. I shall now proceed to treat of the

third division, which is of Lower Miocene age. Nearly the whole of this

Lower Molasse is fresh-water, yet some of the inferior beds contain a

mixture of marine and fluviatile shells, the _Cerithium margaritaceum,_

a well-known Lower Miocene fossil, being one of the marine species.

Notwithstanding, therefore, that some of these Lower Miocene strata

consist of old shingle-beds several thousand feet in thickness, as in

the Rigi, near Lucerne, and in the Speer, near Wesen, mountains 5000

and 7000 feet above the sea, the deposition of the whole series must

have begun at or below the sea-level.

The conglomerates, as might be expected, are often very unequal in

thickness, in closely adjoining districts, since in a littoral

formation accumulations of pebbles would swell out in certain places

where rivers entered the sea, and would thin out to comparatively small

dimensions where no streams or only small ones came down to the coast.

For ages, in spite of a gradual depression of the land and adjacent

sea-bottom, the rivers continued to cover the sinking area with their

deltas; until finally, the subsidence being in excess, the sea of the

Middle Molasse gained upon the land, and marine beds were thrown down

over the dense mass of fresh-water and brackish-water deposit, called

the Lower Molasse, which had previously accumulated.

Flora of the Lower Molasse.—In part of the Swiss Molasse, which belongs

exclusively to the Lower Miocene period, the number of plants has been

estimated at more than 500 species, somewhat exceeding those which were

before enumerated as occurring in the two upper divisions. The Swiss

Lower Miocene may best be studied on the northern borders of the Lake

of Geneva, between Lausanne and Vevay, where the contiguous villages of

Monod and Rivaz are situated. The strata there, which I have myself

examined, consist of alternations of conglomerate, sandstone, and

finely laminated marls with fossil plants. A small stream falls in a

succession of cascades over the harder beds of pudding-stone, which

resist, while the sandstone and plant-bearing shales and marls give

way. From the latter no less than 193 species of plants have been

obtained by the exertions of MM. Heer and Gaudin, and they are

considered to afford a true type of the vegetation of the Lower Miocene

formations of Switzerland—a vegetation departing farther in its

character from that now flourishing in Europe than any of the higher

members of the series before alluded to, and yet displaying so much

affinity to the flora of Œningen as to make it natural for the botanist

to refer the whole to one and the same Miocene period. There are,

indeed, no less than 81 species of these Older Miocene plants which

pass up into the flora of Œningen.

This fact is important as bearing on the propriety of classing the

Lower Molasse of Switzerland as belonging to the Miocene rather than to

the latter part of the Eocene period. There are, indeed, so many types

among the fossils, both specific and generic, which have a wide range

through the whole of the Molasse, that a unity of character is thereby

stamped on the whole flora, in spite of the contrast between the plants

of the uppermost and lowest formations, or between Oeningen and Monod.

The proofs of a warmer climate, and the excess of arborescent over

herbaceous plants, and of evergreen trees over deciduous species, are

characters common to the whole flora, but which are intensified as we

descend to the inferior deposits.

Nearly all the plants at Monod are contained in three layers of marl

separated by two of soft sandstone. The thickness of the marls is ten

feet, and vegetable matter predominates so much in some layers as to

form an imperfect lignite. One bed is filled with large leaves of a

species of fig (_Ficus populina_), and of a hornbeam (_Carpinus

grandis_), the strength of the wind having probably been great when

they were blown into the lake; whereas another contiguous layer

contains almost exclusively smaller leaves, indicating, apparently, a

diminished strength in the wind. Some of the upper beds at Monod abound

in leaves of Proteaceæ, Cyperaceæ, and ferns, while in some of the

lower ones _Sequoia, Cinnamomum,_ and _Sparganium_ are common. In one

bed of sandstone the trunk of a large palm-tree was found unaccompanied

by other fossils, and near Vevay, in the same series of Lower Miocene

strata, the leaves of a palm of the genus _Sabal_ (Fig. 151), a genus

now proper to America, were obtained.

Fig. 151: Sabal major

Among other genera of the same class is a _Flabellaria_ occurring near

Lausanne, and a magnificent _Phœnicites_ allied to the date palm. When

these plants flourished the climate must have been much hotter than

now. The Alps were no doubt much lower, and the palms now found fossil

in strata elevated 2000 feet above the sea grew nearly at the

sea-level, as is demonstrated by the brackish-water character of some

of the beds into which they were carried by winds or rivers from the

adjoining coast.

In the same plant-bearing deposits of the Lower Molasse in Switzerland

leaves have been found which have been ascribed to the order Proteaceæ

already spoken of as well represented in the Œningen beds (see p. 221).

The Proteas and other plants of this family now flourish at the Cape of

Good Hope; while the Banksias, and a set of genera distinct from those

of Africa, grow most luxuriantly in the southern and temperate parts of

Australia. They were probably inhabitants, says Heer, of dry hilly

ground, and the stiff leathery character of their leaves must have been

favourable to their preservation, allowing them to float on a river for

great distances without being injured, and then to sink, when

water-logged, to the bottom. It has been objected that the fruit of the

Proteaceæ is of so tough and enduring a texture that it ought to have

been more commonly met with; but in the first place we must not forget

the numerous cones found in the Eocene strata of Sheppey, which all

admit to be proteaceous and to belong to at least two species (see p.

222). Secondly, besides the fruit of Hakea before mentioned (p. 221),

Heer found associated with fossil leaves, having the exact form and

nervation of Banksia, fruit precisely such as may have come from a cone

of that plant, and lately he has received another similar fruit from

the Lower Miocene strata of Lucerne. They may have fallen out of a

decayed cone in the same way as often happens to the seeds of the

spruce fir, _Pinus abies,_ found scattered over the ground in our

woods. It is a known fact that among the living Proteaceæ the cones are

very firmly attached to the branches, so that the seeds drop out

without the cone itself falling to the ground, and this may perhaps be

the reason why, in some instances in which fossil seeds have been

found, no traces of the cone have been observed.

Fig. 152: Fruit of fossil Banksia and leaf of Banksia. Fig. 153:

Sequoia Langsdorfii.

Among the Coniferæ the Sequoia here figured is common at Rivaz, and is

one of the most universal plants in the Lowest Miocene of Switzerland,

while it also characterises the Miocene Brown Coals of Germany and

certain beds of the Val d’Arno, which I have called Older Pliocene, p.

208.

Fig. 154: Lastræa stiriaca.

Among the ferns met with in profusion at Monod is the _ Lastræa

stiriaca,_ Unger, which has a wide range in the Miocene period from

strata of the age of Œningen to the lowest part of the Swiss Molasse.

In some specimens, as shown in Fig. 154, the fructification is

distinctly seen.

Among the laurels several species of _Cinnamomum_ are very conspicuous.

Besides the _C. polymorphum,_ before figured, p. 219, another species

also ranges from the Lower to the Upper Molasse of Switzerland, and is

very characteristic of different deposits of Brown Coal in Germany. It

has been called _Cinnamomum Rossmässleri_ by Heer (see Fig. 155). The

leaves are easily recognised as having two side veins, which run up

uninterruptedly to their point.

Fig. 155: Cinnamomum Rossmässleri.

American Character of the Flora.—If we consider not merely the number

of species but those plants which constitute the mass of the Lower

Miocene vegetation, we find the European part of the fossil flora very

much less prominent than in the Œningen beds, while the foreground is

occupied by American forms, by evergreen oaks, maples, poplars, planes,

Liquidambar, Robinia, Sequoia, Taxodium, and ternate-leaved pines.

There is also a much greater fusion of the characters now belonging to

distinct botanical provinces than in the Upper Miocene flora, and we

shall find this fusion still more strikingly exemplified as we go back

to the antecedent Eocene and Cretaceous periods.

Professor Heer has advocated the doctrine, first advanced by Unger to

explain the large number of American genera in the Miocene flora of

Europe, that the present basin of the Atlantic was occupied by land

over which the Miocene flora could pass freely. But other able

botanists have shown that it is far more probable that the American

plants came from the east and not from the west, and instead of

reaching Europe by the shortest route over an imaginary Atlantis,

migrated in an opposite direction, crossing the whole of Asia.

Arctic Miocene Flora.—But when we indulge in speculations as to the

geographical origin of the Miocene plants of Central Europe, we must

take into account the discoveries recently made of a rich terrestrial

flora having flourished in the Arctic Regions in the Miocene period

from which many species may have migrated from a common centre so as to

reach the present continents of Europe, Asia, and America. Professor

Heer has examined the various collections of fossil plants that have

been obtained in North Greenland (lat. 70°), Iceland, Spitzbergen, and

other parts of the Arctic regions, and has determined that they are of

Miocene age and indicate a temperate climate.[2] Including the

collections recently brought from Greenland by Mr. Whymper, the Arctic

Miocene flora now comprises 194 species, and that of Greenland 137

species, of which 46, or exactly one-third, are identical with plants

found in the Miocene beds of Central Europe. Considerably more than

half the number are trees, which is the more remarkable since, at the

present day, trees do not exist in any part of Greenland even 10

degrees farther south.

More than thirty species of Coniferæ have been found, including several

Sequoias (allied to the gigantic Wellingtonia of California), with

species of Thujopsis and Salisburia now peculiar to Japan. There are

also beeches, oaks, planes, poplars, maples, walnuts, limes, and even a

magnolia, two cones of which have recently been obtained, proving that

this splendid evergreen not only lived but ripened its fruit within the

Arctic circle. Many of the limes, planes, and oaks were large-leaved

species, and both flowers and fruit, besides immense quantities of

leaves, are in many cases preserved. Among the shrubs were many

evergreens, as _ Andromeda,_ and two extinct genera, _Daphnogene_ and _

M’Clintockia,_ with fine leathery leaves, together with hazel,

blackthorn, holly, logwood, and hawthorn. A species of Zamia

(_Zamites_) grew in the swamps, with _Potamogeton, Sparganium,_ and

_Menyanthes,_ while ivy and vines twined around the forest trees and

broad-leaved ferns grew beneath their shade. Even in Spitzbergen, as

far north as latitude 78° 56′, no less than ninety-five species of

fossil plants have been obtained, including _Taxodium_ of two species,

hazel, poplar, alder, beech, plane-tree, and lime. Such a vigorous

growth of trees within 12 degrees of the pole, where now a dwarf willow

and a few herbaceous plants form the only vegetation, and where the

ground is covered with almost perpetual snow and ice, is truly

remarkable.

The identity of so many of the fossils with Miocene species of Central

Europe and Italy not only proves that the climate of Greenland was much

warmer than it is now, but also renders it probable that a much more

uniform climate prevailed over the entire northern hemisphere. This is

also indicated by the whole character of the Upper Miocene flora of

Central Europe, which does not necessitate a mean temperature very much

greater than exists at present, if we suppose such absence of winter

cold as is proper to insular climates. Professor Heer believes that the

mean temperature of North Greenland must have been at least 30 degrees

higher than at present, while an addition of 10 degrees to the mean

temperature of Central Europe would probably be as much as was

required. The chief locality where this wonderful flora is preserved is

at Atanekerdluk in North Greenland (lat. 70°), on a hill at an

elevation of about 1200 feet above the sea. There is here a

considerable succession of sedimentary strata pierced by volcanic

rocks. Fossil plants occur in all the beds, and the erect trunks as

thick as a man’s body which are sometimes found, together with the

abundance of specimens of flowers and fruit in good preservation,

sufficiently prove that the plants grew where they are now found. At

Disco island and other localities on the same part of the coast, good

coal is abundant, interstratified with beds of sandstone, in some of

which fossil plants have also been found, similar to those at

Atanekerdluk.

Fig. 156: Leda (Nucula) Deshayesiana. Lower Miocene, Belgium.—The Upper

Miocene Bolderberg beds, mentioned in p. 224, rest on a Lower Miocene

formation called the Rupelian of Dumont. This formation is best seen at

the villages of Rupelmonde and Boom, ten miles south of Antwerp, on the

banks of the Scheldt and near the junction with it of a small stream

called the Rupel. A stiff clay abounding in fossils is extensively

worked at the above localities for making tiles. It attains a thickness

of about 100 feet, and though very different in age, much resembles in

mineral character the “London clay,” containing, like it, septaria or

concretions of argillaceous limestone traversed by cracks in the

interior, which are filled with calc-spar. The shells, referable to

about forty species, have been described by MM. Nyst and De Koninck.

Among them _Leda_ (or Nucula) _Deshayesiana_ (see Fig. 156) is by far

the most abundant; a fossil unknown as yet in the English tertiary

strata, but when young much resembling Leda amygdaloides of the London

Clay proper (see Fig. 213). Among other characteristic shells are

_Pecten Hœninghausii,_ and a species of _ Cassidaria,_ and several of

the genus _Pleurotoma._ Not a few of these testacea agree with English

Eocene species, such as _Actæon simulatus,_ Sowb, _Cancellaria evulsa,_

Brander, _Corbula pisum_ (Fig. 157), and _Nautilus (Aturia) ziczac._

They are accompanied by many teeth of sharks, as _Lamna contortidens,_

Ag., _ Oxyrhinaxiphodon,_ Ag., _Carcharodon angustidens_ (see Fig.

196), Ag., and other fish, some of them common to the Middle Eocene

strata.