_Kleyn Spawen beds._—The succession of the Lower Miocene strata of

Belgium can be best studied in the environs of Kleyn Spawen, a village

situated about seven miles west of Maestricht, in the old province of

Limburg in Belgium. In that region, about 200 species of testacea,

marine and fresh-water, have been obtained, with many foraminifera and

remains of fish. In none of the Belgian Lower Miocene strata could I

find any nummulites; and M. d’Archiac had previously observed that

these foraminifera characterise his “Lower Tertiary Series,” as

contrasted with the Middle, and they therefore serve as a good test of

age between Eocene and Miocene, at least in Belgium and the North of

France.[3] Between the Bolderberg beds and the Rupelian clay there is a

great gap in Belgium, which seems, according to M. Beyrich, to be

filled up in the North of Germany by what he calls the Sternberg beds,

and which, had Dumont found them in Belgium, he might probably have

termed Upper Rupelian.

Lower Miocene of Germany.—_Rupelian Clay of Hermsdorf, near

Berlin._—Professor Beyrich has described a mass of clay, used for

making tiles, within seven miles of the gates of Berlin, near the

village of Hermsdorf, rising up from beneath the sands with which that

country is chiefly overspread. This clay is more than forty feet thick,

of a dark bluish-grey colour, and, like that of Rupelmonde, contains

septaria. Among other shells, the _Leda Deshayesiana,_ before mentioned

(Fig. 156), abounds, together with many species of _ Pleurotoma,

Voluta,_ etc., a certain proportion of the fossils being identical in

species with those of Rupelmonde.

_Mayence Basin._—An elaborate description has been published by Dr. F.

Sandberger of the Mayence tertiary area, which occupies a tract from

five to twelve miles in breadth, extending for a great distance along

the left bank of the Rhine from Mayence to the neighbourhood of

Manheim, and which is also found to the east, north, and south-west of

Frankfort. M. De Koninck, of Liege, first pointed out to me that the

purely marine portion of the deposit contained many species of shells

common to the Kleyn Spawen beds, and to the clay of Rupelmonde, near

Antwerp. Among these he mentioned _Cassidaria depressa, Tritonium

argutum,_ Brander (_T. flandricum,_ De Koninck), _ Tornatella simulata,

Aporrhais Sowbyi, Leda Deshayesiana_ (Fig. 156), _Corbula pisum,_ (Fig.

158) and others.

Lower Miocene Beds of Croatia.—The Brown Coal of Radaboj, near Angram

in Croatia, not far from the borders of Styria, is covered, says Von

Buch, by beds containing the marine shells of the Vienna basin, or, in

other words, by Upper Miocene or Falunian strata. They appear to

correspond in age to the Mayence basin, or to the Rupelian strata of

Belgium. They have yielded more than 200 species of fossil plants,

described by the late Professor Unger. These plants are well preserved

in a hard marlstone, and contain several palms; among them the Sabal,

Fig. 151, p. 237, and another genus allied to the date-palm _

Phœnicites spectabilis._ The only abundant plant among the Radaboj

fossils which is characteristic of the Upper Miocene period is the

_Populus mutabilis,_ whereas no less than fifty of the Radaboj species

are common to the more ancient flora of the Lower Molasse of

Switzerland.

Fig. 157: Vanessa Pluto.

The insect fauna is very rich, and, like the plants, indicates a more

tropical climate than do the fossils of Œningen presently to be

mentioned. There are ten species of Termites, or white ants, some of

gigantic size, and large dragon-flies with speckled wings, like those

of the Southern States in North America; there are also grasshoppers of

considerable size, and even the Lepidoptera are not unrepresented. In

one instance, the pattern of a butterfly’s wing has escaped

obliteration in the marl-stone of Radaboj; and when we reflect on the

remoteness of the time from which it has been faithfully transmitted to

us, this fact may inspire the reader with some confidence as to the

reliable nature of the characters which other insects of a more durable

texture, such as the beetles, may afford for specific determination.

The Vanessa above figured retains, says Heer, some of its colours, and

corresponds with _V. Hadena_ of India.

Professor Beyrich has made known to us the existence of a long

succession of marine strata in North Germany, which lead by an almost

gradual transition from beds of Upper Miocene age to others of the age

of the base of the Lower Miocene. Although some of the German lignites

called Brown Coal belong to the upper parts of this series, the most

important of them are of Lower Miocene date, as, for example, those of

the Siebengebirge, near Bonn, which are associated with volcanic rocks.

Professor Beyrich confines the term “Miocene” to those strata which

agree in age with the faluns of Touraine, and he has proposed the term

“Oligocene” for those older formations called Lower Miocene in this

work.

Lower Miocene of Italy.—In the hills of which the Superga forms a part

there is a great series of Tertiary strata which pass downward into the

Lower Miocene. Even in the Superga itself there are some fossil plants

which, according to Heer, have never been found in Switzerland so high

as the marine Molasse, such as _Banksia longifolia,_ and _Carpinus

grandis._ In several parts of the Ligurian Apennines, as at Dégo and

Carcare, the Lower Miocene appears, containing some nummulites, and at

Cadibona, north of Savona, fresh-water strata of the same age occur,

with dense beds of lignite inclosing remains of the _ Anthracotherium

magnum_ and _A. minimum,_ besides other mammalia enumerated by

Gastaldi. In these beds a great number of the Lower Miocene plants of

Switzerland have been discovered.

Lower Miocene of England—Hempstead Beds.—We have already stated that

the Upper Miocene formation is nowhere represented in the British

Isles; but strata referable to the Lower Miocene period are found both

in England, Scotland, and Ireland. In the Hampshire basin these occupy

a very small superficial area, having been discovered by the late

Edward Forbes at Hempstead near Yarmouth, in the northern part of the

Isle of Wight, where they are 170 feet thick, and rich in

characteristic marine shells. They overlie the uppermost of an

extensive series of Eocene deposits of marine, brackish, and

fresh-water formations, which rest on the Chalk and terminate upward in

strata corresponding in age to the Paris gypsum, and containing the

same extinct genera of quadrupeds, _Palæotherium, Anoplotherium,_ and

others which Cuvier first described. The following is the succession of

these Lower Miocene strata, most of them exposed in a cliff east of

Yarmouth:

1. The uppermost or Corbula beds, consisting of marine sands and clays,

contain _Voluta Rathieri,_ a characteristic Lower Miocene shell;

_Corbula pisum_ (Fig. 158), a species common to the Upper Eocene clay

of Barton; Cyrena semistriata (Fig. 159), several Cerithia, and other

shells peculiar to this series.

Fig. 158: Corbula pisum. Fig. 159: Cyrena semistriata. Fig. 160:

Cerithium plicatum. Fig. 161: Cerithium elegans. Fig. 162: Rissoa

Chastelii. Fig. 163: Paludina lenta.

2. Next are fresh-water and estuary marls and carbonaceous clays in the

brackish-water portion of which are found abundantly _ Cerithium

plicatum,_ Lam. (Fig. 160), _Cerithium elegans_ (Fig. 161), and

_Cerithium tricinctum_; also _Rissoa Chastelii_ (Fig. 162), a very

common Kleyn Spawen shell, and which occurs in each of the four

subdivisions of the Hempstead series down to its base, where it passes

into the Bembridge beds. In the fresh-water portion of the same beds

_Paludina lenta_ (Fig. 163) occurs; a shell identified by some

conchologists with a species now living, _P. unicolor_; also several

species of _ Lymneus, Planorbis,_ and _Unio._

3. The next series, or middle fresh-water and estuary marls, are

distinguished by the presence of _Melania fasciata, Paludina lenta,_

and clays with _Cypris_; the lowest bed contains _Cyrena semistriata_

(Fig. 159), mingled with Cerithia and a _panopæa._

4. The lower fresh-water and estuary marls contain _Melania costata,_

Sowerby, _Melanopsis,_ etc. The bottom bed is carbonaceous, and called

the “Black band,” in which _ Rissoa Chastelii_ (Fig. 162), before

alluded to, is common. This bed contains a mixture of Hempstead shells

with those of the underlying Upper Eocene or Bembridge series. The

mammalia, among which is _Hyopotamus bovinus,_ differ, so far as they

are known, from those of the Bembridge beds. Among the plants,

Professor Heer has recognised four species common to the lignite of

Bovey Tracey, a Lower Miocene formation presently to be described:

namely, _Sequoia Couttsiæ,_ Heer; _Andromeda reticulata,_ Ettings.;

_Nelumbium (Nymphœa) doris,_ Heer; and _Carpolithes Websteri,_

Brong.[4] The seed-vessels of _Chara medicaginula,_ Brong, and _C.

helicteres_ are characteristic of the Hempstead beds generally.

The _Hyopotamus_ belongs to the hog tribe, or the same family as the

Anthracotherium, of which seven species, varying in size from the

hippopotamus to the wild boar, have been found in Italy and other part

of Europe associated with the lignites of the Lower Miocene period.

Lignites and Clays of Bovey Tracey, Devonshire.—Surrounded by the

granite and other rocks of the Dartmoor hills in Devonshire, is a

formation of clay, sand, and lignite, long known to geologists as the

Bovey Coal formation, respecting the age of which, until the year 1861,

opinions were very unsettled. This deposit is situated at Bovey Tracey,

a village distant eleven miles from Exeter in a south-west, and about

as far from Torquay in a north-west direction. The strata extend over a

plain nine miles long, and they consist of the materials of decomposed

and worn-down granite and vegetable matter, and have evidently filled

up an ancient hollow or lake-like expansion of the valleys of the Bovey

and Teign.

The lignite is of bad quality for economical purposes, as there is a

great admixture in it of iron pyrites, and it emits a sulphurous odour,

but it has been successfully applied to the baking of pottery, for

which some of the fine clays are well adapted. Mr. Pengelly has

confirmed Sir H. De la Beche’s opinion that much of the upper portion

of this old lacustrine formation has been removed by denudation.[5]

At the surface is a dense covering of clay and gravel with angular

stones probably of the Post-pliocene period, for in the clay are three

species of willow and the dwarf birch, _Betula nana,_ indicating a

climate colder than that of Devonshire at the present day.

Below this are Lower Miocene strata about 300 feet in thickness, in the

upper part of which are twenty-six beds of lignite, clay, and sand, and

at their base a ferruginous quartzose sand, varying in thickness from

two to twenty-seven feet. Below this sand are forty-five beds of

alternating lignite and clay. No shells or bones of mammalia, and no

insect, with the exception of one fragment of a beetle (_Buprestis_);

in a word, no organic remains, except plants, have as yet been found.

These plants occur in fourteen of the beds—namely, in two of the clays,

and the rest in the lignites. One of the beds is a perfect mat of the

debris of a coniferous tree, called by Heer _Sequoia Couttsiæ,_

intermixed with leaves of ferns. The same Sequoia (before mentioned as

a Hempstead fossil, p. 246) is spread through all parts of the

formation, its cones, and seeds, and branches of every age being

preserved. It is a species supplying a link between _Sequoia

Langsdorfii_ (see Fig. 153, p. 238) and _S. Sternbergi,_ the widely

spread fossil representatives of the two living trees _S. sempervirens_

and _S. gigantea_ (or Wellingtonia), both now confined to California.

Another bed is full of the large rhizomes of ferns, while two others

are rich in dicotyledonous leaves. In all, Professor Heer enumerates

forty-nine species of plants, twenty of which are common to the Miocene

beds of the Continent, a majority of them being characteristic of the

Lower Miocene. The new species, also of Bovey, are allied to plants of

the older Miocene deposits of Switzerland, Germany, and other

Continental countries. The grape-stones of two species of vine occur in

the clays, and leaves of the fig and seeds of a water-lily. The oak and

laurel have supplied many leaves. Of the triple-nerved laurels several

are referred to Cinnamomum. There are leaves also of a palm of which

the genus is not determined. Leaves also of proteaceous forms, like

some of the Continental fossils before mentioned, occur, and ferns like

the well-known _ Lastræa stiriaca_ (Fig. 154, p. 238), displaying at

Bovey, as in Switzerland, its fructification.

The croziers of some of the young ferns are very perfect, and were at

first mistaken by collectors for shells of the genus _ Planorbis._ On

the whole, the vegetation of Bovey implies the existence of a

sub-tropical climate in Devonshire, in the Lower Miocene period.

Scotland: Isle of Mull.—In the sea-cliffs forming the headland of

Ardtun, on the west coast of Mull, in the Hebrides, several bands of

tertiary strata containing leaves of dicotyledonous plants were

discovered in 1851 by the Duke of Argyll.[6] From his description it

appears that there are three leaf-beds, varying in thickness from 1½ to

5½ feet, which are interstratified with volcanic tuff and trap, the

whole mass being about 130 feet in thickness. A sheet of basalt 40 feet

thick covers the whole; and another columnar bed of the same rock, ten

feet thick, is exposed at the bottom of the cliff. One of the leaf-beds

consists of a compressed mass of leaves unaccompanied by any stems, as

if they had been blown into a marsh where a species of _Equisetum_

grew, of which the remains are plentifully imbedded in clay.

It is supposed by the Duke of Argyll that this formation was

accumulated in a shallow lake or marsh in the neighbourhood of a

volcano, which emitted showers of ashes and streams of lava. The

tufaceous envelope of the fossils may have fallen into the lake from

the air as volcanic dust, or have been washed down into it as mud from

the adjoining land. Even without the aid of organic remains we might

have decided that the deposit was newer than the chalk, for

chalk-flints containing cretaceous fossils were detected by the duke in

the principal mass of volcanic ashes or tuff.[7]

The late Edward Forbes observed that some of the plants of this

formation resembled those of Croatia, described by Unger, and his

opinion has been confirmed by Professor Heer, who found that the

conifer most prevalent was the _Sequoia Langsdorfii_ (Fig. 153, p.

238), also _Corylus grossedentata,_ a Lower Miocene species of

Switzerland and of Menat in Auvergne. There is likewise a plane-tree,

the leaves of which seem to agree with those of _Platanus aceroides_

(Fig. 141), and a fern which is as yet peculiar to Mull, _Filicites

hebridica,_ Forbes.

These interesting discoveries in Mull led geologists to suspect that

the basalt of Antrim, in Ireland, and of the celebrated Giant’s

Causeway, might be of the same age. The volcanic rocks that overlie the

chalk, and some of the strata associated with and interstratified

between masses of basalt, contain leaves of dicotyledonous plants,

somewhat imperfect, but resembling the beech, oak, and plane, and also

some coniferæ of the genera pine and Sequoia. The general dearth of

strata in the British Isles, intermediate in age between the formation

of the Eocene and Pliocene periods, may arise, says Professor Forbes,

from the extent of dry land which prevailed in that vast interval of

time. If land predominated, the only monuments we are likely ever to

find of Miocene date are those of lacustrine and volcanic origin, such

as the Bovey Coal in Devonshire, the Ardtun beds in Mull, or the

lignites and associated basalts in Antrim.

Lower Miocene, United states: Nebraska.—In the territory of Nebraska,

on the Upper Missouri, near the Platte River, lat. 42° N., a tertiary

formation occurs, consisting of white limestone, marls, and siliceous

clay, described by Dr. D. Dale Owen,[8] in which many bones of extinct

quadrupeds, and of chelonians of land or fresh-water forms, are met

with. Among these, Dr. Leidy describes a gigantic quadruped, called by

him _Titanotherium,_ nearly allied to the _Palæotherium,_ but larger

than any of the species found in the Paris gypsum. With these are

several species of the genus _Oreodon,_ Leidy, uniting the characters

of pachyderms and ruminants also; _Eucrotaphus,_ another new genus of

the same mixed character; two species of rhinoceros of the sub-genus

_Acerotherium,_ a Lower Miocene form of Europe before mentioned; two

species of _Archæotherium,_ a pachyderm allied to _Chæropotamus_ and _

Hyracotherium_; also _Pæbrotherium,_ an extinct ruminant allied to

_Dorcatherium,_ Kaup; also _ Agriochoerus,_ of Leidy, a ruminant allied

to _ Merycopotamus_ of Falconer and Cautley; and, lastly, a large

carnivorous animal of the genus _Machairodus,_ the most ancient example

of which in Europe occurs in the Lower Miocene strata of Auvergne, but

of which some species are found in Pliocene deposits. The turtles are

referred to the genus _Testudo,_ but have some affinity to _Emys._ On

the whole, the Nebraska formation is probably newer than the Paris

gypsum, and referable to the Lower Miocene period, as above defined.

[1] Bulletin, 1856, Journ., vol. xii, p. 768.

[2] Heer “Miocene baltische Flora” and “Fossil-flora von Alaska” 1869.

[3] D’Archiac Monogr., pp. 79, 100.

[4] Pengelly, preface to The Lignite Formation of Bovey Tracey, p.

xvii, London, 1863.

[5] Philos. Trans., 1863. Paper by W. Pengelly, F.R.S., and Dr. Oswald

Heer.

[6] Quart. Geol. Journal, 1851, p. 19.

[7] Quart. Geol. Journal, 1851, p. 90.

[8] David Dale Owen, Geol. Survey of Wisconsin, etc., Philad., 1852.

CHAPTER XVI.

EOCENE FORMATIONS.

Eocene Areas of North of Europe. — Table of English and French Eocene

Strata. — Upper Eocene of England. — Bembridge Beds. — Osborne or St.

Helen’s Beds. — Headon Series. — Fossils of the Barton Sands and Clays.

— Middle Eocene of England. — Shells, Nummulites, Fish and Reptiles of

the Bracklesham Beds and Bagshot Sands. — Plants of Alum Bay and

Bournemouth. — Lower Eocene of England. — London Clay Fossils. —

Woolwich and Reading Beds formerly called “Plastic Clay.” Fluviatile

Beds underlying Deep-sea Strata. — Thanet Sands. — Upper Eocene Strata

of France. — Gypseous Series of Montmartre and Extinct Quadrupeds. —

Fossil Footprints in Paris Gypsum. — Imperfection of the Record. —

Calcaire Silicieux. — Gres de Beauchamp. — Calcaire Grossier. —

Miliolite Limestone. — Soissonnais Sands. — Lower Eocene of France. —

Nummulitic Formations of Europe, Africa, and Asia. — Eocene Strata in

the United States. — Gigantic Cetacean.

Eocene Areas of the North of Europe.—The strata next in order in the

descending series are those which I term Eocene.

Fig. 164: Map of the principal Eocene areas of North-western Europe.

In the map (Fig. 164) the position of several Eocene areas in the north

of Europe is pointed out. When this map was constructed I classed as

the newer part of the Eocene those Tertiary strata which have been

described in the last chapter as Lower Miocene, and to which M. Beyrich

has given the name of Oligocene. None of these occur in the London

Basin, and they occupy in that of Hampshire, as we have seen at p. 244,

too insignificant a superficial area to be noticed in a map on this

scale. They fill a larger space in the Paris Basin between the Seine

and the Loire, and constitute also part of the northern limits of the

area of the Netherlands which are shaded in the map.

It is in the northern part of the Isle of Wight that we have the

uppermost beds of the true Eocene best exhibited—namely, those which

correspond in their fossils with the celebrated gypsum of the Paris

basin before alluded to, p. 231 (see Table, p. 252). That gypsum has

been selected by almost all Continental geologists as affording the

best line of demarkation between the Middle and Lower Tertiary, or, in

other words, between the Lower Miocene and Eocene formations.

In reference to the Table I may observe, that the correlation of the

French and English subdivisions here laid down is often a matter of

great doubt and difficulty, notwithstanding their geographical

proximity. This arises from various circumstances, partly from the

former prevalence of marine conditions in one basin simultaneously with

fluviatile or lacustrine in the other, and sometimes from the existence

of land in one area causing a break or absence of all records during a

period when deposits may have been in progress in the other basin. As

bearing on this subject, it may be stated that we have unquestionable

evidence of oscillations of level shown by the superposition of salt or

brackish-water strata to fluviatile beds; and those of deep-sea origin

to strata formed in shallow water. Even if the upward and downward

movements were uniform in amount and direction, which is very

improbable, their effect in producing the conversion of sea into land

or land into sea would be different, according to the previous shape

and varying elevation of the land and bottom of the sea. Lastly,

denudation, marine and subaërial, has frequently caused the absence of

deposits in one basin of corresponding age to those in the other, and

this destructive agency has been more than ordinarily effective on

account of the loose and unconsolidated nature of the sands and clays.

TABLE OF ENGLISH AND FRENCH EOCENE STRATA.

UPPER EOCENE

English subdivisions French equivalents A.1. Bembridge series, Isle

of Wight, p. 252. A.1. Gypseous series of Montmartre, p. 270. A.2.

Osborne or St. Helen’s series, Isle of Wight, p. 255. A.2 and 3.

Calcaire siliceux, or Travertin Inférieur, p. 273. A.3. Headon series,

Isle of Wight, p. 255. A.4. Barton series. Sands and clays of Barton

Cliff, Hants, p. 258. A.4. Grès de Beauchamp, or Sables Moyens, p.

273. MIDDLE EOCENE B.1. Bracklesham series, p. 259. B.1. Calcaire

Grossier p. 274 B.2. Alum Bay and Bournemouth beds, p. 259. B.2.

Wanting in France? B.2. Wanting in England? B.2. Soissonnais Sands,

or Lits Coquilliers, p. 275 LOWER EOCENE C.1. London Clay, p.

263. C.1. Argile de Londres, Cassel, near Dunkirk. C.2. Woolwich and

Reading series, p. 267. C.2. Argile plastique and lignite, p. 276

C.3. Thanet sands, p. 269. C.3. Sables de Bracheux, p. 276

UPPER EOCENE, ENGLAND.

Bembridge Series, A.1.—These beds are about 120 feet thick, and, as

stated in p. 245, lie immediately under the Hempstead beds, near

Yarmouth, in the Isle of Wight, being conformable with those Lower

Miocene strata. They consist of marls, clays, and limestones of

fresh-water, brackish, and marine origin. Some of the most abundant

shells, as _Cyrena semistriata_ var., and _Paludina lenta,_ Fig. 163,

are common to this and to the overlying Hempstead series; but the

majority of the species are distinct. The following are the

subdivisions described by the late Professor Forbes:

_a._ Upper marls, distinguished by the abundance of _Melania

turritissima,_ Forbes (Fig. 165).

_b._ Lower marls, characterised by _Cerithium mutabile, Cyrena

pulchra,_ etc., and by the remains of _Trionyx_ (see Fig. 166).

_c._ Green marls, often abounding in a peculiar species of oyster,

and accompanied by _ Cerithium, Mytilus, Arca, nucula,_ etc.

_d._ Bembridge limestones, compact cream-coloured limestones

alternating with shales and marls, in all of which land-shells are

common, especially at Sconce, near Yarmouth, as described by Mr.

F. Edwards. The _Bulimus ellipticus,_ Fig. 167, and _Helix

occlusa,_ Fig. 168, are among its best known land-shells.

_Paludina orbicularis,_ Fig. 169, is also of frequent occurrence.

One of the bands is filled with a little globular _Paludina._

Among the fresh-water pulmonifera, _ Lymnea longiscata_ (Fig. 171)

and _Planorbis discus_ (Fig. 170) are the most generally

distributed: the latter represents or takes the place of the

_Planorbis euomphalus_ (see Fig. 175) of the more ancient Headon

series. _Chara tuberculata_ (Fig. 172) is the characteristic

Bembridge gyrogonite or seed-vessel.

Fig. 165: Melania turritissima, Fig. 166: Fragment of Carapace of

Trionyx, Fig. 167: Bulimus ellipticus, Fig. 168: Helix occlusa, Fig.

169: Paludina orbicularis, Fig. 170: Planorbis discus, Fig. 171: Lymnea

longiscata, Fig. 172: Chara tuberculata.

Fig. 173: Lower molar tooth.

From this formation on the shores of Whitecliff Bay, Dr. Mantell

obtained a fine specimen of a fan palm, _Flabellaria Lamanonis,_

Brong., a plant first obtained from beds of corresponding age in the

suburbs of Paris. The well-known building-stone of Binstead, near Ryde,

a limestone with numerous hollows caused by Cyrenæ which have

disappeared and left the moulds of their shells, belongs to this

subdivision of the Bembridge series. In the same Binstead stone Mr.

Pratt and the Reverend Darwin Fox first discovered the remains of

mammalia characteristic of the gypseous series of Paris, as _

Palæotherium magnum_ (Fig. 174), _P. medium, P. minus, P. minimum, P.

curtum, P. crassum_; also _Anoplotherium commune_ (Fig. 173), _A.

secundarium, Dichobune cervinum,_ and _Chæropotamus Cuvieri._ The

Palæothere above alluded to resembled the living tapir in the form of

the head, and in having a short proboscis, but its molar teeth were

more like those of the rhinoceros. _Palæotherium magnum_ was of the

size of a horse, three or four feet high. The woodcut, Fig. 174, is one

of the restorations which Cuvier attempted of the outline of the living

animal, derived from the study of the entire skeleton. As the vertical

range of particular species of quadrupeds, so far as our knowledge

extends, is far more limited than that of the testacea, the occurrence

of so many species at Binstead, agreeing with fossils of the Paris

gypsum, strengthens the evidence derived from shells and plants of the

synchronism of the two formations.

Fig. 174: Palæotherium magnum.

Osborne or St. Helen’s Series, A.2.—This group is of fresh and

brackish-water origin, and very variable in mineral character and

thickness. Near Ryde, it supplies a freestone much used for building,

and called by Professor Forbes the Nettlestone grit. In one part

ripple-marked flagstones occur, and rocks with fucoidal markings. The

Osborne beds are distinguished by peculiar species of _Paludina,

Melania,_ and _ Melanopsis,_ as also of _Cypris_ and the seeds of _

Chara._

Fig. 175: Planorbis euomphalus, Fig. 176: Helix labyrinthica.

Headon Series A.3.—These beds are seen both in Whitecliff Bay, Headon

Hill, and Alum Bay, or at the east and west extremities of the Isle of

Wight. The upper and lower portions are fresh-water, and the middle of

mixed origin, sometimes brackish and marine. Everywhere _Planorbis

euomphalus,_ Fig. 175, characterises the fresh-water deposits, just as

the allied form, P. discus, Fig. 170, does the Bembridge limestone. The

brackish-water beds contain _Potamomya plana, Cerithium mutabile,_ and

_Potamides cinctus_ (Fig. 37), and the marine beds _ Venus_ (or

_Cytherea_) _incrassata,_ a species common to the Limburg beds and Grès

de Fontainebleau, or the Lower Miocene series. The prevalence of

salt-water remains is most conspicuous in some of the central parts of

the formation.

Fig. 177: Neritina concava.

Among the shells which are widely distributed through the Headon series

are _Neritina concava_ (Fig. 177), _Lymnea caudata_ (Fig. 178), and _

Cerithium concavum_ (Fig. 179). _Helix labyrinthica,_ Say (Fig. 176), a

land-shell now inhabiting the United States, was discovered in this

series by Mr. Searles Wood in Hordwell Cliff. It is also met with in

Headon Hill, in the same beds. At Sconce, in the Isle of Wight, it

occurs in the Bembridge series, and affords a rare example of an Eocene

fossil of a species still living, though, as usual in such cases,

having no local connection with the actual geographical range of the

species. The lower and middle portion of the Headon series is also met

with in Hordwell Cliff (or Hordle, as it is often spelt), near

Lymington, Hants. Among the shells which abound in this cliff are

_Paludina lenta_ and various species of _Lymnea, Planorbis, Melania,

Cyclas, Unio, Potamomya, Dreissena,_ etc.

Fig. 178: Lymnea caudata, Fig. 179: Cerithium concavum.

Among the chelonians we find a species of _Emys,_ and no less than six

species of _Trionyx_; among the saurians an alligator and a crocodile;

among the ophidians two species of land-snakes (_Paleryx,_ Owen); and

among the fish Sir P. Egerton and Mr. Wood have found the jaws, teeth,

and hard shining scales of the genus _Lepidosteus,_ or bony pike of the

American rivers. This same genus of fresh-water ganoids has also been

met with in the Hempstead beds in the Isle of Wight. The bones of

several birds have been obtained from Hordwell, and the remains of

quadrupeds of the genera _Palæotherium (P. minus), Anoplotherium,

Anthracotherium, Dichodon, Dichobune, Spalacodon,_ and _Hyænodon._ The

latter offers, I believe, the oldest known example of a true

carnivorous animal in the series of British fossils, although I attach

very little theoretical importance to the fact, because herbivorous

species are those most easily met with in a fossil state in all save

cavern deposits. In another point of view, however, this fauna deserves

notice. Its geological position is considerably lower than that of the

Bembridge or Montmartre beds, from which it differs almost as much in

species as it does from the still more ancient fauna of the Lower

Eocene beds to be mentioned in the sequel. It therefore teaches us what

a grand succession of distinct assemblages of mammalia flourished on

the earth during the Eocene period.

Many of the marine shells of the brackish-water beds of the above

series, both in the Isle of Wight and Hordwell Cliff, are common to the

underlying Barton Clay: and, on the other hand, there are some

fresh-water shells, such as _Cyrena obovata,_ which are common to the

Bembridge beds, notwithstanding the intervention of the St. Helen’s

series. The white and green marls of the Headon series, and some of the

accompanying limestones, often resemble the Eocene strata of France in

mineral character and colour in so striking a manner as to suggest the

idea that the sediment was derived from the same region or produced

contemporaneously under very similar geographical circumstances.

At Brockenhurst, near Lyndhurst, in the New Forest, marine strata have

recently been found containing fifty-nine shells, of which many have

been described by Mr. Edwards. These beds rest on the Lower Headon, and

are considered as the equivalent of the middle part of the Headon

series, many of the shells being common to the brackish-water or Middle

Headon beds of Colwell and Whitecliff Bays, such as _Cancellaria

muricata,_ Sowerby, _ Fusus labiatus,_ Sowerby, etc. In these beds at

Brockenhurst, corals, ably described by Dr. Duncan, have recently been

found in abundance and perfection; see Fig. 180, _Solenastræa

cellulosa._

Fig. 180: Solenastræa cellulosa.

Baron von Könen[1] has pointed out that no less than forty-six out of

the fifty-nine Brockenhurst shells, or a proportion of 78 per cent,

agree with species occurring in Dumont’s Lower Tongrian formation in

Belgium. This being the case, we might fairly expect that if we had a

marine equivalent of the Bembridge series or of the contemporaneous

Paris gypsum, we should find it to contain a still greater number of

shells common to the Tongrian beds of Belgium, but the exact

correlation of these fresh-water groups of France, Belgium, and Britain

has not yet been fully made out. It is possible that the Tongrian of

Dumont may be newer than the Bembridge series, and therefore referable

to the Lower Miocene. If ever the whole series should be complete, we

must be prepared to find the marine equivalent of the Bembridge beds,

or the uppermost Eocene, passing by imperceptible shades into the

inferior beds of the overlying Miocene strata.

Among the fossils found in the Middle Headon are _Cytherea incrassata_

and _Cerithium plicatum_ (Fig. 160). These shells, especially the

latter, are very characteristic of the Lower Miocene, and their

occurrence in the Headon series has been cited as an objection to the

line proposed to be drawn between Miocene and Eocene. But if we were to

attach importance to such occasional passages, we should soon find that

no lines of division could be drawn anywhere, for in the present state

of our knowledge of the Tertiary series there will always be species

common to beds above and below our boundary-lines.

Fig. 181: Chama squamosa.

Barton Series (_Sands and Clays_), A.4 Table—Both in the Isle of Wight,

and in Hordwell Cliff, Hants, the Headon beds, above-mentioned, rest on

white sands usually devoid of fossils, and used in the Isle of Wight

for making glass. In one of these sands Dr. Wright found _ Chama

squamosa,_ a Barton Clay shell, in great plenty, and certain

impressions of marine shells have been found in sands supposed to be of

the same age in Whitecliff Bay. These sands have been called Upper

Bagshot in the maps of our Government Survey, but this identification

of a fossiliferous series in the Isle of Wight with an unfossiliferous

formation in the London Basin can scarcely be depended upon. The Barton

Clay, which immediately underlies these sands, is seen vertical in Alum

Bay, Isle of Wight, and nearly horizontal in the cliffs of the mainland

near Lymington. This clay, together with the Bracklesham beds,

presently to be described, has been termed Middle Bagshot by the

Survey. In Barton Cliff, where it attains a thickness of about 300

feet, it is rich in marine fossils.

It was formerly confounded with the London Clay, an older Eocene

deposit of very similar mineral character, to be mentioned (p. 263),

which contains many shells in common, but not more than one-fourth of

the whole. In other words, there are known at present 247 species in

the London Clay and 321 in that of Barton, and only 70 common to the

two formations. Fifty-six of these have been found in the intermediate

Bracklesham beds, and the reappearance of the other 14 may imply a

return of similar conditions, whether of temperature or depth or of a

muddy argillaceous bottom, common to the two periods of the London and

Barton Clays. According to M. Hebert, the most characteristic Barton

Clay fossils correspond to those of the Gres de Beauchamp, or Sables

Moyens, of the Paris Basin, but it also contains many common to the

older Calcaire Grossier.

SHELLS OF THE BARTON CLAY.

Certain foraminifera called Nummulites begin, when we study the

Tertiary formations in a descending order, to make their first

appearance in these beds. A small species called _ Nummulites

variolaria,_ Fig. 190, is found both on the Hampshire coast and in beds

of the same age in Whitecliff Bay, in the Isle of Wight. Several marine

shells, such as _Corbula pisum_ (Fig. 158), are common to the Barton

beds and the Hempstead or Lower Miocene series, and a still greater

number, as before stated, are common to the Headon series.

Fig. 182: Mitra scabra, Fig. 183: Voluta ambigua, Fig. 184: Typhis

pungens, Fig. 185: Voluta athleta, Fig. 186: Terebellum fusiforme, Fig.

187: Terebellum sopita, Fig. 188: Cardita sulcata, Fig. 189:

Crassatella sulcata, Fig. 190: Nummulites variolaria.

MIDDLE EOCENE, ENGLAND.

Bracklesham Beds and Bagshot Sands, B.1, Table—Beneath the Barton Clay

we find in the north of the Isle of Wight, both in Alum and Whitecliff

Bays, a great series of various coloured sands and clays for the most

part unfossiliferous, and probably of estuarine origin. As some of

these beds contain _Cardita planicosta_ (Fig. 191) they have been

identified with the marine beds much richer in fossils seen in the

coast section in Bracklesham Bay near Chichester in Sussex, where the

strata consist chiefly of green clayey sands with some lignite. Among

the Bracklesham fossils besides the Cardita, the huge _Cerithium

giganteum_ is seen, so conspicuous in the Calcaire Grossier of Paris,

where it is sometimes two feet in length. The _Nummulites lævigata_

(see Fig. 192), so characteristic of the lower beds of the Calcaire

Grossier in France, where it sometimes forms stony layers, as near

Compiègne, is very common in these beds, together with _N. scabra_ and

_N. variolaria._ Out of 193 species of testacea procured from the

Bagshot and Bracklesham beds in England, 126 occur in the Calcaire

Grossier in France. It was clearly, therefore, coeval with that part of

the Parisian series more nearly than with any other.

Fig. 191: Cardita (Venericardia) planicosta, Fig. 192: Nummulites

(Nummularia) lavigata.

According to tables compiled from the best authorities by Mr.

Etheridge, the number of mollusca now known from the Bracklesham beds

in Great Britain is 393, of which no less than 240 are peculiar to this

subdivision of the British Eocene series, while 70 are common to the

Older London Clay, and 140 to the Newer Barton Clay. The volutes and

cowries of this formation, as well as the lunulites and corals, favour

the idea of a warm climate having prevailed, which is borne out by the

discovery of a serpent, _Palæophis typhœus_ (see Fig. 193), exceeding,

according to Professor Owen, twenty feet in length, and allied in its

osteology to the Boa, Python, Coluber, and Hydrus. The compressed form

and diminutive size of certain caudal vertebræ indicate so much analogy

with Hydrus as to induce Professor Owen to pronounce this extinct

ophidian to have been marine.[2] Among the companions of the sea-snake

of Bracklesham was an extinct crocodile (_Gavialis Dixoni,_ Owen), and

numerous fish, such as now frequent the seas of warm latitudes, as the

Ostracion of the family Balistidæ, of which a dorsal spine is figured

(see Fig. 194), and gigantic rays of the genus _ Myliobates_ (see Fig.

195).

Fig. 193: Palæophis typhoeus, Owen; an Eocene sea-serpent, Fig. 194:

Defensive spine of Ostracion.

Fig. 195: Dental plates of Myliobates Edwardsi.

The teeth of sharks also, of the genera _Carcharodon, Otodus, Lamna,

Galeocerdo,_ and others, are abundant. (See Figs. 196, 197, 198, 199.)

Fig. 196: Carcharodon angustidens, Fig. 197: Otodus obliquus, Fig. 198:

Lamna elegans, Fig. 199: Galcocerdo latidens.

MARINE SHELLS OF BRACKLESHAM BEDS.

Alum Bay and Bournemouth Beds. (_Lower Bagshot of English Survey_),

B.2, Table—To that great series of sands and clays which intervene

between the equivalents of the Bracklesham Beds and the London Clay or

Lower Eocene, our Government Survey has given the name of the Lower

Bagshot sands, for they are supposed to agree in age with the inferior

unfossiliferous sands of the country round Bagshot in the London Basin.

This part of the series is finely exposed in the vertical beds of Alum

bay, in the Isle of Wight, and east and west of Bournemouth, on the

south coast of Hampshire. In some of the close and white compact clays

of this locality, there are not only dicotyledonous leaves, but

numerous fronds of ferns allied to Gleichenia which are well preserved

with their fruit.

Fig. 200: Pleurotoma attenuata, Fig. 201: Voluta Selseïensis, Fig. 202:

Turritella multisulcata, Fig. 203: Lucina serrata, Fig. 204: Conus

deperditus.

None of the beds are of great horizontal extent, and there is much

cross-stratification in the sands, and in some places black

carbonaceous seams and lignite. In the midst of these leaf-beds in

Studland Bay, Purbeck shells of the genus Unio attest the fresh-water

origin of the white clay.

No less than forty species of plants are mentioned by MM. de la Harpe

and Gaudin from this formation in Hampshire, among which the Proteaceæ

(_Dryandra,_ etc.) and the fig tribe are abundant, as well as the

cinnamon and several other laurineæ, with some papilionaceous plants.

On the whole, they remind the botanist of the types of subtropical

India and Australia.[3]

Heer has mentioned several species which are common to this Alum Bay

flora and that of Monte Bolca, near Verona, so celebrated for its

fossil fish, and where the strata contain nummulites and other Middle

Eocene fossils. He has particularly alluded to _Aralia primigenia_ (of

which genus a fruit has since been found by Mr. Mitchell at

Bournemouth), _Daphnogene Veronensis,_ and _ Ficus granadilla,_ as

among the species common to and characteristic of the Isle of Wight and

Italian Eocene beds; and he observes that in the flora of this period

these forms of a temperate climate which constitute a marked feature in

the European Miocene formations, such as the willow, poplar, birch,

alder, elm, hornbeam, oak, fir, and pine, are wanting. The American

types are also absent, or much more feebly represented than in the

Miocene period, although fine specimens of the fan-palm (_Sabal_) have

been found in these Eocene clays at Studland. The number of exotic

forms which are common to the Eocene and Miocene strata of Europe, like

those to be alluded to in the sequel which are common to the Eocene and

Cretaceous fauna, demonstrate the remoteness of the times in which the

geographical distribution of living plants originated. A great majority

of the Eocene genera have disappeared from our temperate climates, but

not the whole of them; and they must all have exerted some influence on

the assemblages of species which succeeded them. Many of these last

occurring in the Upper Miocene are indeed so closely allied to the

flora now surviving as to make it questionable, even in the opinion of

naturalists opposed to the doctrine of transmutation, whether they are

not genealogically related the one to the other.

LOWER EOCENE FORMATIONS, ENGLAND.

London Clay, C.1, Table—This formation underlies the preceding, and

sometimes attains a thickness of 500 feet. It consists of tenacious

brown and bluish-grey clay, with layers of concretions called septaria,

which abound chiefly in the brown clay, and are obtained in sufficient

numbers from sea-cliffs near Harwich, and from shoals off the coast of

Essex and the Isle of Sheppey, to be used for making Roman cement. The

total number of British fossil mollusca known at present (January,

1870) in this formation are 254, of which 166 are peculiar, or not

found in other Eocene beds in this country. The principal localities of

fossils in the London clay are Highgate Hill, near London, the Island

of Sheppey at the mouth of the Thames, and Bognor on the Sussex coast.

Out of 133 fossil shells, Mr. Prestwich found only 20 to be common to

the Calcaire Grossier (from which 600 species have been obtained),

while 33 are common to the “Lits Coquilliers” (p. 275), in which 200

species are known in France.

In the Island of Sheppey near the mouth of the Thames, the thickness of

the London Clay is estimated by Mr. Prestwich to be more than 500 feet,

and it is in the uppermost 50 feet that a great number of fossil fruits

were obtained, being chiefly found on the beach when the sea has washed

away the clay of the rapidly wasting cliffs.

Fig. 205: Nipadites ellipticus.

Mr. Bowerbank, in a valuable publication on these fossil fruits and

seeds, has described no less than thirteen fruits of palms of the

recent type _Nipa,_ now only found in the Molucca and Philippine

Islands, and in Bengal (see Fig. 205). In the delta of the Ganges, Dr.

Hooker observed the large nuts of _Nipa fruticans_ floating in such

numbers in the various arms of that great river, as to obstruct the

paddle-wheels of steamboats. These plants are allied to the cocoanut

tribe on the one side, and on the other to the _Pandanus,_ or

screw-pine. There are also met with three species of _Anona,_ or

custard-apple; and cucurbitaceous fruits (of the gourd and melon

family), and fruits of various species of _Acacia._

Besides fir-cones or fruit of true Coniferæ there are cones of

Proteaceæ in abundance, and the celebrated botanist the late Robert

Brown pointed out the affinity of these to the New Holland types

_Petrophila_ and _Isopogon._ Of the first there are about fifty, and of

the second thirty described species now living in Australia.

Ettingshausen remarked in 1851 that five of the fossil species from

Sheppey, named by Bowerbank[4] were specimens of the same fruit (see

Fig. 206), in different states of preservation; and Mr. Carruthers,

having examined the original specimens now in the British Museum, tells

me that all these cones from Sheppey may be reduced to two species,

which have an undoubted affinity to the two existing Australian genera

above mentioned, although their perfect identity in structure cannot be

made out.

Fig. 206: Eocene Proteaceous Fruit (Petrophiloides Richardsoni.

The contiguity of land may be inferred not only from these vegetable

productions, but also from the teeth and bones of crocodiles and

turtles, since these creatures, as Dean Conybeare remarked, must have

resorted to some shore to lay their eggs. Of turtles there were

numerous species referred to extinct genera. These are, for the most

part, not equal in size to the largest living tropical turtles. A

sea-snake, which must have been thirteen feet long, of the genus

_Palæophis_ before mentioned (p. 261) has also been described by

Professor Owen from Sheppey, of a different species from that of

Bracklesham, and called _P. toliapicus._ A true crocodile, also,

_Crocodilus toliapicus,_ and another saurian more nearly allied to the

gavial, accompany the above fossils; also the relics of several birds

and quadrupeds. One of these last belongs to the new genus

_Hyracotherium_ of Owen, of the hog tribe, allied to Chæropotamus,

another is a _Lophiodon_; a third a pachyderm called _Coryphodon

eocænus_ by Owen, larger than any existing tapir. All these animals

seem to have inhabited the banks of the great river which floated down

the Sheppey fruits. They imply the existence of a mammiferous fauna

antecedent to the period when nummulites flourished in Europe and Asia,

and therefore before the Alps, Pyrenees, and other mountain-chains now

forming the backbones of great continents, were raised from the deep;

nay, even before a part of the constituent rocky masses now entering

into the central ridges of these chains had been deposited in the sea.

The marine shells of the London Clay confirm the inference derivable

from the plants and reptiles in favour of a high temperature. Thus many

species of _Conus_ and _ Voluta_ occur, a large _Cypræa, C. oviformis,_

a very large _Rostellaria_ (Fig. 209), a species of _Cancellaria,_ six

species of _Nautilus_ (Fig. 211), besides other Cephalopoda of extinct

genera, one of the most remarkable of which is the _ Belosepia_ (Fig.

212). Among many characteristic bivalve shells are _Leda amygdaloides_

(Fig. 213) and _Cryptodon angulatum_ (Fig. 214), and among the Radiata

a star-fish, _Astropecten_ (Fig. 215.)

Fig. 207: Voluta nodosa, Fig. 208: Phorus extensus, Fig. 209:

Rostellaria (Hippocrenes) ampla, Fig. 210: Nautilus centralis, Fig.

211: Aturia ziczac, Fig. 212: Belosepia sepioidea, Fig. 213: Leda

amygdaloides, Fig. 214: Cyptodon (Axinus) angulatum, Fig. 215:

Astropecten crispatus.

These fossils are accompanied by a sword-fish (_Tetrapterus priscus,_

Agassiz), about eight feet long, and a saw-fish (_Pristis bisulcatus,_

Agassiz), about ten feet in length; genera now foreign to the British

seas. On the whole, about eighty species of fish have been described by

M. Agassiz from these beds of Sheppey, and they indicate, in his

opinion, a warm climate.

In the lower part of the London clay at Kyson, a few miles east of

Woodbridge, the remains of mammalia have been detected. Some of these

have been referred by Professor Owen to an opossum, and others to the

genus _Hyracotherium._ The teeth of this last-mentioned pachyderm were

at first, in 1840, supposed to belong to a monkey, an opinion

afterwards abandoned by Owen when more ample materials for comparison

were obtained.

Woolwich and Reading Series, C.2, Table—This formation was formerly

called the Plastic Clay, as it agrees with a similar clay used in

pottery which occupies the same position in the French series, and it

has been used for the like purposes in England.[5]

No formations can be more dissimilar, on the whole, in mineral

character than the Eocene deposits of England and Paris; those of our

own island being almost exclusively of mechanical origin—accumulations

of mud, sand, and pebbles; while in the neighbourhood of Paris we find

a great succession of strata composed of limestones, some of them

siliceous, and of crystalline gypsum and siliceous sandstone, and

sometimes of pure flint used for millstones. Hence it is often

impossible, as before stated, to institute an exact comparison between

the various members of the English and French series, and to settle

their respective ages. But in regard to the division which we have now

under consideration, whether we study it in the basins of London,

Hampshire, or Paris, we recognise as a general rule the same mineral

character, the beds consisting over a large area of mottled clays and

sand, with lignite, and with some strata of well-rolled flint pebbles,

derived from the chalk, varying in size, but occasionally several

inches in diameter. These strata may be seen in the Isle of Wight in

contact with the chalk, or in the London basin, at Reading, Blackheath,

and Woolwich. In some of the lowest of them, banks of oysters are

observed, consisting of _Ostrea bellovacina,_ so common in France in

the same relative position. In these beds at Bromley, Dr. Buckland

found a large pebble to which five full-grown oysters were affixed, in

such a manner as to show that they had commenced their first growth

upon it, and remained attached to it through life.

Fig. 216: Cyrena cuneiformis, Fig. 217: Melania (Melanatria) inquinata.

In several places, as at Woolwich on the Thames, at Newhaven in Sussex,

and elsewhere, a mixture of marine and fresh-water testacea

distinguishes this member of the series. Among the latter, _ Cyrena

cuneiformis_ (see Fig. 216) and _Melania inquinata_ (see Fig. 217) are

very common, as in beds of corresponding age in France. They clearly

indicate points where rivers entered the Eocene sea. Usually there is a

mixture of brackish, fresh-water, and marine shells, and sometimes, as

at Woolwich, proofs of the river and the sea having successively

prevailed on the same spot. At New Charlton, in the suburbs of

Woolwich, Mr. de la Condamine discovered in 1849, and pointed out to

me, a layer of sand associated with well-rounded flint pebbles in which

numerous individuals of the _Cyrena tellinella_ were seen standing

endwise with both their valves united, the siphonal extremity of each

shell being uppermost, as would happen if the mollusks had died in

their natural position. I have described[6] a bank of sandy mud, in the

delta of the Alabama River at Mobile, on the borders of the Gulf of

Mexico, where in 1846 I dug out at low tide specimens of living species

of _Cyrena_ and of a _ Gnathodon,_ which were similarly placed with

their shells erect, or in a posture which enables the animal to

protrude its siphon upward, and draw in or reject water at pleasure.

The water at Mobile is usually fresh, but sometimes brackish. At

Woolwich a body of river-water must have flowed permanently into the

sea where the _Cyrenæ_ lived, and they may have been killed suddenly by

an influx of pure salt-water, which invaded the spot when the river was

low, or when a subsidence of land took place. Traced in one direction,

or eastward towards Herne Bay, the Woolwich beds assume more and more

of a marine character; while in an opposite, or south-western

direction, they become, as near Chelsea and other places, more

fresh-water, and contain _Unio, Paludina,_ and layers of lignite, so

that the land drained by the ancient river seems clearly to have been

to the south-west of the present site of the metropolis.

_Fluviatile Beds underlying Deep-sea Strata._—Before the minds of

geologists had become familiar with the theory of the gradual sinking

of land, and its conversion into sea at different periods, and the

consequent change from shallow to deep water, the fluviatile and

littoral character of this inferior group appeared strange and

anomalous. After passing through hundreds of feet of London clay,

proved by its fossils to have been deposited in deep salt-water, we

arrive at beds of fluviatile origin, and associated with them masses of

shingle, attaining at Blackheath, near London, a thickness of 50 feet.

These shingle banks are probably of marine origin, but they indicate

the proximity of land, and the existence of a shore where the flints of

the chalk were rolled into sand and pebbles, and spread over a wide

space. We have, therefore, first, as before stated (p. 268), evidence

of oscillations of level during the accumulation of the Woolwich

series, then of a great submergence, which allowed a marine deposit 500

thick to be laid over the antecedent beds of fresh and brackish water

origin.

Thanet Sands, C.3, Table—The Woolwich or plastic clay above described

may often be seen in the Hampshire basin in actual contact with the

chalk, constituting in such places the lowest member of the British

Eocene series. But at other points another formation of marine origin,

characterised by a somewhat different assemblage of organic remains,

has been shown by Mr. Prestwich to intervene between the chalk and the

Woolwich series. For these beds he has proposed the name of “Thanet

Sands,” because they are well seen in the Isle of Thanet, in the

northern part of Kent, and on the sea-coast between Herne Bay and the

Reculvers, where they consist of sands with a few concretionary masses

of sandstone, and contain, among other fossils, _Pholadomya cuneata,

Cyprina morrisii, Corbula longirostris, Scalaria Bowerbankii,_ etc. The

greatest thickness of these beds is 90 feet.

UPPER EOCENE FORMATIONS OF FRANCE.

The tertiary formations in the neighbourhood of Paris consist of a

series of marine and fresh-water strata, alternating with each other,

and filling up a depression in the chalk. The area which they occupy

has been called the Paris Basin, and is about 180 miles in its greatest

length from north to south, and about 90 miles in breadth from east to

west. MM. Cuvier and Brongniart attempted, in 1810, to distinguish five

different groups, comprising three fresh-water and two marine, which

were supposed to imply that the waters of the ocean, and of rivers and

lakes, had been by turns admitted into and excluded from the same area.

Investigations since made in the Hampshire and London basins have

rather tended to confirm these views, at least so far as to show that

since the commencement of the Eocene period there have been great

movements of the bed of the sea, and of the adjoining lands, and that

the superposition of deep-sea to shallow-water deposits (the London

Clay, for example, to the Woolwich beds) can only be explained by

referring to such movements. It appears, notwithstanding, from the

researches of M. Constant Prevost, that some of the minor alternations

and intermixtures of fresh-water and marine deposits, in the Paris

basin, may be accounted for without such changes of level, by imagining

both to have been simultaneously in progress, in the same bay of the

same sea, or a gulf into which many rivers entered.

Gypseous Series of Montmartre, A.1, Table—To enlarge on the numerous

subdivisions of the Parisian strata would lead me beyond my present

limits; I shall therefore give some examples only of the most important

formations. Beneath the Grès de Fontainebleau, belonging to the Lower

Miocene period, as before stated, we find, in the neighbourhood of

Paris, a series of white and green marls, with subordinate beds of

gypsum. These are most largely developed in the central parts of the

Paris basin, and, among other places, in the hill of Montmartre, where

its fossils were first studied by Cuvier.

The gypsum quarried there for the manufacture of plaster of Paris

occurs as a granular crystalline rock, and, together with the

associated marls, contains land and fluviatile shells, together with

the bones and skeletons of birds and quadrupeds. Several land-plants

are also met with, among which are fine specimens of the fan-palm or

palmetto tribe (_Flabellaria_). The remains also of fresh-water fish,

and of crocodiles and other reptiles, occur in the gypsum. The

skeletons of mammalia are usually isolated, often entire, the most

delicate extremities being preserved; as if the carcasses, clothed with

their flesh and skin, had been floated down soon after death, and while

they were still swollen by the gases generated by their first

decomposition. The few accompanying shells are of those light kinds

which frequently float on the surface of rivers, together with wood.

In this formation the relics of about fifty species of quadrupeds,

including the genera _Palæotherium_ (see Fig. 174), _Anoplotherium_

(see Fig. 218), and others, have been found, all extinct, and nearly

four-fifths of them belonging to the Perissodactyle or odd-toed

division of the order _Pachydermata,_ which now contains only four

living genera, namely, rhinoceros, tapir, horse, and hyrax. With them a

few carnivorous animals are associated, among which are the _Hyænodon

dasyuroides,_ a species of dog, _Canis Parisiensis,_ and a weasel,

_Cynodon Parisiensis._ Of the _Rodentia_ are found a squirrel; of the

_Cheiroptera,_ a bat; while the _Marsupalia_ (an order now confined to

America, Australia, and some contiguous islands) are represented by an

opossum.

Of birds, about ten species have been ascertained, the skeletons of

some of which are entire. None of them are referable to existing

species.[7] The same remark, according to MM. Cuvier and Agassiz,

applies both to the reptiles and fish. Among the last are crocodiles

and tortoises of the genera _Emys_ and _ Trionyx._

Fig. 218: Xiphodon gracile, or Anoplotherium gracile.

The tribe of land quadrupeds most abundant in this formation is such as

now inhabits alluvial plains and marshes, and the banks of rivers and

lakes, a class most exposed to suffer by river inundations. Among these

were several species of _ Palæotherium,_ a genus before alluded to.

These were associated with the Anoplotherium, a tribe intermediate

between pachyderms and ruminants. One of the three divisions of this

family was called by Cuvier _Xiphodon._ Their forms were slender and

elegant, and one, named _Xiphodon gracile_ (Fig. 218), was about the

size of the chamois; and Cuvier inferred from the skeleton that it was

as light, graceful, and agile as the gazelle.

_Fossil Footprints._—There are three superimposed masses of gypsum in

the neighbourhood of Paris, separated by intervening deposits of

laminated marl. In the uppermost of the three, in the valley of

Montmorency, M. Desnoyers discovered in 1859 many footprints of animals

occurring at no less than six different levels.[8] The gypsum to which

they belong varies from thirty to fifty feet in thickness, and is that

which has yielded to the naturalist the largest number of bones and

skeletons of mammalia, birds, and reptiles. I visited the quarries,

soon after the discovery was made known, with M. Desnoyers, who also

showed me large slabs in the Museum at Paris, where, on the upper

planes of stratification, the indented foot-marks were seen, while

corresponding casts in relief appeared on the lower surfaces of the

strata of gypsum which were immediately superimposed. A thin film of

marl, which before it was dried and condensed by pressure must have

represented a much thicker layer of soft mud, intervened between the

beds of solid gypsum. On this mud the animals had trodden, and made

impressions which had penetrated to the gypseous mass below, then

evidently unconsolidated. Tracks of the _ Anoplotherium_ with its

bisulcate hoof, and the trilobed footprints of _Palæotherium,_ were

seen of different sizes, corresponding to those of several species of

these genera which Cuvier had reconstructed, while in the same beds

were foot-marks of carnivorous mammalia. The tracks also of fluviatile,

lacustrine, and terrestrial tortoises (_Emys, Trionyx,_ etc.) were

discovered, also those of crocodiles, iguanas, geckos, and great

batrachians, and the footprints of a huge bird, apparently a wader, of

the size of the gastornis, to be mentioned in the sequel. There were

likewise the impressions of the feet of other creatures, some of them

clearly distinguishable from any of the fifty extinct types of mammalia

of which the bones have been found in the Paris gypsum. The whole

assemblage, says Desnoyers, indicate the shores of a lake, or several

small lakes communicating with each other, on the borders of which many

species of pachyderms wandered, and beasts of prey which occasionally

devoured them. The tooth-marks of these last had been detected by

palæontologists long before on the bones and skulls of Paleotheres

entombed in the gypsum.

_Imperfection of the Record._—These foot-marks have revealed to us new

and unexpected proofs that the air-breathing fauna of the Upper Eocene

period in Europe far surpassed in the number and variety of its species

the largest estimate which had previously been formed of it. We may now

feel sure that the mammalia, reptiles, and birds which have left

portions of their skeletons as memorials of their existence in the

solid gypsum constituted but a part of the then living creation.

Similar inferences may be drawn from the study of the whole succession

of geological records. In each district the monuments of periods

embracing thousands, and probably in some instances hundreds of

thousands of years, are totally wanting. Even in the volumes which are

extant the greater number of the pages are missing in any given region,

and where they are found they contain but few and casual entries of the

physical events or living beings of the times to which they relate. It

may also be remarked that the subordinate formations met with in two

neighbouring countries, such as France and England (the minor Tertiary

groups above enumerated), commonly classed as equivalents and referred

to corresponding periods, may nevertheless have been by no means

strictly coincident in date. Though called contemporaneous, it is

probable that they were often separated by intervals of many thousands

of years. We may compare them to double stars, which appear single to

the naked eye because seen from a vast distance in space, and which

really belong to one and the same stellar system, though occupying

places in space extremely remote if estimated by our ordinary standard

of terrestrial measurements.

Calcaire silicieux, or Travertin inférieur, A.2 and 3, Table—This

compact siliceous limestone extends over a wide area. It resembles a

precipitate from the waters of mineral springs, and is often traversed

by small empty sinuous cavities. It is, for the most part, devoid of

organic remains, but in some places contains fresh-water and land

species, and never any marine fossils. The calcaire siliceux and the

calcaire grossier usually occupy distinct parts of the Paris basin, the

one attaining its fullest development in those places where the other

is of slight thickness. They are described by some writers as

alternating with each other towards the centre of the basin, as at

Sergy and Osny.

The gypsum, with its associated marls before described, is in greatest

force towards the centre of the basin, where the calcaire grossier and

calcaire silicieux are less fully developed.

Grès de Beauchamp, or Sables Moyens, A.4, Table—In some parts of the

Paris basin, sands and marls, called the Grès de Beauchamp, or Sables

moyens, divide the gypseous beds from the calcaire grossier proper.

These sands, in which a small nummulite (N. variolaria) is very

abundant, contain more than 300 species of marine shells, many of them

peculiar, but others common to the next division.

MIDDLE EOCENE FORMATIONS OF FRANCE.

Calcaire Grossier, upper and middle, B.1, Table—The upper division of

this group consists in great part of beds of compact, fragile

limestone, with some intercalated green marls. The shells in some parts

are a mixture of _Cerithium, Cyclostoma,_ and _Corbula_; in others

_Limnea, Cerithium, Paludina,_ etc. In the latter, the bones of

reptiles and mammalia, _Palæotherium_ and _ Lophiodon,_ have been

found. The middle division, or calcaire grossier proper, consists of a

coarse limestone, often passing into sand. It contains the greater

number of the fossil shells which characterise the Paris basin. No less

than 400 distinct species have been procured from a single spot near

Grignon, where they are imbedded in a calcareous sand, chiefly formed

of comminuted shells, in which, nevertheless, individuals in a perfect

state of preservation, both of marine, terrestrial, and fresh-water

species, are mingled together. Some of the marine shells may have lived

on the spot; but the _Cyclostoma_ and _Limnea,_ being land and

fresh-water shells, must have been brought thither by rivers and

currents, and the quantity of triturated shells implies considerable

movement in the waters.

Nothing is more striking in this assemblage of fossil testacea than the

great proportion of species referable to the genus _ Cerithium_ (see p.

245). There occur no less than 137 species of this genus in the Paris

basin, and almost all of them in the calcaire grossier. Most of the

living _Cerithia_ inhabit the sea near the mouths of rivers, where the

waters are brackish; so that their abundance in the marine strata now

under consideration is in harmony with the hypothesis that the Paris

basin formed a gulf into which several rivers flowed.

In some parts of the calcaire grossier round Paris, certain beds occur

of a stone used in building, and called by the French geologists

“Miliolite limestone.” It is almost entirely made up of millions of

microscopic shells, of the size of minute grains of sand, which all

belong to the class Foraminifera. Examples of some of these are given

in Figs. 219 to 221. As this miliolitic stone never occurs in the

Faluns, or Upper Miocene strata of Brittany and Touraine, it often

furnishes the geologist with a useful criterion for distinguishing the

detached Eocene and Upper Miocene formations scattered over those and

other adjoining provinces. The discovery of the remains of Palæotherium

and other mammalia in some of the upper beds of the calcaire grossier

shows that these land animals began to exist before the deposition of

the overlying gypseous series had commenced.

Fig. 219: Calcarina rarispina, Fig. 220: Spirolina stenostoma, Fig.

221: Triloculina inflata.

Lower Calcaire grossier, or Glauconie grossiere, B.1, Table—The lower

part of the calcaire grossier, which often contains much green earth,

is characterised at Auvers, near Pontoise, to the north of Paris, and

still more in the environs of Compiègne, by the abundance of

nummulites, consisting chiefly of _N. lævigata, N. scabra,_ and _ N.

Lamarcki,_ which constitute a large proportion of some of the stony

strata, though these same foraminifera are wanting in beds of similar

age in the immediate environs of Paris.

Fig. 222: Nerita conoidea.

Soissonnais sands, or Lits coquilliers, B.2, Table—Below the preceding

formation, shelly sands are seen, of considerable thickness, especially

at Cuisse-Lamotte, near Compiègne, and other localities in the

Soissonnais, about fifty miles N.E. of Paris, from which about 300

species of shells have been obtained, many of them common to the

calcaire grossier and the Bracklesham beds of England, and many

peculiar. The _Nummulites planulata_ is very abundant, and the most

characteristic shell is the _Nerita conoidea,_ Lam., a fossil which has

a very wide geographical range; for, as M. d’Archiac remarks, it

accompanies the nummulitic formation from Europe to India, having been

found in Cutch, near the mouths of the Indus, associated with

_Nummulites scabra._ No less than 33 shells of this group are said to

be identical with shells of the London clay proper, yet, after visiting

Cuisse-Lamotte and other localities of the “Sables inférieurs” of

Archiac, I agree with Mr. Prestwich, that the latter are probably newer

than the London clay, and perhaps older than the Bracklesham beds of

England. The London clay seems to be unrepresented in the Paris basin,

unless partially so, by these sands.[9]

LOWER EOCENE FORMATIONS OF FRANCE.

Argile Plastique, C.2, Table—At the base of the tertiary system in

France are extensive deposits of sands, with occasional beds of clay

used for pottery, and called “argile plastique.” Fossil oysters

(_Ostrea bellovacina_) abound in some places, and in others there is a

mixture of fluviatile shells, such as _Cyrena cuneiformis_ (Fig. 216),

_ Melania inquinata_ (Fig. 216), and others, frequently met with in

beds occupying the same position in the London Basin. Layers of lignite

also accompany the inferior clays and sands.

Immediately upon the chalk at the bottom of all the tertiary strata in

France there generally is a conglomerate or breccia of rolled and

angular chalk-flints, cemented by siliceous sand. These beds appear to

be of littoral origin, and imply the previous emergence of the chalk,

and its waste by denudation. In the year 1855, the tibia and femur of a

large bird equalling at least the ostrich in size were found at Meudon,

near Paris, at the base of the Plastic clay. This bird, to which the

name of _Gastornis Parisiensis_ has been assigned, appears, from the

Memoirs of MM. Hébert, Lartet, and Owen, to belong to an extinct genus.

Professor Owen refers it to the class of wading land birds rather than

to an aquatic species.[10]

That a formation so much explored for economical purposes as the Argile

plastique around Paris, and the clays and sands of corresponding age

near London, should never have afforded any vestige of a feathered

biped previously to the year 1855, shows what diligent search and what

skill in osteological interpretation are required before the existence

of birds of remote ages can be established.

Sables de Bracheux, C.3, Table—The marine sands called the Sables de

Bracheux (a place near Beauvais), are considered by M. Hébert to be

older than the Lignites and Plastic clay, and to coincide in age with

the Thanet Sands of England. At La Fère, in the Department of Aisne, in

a deposit of this age, a fossil skull has been found of a quadruped

called by Blainville _Arctocyon primævus,_ and supposed by him to be

related both to the bear and to the Kinkajou (_Cercoleptes_). This

creature appears to be the oldest known tertiary mammifer.

Nummulitic Formations of Europe, Asia, etc.—Of all the rocks of the

Eocene period, no formations are of such great geographical importance

as the Upper and Middle Eocene, as above defined, assuming that the

older tertiary formation, commonly called nummulitic, is correctly

ascribed to this group. It appears that of more than fifty species of

these foraminifera described by D’Archiac, one or two species only are

found in other tertiary formations whether of older or newer date.

_Nummulites intermedia,_ a Middle Eocene form, ascends into the Lower

Miocene, but it seems doubtful whether any species descends to the

level of the London clay, still less to the Argile plastique or

Woolwich beds. Separate groups of strata are often characterised by

distinct species of nummulite; thus the beds between the lower Miocene

and the lower Eocene may be divided into three sections, distinguished

by three different species of nummulites, _N. variolaria_ in the upper,

_N. lævigata_ in the middle, and _N. planulata_ in the lower beds. The

nummulitic limestone of the Swiss Alps rises to more than 10,000 feet

above the level of the sea, and attains here and in other mountain

chains a thickness of several thousand feet. It may be said to play a

far more conspicuous part than any other tertiary group in the solid

framework of the earth’s crust, whether in Europe, Asia, or Africa. It

occurs in Algeria and Morocco, and has been traced from Egypt, where it

was largely quarried of old for the building of the Pyramids, into Asia

Minor, and across Persia by Bagdad to the mouths of the Indus. It has

been observed not only in Cutch, but in the mountain ranges which

separate Scinde from Persia, and which form the passes leading to

Caboul; and it has been followed still farther eastward into India, as

far as eastern Bengal and the frontiers of China.

Dr. T. Thompson found nummulites at an elevation of no less than 16,500

feet above the level of the sea, in Western Thibet. One of the species,

which I myself found very abundant on the flanks of the Pyrenees, in a

compact crystalline marble (Fig. 223) is called by M. d’Archiac

_Nummulites Puschi._ The same is also very common in rocks of the same

age in the Carpathians. In many distant countries, in Cutch, for

example, some of the same shells, such as _Nerita conoidea_ (Fig. 222),

accompany the nummulites, as in France. The opinion of many observers,

that the Nummulitic formation belongs partly to the cretaceous era,

seems chiefly to have arisen from confounding an allied genus,

Orbitoides, with the true Nummulite.

Fig. 223: Nummulites Puschi.

When we have once arrived at the conviction that the nummulitic

formation occupies a middle and upper place in the Eocene series, we

are struck with the comparatively modern date to which some of the

greatest revolutions in the physical geography of Europe, Asia, and

Northern Africa must be referred. All the mountain-chains, such as the

Alps, Pyrenees, Carpathians, and Himalayas, into the composition of

whose central and loftiest parts the nummulitic strata enter bodily,

could have had no existence till after the Middle Eocene period. During

that period the sea prevailed where these chains now rise, for

nummulites and their accompanying testacea were unquestionably

inhabitants of salt water. Before these events, comprising the

conversion of a wide area from a sea to a continent, England had been

peopled, as I before pointed out (p. 267), by various quadrupeds, by

herbivorous pachyderms, by insectivorous bats, and by opossums.

Almost all the volcanoes which preserve any remains of their original

form, or from the craters of which lava streams can be traced, are more

modern than the Eocene fauna now under consideration; and besides these

superficial monuments of the action of heat, Plutonic influences have

worked vast changes in the texture of rocks within the same period.

Some members of the nummulitic and overlying tertiary strata called

_flysch_ have actually been converted in the central Alps into

crystalline rocks, and transformed into marble, quartz-rock,

micha-schist, and gneiss.[11]

Eocene Strata in the United States.—In North America the Eocene

formations occupy a large area bordering the Atlantic, which increases

in breadth and importance as it is traced southward from Delaware and

Maryland to Georgia and Alabama. They also occur in Louisiana and other

States both east and west of the valley of the Mississippi. At

Claiborne, in Alabama, no less than 400 species of marine shells, with

many echinoderms and teeth of fish, characterise one member of this

system. Among the shells, the _Cardita planicosta,_ before mentioned

(Fig. 191), is in abundance; and this fossil and some others identical

with European species, or very nearly allied to them, make it highly

probable that the Claiborne beds agree in age with the central or

Bracklesham group of England, and with the calcaire grossiere of

Paris.[12]

Higher in the series is a remarkable calcareous rock, formerly called

“the nummulite limestone,” from the great number of discoid bodies

resembling nummulites which it contains, fossils now referred by A.

d’Orbigny to the genus _Orbitoides,_ which has been demonstrated by Dr.

Carpenter to belong to the foraminifera.[13] That naturalist, moreover,

is of opinion that the Orbitoides alluded to (_O. Mantelli_) is of the

same species as one found in Cutch, in the Middle Eocene or nummulitic

formation of India.

Above the orbitoidal limestone is a white limestone, sometimes soft and

argillaceous, but in parts very compact and calcareous. It contains

several peculiar corals, and a large Nautilus allied to _N. ziczac_;

also in its upper bed a gigantic cetacean, called _Zeuglodon_ by

Owen.[14]

The colossal bones of this cetacean are so plentiful in the interior of

Clarke County, Alabama, as to be characteristic of the formation. The

vertebral column of one skeleton found by Dr. Buckley at a spot visited

by me, extended to the length of nearly seventy feet, and not far off

part of another backbone nearly fifty feet long was dug up. I obtained

evidence, during a short excursion, of so many localities of this

fossil animal within a distance of ten miles, as to lead me to conclude

that they must have belonged to at least forty distinct individuals.

Professor Owen first pointed out that this huge animal was not

reptilian, since each tooth was furnished with double roots (Fig. 224),

implanted in corresponding double sockets; and his opinion of the

cetacean nature of the fossil was afterwards confirmed by Dr. Wyman and

Dr. R. W. Gibbes. That it was an extinct mammal of the whale tribe has

since been placed beyond all doubt by discovery of the entire skull of

another fossil species of the same family, having the double occipital

condyles only met with in mammals, and the convoluted tympanic bones

which are characteristic of cetaceans.

Fig. 224: Zeuglodon cetoides, Fig 225: Basilosaurus.

[1] Quart. Geol. Journal, vol. xx, p. 97, 1864.

[2] Palæont. Soc. Monograph, Rept., pt. ii, p. 61.

[3] Heer, Climat et Végétation du Pays Tertiaire, p. 172.

[4] Bowerbank, Fossil Fruits and Seeds of London Clay, Plates ix and

x.

[5] Prestwich, Quart. Geol. Journ., vol. x.

[6] Second Visit to the United States, vol. ii, p. 104.

[7] Cuvier, Oss. Foss., tome iii, p. 255.

[8] Sur des Empreintes de Pas d’Animaux par M. J. Desnoyers. Compte

rendu de l’Institut, 1859.

[9] D’Archiac, Bulletin, tome x; and Prestwich, Quart. Geol. Journ.,

1847, p. 377.

[10] Quart. Geol. Journ., vol. xii, p. 204, 1856.

[11] Murchison, Quart. Journ. of Geol. Soc., vol. v, and Lyell, vol.

vi, 1850. Anniversary Address.

[12] See paper by the Author, Quart. Journ. of Geol. Soc., vol. iv, p.

12; and Second Visit to the United States, vol. ii, p. 59.

[13] Quart. Journ. of Geol. Soc., vol. vi, p. 32.

[14] See Memoir by R. W. Gibbes, Journ. of Acad. Nat. Sci. Philad.,

vol. i, 1847.

CHAPTER XVII.

UPPER CRETACEOUS GROUP.

Lapse of Time between Cretaceous and Eocene Periods. — Table of

successive Cretaceous Formations. — Maestricht Beds. — Pisolitic

Limestone of France. — Chalk of Faxoe. — Geographical Extent and Origin

of the White Chalk. — Chalky Matter now forming in the Bed of the

Atlantic. — Marked Difference between the Cretaceous and existing

Fauna. — Chalk-flints. — Pot-stones of Horstead. — Vitreous Sponges in

the Chalk. — Isolated Blocks of Foreign Rocks in the White Chalk

supposed to be ice-borne. — Distinctness of Mineral Character in

contemporaneous Rocks of the Cretaceous Epoch. — Fossils of the White

Chalk. — Lower White Chalk without Flints. — Chalk Marl and its

Fossils. — Chloritic Series or Upper Greensand. — Coprolite Bed near

Cambridge. — Fossils of the Chloritic Series. — Gault. — Connection

between Upper and Lower Cretaceous Strata. — Blackdown Beds. — Flora of

the Upper Cretaceous Period. — Hippurite Limestone. — Cretaceous Rocks

in the United States.

We have treated in the preceding chapters of the Tertiary or Cainozoic

strata, and have next to speak of the Secondary or Mesozoic formations.

The uppermost of these last is commonly called the chalk or the

cretaceous formation, from creta, the latin name for that remarkable

white earthy limestone, which constitutes an upper member of the group

in those parts of Europe where it was first studied. The marked

discordance in the fossils of the tertiary, as compared with the

cretaceous formations, has long induced many geologists to suspect that

an indefinite series of ages elapsed between the respective periods of

their origin. Measured, indeed, by such a standard, that is to say, by

the amount of change in the Fauna and Flora of the earth effected in

the interval, the time between the Cretaceous and Eocene may have been

as great as that between the Eocene and Recent periods, to the history

of which the last seven chapters have been devoted. Several deposits

have been met with here and there, in the course of the last half

century, of an age intermediate between the white chalk and the plastic

clays and sands of the Paris and London districts, monuments which have

the same kind of interest to a geologist which certain medieval records

excite when we study the history of nations. For both of them throw

light on ages of darkness, preceded and followed by others of which the

annals are comparatively well-known to us. But these newly-discovered

records do not fill up the wide gap, some of them being closely allied

to the Eocene, and others to the Cretaceous type, while none appear as

yet to possess so distinct and characteristic a fauna as may entitle

them to hold an independent place in the great chronological series.

Among the formations alluded to, the Thanet Sands of Prestwich have

been sufficiently described in the last chapter, and classed as Lower

Eocene. To the same tertiary series belong the Belgian formations,

called by Professor Dumont, Landenian. On the other hand, the

Maestricht and Faxoe limestones are very closely connected with the

chalk, to which also the Pisolitic limestone of France is referable.

Classification of the Cretaceous Rocks.—The cretaceous group has

generally been divided into an Upper and a Lower series, the Upper

called familiarly _the chalk,_ and the Lower _the greensand_; the one

deriving its name from the predominance of white earthy limestone and

marl, of which it consists in a great part of France and England, the

other or lower series from the plentiful mixture of green or chloritic

grains contained in some of the sands and cherts of which it largely

consists in the same countries. But these mineral characters often

fail, even when we attempt to follow out the same continuous

subdivisions throughout a small portion of the north of Europe, and are

worse than valueless when we desire to apply them to more distant

regions. It is only by aid of the organic remains which characterise

the successive marine subdivisions of the formation that we are able to

recognise in remote countries, such as the south of Europe or North

America, the formations which were there contemporaneously in progress.

To the English student of geology it will be sufficient to begin by

enumerating those groups which characterise the series in this country

and others immediately contiguous, alluding but slightly to those of

more distant regions. In the table (p. 283) it will be seen that I have

used the term Neocomian for that commonly called “Lower Greensand;” as

this latter term is peculiarly objectionable, since the green grains

are an exception to the rule in many of the members of this group even

in districts where it was first studied and named.

UPPER CRETACEOUS OR CHALK PERIOD.

Maestricht Beds and Faxoe Limestone.

Upper White Chalk, with flints.

Lower White Chalk, without flints.

Chalk Marl.

Chloritic series (or Upper Greensand).

Gault.

LOWER CRETACEOUS OR NEOCOMIAN. Marine Fresh-water

Marine: Upper Neocomian, see p.308

Marine: Middle Neocomian, see p.312

Marine: Lower Neocomian, see p.312

Wealden Beds (upper part).

Belemnitella mucronata. Belemnitella mucronata,

Maestricht, Faxoe, and White Chalk.

_a/_ Entire specimen, showing vascular impression on outer surface, and

characteristic slit. _b._ Section of same, showing place of

phragmocone.[1]

_Maestricht Beds._—On the banks of the Meuse, at Maestricht, reposing

on ordinary white chalk with flints, we find an upper calcareous

formation about 100 feet thick, the fossils of which are, on the whole,

very peculiar, and all distinct from tertiary species. Some few are of

species common to the inferior white chalk, among which may be

mentioned _Belemnitella mucronata_ (Fig. 226) and _Pecten

quadricostatus,_ a shell regarded by many as a mere variety of _P.

quinquecostatus_ (see Fig. 270). Besides the Belemnite there are other

_genera,_ such as _Baculites_ and _Hamites,_ never found in strata

newer than the cretaceous, but frequently met with in these Maestricht

beds. On the other hand, _Voluta, Fasciolaria,_ and other genera of

univalve shells, usually met with only in tertiary strata, occur.

The upper part of the rock, about 20 feet thick, as seen in St. Peter’s

Mount, in the suburbs of Maestricht, abounds in corals and Bryozoa,

often detachable from the matrix; and these beds are succeeded by a

soft yellowish limestone 50 feet thick, extensively quarried from time

immemorial for building. The stone below is whiter, and contains

occasional nodules of grey chert or chalcedony.

M. Bosquet, with whom I examined this formation (August, 1850), pointed

out to me a layer of chalk from two to four inches thick, containing

green earth and numerous encrinital stems, which forms the line of

demarkation between the strata containing the fossils peculiar to

Maestricht and the white chalk below. The latter is distinguished by

regular layers of black flint in nodules, and by several shells, such

as _Terebratula carnea_ (see Fig. 246), wholly wanting in beds higher

than the green band. Some of the organic remains, however, for which

St. Peter’s Mount is celebrated, occur both above and below that

parting layer, and, among others, the great marine reptile called

_Mosasaurus_ (see Fig. 227), a saurian supposed to have been 24 feet in

length, of which the entire skull and a great part of the skeleton have

been found. Such remains are chiefly met with in the soft freestone,

the principal member of the Maestricht beds. Among the fossils common

to the Maestricht and white chalk may be instanced the echinoderm, Fig.

228.

Mosasaurus Camperi.

Hemipneustes radiatus.

I saw proofs of the previous denudation of the white chalk exhibited in

the lower bed of the Maestricht formation in Belgium, about 30 miles

S.W. of Maestricht, at the village of Jendrain, where the base of the

newer deposit consisted chiefly of a layer of well-rolled, black

chalk-flint pebbles, in the midst of which perfect specimens of

_Thecidea papillata_ and _Belemnitella mucronata_ are imbedded. To a

geologist accustomed in England to regard rolled pebbles of chalk-flint

as a common and distinctive feature of tertiary beds of different ages,

it is a new and surprising phenomenon to behold strata made up of such

materials, and yet to feel no doubt that they were accumulated in a sea

in which the belemnite and other cretaceous mollusca flourished.

Pisolitic Limestone of France.—Geologists were for many years at

variance respecting the chronological relations of this rock, which is

met with in the neighbourhood of Paris, and at places north, south,

east, and west of that metropolis, as between Vertus and Laversines,

Meudon and Montereau. By many able palæontologists the species of

fossils, more than fifty in number, were declared to be more Eocene in

their appearance than Cretaceous. But M. Hébert found in this formation

at Montereau, near Paris, the _Pecten quadricostatus,_ a well-known

Cretaceous species, together with some other fossils common to the

Maestricht chalk and to the Baculite limestone of the Cotentin, in

Normandy. He therefore, as well as M. Alcide d’Orbigny, who had

carefully studied the fossils, came to the opinion that it was an upper

member of the Cretaceous group. It is usually in the form of a coarse

yellowish or whitish limestone, and the total thickness of the series

of beds already known is about 100 feet. Its geographical range,

according to M. Hébert, is not less than 45 leagues from east to west,

and 35 from north to south. Within these limits it occurs in small

patches only, resting unconformably on the white chalk.

The _Nautilus Danicus,_ Fig. 230, and two or three other species found

in this rock, are frequent in that of Faxoe, in Denmark, but as yet no

Ammonites, Hamites, Scaphites, Turrilites, Baculites, or Hippurites

have been met with. The proportion of peculiar species, many of them of

tertiary aspect, is confessedly large; and great aqueous erosion

suffered by the white chalk, before the pisolitic limestone was formed,

affords an additional indication of the two deposits being widely

separated in time. The pisolitic formation, therefore, may eventually

prove to be somewhat more intermediate in date between the secondary

and tertiary epochs than the Maestricht rock.

Chalk of Faxoe.— In the island of Seeland, in Denmark, the newest

member of the chalk series, seen in the sea-cliffs at Stevensklint

resting on white chalk with flints, is a yellow limestone, a portion of

which, at Faxoe, where it is used as a building stone, is composed of

corals, even more conspicuously than is usually observed in recent

coral reefs. It has been quarried to the depth of more than 40 feet,

but its thickness is unknown. The imbedded shells are chiefly casts,

many of them of univalve mollusca, which are usually very rare in the

white chalk of Europe. Thus, there are two species of _Cypræa,_ one of

_Oliva,_ two of _Mitra,_ four of the genus _Cerithium,_ six of _Fusus,_

two of _Trochus,_ one of _Patella,_ one of _Emarginula,_ etc.; on the

whole, more than thirty univalves, spiral or patelliform. At the same

time, some of the accompanying bivalve shells, echinoderms, and

zoophytes, are specifically identical with fossils of the true

Cretaceous series. Among the cephalopoda of Faxoe may be mentioned

_Baculites Faujasii_ (Fig. 229), and _Belemnitella mucronata_ (Fig.

226), shells of the white chalk. The _Nautilus Danicus_ (see Fig. 230)

is characteristic of this formation; and it also occurs in France in

the calcaire pisolitique of Laversin (Department of Oise). The claws

and entire skull of a small crab, _Brachyurus rugosus_ (Schlott.), are

scattered through the Faxoe stone, reminding us of similar crustaceans

inclosed in the rocks of modern coral reefs. Some small portions of

this coralline formation consist of white earthy chalk.

Fig. 229: Portion of Baculites Faujasii, Fig. 230: Nautilus Danicus.

Composition, Extent and Origin of the White Chalk.—The highest beds of

chalk in England and France consist of a pure, white, calcareous mass,

usually too soft for a building-stone, but sometimes passing into a

more solid state. It consists, almost purely, of carbonate of lime; the

stratification is often obscure, except where rendered distinct by

interstratified layers of flint, a few inches thick, occasionally in

continuous beds, but oftener in nodules, and recurring at intervals

generally from two to four feet distant from each other. This upper

chalk is usually succeeded, in the descending order, by a great mass of

white chalk without flints, below which comes the chalk marl, in which

there is a slight admixture of argillaceous matter. The united

thickness of the three divisions in the south of England equals, in

some places, 1000 feet. The section in Fig. 231 will show the manner in

which the white chalk extends from England into France, covered by the

tertiary strata described in former chapters, and reposing on lower

cretaceous beds.

The area over which the white chalk preserves a nearly homogeneous

aspect is so vast, that the earlier geologists despaired of discovering

any analogous deposits of recent date. Pure chalk, of nearly uniform

aspect and composition, is met with in a north-west and south-east

direction, from the north of Ireland to the Crimea, a distance of about

1140 geographical miles, and in an opposite direction it extends from

the south of Sweden to the south of Bordeaux, a distance of about 840

geographical miles. In Southern Russia, according to Sir R. Murchison,

it is sometimes 600 feet thick, and retains the same mineral character

as in France and England, with the same fossils, including _Inoceramus

Cuvieri, Belemnitella mucronata,_ and _Ostrea vesicularis_ (Fig. 251).

Diagrammatic section from Hertfordshire, in England, to Sens, in

France.

Great light has recently been thrown upon the origin of the

unconsolidated white chalk by the deep soundings made in the North

Atlantic, previous to laying down, in 1858, the electric telegraph

between Ireland and Newfoundland. At depths sometimes exceeding two

miles, the mud forming the floor of the ocean was found, by Professor

Huxley, to be almost entirely composed (more than nineteen-twentieths

of the whole) of minute Rhizopods, or foraminiferous shells of the

genus Globigerina, especially the species _Globigerina bulloides_ (see

Fig. 232.) the organic bodies next in quantity were the siliceous

shells called _ Polycystineæ,_ and next to them the siliceous skeletons

of plants called _Diatomaceæ_ (Figs. 233, 234, 235), and occasionally

some siliceous spiculæ of sponges (Fig. 236) were intermixed. These

were connected by a mass of living gelatinous matter to which he has

given the name of _Bathybius,_ and which contains abundance of very

minute bodies termed Coccoliths and Coccospheres, which have also been

detected fossil in chalk.

Sir Leopold MacClintock and Dr. Wallich have ascertained that 95 per

cent of the mud of a large part of the North Atlantic consists of

Globigerina shells. But Captain Bullock, R.N., lately brought up from

the enormous depth of 16,860 feet a white, viscid, chalky mud, wholly

devoid of Globigerinæ. This mud was perfectly homogeneous in

composition, and contained no organic remains visible to the naked eye.

Mr. Etheridge, however, has ascertained by microscopical examination

that it is made up of _ Coccoliths, Discoliths,_ and other minute

fossils like those of the Chalk classed by Huxley as _Bathybius,_ when

this term is used in its widest sense. This mud, more than three miles

deep, was dredged up in latitude 20° 19′ N., longitude 4° 36′ E., or

about midway between Madeira and the Cape of Good Hope.

Fig. 232: Globigerina bulloides, Calcareous Rhizopod. Fig. 233:

Actinocyclus, Fig. 234: Pinnularia, Fig. 235: Eunotia bidens, Siliceous

Diatomaceæ. Fig. 236: Spicula of sponge, Siliceous sponge.

The recent deep-sea dredgings in the Atlantic conducted by Dr. Wyville

Thomson, Dr. Carpenter, Mr. Gwyn Jeffreys, and others, have shown that

on the same white mud there sometimes flourish Mollusca, Crustacea, and

Echinoderms, besides abundance of siliceous sponges, forming, on the

whole, a marine fauna bearing a striking resemblance in its general

character to that of the ancient chalk.

Popular Error as to the Geological Continuity of the Cretaceous

Period.—We must be careful, however, not to overrate the points of

resemblance which the deep-sea investigations have placed in a strong

light. They have been supposed by some naturalists to warrant a

conclusion expressed in these words: “We are still living in the

Cretaceous epoch;” a doctrine which has led to much popular delusion as

to the bearing of the new facts on geological reasoning and

classification. The reader should be reminded that in geology we have

been in the habit of founding our great chronological divisions, not on

foraminifera and sponges, nor even on echinoderms and corals, but on

the remains of the most highly organised beings available to us, such

as the mollusca; these being met with, as explained (p. 142), in

stratified rocks of almost every age. In dealing with the mollusca, it

is those of the highest or most specialised organisation, which afford

us the best characters in proportion as their vertical range is the

most limited. Thus the Cephalopoda are the most valuable, as having a

more restricted range in time than the Gasteropoda; and these, again,

are more characteristic of the particular stratigraphical subdivisions

than are the Lamellibranchiate Bivalves, while these last, again, are

more serviceable in classification than the Brachiopoda, a still lower

class of shell-fish, which are the most enduring of all.

When told that the new dredgings prove that “we are still living in the

Chalk Period,” we naturally ask whether some cuttle-fish has been found

with a Belemnite forming part of its internal framework; or have

Ammonites, Baculites, Hamites, Turrilites, with four or five other

Cephalopodous genera characteristic of the chalk and unknown as

tertiary, been met with in the abysses of the ocean? Or, in the absence

of these long-extinct forms, has a single spiral univalve, or species

of Cretaceous Gasteropod, been found living? Or, to descend still lower

in the scale, has some characteristic Cretaceous genus of

Lamellibranchiate Bivalve, such as the Inoceramus, or Hippurite,

foreign to the Tertiary seas, been proved to have survived down to our

time? Or, of the numerous genera of lamellibranchiates common to the

Cretaceous and Recent seas, has one species been found living? The

answer to all these questions is—not one has been found. Even of the

humblest shell-fish, the Brachiopods, no new species common to the

Cretaceous and recent seas has yet been met with. It has been very

generally admitted by conchologists that out of a hundred species of

this tribe occurring fossil in the Upper Chalk—one, and one only,

_Terebratulina striata,_ is still living, being thought to be identical

with _Terebratula caput-serpentis._ Although this identity is still

questioned by some naturalists of authority, it would certainly not

surprise us if another lamp-shell of equal antiquity should be met with

in the deep sea.

Had it been declared that we are living in the Eocene epoch, the idea

would not be so extravagant, for the great reptiles of the Upper Chalk,

the Mosasaurus, Pliosaurus, and Pterodactyle, and many others, as well

as so many genera of chambered univalves, had already disappeared from

the earth, and the marine fauna had made a greater approach to our own

by nearly the entire difference which separates it from the fauna of

the Cretaceous seas. The Eocene nummulitic limestone of Egypt is a rock

mainly composed, like the more ancient white chalk, of globigerine mud;

and if the reader will refer to what we have said of the extent to

which the nummulitic marine strata, formed originally at the bottom of

the sea, now enter into the frame-work of mountain chains of the

principal continents, he will at once perceive that the present

Atlantic, Pacific, and Indian Oceans are geographical terms, which must

be wholly without meaning when applied to the Eocene, and still more to

the Cretaceous Period; so that to talk of the chalk having been

uninterruptedly forming in the Atlantic from the Cretaceous Period to

our own, is as inadmissible in a geographical as in a geological sense.

Chalk-flints.—The origin of the layers of flint, whether in the form of

nodules, or continuous sheets, or in veins or cracks not parallel to

the stratification, has always been more difficult to explain than that

of the white chalk. But here, again, the late deep-sea soundings have

suggested a possible source of such mineral matter. During the cruise

of the “Bulldog,” already alluded to, it was ascertained that while the

calcareous _Globigerinæ_ had almost exclusive possession of certain

tracts of the sea-bottom, they were wholly wanting in others, as

between Greenland and Labrador. According to Dr. Wallich, they may

flourish in those spaces where they derive nutriment from organic and

other matter, brought from the south by the warm waters of the Gulf

Stream, and they may be absent where the effects of that great current

are not felt. Now, in several of the spaces where the calcareous

Rhizopods are wanting, certain microscopic plants, called _Diatomaceæ,_

above mentioned (Figs. 233-235), the solid parts of which are

siliceous, monopolise the ground at a depth of nearly 400 fathoms, or

2400 feet.

The large quantities of silex in solution required for the formation of

these plants may probably arise from the disintegration of feldspathic

rocks, which are universally distributed. As more than half of their

bulk is formed of siliceous earth, they may afford an endless supply of

silica to all the great rivers which flow into the ocean. We may

imagine that, after a lapse of many years or centuries, changes took

place in the direction of the marine currents, favouring at one time a

supply in the same area of siliceous, and at another of calcareous

matter in excess, giving rise in the one case to a preponderance of

Globigerinæ, and in the other of Diatomaceæ. These last, and certain

sponges, may by their decomposition have furnished the silex, which,

separating from the chalky mud, collected round organic bodies, or

formed nodules, or filled shrinkage cracks.

Pot-stones.—A more difficult enigma is presented by the occurrence of

certain huge flints, or pot-stones, as they are called in Norfolk,

occurring singly, or arranged in nearly continuous columns at right

angles to the ordinary and horizontal layers of small flints. I visited

in the year 1825 an extensive range of quarries then open on the river

Bure, near Horstead, about six miles from Norwich, which afforded a

continuous section, a quarter of a mile in length, of white chalk,

exposed to the depth of about twenty-six feet, and covered by a bed of

gravel. The pot-stones, many of them pear-shaped, were usually about

three feet in height and one foot in their transverse diameter, placed

in vertical rows, like pillars, at irregular distances from each other,

but usually from twenty to thirty feet apart, though sometimes nearer

together, as in Figure 237. These rows did not terminate downward in

any instance which I could examine, nor upward, except at the point

where they were cut off abruptly by the bed of gravel. On breaking open

the pot-stones, I found an internal cylindrical nucleus of pure chalk,

much harder than the ordinary surrounding chalk, and not crumbling to

pieces like it, when exposed to the winter’s frost. At the distance of

half a mile, the vertical piles of pot-stones were much farther apart

from each other. Dr. Buckland has described very similar phenomena as

characterising the white chalk on the north coast of Antrim, in

Ireland.[2]

View of a chalk-pit at Horstead, near Norwich, showing the position of

the pot-stones.

Vitreous Sponges of the Chalk.—These pear-shaped masses of flint often

resemble in shape and size the large sponges called Neptune’s Cups

(_Spongia patera,_ Hardw.), which grow in the seas of Sumatra; and if

we could suppose a series of such gigantic sponges to be separated from

each other, like trees in a forest, and the individuals of each

successive generation to grow on the exact spot where the parent sponge

died and was enveloped in calcareous mud, so that they should become

piled one above the other in a vertical column, their growth keeping

pace with the accumulation of the enveloping calcareous mud, a

counterpart of the phenomena of the Horstead pot-stones might be

obtained.

Fig. 238: Ventriculites radiatus. White chalk.

Professor Wyville Thomson, describing the modern soundings in 1869 off

the north coast of Scotland, speaks of the ooze or chalk mud brought

from a depth of about 3000 feet, and states that at one haul they

obtained forty specimens of vitreous sponges buried in the mud. He

suggests that the Ventriculites of the chalk were nearly allied to

these sponges, and that when the silica of their spicules was removed,

and was dissolved out of the calcareous matrix, it set into flint.

Boulders and Groups of Pebbles in Chalk.—The occurrence here and there,

in the white chalk of the south of England, of isolated pebbles of

quartz and green schist has justly excited much wonder. It was at first

supposed that they had been dropped from the roots of some floating

tree, by which means stones are carried to some of the small coral

islands of the Pacific. But the discovery in 1857 of a group of stones

in the white chalk near Croydon, the largest of which was syenite and

weighed about forty pounds, accompanied by pebbles and fine sand like

that of a beach, has been shown by Mr. Godwin Austen to be inexplicable

except by the agency of floating ice. If we consider that icebergs now

reach 40 degrees north latitude in the Atlantic, and several degrees

nearer the equator in the southern hemisphere, we can the more easily

believe that even during the Cretaceous epoch, assuming that the

climate was milder, fragments of coast ice may have floated

occasionally as far as the south of England.

Distinctness of Mineral Character in Contemporaneous Rocks of the

Cretaceous Period.—But we must not imagine that because pebbles are so

rare in the white chalk of England and France there are no proofs of

sand, shingle, and clay having been accumulated contemporaneously even

in European seas. The siliceous sandstone called “upper quader” by the

Germans overlies white argillaceous chalk or “pläner-kalk,” a deposit

resembling in composition and organic remains the chalk marl of the

English series. This sandstone contains as many fossil shells common to

our white chalk as could be expected in a sea-bottom formed of such

different materials. It sometimes attains a thickness of 600 feet, and,

by its jointed structure and vertical precipices, plays a conspicuous

part in the picturesque scenery of Saxon Switzerland, near Dresden. It

demonstrates that in the Cretaceous sea, as in our own, distinct

mineral deposits were simultaneously in progress. The quartzose

sandstone alluded to, derived from the detritus of the neighbouring

granite, is absolutely devoid of carbonate of lime, yet it was formed

at the distance only of four hundred miles from a sea-bottom now

constituting part of France, where the purely calcareous white chalk

was forming. In the North American continent, on the other hand, where

the Upper Cretaceous formations are so widely developed, true white

chalk, in the ordinary sense of that term, does not exist.

Fig. 239: Ananchytes ovatus. White chalk, upper and lower.

Fossils of the White Chalk.—Among the fossils of the white chalk,

echinoderms are very numerous; and some of the genera, like

_Ananchytes_ (see Fig. 239), are exclusively cretaceous. Among the

Crinoidea, the _Marsupites_ (Fig. 242) is a characteristic genus. Among

the mollusca, the cephalopoda are represented by Ammonites, Baculites

(Fig. 229), and Belemnites (Fig. 226). Although there are eight or more

species of Ammonites and six of them peculiar to it, this genus is much

less fully represented than in each of the other subdivisions of the

Upper Cretaceous group.

Among the brachiopoda in the white chalk, the _ Terebratulæ_ are very

abundant (see Figs. 243-247). With these are associated some forms of

oyster (see Fig. 251), and other bivalves (Figs. 249, 250).

Fig. 240: Micraster cor-angumum. White chalk. Fig. 241: Galerites

albogalerus. White chalk. Fig. 242: Marsupites Milleri. White chalk.

Fig. 243: Terebratulina striata. Upper white chalk. Fig. 244:

Rhynchonella octoplicata. Upper white chalk. Fig. 245: Magas pumila.

Upper white chalk. Fig. 246: Terebratula carnea. Upper white chalk.

Fig. 247: Terebratula biplicata. Upper cretaceous. Fig. 248: Crania

Parisiensis. Inferior or attached valve. Upper white chalk. Fig. 249:

Peten Beaveri. Lower white chalk and chalk marl. Fig. 250: Lima

spinosa. Upper white chalk.

Among the bivalve mollusca, no form marks the Cretaceous era in Europe,

America, and India in a more striking manner than the extinct genus

_Inoceramus_ (_Catillus_ of Lam.; see Fig. 252), the shells of which

are distinguished by a fibrous texture, and are often met with in

fragments, having probably been extremely friable.

Of the singular family called _Rudistes_ by Lamarck, hereafter to be

mentioned as extremely characteristic of the chalk of southern Europe,

a single representative only (Fig. 253) has been discovered in the

white chalk of England.

Fig. 251: Ostrea vesicularis. Upper chalk and upper greensand. Fig.

252: Inoceramus Lamarckii. White chalk.

_Radiolites Mortoni_, Mantell. Houghton, Sussex. White chalk.

Diameter one-seventh nat. size.

Fig. 253. Two individuals deprived of their upper valves, adhering

together.

Fig. 254. Same seen from above.

Fig. 255. Transverse section of part of the wall of the shell,

magnified to show the structure.

Fig. 256. Vertical section of the same.

On the side where the shell is thinnest, there is one external furrow

and corresponding internal ridge, _a_, _b_, figs. 255, 256; but they

are usually less prominent than in these figures. The upper or

opercular valve is wanting.

The general absence of univalve mollusca in the white chalk is very

marked. Of bryozoa there is an abundance, such as _Eschara_ and

_Escharina_ (Figs. 257, 258). These and other organic bodies,

especially sponges, such as _Ventriculites_ (Fig. 238), are dispersed

indifferently through the soft chalk and hard flint, and some of the

flinty nodules owe their irregular forms to inclosed sponges, such as

Fig. 259, _a,_ where the hollows in the exterior are caused by the

branches of a sponge (Fig. 259, _b_), seen on breaking open the flint.

Fig. 257: Eschara disticha. White chalk. Fig. 258: Escharina oceani.

White chalk. Fig. 259: A branching sponge in a flint, from the white

chalk.

The remains of fishes of the Upper Cretaceous formations consist

chiefly of teeth belonging to the shark family. Some of the genera are

common to the Tertiary formations, and some are distinct. To the latter

belongs the genus _Ptychodus_ (Fig. 260), which is allied to the living

Port Jackson shark, _Cestracion Phillippi,_ the anterior teeth of which

(see Fig. 261, _a_) are sharp and cutting, while the posterior or

palatal teeth (_b_) are flat (Fig. 260). But we meet with no bones of

land-animals, nor any terrestrial or fluviatile shells, nor any plants,

except sea-weeds, and here and there a piece of drift-wood. All the

appearances concur in leading us to conclude that the white chalk was

the product of an open sea of considerable depth.

Fig. 260: Palatal tooth of Ptychodus decurrens. Lower white chalk.

The existence of turtles and oviparous saurians, and of a Pterodactyl

or winged lizard, found in the white chalk of Maidstone, implies, no

doubt, some neighbouring land; but a few small islets in mid-ocean,

like Ascension, formerly so much frequented by migratory droves of

turtle, might perhaps have afforded the required retreat where these

creatures laid their eggs in the sand, or from which the flying species

may have been blown out to sea. Of the vegetation of such islands we

have scarcely any indication, but it consisted partly of cycadaceous

plants; for a fragment of one of these was found by Captain Ibbetson in

the Chalk Marl of the Isle of Wight, and is referred by A. Brongniart

to _ Clathraria Lyellii,_ Mantell, a species common to the antecedent

Wealden period. The fossil plants, however, of beds corresponding in

age to the white chalk at Aix-la-Chapelle, presently to be described,

like the sandy beds of Saxony, before alluded to (p. 293), afford such

evidence of land as to prove how vague must be any efforts of ours to

restore the geography of that period.

Fig. 261: Cestracion Phillipi; recent.

The Pterodactyl of the Kentish chalk, above alluded to, was of gigantic

dimensions, measuring 16 feet 6 inches from tip to tip of its

outstretched wings. Some of its elongated bones were at first mistaken

by able anatomists for those of birds; of which class no osseous

remains have as yet been derived from the white chalk, although they

have been found (as will be seen on page 299) in the Chloritic sand.

The collector of fossils from the white chalk was formerly puzzled by

meeting with certain bodies which they call larch-cones, which were

afterwards recognised by Dr. Buckland to be the excrement of fish (see

Fig. 262). They are composed in great part of phosphate of lime.

Fig. 262: Coprolites of fish, from the chalk. Fig. 263: Baculites

anceps. Lower chalk. Fig. 264: Ammonites Rhotomagensis. Chalk marl.

Lower White Chalk.—The Lower White Chalk, which is several hundred feet

thick, without flints, has yielded 25 species of Ammonites, of which

half are peculiar to it. The genera Baculite, Hamite, Scaphite,

Turrilite, Nautilus, Belemnite, and Belemnitella, are also represented.

Chalk Marl.—The lower chalk without flints passes gradually downward,

in the south of England, into an argillaceous limestone, “the chalk

marl,” already alluded to. It contains 32 species of Ammonites, seven

of which are peculiar to it, while eleven pass up into the overlying

lower white chalk. _ A. Rhotomagensis_ is characteristic of this

formation. Among the British cephalopods of other genera may be

mentioned _Scaphites æqualis_ (Fig. 266) and _Turrilites costatus_

(Fig. 265).

Chloritic Series (or Upper Greensand).—According to the old

nomenclature, this subdivision of the chalk was called Upper Greensand,

in order to distinguish it from those members of the Neocomian or Lower

Cretaceous series below the Gault to which the name of Greensand had

been applied. Besides the reasons before given (p. 282) for abandoning

this nomenclature, it is objectionable in this instance as leading the

uninitiated to suppose that the divisions thus named Upper and Lower

Greensand are of co-ordinate value, instead of which the chloritic sand

is quite a subordinate member of the Upper Cretaceous group, and the

term Greensand has very commonly been used for the whole of the Lower

Cretaceous rocks, which are almost comparable in importance to the

entire Upper Cretaceous series. The higher portion of the Chloritic

series in some districts has been called chloritic marl, from its

consisting of a chalky marl with chloritic grains. In parts of Surrey,

where calcareous matter is largely intermixed with sand, it forms a

stone called malm-rock or firestone. In the cliffs of the southern

coast of the Isle of Wight it contains bands of calcareous limestone

with nodules of chert.

Fig. 265: Turrilites costatus. Lower chalk and chalk marl. Fig. 266:

Scaphites æqualis. Chloritic marl and sand, Dorsetshire.

_Coprolite Bed._—The so-called coprolite bed, found near Farnham, in

Surrey, and near Cambridge, contains nodules of phosphate of lime in

such abundance as to be largely worked for the manufacture of

artificial manure. It belongs to the upper part of the Chloritic

series, and is doubtless chiefly of animal origin, and may perhaps be

partly coprolitic, derived from the excrement of fish and reptiles. The

late Mr. Barrett discovered in it, near Cambridge, in 1858, the remains

of a bird, which was rather larger than the common pigeon, and probably

of the order Natatores, and which, like most of the Gull tribe, had

well-developed wings. Portions of the metacarpus, metatarsus, tibia,

and femur have been detected, and the determinations of Mr. Barrett

have been confirmed by Professor Owen.

This phosphatic bed in the suburbs of Cambridge must have been formed

partly by the denudation of pre-existing rocks, mostly of Cretaceous

age. The fossil shells and bones of animals washed out of these denuded

strata, now forming a layer only a few feet thick, have yielded a rich

harvest to the collector. A large Rudist of the genus Radiolite, no

less than two feet in height, may be seen in the Cambridge Museum,

obtained from this bed. The number of reptilian remains, all apparently

of Cretaceous age, is truly surprising; more than ten species of

Pterodactyl, five or six of Ichthyosaurus, one of Pliosaurus, one of

Dinosaurus, eight of Chelonians, besides other forms, having been

recognised.

The chloritic sand is regarded by many geologists as a littoral deposit

of the Chalk Ocean, and therefore contemporaneous with part of the

chalk marl, and even, perhaps, with some part of the white chalk. For,

as the land went on sinking, and the cretaceous sea widened its area,

white mud and chloritic sand were always forming somewhere, but the

line of sea-shore was perpetually shifting its position. Hence, though

both sand and mud originated simultaneously, the one near the land, the

other far from it, the sands in every locality where a shore became

submerged might constitute the underlying deposit.

Fig. 267: Ostrea columba. Chloritic sand. Fig. 268: Ostrea carinata.

Chalk marl and chloritic sand.

Among the characteristic mollusca of the chloritic sand may be

mentioned _Terebrirostra lyra_ (Fig. 269), _Plagiostoma Hoperi_ (Fig.

271), _Pecten quinque-costatus_ (Fig. 270), and _Ostrea columba_ (Fig.

267).

Fig. 269: Terebrirostra lyra. Chloritic sand. Fig. 270: Pecten

5-costatus. White chalk and chloritic sand. Fig. 271: Plagiostoma

Hoperi. White chalk and chloritic sand.

The Cephalopoda are abundant, among which 40 species of Ammonites are

now known, 10 being peculiar to this subdivision, and the rest common

to the beds immediately above or below.

Gault.—The lowest member of the Upper Cretaceous group, usually about

100 feet thick in the S.E. of England, is provincially termed Gault. It

consists of a dark blue marl, sometimes intermixed with green sand.

Many peculiar forms of cephalopoda, such as the _Hamite_ (Fig. 272),

and _ Scaphite,_ with other fossils, characterise this formation,

which, small as is its thickness, can be traced by its organic remains

to distant parts of Europe, as, for example, to the Alps.

Fig. 272: Ancyloceras spinigerum. Near Folkestone.

Twenty-one species of British Ammonites are recorded as found in the

Gault, of which only eight are peculiar to it, ten being common to the

overlying Chloritic series.

Connection between Upper and Lower Cretaceous Strata.—Blackdown

Beds.—The break between the Upper and Lower Cretaceous formations will

be appreciated when it is stated that, although the Neocomian contains

31 species of Ammonite, and the Gault, as we have seen, 21, there are

only three of those common to both divisions. Nevertheless, we may

expect the discovery in England, and still more when we extend our

survey to the Continent, of beds of passage intermediate between the

Upper and Lower Cretaceous. Even now the Blackdown beds in Devonshire,

which rest immediately on Triassic strata, and which evidently belong

to some part of the Cretaceous series, have been referred by some

geologists to the Upper group, by others to the Lower or Neocomian.

They resemble the Folkestone beds of the latter series in mineral

character, and 59 out of 156 of their fossil mollusca are common to

them; but they have also 16 species common to the Gault, and 20 to the

overlying Chloritic series; and what is very important, out of seven

Ammonites six are found also in the Gault and Chloritic series, only

one being peculiar to the Blackdown beds.

Professor Ramsay has remarked that there is a stratigraphical break;

for in Kent, Surrey, and Sussex, at those few points where there are

exposures of junctions of the Gault and Neocomian, the surface of the

latter has been much eroded or denuded, while to the westward of the

great chalk escarpment the unconformability of the two groups is

equally striking. At Blackdown this unconformability is still more

marked, for though distant only 100 miles from Kent and Surrey, no

formation intervenes between these beds and the Trias; all intermediate

groups, such as the Lower Neocomian and Oolite, having either not been

deposited or destroyed by denudation.

Flora of the Upper Cretaceous Period.—As the Upper Cretaceous rocks of

Europe are, for the most part, of purely marine origin, and formed in

deep water usually far from the nearest shore, land-plants of this

period, as we might naturally have anticipated, are very rarely met

with. In the neighbourhood of Aix-la-Chapelle, however, an important

exception occurs, for there certain white sands and laminated clays,

400 feet in thickness, contain the remains of terrestrial plants in a

beautiful state of preservation. These beds are the equivalents of the

white chalk and chalk marl of England, or Senonien of d’Orbigny,

although the white siliceous sands of the lower beds, and the green

grains in the upper part of the formation, cause it to differ in

mineral character from our white chalk.

Beds of fine clay, with fossil plants, and with seams of lignite, and

even perfect coal, are intercalated. Floating wood, containing

perforating shells, such as Pholas and Gastrochoena, occur. There are

likewise a few beds of a yellowish-brown limestone, with marine shells,

which enable us to prove that the lowest and highest plant-beds belong

to one group. Among these shells are _Pecten quadricostatus,_ and

several others which are common to the upper and lower part of the

series, and _ Trigonia limbata,_ D’Orbigny, a shell of the white chalk.

On the whole, the organic remains and the geological position of the

strata prove distinctly that in the neighbourhood of Aix-la-Chapelle a

gulf of the ancient Cretaceous sea was bounded by land composed of

Devonian rocks. These rocks consisted of quartzose and schistose beds,

the first of which supplied white sand and the other argillaceous mud

to a river which entered the sea at this point, carrying down in its

turbid waters much drift-wood and the leaves of plants. Occasionally,

when the force of the river abated, marine shells of the genera

_Trigonia, Turritella, Pecten,_ etc., established themselves in the

same area, and plants allied to _Zostera_ and _Fucus_ grew on the

bottom.