THE LAMMERMUIRS—THE BORDER LAND—GENERAL STRUCTURE OF SCOTLAND.
The interest which attaches to this division of our sketches of Scottish
geology is in no degree impaired by the consideration that the rocks,
all of them, belong to one or other of the systems which have already
passed under review. A belt of undisputed Silurian deposit here meets
us for the first time, flanked on all sides, and nearly throughout its
length, by the old red sandstone. Porphyritic hills, greenstone bosses
and dykes, and the various phenomena of trap intrusion and dislocation,
are again presented in many and very striking illustrative details. “The
border land,” physically as well as morally, could not well be without
its points of contention; and, accordingly, geologists have made “raide
across the marches,” and claimed as of Scottish origin an extensive
domain of the English NEW RED sandstone, or Permian system. Corncockle
Moor, too, and the quarries near Dumfries, unfold as curious a page in
the history of the old world as does the Crigup Lynn, hewn out of the
same family of rocks, of the stern warfare and fierce contendings which
adorn, as they likewise disgrace, the annals of the seventeenth century.
The GENERAL STRUCTURE of the district, as now indicated, is determined
in the main by the Lammermuirs, a high mountain-range of sedimentary
rocks, which formed the northern barrier of an extensive inland basin
or sea, and of which the Solway and Tweed occupy the central stretch or
depression. The old red sandstone was herein deposited, the strata of
which rest unconformably upon the older rocks. The carboniferous beds
succeeded, but at a period when the floor of the basin was elevated,
and the dimensions contracted; hence these beds, though reposing
conformably for the most part on those of the old red and not separable
on physical grounds, do not occupy the same extent of surface. Creeks
and bays existed around the silurian shores, into which the materials
of the sandstone were carried, and thus along the southern slope, from
St. Abb’s Head to Portpatrick, the old red is traceable in every opening
and indentation, running up in long narrow tongues, or detached stripes,
among the mountains. The coal series appear at various intervals in small
isolated basins, forming on the west the coal-field of Whitehaven, which
dips into the Solway, and on the east occupying from Kelso to Berwick,
the valley of the Tweed, where the metals lie in very thin bands, and
_underneath_ the mountain limestone. Here are porphyries, which have
disrupted and broken through the old red sandstone, and therefore,
corresponding in age to those of the Sidlaws, Ochils, and Pentlands; and
augite traps and greenstone, scattered over the coal-measures, which are
as clearly the product of the movements that issued in the elevation of
Arthur’s Seat and the Lomonds.
The Lammermuirs have an extent of nearly one hundred and fifty miles
in length, by an average breadth of twenty-five to thirty miles. The
axis of the chain runs from E.N.E. to W.S.W., broken at intervals by
rivers and their divergent valleys, and constituting the great frontier
barrier of Scotland. The Lowthers, Corston-cone, Queensberry, and the
high grounds along the upper right bank of the Nith, form outliers or
extensions of the general mass. Long regarded as furnishing a true
type of _Graywacke_ rock, the Lammermuirs are now, by general consent,
admitted into the family of SILURIANS, bearing affinities both to
the Upper and Lower series, and partaking likewise in some of the
characteristics of the Cambrian group. The eastern division of the chain
consists of very thick beds of a coarse brecciated rock, covered on the
southern side by a fine-grained clay slate. In Kirkcudbrightshire, the
slate-band and conglomerate, seen on the main land, and at White Bay,
in Little Ross Island, are very closely allied in their mineralogical
characters. And in the center division, about Innerleithen, the intrusive
traps constitute a marked and interesting feature, more particularly
as they there assume a subcrystalline granite structure, and convert
the sedimentary deposits into hard flinty slates, or Lydian stone.
The organic remains are not abundant: they are scattered, too, at wide
intervals, but still sufficiently characteristic of the formation. They
consist of graptolites, encrinites, trilobites, and several genera of
shells. The list of conchiferæ, in some beds, is almost entirely Lower
Silurian, while the _smooth Asaphi_ would seem to connect this range of
hills with the lower Silurian rocks of Tyrone and Fermanagh, in Ireland,
which have furnished the only other specimens yet detected in Britain.
The fossil localities are the lime quarries of Wrae, near Broughton,
Greiston slate quarry, near Traquair, St. Mary’s Isle, Kirkcudbright,
Loch Ryan, and Little Ross Island; and in certain graywacke beds
in Liddesdale, Mr. Nicol records the discovery of “fragments of
plants, not unlike the broken reeds, and other imperfect vegetable
remains, seen on some carboniferous sandstones.” The collection of
Lord Selkirk, from the vicinity of his residence, consists according
to Mr. Salter, of—_Terebratula semisulcata_, _Leptæna sarcinulata_,
_Atrypa reticularis_, _Bellerophon trilobatus_, _Natica_, _Turritellæ_,
_Murchisonia_, _Avicula lineata_, _Orthonaia cingulata_, _Phacops
caudatus_, _Beyrichia tuberculata_, and _Graptolites ludensis_. These
characteristic Upper Silurian fossils are accompanied by a _Leptæna
sericea_, and _Orthoceras tenuicinctum_ of Portlock, and appear to be
of the date of Wenlock shale. Their latest historian, indeed, ascribes
a vast indefinite antiquity to the whole range, and considers that the
depository matter has been _twice_ reduced to a muddy arenaceous state:
that a chain of hills existed in these parts at an age long anterior
to the Lammermuirs, and that another stratified formation has to be
intercalated in this district, between the oldest existing strata and the
parent rock, whence the sediment was derived. This opinion is founded
chiefly on the circumstance, that in none of the beds have there ever
been observed any fragments of granite, or the associated crystalline
gneiss and schists, while fragments of clay-slate and graywacke are not
uncommon amongst the conglomerate or coarser varieties. But, admitting
the truth of the statement, does it warrant the inference deduced? The
clay-slates and graywacke of the Highlands are equally destitute of the
inclosed granitoid portions so abundant in the superimposed conglomerates
of the old red; and, upon the supposition of an intensely but unequally
heated sea-bottom, and partial outbursts of irruptive matter, these
appearances in the Lammermuirs, where certain strata contain included
fragments of similar consolidated rock, receive an intelligible and less
extravagant explanation. We more willingly accede to the conclusion
of Mr. Nicol, that we have still here much of the original shape and
contour of this ancient land; that the rivers and valleys are all in
their olden places, and that since the elevation of the group there has
been no important change in their general character and physical outline.
The Lammermuirs, too, connected as they are with the great silurian
deposits of England, Wales, and Ireland, lend confirmation to the theory,
repeatedly adverted to, that these mountains, as well as those of the
preceding epoch, formed the land on which grew part at least of the
exuberant vegetation entombed in the coal formations of Great Britain. It
may have been a peninsula projecting into a sea, whose waves washed the
Grampians on the north, covered all the midland and eastern districts of
England on the south, and were bounded by the primary and silurian girdle
of rocks on the west. Through these depths roamed the successive races of
holoptychius, palæoniscus, gyracanthus, and megalichthys; the shallows
and bottom teemed with swarms of molluscs, trilobites, cephalaspes,
pamphracti; while the dense forests of ferns, palms, and pines, which
clothed the shores and uplands, have been distributed among the various
basins of the coal-measures.
Ascend the Eildons, or, as the route may be, Carterfell, Hartfell, or
Criffel, and witness the changes, as the different systems of rocks
were drifted into their places, and rose above that expanse of waters.
Criffel, the loftiest mountain on the west, is composed of granite, and
formed a solitary islet there, or one of a series of islands, of the
primary crystalline formation. The silurian chains, in their respective
positions, are next elevated to the surface. The old red sandstones
collect and form along their bases, spreading over vast areas all
around. These are lifted into day by the Eildons, and the numerous hills
of claystone porphyry, which give such diversity of character through
Liddesdale, Lauderdale, Cheviotdale, and the whole border landscape.
Carterfell, which consists of a dark greenstone trap, resting on a white
or light reddish sandstone, marks the upheaval of the carboniferous
strata, and probable retirement of the sea from these districts, where we
find no traces of any of the secondary or newer systems of rocks. Thus
the line of the Scottish Border, from Annan to Roxburghshire, consists
of the _under series_ of the coal formation passing down the Tweed,
by Kelso, Sprouston, Coldstream, to Berwick. The old red sandstone is
largely developed by Chester, Hawick, Melrose, Greenlaw, Dunse; and
again, after an interruption of trap and the coal-measures, it resumes
its course by Chirnside, Foulden, and Mornington, to the sea. Scales of
the Holoptychius and Dendrodus are found in the strata at Prestonhaugh,
near Jedburgh, and likewise at the Knock Hill, in Berwickshire. On the
higher grounds, from the Eildons to Hartfell and Peebles, the graywacke
and slate beds everywhere prevail, presenting at St. Abb’s Head, Selkirk,
and Ettrick Bridge, interesting specimens of crumpled and bent strata.
Remarkable veins of trap and calc-spar are to be observed near St. Mary’s
Loch; silver and other metallic ores are said to have been found in the
neighboring hills: near Moffat, gypsum, pyritous graywacke, and alum
slate, are very abundant—formations probably connected with the mineral
waters of Moffat Well and Hartfell spa. At Glendinning, in the parish of
Westerkirk, an antimony mine has been long wrought, which is about twenty
inches wide, and once rich in the valuable mineral. A vein of galena
or lead, lined with heavy-spar, crosses the Esk at Broomholm, below
Langholm, and here the usual series of shales, limestone, sandstone, and
thin bands of coal, are developed for miles, resting on the graywacke of
Hermitage, Ernton, and Witterhope Burn hills.
The valley of the Nith, from the pass of Dalveen to Barjarg, incloses
a space of nearly ten miles in length by four in breadth, filled with
red sandstone and beds of limestone, and exhibits one of those original
creeks or bays in the primary and silurian rocks which characterize this
ancient belt. The lower basin, toward Dumfries and the Solway, presents
the same series of extremely fine-grained strata. The small isolated
basin of red sandstone near Lochmaben, and which contains the celebrated
impressions of foot-marks in the beds at Corncockle Moor, as well as the
very limited patch of sandstone in the vale of the Annan near Moffat,
are probably referable to one and the same system with the above. And
what is that system—the Devonian or Permian? The position of all these
beds, and of others in Annandale, has long formed a fruitful subject of
discussion with geologists and practical engineers, whether to regard
them as an extension of the English new red, or to refer them to the
predominant rock of the country. The latter view is borne out so far by
the fact, that no borings, which have been both numerous and deep, have
penetrated to the coal metals. On Greenough’s map, on the other hand,
the former theory is adopted, where the coal-measures are represented as
extending _underneath_ from Canobie, through Annandale to Arkit Muir, and
as again emerging at Arbigland near Criffel. It has likewise been argued,
that the foot-impressions on the slabs near Dumfries and at Corncockle
Moor, have no analogues anywhere in the true old red of Scotland,
while they are abundantly represented by the foot-prints of the newer
sandstones of England and America. But now indeed such proofs are not
wanting in America, that wide field of all organic things; the discovery
has been made and assented to by the most competent authorities, that,
in the old red sandstone of Pennsylvania, and 8,500 feet below the
upper part of the coal formation, reptilian foot-prints are numerously
and distinctly impressed, allied in form to the tread of the existing
alligator. Then the larger orthoceræ and other testaceæ, found so
plentifully in the limestones of Closeburn and Barjarg, also at Linburn
and Shielgreen, would seem to claim very clearly and decidedly for the
deposit in the middle basin of Nithsdale a Devonian origin.
We must refrain from entering upon the details of the extensive
geological fields which have just been glanced at. A volume would
not suffice to exhaust the subject. But, rapid as our sketch has
necessarily been, enough has been advanced to show how intimately
connected with the great fundamental principles of the science, and
with the original configuration of our planet more especially, are all
the deeply-interesting phenomena of the region in question. If at times
the reader, as well as explorer, is apt to complain of the dryness
of particulars, that the nomenclature is harsh and scholastic, how
delightful to close, even in imagination, the day’s excursion amid these
lovely valleys, to be steeped in fairy lore by St. Mary’s Loch, to dream
of legends and minstrelsy until morning dawn by Newark’s Tower. Nith,
Gala, Ettrick, Yarrow, Teviot, silvery Tweed!—who, indeed, will ever
associate with the minerals, sections, and technicalities of geology.
Still how refreshing to lie down, traveled and weary-worn, by their
green pastures and pure waters. How beautifully do these rivers, all of
them with an origin so remote, hold on in their pebbly courses—winding
and gathering from so many rills amidst the pastoral uplands—“making
sweet music with th’ enameled stones”—and anon with all their affluents
sweeping in placid majesty to the main. Hither will men of all
professions and pursuits,—the sportsman, poet, philosopher,—eagerly and
rejoicingly resort, each with his own object or his own care. Finely, in
imperishable verse, has the truth been expressed of that many-colored
tide of human life on which all are embarked—
“Which, though it change in ceaseless flow,
Retains each grief, retains each crime”—
—but NOW these streams, dales, and hills retain no impress of strife or
blood; and hence will the wish, age after age, breathe from many a heart—
“By Yarrow’s stream still let me stray,
Though none should guide my feeble way:
Still feel the breeze down Ettrick break,
Although it chill my withered cheek;
Still lay my head by Teviot stone,
Though there forgotten and alone.”
And so human life will glide away, a new epoch will come, and the
development of man’s immortal being will be accomplished in the new and
brighter earth that is to arise.
We here close our review, over Scottish ground, of the earliest lessons
to which we have access of the mineral structure of our globe. All the
primary, palæozoic, and older class of the secondary rocks, are largely
developed, leading us, indeed, a very little way into the inner chambers
of the earth, but back through periods of time into the records of its
history, for which the science itself furnishes no real standard of
measurement. Vast, inconceivable cycles pass before the imagination, and
fascinate the speculatist, while the sober inquirer pauses, doubts—nay,
startles—at such remote undefined annals of creation. The legends and
chronicles of Scotland are old indeed; but give geologists their own
way, and what an antiquity would they assign to the mountains, valleys,
and rivers of ancient Caledon! And yet, true it is, no rocks on the face
of the earth can claim a deeper origin, an earlier arrangement, a more
ancient ascent above the waters, than those whose nature and position we
have so cursorily described.
Leaving for the present the question as to Time, geology has this
advantage, in facilitating an acquaintance with its principles, that
its lessons are as general as they are particular. Go where you will
the record is before you, so that, generally speaking, what is observed
of its subject in one district or country, or even continent, has its
counterpart in some other place near or remote. The rocks of Scotland
are all on the great scale, not solitary and individual specimens, but
wide-spread formations along the face of the country. With scarcely a
single exception, every class of rocks described in our course stretches
from sea to sea over the island. The structure of Scotland is peculiar
in this, that the bearing and the strike of the various strata, are
correspondent and continuous. Hence the parallelism of the great straths
and valleys. The principal rivers are observant of the same law. The
several formations, from the primary crystalline to the coal and upper
sandstones, have a common axis of elevation from nearly E. N. E. to W. S.
W., partaking more of an equatorial than of a meridional direction. The
porphyries and chains of the older traps maintain a similar direction.
The greenstones and basalts, polygonal and jointed, or otherwise, are
for the most part to be found _within_ the area of the coal measures, or
rising along the out-crop of the basins. Hence a description of any one
locality will generally, in respect of the same series of rocks, be found
applicable to another. The student may indifferently begin his researches
as his convenience or sojourn for the time may direct. And whether it be
the granite on the coasts of Aberdeen or of Arran—the schists of Glenisla
or the Mull of Cantire—the silurian of St. Abb’s Head or Portpatrick—the
devonian of Stonehaven or Girvan—the porphyries of Dundee or Largs—the
shales and limestones of St. Andrews, Glasgow, or Ayr—the columnar
basalts of Earlsferry, Orrock, Campsie, or Staffa—the lesson throughout
will be one and the same, either as respects the mineral texture or
the geological position of the rocks examined. A section, therefore,
commencing at Ben Nevis and terminating at Kirkcudbright on the Solway,
would present the very same series in all the main phenomena of
superposition, structure, dislocation, and fossil remains, as the section
adopted from Ben-Mac-Dhui to the Cheviots. Granite, gneiss, quartz
rock, mica schist, and clay slate, underlie the old red sandstone which
traverses the upper district of Stirlingshire. The traps of the Campsie
Hills have thrown up, and form the boundary of the great coal-basin, of
which Glasgow constitutes the center, and within whose area and suburbs
are exhibited all the most striking features of the basalt and greenstone
family—the elevation at the Necropolis beautifully showing the effects
of their intrusion, and the induration of the sedimentary deposits. On
the south, the coal metals are again succeeded by the old red sandstone
and the porphyries, which in their turn are replaced by the silurian or
graywacke rocks of the border counties. The section throughout is of
the most varied and instructive character, diversified by the grandest
mountain scenery, the loveliest of the Scottish lakes, and a development
of the arts and sciences over inexhaustible coal and iron treasures which
has rendered the name of the western metropolis illustrious among the
cities of the world.
Should the geologist desire to extend his researches along the
western coast and among the islands, he will experience an additional
interest, arising chiefly from the numerous junctions of the different
formations or sets of rocks which the constant erosion of the Atlantic
has everywhere exposed to view. Gigantic isolated portions of granite
or syenite, bared all around, are to be seen on every headland. The
twistings and flexures of gneiss and the schists are frequent and
remarkable. Columnar basalt, similar to Staffa, fringes the base of
every islet and promontory; and from appearances like these, he will
invariably infer the presence of the carboniferous deposits, which, in
small detached patches are of common occurrence. Here, likewise, are
to be found the lias and oolites, in marginal stripes on several of
the islands, easily distinguished by their characteristic fossils,
and giving unequivocal indications of a far greater extension, and
continuity with the main land, ere the inroads of the sea had broken up
and parted so much of the aboriginal structure of the district. The _vi
et sæpe cadendo_ of geological agency—the convulsions of subterranean
forces, and the destroying powers of water—are exhibited in all their
grandeur, where, in the face of cliffs exposed to their foundations,
the hardest rocks may be observed yielding to every wave, and the whole
inner machinery of granitic and basaltic dykes which upheaved them from
their basis traced in their most varying forms and complicity. Out of the
Ægean a finer group of islands is nowhere to be threaded—some scarcely
raised above sea-level—some towering into the clouds, as in the lofty
peaks of Mull, Jura, and Rum, with an altitude almost equal to their
length—most of them glorying in names soft and euphonious as the choicest
of classic Greece—and yet, all fragmentary and disrupted, as if but
yesterday shivered by the thunder cloud. Skye exhibits an epitome not
of the islands only, but nearly of our whole British geology, in which
there is every variety of trap, combined with the primary series—coal,
white sandstone, and limestone—the lias and oolites of secondary
formation—and mountains 3,300 feet in height, composed of Labrador
feldspar and hypersthene, whose crystals in the dark composite mass rival
in structure, if not in beauty, the stalactitic concretions of the Spar
Cave itself. Rocks, too, are here, of metamorphic texture, to which a
Macculloch did not venture to assign a name or position in his list.
And the serrated jagged pinnacles of the Coolin ridge, with the black
Coruisk inclosed as in a crater, who will attempt to describe—unlike to
everything else in bleak, naked, precipitous grandeur! The poet of the
Isles has sketched the picture—
“Such are the scenes, where savage grandeur wakes
An awful thrill that softens into sighs;
Such feelings rouse them by dim Rannoch’s lakes,
In dark Glencoe such gloomy raptures rise:
Or farther, where, beneath the northern skies,
Chides wild Loch-Eribol, his caverns hoar—
But, be the minstrel judge, they yield the prize
Of desert dignity to that dread shore
That sees grim Coolin rise, and hears Coriskin roar.”
ENGLAND.
PART II.
CHAPTER I.
ENGLAND—GENERAL SKETCH.
Differing as England does in people, manners, language, laws, and
institutions from Scotland, a still greater difference will be found
to exist in the physical structure, the mineral qualities, the organic
remains, and in all the other phenomena of her geological development.
In the ascending series of rocks, Scotland furnishes only a few steps of
the building—the lower courses of a gigantic pyramid; across the borders,
strata upon strata follow each other in regular gradation, until they
attain their apex of elevation in the center of the capital. Another
distinction exists in the quantity and extent of those rocks which are
common to both countries. All the primary, transition, and igneous
formations are more abundant in the northern division of the island,
constituting nearly three-fourths of its surface, while in the southern
division they do not amount to a fiftieth part; but, on the other hand,
the secondary and tertiary formations, which in Scotland are scarcely
recognized, or only found in patches, form in England about two-thirds
of its superficial area. Hence, on English ground, a new interest begins
as a totally new series of mineral strata rises into view, and all
charged with types and families of creatures of equally new and marvelous
organization.
The new series of rocks to be described, are termed the Permian,
triassic, oolitic, cretaceous, and tertiary systems. Some of these
deposits are of vast thickness and extent. They all abound in fossils,
some in the greatest profusion, others only in the rarest and most
remarkable types. In consequence of these accumulations, England, as
compared with her sister kingdom, may be described as the full organic
form in bones, muscles, and fleshy appendages, plump and rounded all
over, where one sees little of the framework or internal ossification.
The great masses are so covered over, the ribs and members are so silted
up, that the ridges and hills of the country, save on the outskirts,
dwindle into insignificance. Every original depression has been
concealed, new increments of matter are everywhere added, layer upon
layer superinduced, until the older fabric is nearly obliterated, or only
at wide intervals observed to rise above the surface. Scotland exhibits
the huge trunk, stripped and laid bare; every yielding thing has been
eroded and torn off; and little remains, except the giant skeleton, the
lineamentary fragments of the primeval world.
What is common to the two countries, among the primary and crystalline
rocks, occupies the whole western line of coast. The eastern shores of
Ireland, correspond in mineralogical character with the opposite shores
of Scotland, England, and Wales, where a great silurian belt covers,
almost continuously, both lines of coast. These districts have thus all a
common origin, are all of the same geological epoch, and were probably at
one period more united than appearances now indicate. The Cumbrian group
is isolated from the other portions of the system, and, as described by
Professor Sedgwick, comprehends the lowest fossiliferous beds in the
island, or perhaps as yet known in the crust of the globe. The elaborate
work of Sir R. I. Murchison on “THE SILURIAN SYSTEM,” has made every one
acquainted with the extensive deposits in Wales and Cornwall, in which
the divisions of the system are fully pointed out, their fossil contents
amply detailed, and their relations to analogous deposits in other parts
of the world satisfactorily demonstrated. Through all these regions,
therefore, we are again carried back among the earlier records already
noticed. Coincident with the same are the old red sandstone deposits
which stretch along the base of the more highly-inclined silurians,
covering the greater portion of Herefordshire and Devonshire; and here,
as in Scotland, the sandstones and conglomerates are immediately
succeeded by the rich treasures of the carboniferous age. In the rocks of
the three families lie, in profuse abundance, the organic remains of the
epochs which produced them—cast like wreck among the silts and sands now
hardened and upheaved into mountains—the peaks of Skiddaw and Snowdon, of
Plinlimmon and Helvellyn, once the beaches or floors of our ancient seas.
The Cumberland group of mountains, with its varied scenery and lakes, is
surrounded with the carboniferous rocks—as bright and lovely a picture,
set in a framework of jet or ebony, as the mind can contemplate. The
great _scar_, or mountain limestone, constitutes the base of the coal
series, resting on the old red conglomerate. This calcareous deposit is
of vast thickness, range, and extent—a concrete mass of animal remains
of five or six hundred feet. It presents the outline of a great coral
reef which anciently fringed the center cluster of the lake mountains:
and is still, with a few breaks, traceable along their wide and irregular
circumference. The sublime gorge of Gordale, the fine gray precipices
at the foot of Ingleborough, the caverns of Chapel-le-Dale and Clapham,
the rocks of Kirby Londsdale Bridge, and the great white terrace of
Whitbarrow, all derive their peculiar features from the effects of
erosive action on this formation. Diverging from the great terminal group
of the Cumbrians, the same deposit rises along the center of the district
into an independent ridge, taking up the most commanding positions—the
towering summit of Cross Fell on the one hand, and the celebrated High
Peak of Derby on the other, with all its wondrous caves and sparkling
fluor-crystals. The intermediate range of the Penine Alps, so denominated
by the Romans, is chiefly composed of the formation. The caves of
Kirkdale, the haunt of the British hyena and other extinct carnivora, are
situated in the same limestone, which is also the repository of numerous
lead mines, distinguished for their splendid metallic concretions and
fluor-spars. And here, too, are rivers which are lost in its dark
caverns; and that wonder of wonders, an astronomical paradox, where, from
the peculiar conformation of the hills and ravines, the sun does not rise
upon the inhabitants of Narrowdale, until he has passed his meridian,
and, as if to repair the loss, twice sets upon their horizon in the
course of every evening.
The coal-measures on the eastern side of this chain consist of the
Northumberland, Durham, Yorkshire, Nottingham, and Derby fields; on the
west and north, Whitehaven, Lancashire, Manchester, and North Stafford;
and on the south lie the basins of Ashborne, Loughborough, Wolverhampton,
and Dudley. The limestone skirts the out-crop of the metals in all these
localities, and thus serves to define the relations of the several
basins, and the cause of so many divisions in the field, occasioned by
the net-work of coral reef with which it has been originally penetrated.
The Wolverhampton basin is remarkable for the number of roots and stumps
of fossil trees found “in situ;” in the Derby field the railway tunnel
has exposed to view a group of sigillaria, forty in number, standing at
right angles to the plane of the beds, and not more than three or four
feet apart. Many of the tree fossils occupy a similar position in the
Northumberland and Newcastle coal-measures, reminding us of the submerged
forests of which, within the modern epoch, our sea-coasts furnish so
many examples. The Newcastle coal-field embraces an area of nearly eight
hundred square miles, being forty-eight miles in length by twenty-four
in breadth; the depth of the shaft is about three hundred fathoms, from
which are annually brought to the surface an average of six million tons
of coal. Sixty thousand persons are employed in the mining operations;
and fourteen hundred vessels are engaged in carrying the mineral to
London and its environs. The iron trade, connected with the different
English coal-fields, is upon a corresponding scale of magnitude, there
being little short of a million and a half tons of the metal annually
smelted and brought to the market, estimated to be worth, upon an
average, twenty millions of pounds sterling, and comprising within the
dimensions of this small island, as much as is exhumed by all the other
nations of the globe. The Newcastle coal-measures have been singularly
disturbed. A basaltic dyke, in some places eighteen yards wide, crosses
the southern part of the field, throwing down the metals on one side
ninety fathoms, and reducing the coal, at the distance of fifty yards,
to a state of cinder. This great dyke is traceable through a course of
seventy miles. As an example of the prodigious power with which these
subterranean forces have acted in the district, suffice it to mention,
that the limestone which underlies the coal metals has been elevated
nearly to the summit of Cross Fell, a mountain three thousand feet in
height; and estimating the thickness of the formation at four thousand
feet, the limestone, it will thus appear, has been raised above its
original position upward of six thousand feet.
The “green rock,” or basaltic greenstone of the South Staffordshire
coal-field, presents an interesting subject of geological research.
The center of the formation, as also that of the eruptive agency of
the tract, may be considered to be in the Rowley Hills, from which the
latter diverges on all sides, setting off innumerable veins or vertical
dykes, which are subdivided into smaller veins of a white color, and
everywhere penetrating and altering the shales, sandstones, and coal
metals. This igneous mass is more of an underground than super-surface
rock, occupying an area of twenty-five square miles, and rising only
into slightly-elevated and detached ridges. It corresponds, in mineral
characters and position, with another extensive effusion of trap in the
northern coal-fields, termed the “Whinsill.” This consists of a bed of
basalt, which has been injected among the strata of the coal-measures,
or, as some conjecture, has been poured over them as a cotemporaneous
formation—an overflood of lava produced during the deposition of the
mountain limestone group, and overlaid in turn by the succeeding series
of upper strata. Nearly the entire coal-measures of the north of England
have been more or less influenced by the eruption of the Whinsill, from
which dykes are thrown off in every direction, accompanied by phenomena
precisely similar to those exhibited in the coal districts of Scotland.
In both countries the same agencies are thereby demonstrated to have been
at work, originating in the same causes and producing similar effects,
and doubtless cotemporaneous in their operations over these and other
immense areas of the globe.
The rocks which constitute the SECONDARY and TERTIARY DIVISIONS in
the great geological series remain to be described. These, generally,
all range eastward from the older formations, to which they succeed
in the order of superposition. The line of section of the whole bears
from Whitehaven on the north-west, to Newhaven on the German Ocean by
south-east, where, along this course, every formation in the island is
intersected, ascending from the granite of the Cumbrian mountains through
all the intermediate series to the London clay and upper tertiaries. The
strata of which these formations consist are all, more or less, inclined
to the horizon, dipping under each other, and emerging in succession to
the surface. The outcrop is at right angles to the line of section, so
that each class of rocks rises to and faces the north-west, meeting the
eye of the geologist as they are in turn approached, and narrowing in
extent and receding in proportion as they are vertically removed from the
older systems.
Hence, were our researches to begin here, instead of in the Grampian
range, the starting point would necessarily be in the Lake mountains.
The crystalline primary rocks are developed, though sparingly, in this
district; and these, again, are surrounded and overlaid by the lowest
fossiliferous deposits, termed by their explorer and historian, “The
Cumbrian System.” All the driest details of the science are here too
amply relieved by the charming and magnificent scenery amidst which
they fall to be wrought out, where the inner and outer arrangements
of Nature, in the disposition of her works, are alike fitted to call
forth our admiration and delight. The author of “Elia,” who had spent
his days in a city life and had a prejudice against every other mode
of consuming time, upon his first excursion so far into the country,
describes Coleridge as “dwelling upon a small hill by the side of
Keswick, in a comfortable house, quite enveloped on all sides by a net
of mountains; great floundering bears and monsters they seemed, all
couchant and asleep.” It was enough; the soul of the man of genius was
stirred. He clambered up to the top of Skiddaw; and he waded up the bed
of the Lodore; and he satisfied himself, “that there is such a thing as
tourists call _romantic_.” But Lamb was never meant for a geologist, and
for science of any kind he had no aptitude. The athletic Wordsworth is
of a different mold, compacted of different elements, a mind stored with
the loveliest images; an understanding capable of sounding the depths of
any subject, and a thirst after knowledge from all and every source of
visible creation; and yet, mark how disparagingly he pronounces judgment
upon the student of unquestionably the most poetical of all the branches
of physical inquiry—“that fellow wanderer”—
“He who with pocket hammer smites the edge
Of luckless rock or prominent stone,
The substance classes by some barbarous name,
And hurries on;
and thinks himself enriched,
Wealthier, and doubtless wiser, than before.”
But men, it would seem, can no more command their moods of thought than
their prejudices. The poetical vein, like the geological, will burst
through all restraints to illustrate and vindicate the principles of
truth. We have often repeated, recalling them from memory, as the index
of our own frame of mind, while searching in the crypts of the primeval
world, the beautiful lines—a hymn to Nature’s works, and the study of
them—
“These barren rocks, our stern inheritance,
These fertile fields, that recompense our pains,
The shadowy vale, the sunny mountain top,
Woods waving in the wind their lofty heads,
Or hushed; the roaring waters, and the still.
They see the offering of my lifted hands—
They hear my lips present their sacrifice—
They know if I be silent, morn or even.”
Nor does it rest here, for directly is our science under a deep debt
of gratitude to the author of the “Excursion,” who sought for and
obtained the aid of the geologist’s pencil to fill up the outline
of his own sweet picture of the “Scenery of the Lakes.” Read side
by side, one may well ask, whether the descriptions of the poet, or
the sketches of the philosopher, are the more buoyant in diction,
diversified in illustration, or pregnant with devotional inspiration.
The work of Wordsworth and Sedgwick as a companion of travel is without
a rival, in which, and out of the darkest pages of creation, we see the
light of science falling upon, as if intending in verity to produce,
an illuminated volume, and over which, at one and the same moment
imagination is throwing her gayer and softer colorings. The physical
structure of the district, in fact, furnishes the key to all its
picturesque and delicious scenery. The geology and the poetry are the
counterparts of each other. Wordsworth has drank deep at the fountains,
and told the story of the one: the lessons of the other have been read
by a kindred spirit, who has heard the mighty voice muttered in the dark
recesses of the earth, and, in his own eloquently impassioned diction,
Sedgwick has recorded the truths “of wisdom, of inspiration, and of
gladness; telling us of things unseen by vulgar eyes—of the mysteries
of creation—of the records of God’s will before man’s being—of a spirit
breathing over matter before a living soul was placed within it—of laws
as unchangeable as the oracles of nature.” And out of all the apparent
confusion, and multiplicity of objects so blended together, he has
brought “harmonies” to light, which are to have “their full consummation
only in the end of time, when all the bonds of matter shall be cast away,
and there shall begin the reign of knowledge and universal love.”
[Illustration: Structure of the Cumbrian Group.
1. Granite.
2. Skiddaw Slate.
3. Green Roofing Slate, Porphyry, &c.
4. Coniston Limestone.
5. Silicious Grits.
6. Ireleth Slates.
7. Slaty Flagstone.
8. Old Red Sandstone.
9. Carboniferous Limestone.
10. Magnesian Limestone, and New Red Sandstone.]
Thus, as seen in the preceding section, four geological systems are, in
this charming district of lakes and mountains, all clustered together
and rolled up for the convenient inspection of a few days’ rambles: The
Silurian, Devonian, Carboniferous, and Permian: and to these are to be
added the Granites, Porphyries, and Plutonic family of greenstones and
basalts.
CHAPTER II.
THE PERMIAN SYSTEM—NEW RED SANDSTONE.
The geological formations described are succeeded in the ascending order
by the PERMIAN system of deposits—a term borrowed from the department of
Perm in Russia, where the strata cover an area about twice the size of
France. This constitutes the new red sandstone of English geology, and
has many equivalents in other countries. Thus, in the lower division of
the group or true Permian, there occurs the Zechstein and Lower Bunter
series of strata: in the upper or triassic division, the equivalents
are the Upper Bunter and Grés Bigarré, or variegated sandstone, the
Muschelkalk and Keuper of French and German authors. The system is
largely developed in America, Africa, India and China; where, as in
Britain, the deposits are of extremely varied mineral characters,
consisting of grits, sandstones, marls, limestones, gypsum, and
rock-salt, each presenting its own family types of vegetable and animal
life.
The new red sandstone extends across England without interruption,
through the medial or central counties, and ranges nearly north-east by
south-west. The two great divisions of which it consists are everywhere
well marked, the dolomitic or magnesian limestone forming the base, and
giving character to the lower permian group; the upper triassic group
is sufficiently distinguished by the rock-salt deposit which is wholly
included in this part of the formation. Each, too, has its own peculiar
set of fossils. Those of the former are allied to animals that flourished
during the carboniferous period; two genera of fishes, the palæoniscus
and pylopterus, are common to both. The fauna and flora of the triassic
group are regarded as entirely new, neither borrowing from nor imparting
anything to illustrate the organisms of the older families of rocks.
The one series of strata thus represents the coming of a new, the other
records the departure of a past state of things.
In the central counties of England this deposit expands into a great
plain, surrounded on all sides by the coal-measures, while within its
own area several basins—as those of Leicester, Warwick, and South
Stafford—are included, being completely isolated by the new red. An
interesting economic question hence arises—Do the coal minerals occupy
the whole or any considerable portion, of the extensive area covered by
this formation? An equally important geological problem is connected
with the solution of the question—namely, What are the general relations
of the older to the newer deposits of the district? The researches of
Sir R. I. Murchison, and more recently, of the geological survey, have
shown that the three groups of stratified rocks in South Staffordshire,
the new red sandstone, coal-measures, and silurian beds, are each
unconformable to the other—that the upper rests indifferently upon the
two lower formations—and that where the old red occurs, the new is
sometimes in immediate contact. It is inferred from this, that there was
an uplifting of the silurian rocks, along with considerable denudation,
previous to the deposition of the carboniferous strata. Mr. Jukes has
observed pebbles of coal, in great abundance, in the lower beds of the
new red sandstone, and thence deduces the following conclusions:—1. That
there was a movement and denudation of the coal-measures, amounting,
in some localities, to their entire destruction and removal, before
the deposition of the new red sandstone. 2. That, subsequently to the
deposition of the new red sandstone, there was a very great movement of
all these rocks, producing their present faults and inclined positions.
3. That the boundaries of the South Staffordshire coal-field, as far
as examined, present examples of three kinds of relation between the
coal-measures and new red sandstones; _i. e._, by conformable succession;
by fault, the coal-measures being present on the downcast side; and,
thirdly, where the destruction of the coal-measures has brought the
new red sandstone into immediate contact with the silurian strata. The
author of this paper is farther of opinion that, while there is a great
probability that the larger part of the new red sandstone plain conceals
productive coal-measures, there is the presumption that these will not be
found at a depth of less than 500 or 600 yards below the surface.
Corresponding with these views it will be remembered that, after the
deposition of the coal-measures, there succeeded a period of violent
plutonic action, whereby the formation was dislocated, broken up
into smaller sections or basins, and pierced by the igneous rocks.
There would, consequently, during this season of paroxysm, be a vast
destruction of animal and vegetable life. The indurated crust would
everywhere undergo great trituration. Gravel, sand, and mud of every
quality would be cast along the shores, or silted up in the deeper
hollows. And then again would come a term of general repose, as the
angry elements subsided, exhausted by their own violence. The scene was
actually or nearly as described; and, in the aspect of the older denuded
and uplifted rocks, as above represented, there are the most striking
evidences of the agitations of the period. The exuberant flora of the
carboniferous age, suffered prodigiously, or became utterly extinct.
Conglomerates were formed which exhibit few traces of organic life.
To these succeeded the vast areas of the fine-grained sandstones, and
gypseous and saliferous marls, everywhere nearly horizontal, and still
undisturbed on their ancient beds. The tribes of animals were abridged
in numbers, changed or modified in structure, so as to suit the altered
state of things. The rain-drop, ripple-mark, and foot-print are all
witnesses to be adduced of the mighty change, as they are all proofs of
the doings of Him who holds the waters in the hollow of his hand, makes
the clouds to distill in showers, issues his command to the hurricane and
the earthquake, and restores in renovated beauty the face of nature.
The lowest bed of the formation is the magnesian limestone, which derives
its name from the quantity of carbonate of magnesia distributed through
the matter of the rock, amounting in some instances to as much as sixty
per cent. It is likewise called the _dolomitic_ limestone, from M.
Dolomieu, who first investigated its granular crystalline structure. This
limestone is generally of a yellow color, glimmering luster, passing
occasionally into blue and brick-red varieties, and exfoliates in thin
plates, or breaks up in large botryoidal masses. In this form it occurs
at the cliffs of Durham, where it assumes the grouping and arrangement
of chain-shot; and, as the beds are distinctly stratified, the face of
the rock has a very striking and pleasing effect. In the more southern
counties, this formation exists generally in the form of a conglomerate,
supposed to be derived from the debris of the older carboniferous
limestone united by a dolomitic paste; thus illustrating the source and
mode of the deposit, while in the organic remains there has been traced
a regular gradation between the types of the older sub-carboniferous and
the successive newer strata.
Let us consider some of the more remarkable forms, tracings, and
ingredients of the formation.
I. THE ORGANIC REMAINS are scanty as compared with those of the age
immediately anterior. The vegetable forms, as yet detected, are new and
distinct. The fishes consist of six or seven genera, and about as many
different species. And here commences, it is supposed, the singular
change in their ossification, for which science can assign no reason,
as it cannot detect the least appearance of graduation into the new,
for the first time, begun and completed change. The fishes of the
formation present the HOMOCERCAL—that is, the equally-lobed, or one-lobed
tail-fin,—a structure peculiar to existing races, with the exception
of the shark, sturgeon, and a few others, and form a striking contrast
to those in the antecedent groups, which were all possessed of the
HETEROCERCAL, or unequally-lobed tail-fin.
[Illustration: Heterocercal. Homocercal.]
The Permian system of strata has hitherto been noted for the introduction
of walking, air-breathing animals; hence it has been a canon of the
science, that in these deposits lie entombed the last links of that
ancient chain of organic life which prevailed from the beginning,
and also the first terms of the new series which attained to such
monstrosities and prolific exuberance in the succeeding epoch. Doubtful
as to the existence of reptilian and ornithic creatures during the
carboniferous period, both forms of creation are here distinctly
manifested; and, in the higher members of the triassic group, birds and
reptiles have left traces of their path. Thus remarkably defined, in an
invariable chronological series, was the new red sandstone formation; all
the ancient types of organic life were disappearing; completely new forms
had just begun to replace them. But, while we are writing, the discovery
has been announced that, so old as the devonian age, reptiles existed;
alligator-like foot-prints, in regular alternating order, have been found
impressed in the old red sandstone, near Pottsville in Pennsylvania, and
by Mr. Lea, their discoverer and American conchologist, the animal which
owned them has been named the SAUROPUS PRIMÆVUS. A revolution in geology
is decreed in the words. Many divisions in the systems of rocks will have
to be revised, many distinctions altogether obliterated, theories of
development and of many other things are now sadly misplaced, and out of
keeping with the newly-declared order and progress of organic life.[7]
But without venturing at present to enter upon the consequences to
palæontology involved in this important discovery, we proceed with the
known and recognized history of the formation in question.
The organic remains contained in the upper, or triassic group, differ
considerably from those of the lower division of beds.—While the same
families of vegetable fossils are preserved which characterized the
coal-measures, the particular species and genera have disappeared.
About twenty species of ferns and coniferæ, a few calamites, several
fucoid plants, and a gigantic genus named _Voltzia_, and resembling
the Araucaria or Norfolk Island fir, comprise the thinly-scattered
specimens of the flora of the period. The quarries at Coventry yield some
undetermined stems of trees, and leaves like those of our thick-ribbed
cabbages have been found in the strata near Liverpool. The animal remains
are more numerous as well as varied in their structures; some, indeed,
altogether anomalous in their organization, and foot-prints of the most
puzzling characters and dimensions. There are several new types of
mollusca and crinoidea, among the latter the _Encrinus formosus_, one of
the most beautiful forms in any department of the animal kingdom. The
fishes of the placoid order consist of seven genera and fourteen species,
of ganoids three genera and seven species. The REPTILIA supply the
marvels of the period. Prof. Owen has described six distinct genera from
these singular fossils, in which he has established an affinity to the
batrachia. From the curiously-complicated texture of the teeth, the term
_labyrinthodon_ has been given to one genus, while the same authority
suggests, that the foot-impressions to which the term _cheirotherium_
had already been applied, might belong to this animal. The two genera,
_claydyodon_ and _rhyncosaurus_, are remarkable specimens of organic
structure, the latter combining the lacertian type of skull, with
edentulous jaws, which impart to the forepart of the head the profile of
a parrot.
II. The ICHNOLITES, or foot-prints, constitute a marked feature of the
formation. These geological phenomena were first introduced to the
notice of the public, about twenty years ago, by the late Dr. Duncan
of Ruthwell, when his announcement of the tracks and foot-marks of
animals along the ancient shores of Dumfries-shire created a sensation
among all classes hitherto unprecedented in the history of the fossil
department of the science. Robinson Crusoe was not more moved at the
discovery of a human foot-print on the sands of his lonely island in
the distant main, than were men of science, that traces of organic life
should thus be stereotyped in a deposit believed to be utterly destitute
of fossil relics. The creatures which had traced them, so like to
existing walking things, greatly increased the interest and the wonder
excited by the picture—the tread in all the freshness of yesterday of
the inhabitants of the antediluvian world! The phenomenon, however,
is now one of very general and common occurrence, several quarries in
the same locality—various places in England—in Saxony—in the states of
Connecticut, Massachusetts, and Virginia—having since been found to
yield the impressions in the greatest abundance, and of numerous types
and forms. And so well delineated and perfect are the impressions,
that, in the absence of any other reminiscence of the animal, these
characters have supplied the same aid to the skillful palæontologist that
the fragment of a bone, a fin, or a scale, did to Cuvier and Agassiz,
in the reconstruction of their organic models, and determination of
extinct genera and species. Birds and reptilian quadrupeds have all
contributed their share in the production of these curious lithographs.
Small toe-looking scratches, deep-palmy impressions, cloven hoof-like
indentations, and large gigantic hollows, have all been pictured in clear
distinct outline, covered up, and now again laid patent before you as
by the removal of the coverlit of your album. The Boston “Journal of
Natural History” communicates the following interesting account of the
researches of Dr. Deane:—“I have in my possession,” he says, “consecutive
impressions of tridactyle feet, which measure eighteen inches in length,
by fourteen in breadth, between the extremities of the lateral toes.
Each footstep will hold half a gallon of water, and the stride is four
feet. The original bird must have been four or five times larger than
the African ostrich, and therefore could not have weighed less than
600 pounds. Every step the creature took sank deep, and the substrata
bent beneath the enormous load. If an ox walk over stiffened clay, he
would not sink so deeply as did this tremendous bird.” Sir C. Lyell has
examined most of the foot-print districts in America, and found the
markings so numerous in some places as to resemble the puddled stand of
a sheep-fold or market-place; the very spots, doubtless, whither the
animals had resorted to quench their thirst, or screen them at mid-day
from the scorching heat. The various tracings become more distinct in
proportion to the distance from the scene of common rendezvous, and the
several routes by which they would return to their respective haunts, or
fields of pasturage, are clearly defined.
A considerable doubt hung over the accounts from time to time detailed
in the American journals and other publications, concerning these novel
and extraordinary discoveries, until they were more than matched by the
actual exhumation of the entire skeletons of the feathery tribes, far
exceeding in dimensions anything hitherto dreamed of in the science of
ornithology. The collections of Mr. Williams, and of Mr. W. Mantell,
from the alluvial deposits of New Zealand, utterly confounded all
previous calculations as to the size and bulk attainable by the bird
tribe. The tibia of a Dinornis, in the collection of the University
of Edinburgh, measures thirty-one inches in length, a femur seventeen
inches, the average circumference of both being nearly twelve inches.
From the foot to the top of the clavicle, the animal must have stood
at least thirteen feet in height. With the strut of the turkey, or the
pride of the peacock—head and neck of corresponding altitude—what a
denizen for the wilds and forests of this region of the new world! When
animals of similar dimensions, but of an earlier epoch, frequented the
beaches of Great Britain, we have to imagine the Cumbrian mountains,
the Penine chain, Derby Peak, and the lofty cliffs of Avon, surrounded
by an inland sea stretching by central France, the Black Forest, and
the Hartz mountains, and the shores all round silted with the materials
which now constitute the triassic group. Tortoises, turtles, bird-headed
lizards, birds themselves, salamander and frog-like creatures larger than
crocodiles, resorted as now to the sea-shore, in the cool fresh of the
evening or as tide-mark permitted, and regaled themselves at will on the
food which an ever-bounteous element furnished to their various wants.
The science which, from such _indicia_ as these, has succeeded in
determining not only the class, but the very form and habits, of the
animals which impressed them—no other traces remaining than those
petrified footsteps, covered up and hidden for ages—presents subjects of
study to the inquiring mind, which may well rank among the most valuable,
as well as curious, of human research. Is it not wonderful enough, that
organic impressions merely should have been transmitted so fresh and
entire, as to admit of classification, equal in scientific precision
to that of the families of living things? What matter of suggestive
reflection, inscribed on every page of that history? The tribes which
were created and flourished during the Permian-triassic age perished,
their earthy parts in most cases were all again absorbed by the earth,
dissipated or melted into the viewless air. Still there are memorials of
their existence, enduring and indelible, not of bones and sinews, but of
actions and habits, which the waters cannot obliterate, nor the floods
wash away! Man, a being of a different mold,—and with him
“Will all great Neptune’s ocean wash this blood
Clean from my hand?”
was the cry of instinctive dread—the foreboding of an assured conscience,
that the foul and guilty deed could never be effaced from the memory,
nor blotted from the records of creation. The foot-tread of the robber
has tracked him to his den; the minutest stain of blood has established
the crime of murder; a dream or vision of the night has pointed to the
mangled corse; a word uttered years after all was forgotten, or a rude
ditty chanted, have recalled the pictures of infancy, and the wanderer to
his home. Here we behold, stamped upon the rock, legible as the law upon
the tablets of the heart, intimations of the great universal law, that
an act once committed cannot be canceled; that a cause will be followed
by a sequence of effects; indefinite and ever-extending; and that the
Divine Spirit, which drew illustrations from the fields and taught wisdom
among the rocks of Horeb, still points the moral in these ineffaceable
memorials—that the recording angel so traces in the book of life the
story of every age, of every generation, of every individual, never to
be lost nor forgotten in that eternity whither their works do all follow
them.
III. Other singular records of the age under review have been preserved
in a similar manner; for the ocean itself has not failed to impress its
own movements on the sands laved by its waters. Hence the RIPPLE-MARK
has been detected, a recognized object of the science, and a phenomenon
to be seen in the sandstones of all ages and in all countries. The new
red, from the stiller waters perhaps in which it was formed, contains
everywhere beautifully minute and perfect delineations of the kind. The
_furrowed_ sandstones form a class by themselves, being selected in
the neighborhood of Brighton, as paving-stones for the streets, and in
the stable-yards as a protection for the horses against slipping. The
traces often of the more destructive violence of the sea, even of recent
date, in leveling villages, sweeping down plains, undermining cliffs,
overwhelming proud navies, are completely obliterated or forgotten, while
here the records of its still voice are indelibly engraven on the rock.
Observe other markings as you walk along the sea-shore on a summer’s
eve; how every wavelet that breaks upon the beach leaves its tiny
indentation, until the whole surface becomes furrowed as the reflex
of the ever-shifting flood; there spring up on every side innumerable
hillocks of sand, little blisters through which you detect the movements
of a creature within, and then the trail of the sea-worm is visible
all over. These were _vermes_ and _annelides_ burrowing in the sands,
in those ancient times, with instincts and habits precisely the same.
“We find,” says Dr. Buckland, “on the surface of slabs, both of the
calcareous grit, and Stonesfield slate, near Oxford, and on sandstones of
the Wealden formation, in Sussex and Dorsetshire, perfectly-preserved and
petrified castings of marine worms, at the upper extremity of holes bored
by them in the sand, while it was yet soft at the bottom of the water;
and within the sandstones, traces of tubular holes in which the worms
resided.” Nature here has changed little from her first models; the same
element, which is now chaffing upon the same materials of sand and rock,
has possessed through all time the same ingredients of life-stirring
action.
IV. Nor has the atmosphere—that twin ocean of upper earth—failed to give
evidence of the properties and laws by which it was then governed. The
RAIN-DROP, a singular unmistakeable marking, has also been detected upon
the sandstones of the period. These impressions have been described and
adopted by men of science as the true veritable indices of the showers
and cloud-falls of the old world. The very size of the drop may be
measured, the thick pattering of the rain compared with the scanty or
copious showers of the present day, and the very point detected from
which the wind blew on the day that these showers fell. What a curious
tale is thus disclosed, by a record, no modern version of which any one
will stay to read a moment longer than he can escape to shelter from
its influences. Astronomers tell us, upon the faith of the Herschels,
the measurements of Strüve, Bessel, and Mädler, that, notwithstanding
that light travels at the inconceivable speed of two hundred and
thirteen thousand miles in a second, the light from Uranus, one of our
own planetary system, does not reach our earth until two hours after
it has been emitted from its orb; that, from the edge of the Milky
Way, a star of the twelfth magnitude, careering in all the effulgence
of that luminous ether, cannot be descried until four thousand years
after the ray has begun its journeyings; and yet more, as the results
of the most rigid induction, it is revealed to us that the spots of
clouds, which under the resolving power of the best telescopes seem
more oval flakes or small specks of whiteness, are really distinct and
independent systems, floating at such an immeasurable distance that the
light has to wander millions of years before it can break in its faintest
morning-streak upon our horizon. Mark the analogy, therefore, ere you
scoff at the credulity of the geologist, or the power of the rain-drop
to transmit an image of itself through so many revolutions and ages of
the earth’s history. How impalpable a substance is light! how readily
effaced its impressions, or intercepted its brilliant colorings, by the
interposition of the frailest creation of matter—an insect’s wing, the
covering of a leaf, the disc of a flower-petal. But the light, thus
easily obliterated or dimmed on earth, has been maintaining its own
solitary independent course through every medium, every change, of upper
and netherworlds. The moment of its efflux from remotest orb, in depth
of infinite space, gave to every particle of that feebly or intensely
luminous beam, a separate being and direction, with no return back to
its parent source. And now, says the intelligent astronomer, as it drops
gently into the searcher of his telescope, that is a ray from yon far
distant unresolvable cluster of stars, or of astral systems, for millions
of years traveling through these incalculable heights, when as yet the
Chaldee sages had pointed no instrument to the heavens, nor the learned
of Memphis recorded an observation. Can you deny to other matter, argues
the geologist, a similar tenacity of self-preservation, the vitality of
impress which merely records the uniformity of the laws and constitution
of nature, and which intimates that, through all past time, there
were showers to cheer and to refresh the products of the earth? Truth
becomes more marvelous than fiction when traced in researches such as
these—showing the illimitable range over time and space permitted to
human inquiry—and producing, at the same time, things both of heaven and
of earth scarcely to be dreamt of in human philosophy.
V. But the economic and practically useful, no less than the speculative
or fanciful, form constituents of the new red sandstone formation. The
strata are not only indented with impressions of strange and doubtful
origin; they inclose, like those of the carboniferous system, treasures
of the greatest value; and nature, in ceasing to abound in one kind of
product, has been no less exuberant in others, equally contributive to
the comfort and convenience of man. In this class of rocks are situated
our great deposits of ROCK-SALT and gypsum, of the former of which,
beside supplying the demands of the home market, the mines of Cheshire
alone export from Liverpool upward of half a million of tons weight.
The distribution of the saline mineral is very general over the earth,
and by no means constant in its geognostic position; as, for example,
in Galicia, it is found among the tertiary deposits; in New York, it
occupies the middle of the silurians; while in Hungary, Poland, and
England, it is uniformly associated with the new red sandstone. Rock-salt
has been long known to and prized by mankind; it became an object of
taxation or tribute six hundred and forty years before the Christian era,
as narrated of Ancus Martins, “salinarum vectigal instituit;” and hence
centuries afterward, when Great Britain was in possession of the Romans,
the legions received salt as part of their pay or “salary.” Our richest
mines are in Cheshire, and along the districts watered by the Dee, the
Weaver, and the Mersey. The beds, or rather masses, are imperfectly
stratified, and vary in thickness from a few inches to 120 feet and
upward: gypsum and variegated marls may be regarded as _constants_ in the
formation, the gypseous deposits sometimes attaining the enormous depth
of 150 feet.
We speak of the beds of gypsum as _deposits_, in common with those of
the sandstone matrix in which they are imbedded. It appears, however, on
inquiring into the theory of their origin, that they are not strictly
such in the true sense of deposits—originally as gypseous deposits—but
altered limestones, metamorphosed by the action of gases which have
escaped from beneath, and permeated the calcareous mass. The carbonates
of lime have been converted into the sulphates of lime, by means of
gaseous emanations produced in unknown volcanic depths. Even the
dolomitic member of the group is supposed to have a like metamorphic
origin; the needful elementary agencies having entered into the parent
limestone, and converted it into the magnesian type. Why nature should
not have done these things directly, at the first off-throw, science
could not, perhaps, very satisfactorily answer the skeptically inquiring
mind; but, as the ingredients are all chemically well known, and more
especially as there is a vast laboratory ever at work, filled with
all kinds of elements, in her subterranean regions, any hypothesis of
formation is as rapidly established as it is conceived, and the interest
of the subject humanly speaking augmented. The celebrated Berzelius,
when questioned on the point, had his ready solution of the problem,
easily derived from his unparalleled stores of chemical knowledge:—“Give
me a substance containing sulphur—admit the presence of the vapors of
sulphur, or sulphurous or sulph-hydrous vapors,—let limestone be also
present, and water on the surface or in the atmosphere, AND WE SHALL
READILY HAVE GYPSUM.” The origin of the saltness of the ocean is still a
mystery in science; equally involved in doubt and conjecture is that of
the other member of the series, the rock-salt formation. The generally
adopted theory, however, is, that it was dependent on volcanic agency
for development, as it both contains, and is uniformly associated with,
the acids, and other materials found in connection with volcanoes. The
chlorides of sodium and gypsum, for example, are at present sublimed
from volcanic vents; vapors charged with sulphuric acid are constantly
issuing from the same sources; and these passing through or associated
with the saline waters of the period, must have aided in the formation
of rock-salt and gypsum, which occur more frequently in irregular
masses than in true stratified deposits. An additional corroboration
of the theory is inferred from the circumstance, that the gypsum
accompanying the rock-salt is anhydrous, that is, free from water before
exposure to the action of the atmosphere. Hence the conclusion, that
the consolidation of both the rock-salt and the gypsum must have been
effected by the agency of heat, as, by means of aqueous deposition, a
hydrometric influence would have been sensibly perceived.
Wonderful certainly is all this—the inclosing, the consolidation, the
arrangement of these remarkable substances. The sea, in the first
instance, may readily and abundantly have supplied all the elements
of the formation; but how collected and retained, crystallized and
incrusted, layer upon layer, over the rocky bottom and volcanic inner
chambers, are points still of nice geological inquiry. The celebrated
salt mines of Cracow, in Poland, are wondrous operations of the art of
man, into the still more wondrous products and recesses of nature.
Here the entire arrangements of a city are almost perfected; the
streets, marketplace, chapel, rivers, reservoirs, grottoes, and all the
requirements of comfort and safety gleaming in a blaze of saline crystals.
“Scoop’d in the briny rock long streets extend
Their hoary course, and glittering domes ascend;
Down the bright steeps, emerging into day,
Impetuous fountains burst their headlong way,
O’er milk-white vales in ivory channels spread,
And wondering seek their subterraneous bed.
Long lines of lusters pour their trembling rays,
And the bright vault returns the mingled blaze.”
The deposit near Cracow is worked on four different levels or stories,
divided into innumerable compartments, with thousands of excavations in
every direction, and descending to the vast depth of one thousand feet
below the surface. The length of the several passages, in their windings
and turnings, is calculated to be nearly three hundred miles; about two
thousand men are constantly employed in the mining operations; and,
though the operations have been carrying on for the known period at least
of six hundred years, the mass of rock-salt in the locality is still of
inexhaustible extent.
The mines in our own land are equally remarkable after their kind, and
cannot fail to interest, if not to astonish, the neophyte who ventures a
descent. From the mode in which they are worked, the huge pillars left
to support the roof, the thousand lights that illuminate the caverns,
the reverberations from the blasting which at intervals ring through
their depths, a grandeur and impressiveness are imparted to a scene which
scarcely any other combination of objects could produce. And another
world—a world of coal and iron—in all its magnificence and riches, lies
interred under these glistering stores of lime and salt! How strangely
contrasting in their qualities and structure the two formations. But
except that a wise and far-seeing Providence collected and garnered
up the waste and decay of both for man’s use, no principle have we to
guide us when speculating on their mineral properties and arrangement—no
natural law certainly, self-acting upon matter and evolving new creations
of its own, organic or inorganic, to reveal His inscrutable purposes.
CHAPTER III.
THE OOLITIC OR JURASSIC SYSTEM—AGE OF REPTILES.
When one is about to travel, or to undertake a journey of any distance
from the daily beat of home, it is very seldom indeed that he puts into
his pocket a book of science. Voyages, travels, a review at most, or the
newest novel, may fill up a spare place in the portmanteau: anything
that requires study, or would draw upon the reflective faculties, can be
no fitting companion for the occasion, with at least nine-tenths of our
moving public.
If the preceding pages have been perused with any attention at all, it is
to be hoped that other things will be considered as worthy of a passing
glance, as sure we are they cannot fail to be replete with lessons of
instructive wisdom. On the ground of mere ephemeral curiosities by the
way, geological matters claim consideration. They are exhaustless, too,
and ever varying as you proceed. When you imagine that the last mountain
rock or quarry contained the whole catalogue of Natural History, and
showed you more than Goldsmith, or Buffon, you find that over the next
ridge, or in the neighboring field, there are new subjects for study, and
still renewing matters for wonder.
If you have taken up your abode for the night at classic Rugby, at
sporting Melton-mowbray, or among the academic bowers of Oxford, there
are objects all around, in every hill-side, ravine, or railway section,
to fill you at once with admiration and astonishment. Go, inquire of that
rock. It is the _lias limestone_; beyond it, and at no great distance,
lies the _oolite_; and there, in the immediate vicinity of both, you
have the _Stonesfield slate_. We invite you to examine any one of these
common-place looking stones; and not in Gulliver, not in the history of
the Knight of La Mancha, not in all the Mysteries of Udolpho, not in the
Romance of the Forest whose harmonious periods so charmed our youth, will
you find anything to compare with the marvels therein to be disclosed.
The machinery of a tale may require the aid of giants and genii, but
here is “truth without fiction,” more startling, marvelous, and so
beyond the bounds of nature as now felt and seen, that the most daring
fancy is utterly outstripped in its loftiest flights into the regions of
the ideal. The series of beds which constitute the mineral features of
this extensive district contains the full development of the reptilian
type to which we were introduced in the last chapter. Animals there are
in these rocks, with forms and features, so fantastic, and apparently
disproportioned, that the tales of the most unscrupulous traveler would
suffer in comparison. And in truth, there is no page in the book of
nature—none, certainly, in all the works of man—so fraught with wonders,
or remarkable for stirring incident, as the epoch of animal life whose
history is there inscribed.
I. THE NATURE OF THE ROCKS. The oolitic or Jurassic system, like that
of the new red sandstone, comprises the subdivisions of two well-marked
natural groups, in which the lias or lower series is included. In point
of geographical range, the oolite formation is extensively distributed
over the surface of the globe; in mineral character it is varied in every
possible degree of texture and composition; in geognostic arrangement
there are intercalations, without end, of marine and terrestrial
detritus; the organic remains are in the greatest profusion, both as to
diversity of type and increase of new creations; and, locally, such has
been the appreciation of its various members, that there is scarcely
a town or parish in the south-eastern part of England, that has not
received from or given habitations and name to, some one of its numerous
subdivisions.
Resting upon the triassic formation, there are bands of lias shales,
limestones, sandy and ferruginous strata, and upper shales, including
nodular concretions and beds of limestone. This series is distributed
over the counties of York, Northampton, Somerset, and Dorset. The next
are the lower oolites, which comprise an extensive series of calcareous,
concretionary sands and sandstones, limestone, thin seams of coal and
ligneous clays, and the Cornbrash limestone, which in many localities is
a mere aggregation of shells and other marine exuviæ. The Stonesfield
slate, the Forest marble, and the Fuller’s earth beds, are included
in the group, ranging along the Yorkshire coast, through Northampton,
Oxford, and Gloucester shires; and in Scotland we have their equivalents
in the Brora coal and oolitic limestone of Sutherlandshire, Skye, and
the adjacent islands. The middle oolite succeeds, which includes the
Oxford clay, the Kelloway rock, and the coral-rag, all more or less
distinguished by their profusion and peculiarity of fossils, chiefly
shells, echini, and corals. The whole formation terminates in two well
known deposits, the Kimmeridge clay and Portland oolite, with its bands
of green and red sands, layers of chert and drift-wood. This group
prevails in Oxfordshire, Berks, Wilts, Bucks, and the Isle of Portland;
the matrix of fossilized reptilia, fishes, and cycadeous plants.
The term OOLITE or roestone, as applied to the whole of the groups
enumerated above, is derived from the resemblance between the small
rounded grains of which the limestones are generally composed, and the
roe of a fish. The Jura mountains, which divide France from Switzerland,
consist mainly of these deposits, and hence Jurassic—the _Terrains
Jurrassiques_ of continental geologists. The word lias is simply a
corruption of liers (layers), and has from time immemorial been applied
to the rocks of this group. Their relation and order of superposition are
fully brought out along the sections of the Great Western Railway from
London to Bath. The Birmingham line from Derby by Rugby to the metropolis
intersects nearly every member of the series, until they are covered
about Wallingford by the chalk.
When one looks at these innumerable bands of rock, and the great
diversity of earthy matter of which they are composed, the mind becomes
utterly overwhelmed by the rapidity and vastness of the changes which,
during this epoch, occurred upon the surface of the globe. A turbid, and
often agitated, condition of the waters in which they were deposited is
very clearly indicated. The animals of the period were manifestly of a
class peculiarly adapted to the impregnated element, the slimy banks,
and shallows which prevailed. The flora was abundant, of a kind, and
produced in circumstances, favorable for the formation of a lignite
coal. The spasmodic action which prevailed after the deposition of the
carboniferous beds had not entirely subsided at the Permian period. The
change was of too violent a kind to have been brought about without
great internal, as well as external, commotion. We find, accordingly, in
most districts, that the rocks of this class are upturned and disrupted.
The detritus of the new red sandstone and magnesian limestone, thereby
occasioned, would go to form new land during the submergence of such
portions of the surface as were retained beneath the waters. The
oscillations were numerous and frequent, corresponding with the aggregate
of beds which compose the system; while the quality and arrangement
of the sediment point to changes and alterations in sea-levels, river
courses, land boundaries, estuaries, the size and distribution of the
basins into which the alluvia were transported. The geographic extent,
combined with the frequently insulated position of the oolitic series,
clearly demonstrates a vast alteration in the bed of the ocean, as well
as in the ridges and elevations which gave diversity to the land. The
oolites, in fact, constitute vast calcareous reefs, raised upon the
inverted strata of the older formations, which formed the cliffs and
headlands of a sea swarming with lizards and crocodilians, and over
whose thick umbrageous banks roamed the flying pterodactyle, watching or
perhaps escaping from, the singular saurians that reposed in the thickets
beneath. The substitution of the pyritous clays for the saliferous marls;
the dark argillaceous oolites and blue mottled lias for the yellow
crystalline dolomite, is in harmony and keeping with the plants and
animals which now, for the first time, sprang into existence.
II. THE ORGANIC REMAINS are very abundant, and in both plants and animals
there are various new kinds. Of the former are the cycadeæ, allied to
the existing pine-apple; also the lilaceæ, and some other undescribed
genera. With regard to animals, this has been emphatically called “the
age of reptiles,” along with which there are new families of fishes,
crustacea, mollusca, and corals. The warm-blooded animals now for the
first time appear, of which there are two genera, the _Amphitherium_
and _Phascolotherium_, found in the Stonesfield slate near Oxford, and
considered, by analogy of structure, to be allied to the marsupials
that inhabit the Australian continent. The same interesting locality
has furnished two new genera of insects, the _Prionus Ooliticus_ and
_Coccinella Wittsii_; in the lias, of different places, eleven genera
and species have been discovered, but of which only wings and fragments
have been obtained. A perfect specimen of this order has recently been
found, by the Rev. P. B. Brodie, in the upper lias, near Cheltenham,
resembling the genus _diplax_; but so shattered in the head, that its
precise character cannot be determined. The reptilians supply alike new
terrestrial and marine tortoises and turtles—lizards, whose arms and
legs were provided with a filmy membrane, like bats, to enable them
to fly—amphibious saurians, and water saurians unlike anything now in
existence.
Contrast this catalogue with the few organic remains to be met with in
the preceding period, and ask what called such a newly-inhabited world
into being? The face of nature, so remarkably elaborated out of the
waste and decay of these old stony materials, is moving all over with
life—replenished, so far as yet discovered, with seventy-five generic
and specific forms of new vegetation—a hundred and ten new forms of
hard-working corallines—seven hundred and thirteen genera and species
of the shelly tribes, from the simplest to the most complicated of the
chambered orders—a hundred and sixty distinct races of fishes, placoids
and ganoids—three varieties of the most strangely constructed mammalian
quadrupeds, with thirteen kinds of insects to titillate and keep them in
action—and all this array of organic life moving side by side with forty
families of gigantic reptiles, herbivorous and carnivorous, creeping,
swimming, and flying! The wonders of art have nothing to compare with
this. The structure of a blade of grass will not suffer an atheist to
live. During the six thousand years of man’s existence, one new living
thing, of any order or type, has not been called into being. Astronomy
is daily adding to her achievements, and penetrating farther among
the systems of the universe; but the nebular theory of creation is
gone, and the new-world germs will not expand at its fanciful bidding.
Geology nobly bears testimony in every page to the rule of one supreme
intelligent Creator—an exuberance of life and forms which announces the
authoritative interposition of Him
“Whose word leaps forth at once to its effect;
Who calls for things that are not—and they come.”
And the mandate goes forth, in that awful simplicity of OMNIPOTENCE,
which learning cannot mystify nor ignorance overlook.
This formation abounds in the remains of radiata, mollusca, and
crustacea,—all of them differing specifically from those of the older
secondary strata. The gigantic _crinoidea_ of the carboniferous age
have disappeared, succeeded only by a few dwarfish specimens of the
_apiocrinite_ and pentacrinite, while the _ammonites_ mark an increase of
nearly two hundred species, preserved in the most perfect state in the
shales and limestones of the lias and oolite.
[Illustration: 1. Ammonites obtusus; 2. Section of Ammonites obtusus,
showing the interior chambers and siphuncle; 3. Ammonites nodosus.]
The term Ammonite has been bestowed upon this remarkable shell-fish from
its fancied resemblance to the curved horn on the head of the statue
of Jupiter-Ammon. The spiral form of the shell is divided into several
chambers or compartments, all of which are connected by means of an
interior tube or siphuncle. It belongs to the order of Cephalopoda, among
which are included ancyloceros, belemnites, nautilus, orthoceratite,
and other many-chambered shells. Like the nautilus, the ammonite was
gifted with a singular apparatus by which it could pursue its instincts
either at the bottom or on the surface of the element in which it lived.
The organs of motion were arranged round the head (hence the name
_cephalopoda_); and, by the nicely adaptive arrangements of nature,
the outer chamber of the shell was capable of retaining the entire
body of the animal, while the interior chambers were hollow, thereby
rendering the whole structure of nearly the same specific gravity with
the waters in which it moved. An elastic tube passing through the
siphuncle connected the cavity of the heart with the extremity of the
shell, which enabled the animal to contract or expand itself as its
exigencies required. Being filled with a dense fluid, excreted by the
glandular organs, the creature, when alarmed or wishing to descend,
withdrew itself within the outer chamber, whereby the contraction of the
tube forced the fluid from the heart into the siphuncle, and increasing
the gravity enabled it to descend to the bottom. Upon a reversal of the
process—the simple projection of the arms of the head, and the consequent
expansion of the body—the ammonite rose with equal facility to the
surface, disporting itself at will in its native element. With a view to
resist the pressure, when at the bottom, a provision was made by means
of the _arch-form_ in the structure of the shell; and, additionally, by
the insertion of a series of transverse ribs, which comprise all the
mechanical contrivances for giving strength and solidity which are sought
by the divisions and subdivisions in the vaulted roofs of our Gothic
architecture. The geographical distribution of the ammonite partakes of
the universality so marked in the vegetable economy of the carboniferous
age, the same species even being common to Europe, Asia, North and South
America; and always, along with all its numerous congeners, manifesting
the most striking examples of that adaptation of means to ends which
prevails in every department of creation.
We shall now select a few details of the more remarkable of the reptilian
types of this period, referring the reader to the ample and graphic
descriptions of Buckland, Conybeare, Mantell, Phillips, and more
especially to the Reports of Professor Owen, in the volumes published by
the British Association in 1840-’1.
[Illustration: Ichthyosaurus communis.]
1. The first genus to be noticed is termed the Ichthyosaurus, which
partakes at once of the characters of crocodiles, lizards, and fishes.
So lavish has nature been in providing for the accommodation and wants
of this anomalous creature, that to the paddles of a whale, is added the
sternum of an _ornithorhynchus_; the head of a lizard is joined to the
vertebræ of a fish; and the snout of a porpoise is combined with the jaws
and teeth of a crocodile. The magnitude of the eye is prodigious, and
the jaws, sometimes exceeding six feet in length, are studded with an
apparatus of teeth, amounting in some instances, to a hundred and eighty.
“From the quantity of light admitted in consequence of the prodigious
size of the eye,” says Dr. Buckland, “it must have possessed very great
powers of vision: we have also evidence that it had both microscopic
and telescopic properties. We find on the front of the orbital cavity,
in which this eye was lodged,”—a cavity sometimes fourteen inches in
diameter,—“a circular series of petrified thin bony plates, ranged
round a central aperture, where once was placed the pupil; the form and
thickness of each of these plates very much resembles that of the scales
of the artichoke. It also tends to associate the animal in which it
existed, with the family of lizards, and exclude it from that of fishes.”
These bony plates gave strength to the surface of the eye-ball, which
required protection above and below, from the dashing of the waves when
it reared its head to the storm, and from the pressure of deep water
when it scoured the bottom. The nostrils, it would seem, were placed so
close to the anterior angle of the eye, as to render it impossible to
breathe without raising the organs of sight to the surface of the water.
An ocean, peopled with such monsters! Imagine so many eyes, larger than
a man’s head studding its surface, and illuminating, as with fire-balls,
their terrific jaws, glaring out from the briny flood; and what a scene
to gaze upon, so different from all that now covers these rich alluvial
plains!
[Illustration: Plesiosaurus.]
2. The Plesiosaurus is allied in some respects to the former, but in
other points differs so materially, and possesses characters so strange,
as to claim for it a degree of monstrosity unparalleled, even amid
the ruins of the old world. Here we have the union of the serpent and
chameleon, with a trunk and tail having the proportions of an ordinary
quadruped. The mechanism of the lungs and ribs is peculiar, showing
that the animal must have breathed with such force and rapidity, as to
have rendered the color of the skin changeable, like the chameleon or
dying dolphin. The neck bore a resemblance to that of the swan; the feet
and motions were allied to those of the turtle; and, from the varied
intensity of its inspirations, it is conjectured that the creature
inhabited the shallow pools and marshy waters along the coast. The body
would thus be concealed among the rank vegetable aquatics; while, with
its long flexible neck, it would be prepared suddenly to pounce upon its
prey. Mr. Conybeare compares the Plesiosaurus to a turtle stripped of its
shell; and the ribs, being connected by transverse abdominal processes,
present a close analogy to those of the chameleon. Ichthyosauri and
Plesiosauri have been found in the secondary strata, from the lias to the
chalk inclusive; of the former, twelve species are known and described,
and nearly twenty of the latter. The most remarkable of the enalio-saurii
or marine reptiles, is the Plesiosaurus-dolichodeirus, discovered in
the lias of Lyme-Regis, and which is fertile in the remains of all the
animals of that remote and wonder-producing epoch.
[Illustration: Pterodactyle.]
3. Another example, taken from the lias, is of its kind even more
startling than either of the preceding. This consists of the remains of
an animal called the Pterodactyle, or flying reptile, which, more than
anything ever conceived or bred in poet’s brain, resembles what Milton
must have intended, when to the great arch-fiend he gave a form and
flexibility of body, that
“Swims, or sinks, or wades, or creeps, or flies.”
Certainly each and one of all these evolutions the Pterodactyle could
execute, and he was amply provided with the fitting instruments to
perform them. This animal possessed a head intermediate betwixt that of
a bird and a reptile, which in both cases is comparatively small, and
offering the least resistance to the medium through which it passed, in
quest whether of pleasure or subsistence. The hands were of the most
prehensile character, adapted by the claws attached at once to fix and
firmly grasp its prey, and, when needed for pursuit, to swing itself
squirrel-like from branch to branch, and from tree to tree. The wings
resembled those of the bat, but in length and size allied to nothing
in existing nature, and finding their match only among the dragons of
romance. Then, as to feet and limbs, these were of such a construction
as to allow the animal safely to repose after its toils in a standing
position on the ground, or to perch on trees, or to climb on rocks, or
disport from cliff to cliff. The eyes were large; the wings terminated
in fingers, from which projected long hooks; the beak was furnished
with about sixty sharp piercing teeth. No wonder that naturalists were
astonished at such heterogenous combinations, as they rose upon their
sight—
“That look not like the inhabitants o’ the earth;
And yet are on’t;”
and knew not whether to ascribe them to the air, or the earth, or the
domain of waters. But, in the hands of Cuvier, the entire structure and
relations of the several parts of the framework have been explained
and developed; the libellulæ and other insects on which they fed have
been detected in the same rocks with their own relics; and out of that
apparent mass of inconsistencies and contradictions, the genius of the
skillful anatomist has produced one of the most striking examples of the
harmony that pervades all nature, that has been extended through all
ages, and that manifests the bounteous care of the common Creator in
adapting all living things, each after its kind, to the conditions of its
existence.
4. The Stonesfield strata belong to the lower division of the great
oolite. The slate of the district has been long known and prized for
roofing purposes. The village of Stonesfield lies about twelve miles to
the north-west of Oxford, beautifully situated on the brow of a valley,
both sides of which have been deeply excavated for the extraction of
the slate. Woodstock and Blenheim are both in the vicinity, neither of
whose remarkable heroes ever dreamed of the mighty wars, waged in a far
distant age from their own, by the fierce assailants whose remains have
now been disturbed by these operations. Here are abundant the remains of
palms, aborescent ferns, seed-vessels, leaves, stems of several genera
of coniferæ, and traces of reeds and grasses. Wings and their cases, the
_elytra_ of beetles, and other relics of insects, are mingled with the
teeth, scales, fin-bones, rays of fishes, in the greatest profusion. And
here, on the site of this ancient menagerie or battle-field, are the only
known vestiges of mammalian animals in the secondary formations. One
set of these remains resembles the Wombat, a marsupial didelphys of New
South Wales; the other remains indicate a small insectivorous mammal, the
Amphitherium, with thirty teeth in the lower jaw. Australia, therefore,
supposed to furnish evidence of an entirely new order of things, has
been long anticipated in all its types of plants and animals by the
denizens of our own land—our waters swarming with cestraceonts, trigoniæ,
and terebratulæ—and our fields clothed with araucariæ and cycadeous
plants—when perhaps but little of that continent rose above the waters.
5. The DINOSAURIA constitute a tribe or sub-order of the lacertians,
characterized by the large development of the sacrum, the dorsal
vertebræ, the bones of the extremities, which are all provided with
large medullary cavities. Of this tribe there are three well established
genera—the Megalosaurus, the Hylæosaurus, and the Iguanodon. These were
the gigantic crocodile lizards of the dry land, whose peculiarities
of osteological structure distinguish them as clearly from the modern
terrestrial and amphibious sauria, as the opposite modifications for an
aquatic life, characterize the extinct enaliosauria, or marine lizards.
The Dinosaurians belong properly to the Wealden fresh water formations,
which may be regarded as the true habitat of this order of terrestrial
fossil reptiles.
The Megalosaurus was first described by Cuvier, and the family
determined; he calculated the dimensions of the animal at from forty to
fifty feet in length. Professor Owen, from better preserved specimens,
has reduced it to thirty feet long: the head is five feet, the length of
trunk with sacrum thirteen feet, and the tail about the same, allowing
the Megalosaur to have had the same number of caudal vertebræ as the
crocodile. The sacrum consisted of five anchylosed vertebræ, new in
saurian anatomy: the hind-legs measure two yards, a metatarsal bone
thirteen inches; the teeth are of corresponding dimensions, and curve
backward in the form of a pruning-knife. The structure of the jaw
indicates a long projecting snout, while the curvature of the teeth
fitted them to retain like barbs the prey which they had once penetrated.
All the organs of the monster declare the Megalosaur to have been a land
animal, of carnivorous propensities, and in all probability performed,
as headsman the same office upon the smaller herd of reptiles, sometimes
making a snatch at a Plesiosaur, as both in turn did upon fishes and
crustaceans. The sport of an Indian jungle is child’s play compared
to the onslaught of these grim kings amidst their ancient preserves.
The remains occur in the deposits at Malton in Yorkshire, Cuckfield in
Sussex, Bath, the Purbeck limestone, Tilgate Forest, and the Wealden.
The next genus of the land reptiles was remarkable for the size
of the horny plates by which the body was protected. This is the
Hylæosaurus—that is, forest-reptile—about twenty-five feet long, and
covered with a series of large, flat, and pointed bones. These vary in
length from five to seventeen inches, and are from three to seven and a
half inches in breadth. In addition, as showing the kind of warfare to
which he was exposed, a ridge of thick thorny scales pass along the back,
and form an enormous dermal fringe, like the spines on the back of the
living iguana tribes. The skeleton of the Hylæosaur has been found nearly
entire, and all the parts in almost natural juxtaposition. The Wealden of
Tilgate Forest, the deposits at Bolney and Battle of the same formation,
contain the remains in considerable abundance.
What shall be said of the next figure that crosses the tragic stage,
during this age of tyrant prodigies? The Iguanodon—a gigantic herbivorous
lizard—is related to a family of harmless creatures (_Iguana_), which
swarm in the West Indies, and in all the tropical forests of America,
in certain peculiarities of the teeth greatly differing from those
of other reptiles. The largest of living Iguanas, do not exceed five
feet in length: the extinct genus attained a longitude of upward of
twenty-eight to thirty feet. The caudal member was about thirteen, head
three, trunk with sacrum twelve, and the girth of the body about fifteen
feet. The teeth resemble the teeth of the rhinoceros as to bulk and
general appearance, and, consisting as they do of incisors and molars,
were recognized to belong to the order of herbivorous quadrupeds. The
thigh-bone exceeds that of the largest-sized elephant, being from four
to five feet in height, and presenting a circumference of nearly two
feet in its smallest part. This animal, at its first discovery, was
supposed to have attained the exaggerated proportions of nearly a hundred
feet in length. But even under the reduced dimensions and more accurate
deductions of Professor Owen, confirmed by those of Dr. Mantell, there
is still size sufficient, as well as peculiarities of structure, to
lead us to regard it as one of the wonders of geology. One femur of a
recently-discovered Iguanodon is twenty-seven inches in circumference,
and must have been nearly five feet in length; and a tibia, found with
the same, is four feet long. Dr. Melville has established the important
physiological fact, that the cervical and anterior dorsal vertebræ were
convexo-concave,—that is, convex in front and concave behind, as in
the existing pachyderms; while the reverse form, the concavo-convex,
predominates in the existing crocodilians and lizards. It is farther
established, that in the Iguanodon, as in many fossil and recent
reptiles, the anterior extremities were much shorter and less bulky
than the posterior. As in the existing family, so in the extinct, the
huge body was ornamented with a horn of bone which projected from the
nose. This nasal organ seems to have been worn more for decoration than
for use; unless, perhaps, to assist in perforating its way through
the thickets of vegetation on which it subsisted, to push aside an
unwelcome intruder upon his pasturage, or as a mere set-off against
the unprecedented length of tail. Imagine a herd of these monsters
feeding in a prairie—the denizens of a period when all things partook
of the gigantic! “The concurrence of peculiarities so remarkable,” says
Buckland, “as the union of this nasal horn with a mode of dentition
of which there is no example, except in the Iguanas, affords one of
the many proofs of the universality of the laws of co-existence, which
prevailed no less constantly throughout the extinct genera and species
of the fossil world, than they do among the living members of the animal
kingdom.” Professor Owen writes—“No reptile now exists which combines a
complicated and thecodont dentition with limbs so proportionally large
and strong, having such well-developed marrow-bones, and sustaining the
weight of the trunk by _sychondrosis_ or _anchylosis_ to so long and
complicated a sacrum, as in the order _Dinosauria_. The Megalosaurus and
Iguanodons, rejoicing in these undeniably most perfect modifications of
the reptilian type, attained the greatest bulk, and must have played the
most conspicuous parts, in their respective characters as devourers of
animals and feeders upon vegetables, that this earth has ever witnessed
in oviparous and cold-blooded creatures. They were as superior in
organization and in bulk to the crocodiles that preceded them as to those
which came after them.”
6. We close our enumeration of these fossils by simply stating, that
the CROCODILIANS also flourished at this period. The living species
are twelve in number, all remarkable for the size of their mouth, and
their exuberant abundance of teeth. The extinct species were nearly as
numerous, but all more allied to the gavials of New Holland than to the
other members of the family. They seem chiefly to have subsisted on
fishes, while their modern congeners are furnished with powers which
enable them to prey upon mammalia and other quadrupeds. When Hobbes, the
philosopher of Malmesbury—the old haunt of all these monsters—adopted the
title “leviathan” for his political and anti-Christian views, he did it
more in derision of the name than from any belief that such things as the
term represents had ever or could ever have existed “in rerum natura.”
Persons, even now, to whom the subject is presented for the first time,
will turn with aversion from its details under the influence of the very
opposite feelings from those of the infidel metaphysician. The evidence
of facts however, will yield neither to prejudices nor to theories. And,
while we dream not of representing the patriarch of Uz as drawing his
inferences from geology, still his mind was alive to convictions of the
grandeur and diversity of the works of creation—to a sense of his own
ignorance—and filled at the same time with awe and veneration at the
unsearchable wisdom of the ways of Providence. “STAND STILL AND CONSIDER
THE WONDROUS WORKS OF GOD. HAST THOU ENTERED INTO THE SPRINGS OF THE SEA?
HAST THOU PERCEIVED THE BREADTH OF THE EARTH? DECLARE, IF THOU KNOWEST IT
ALL.”
CHAPTER IV.
THE WEALDEN FORMATION.
The Wealden formation is more local than any of the deposits we have yet
considered. The term has a particular reference to the district features
of Kent, Surrey, Sussex, and Hampshire, known as the _Wolds_, from
the German _wald_, signifying a wood or forest: and as the geological
position of the group is in immediate _superior_ connection with the
oolites, and _inferior_ to the chalk, the character and history of the
Wealden fall to be given in this place. The Specton clay of Yorkshire,
displayed along the cliffs adjoining Filey Bay, is considered to belong
to the same series as the _gault_ or blue and gray marls of Cambridge,
Kent and Sussex; but it contains some characteristic indications of the
Kimmeridge clay, and, therefore, we should expect that, in Yorkshire,
these two strata are not separated as in the south of England.
I. NATURE AND EXTENT OF THE DEPOSIT. The Wealden is a fresh water or
estuary formation, as is clearly established by its fossils as well as by
its lithology. The group consists of layers of clay, sand, shale, with
subordinate beds of limestone, grit, and friable sandstone. The Hastings
sands, Tilgate Forest beds, Tunbridge Wells deposits, and the Ashburn
lignite shales and ferruginous sands, are all constituents of the series.
The Dover Railway traverses the formation between Red Hill and Ashford:
the branch leading to Tunbridge Wells affords excellent sections of the
clay and sands. Thus occupying, in an irregular triangular form, the
south-east of England, the wealden again emerges in the principality of
Hanover, and other places in the north of Germany: continuing in the same
course, it is again found on the British shores, occurring at Linksfield,
near Elgin.
It would not be easy to restore, in imagination, the surrounding aspect
of the superficial area now occupied by patches of the wealden formation.
Take your station on the Peak of Derby, or Shotover Hill, or the heights
of Ivanhoe—not so perilous adventure as that of the heroine of the tale
on the battlements of Malvoisin—and you overlook a vast extent of vale
and woodland, all then one broad expanse of water. This inland sea
filled the whole intermediate district traced above, studded, in all
probability, with islands, and fringed with shallows and rich arborescent
headlands. Sharks prowled and darted in every direction; pterodactyles
may be descried looming along the waste; while in terror or in joy, the
plesiosaurus reared aloft his far-stretching neck, and then withdrew into
his fenny retreats. The saurians, with their strong muscular jaws, are
actively engaged, each according to his kind, by the shores or in the
waters; while over the busy scene, the fierce-weltering ichthyosaurus
looks in wild amazement, his large eyes leaping in their sockets, and
spreading dismay among the tenants of the deep, as even now, when a kite
enters a thorny brake, or pursues his stealthy flight over the meadows
and green fields of timid nestling bird.
Nor would the land animals be less actively employed in maintaining the
laws of their creation. No skeletons of birds have yet been detected; but
their foot-prints, we have seen, are numerous. These clouds of insects,
and other brilliant objects that flit with such rapidity across the sky,
have all been stirred, and are leaping they know not whither, for the
tread of a monster’s feet is heard through the forest, mailed in plated
horn thicker than Ajax’s shield, and, pursued by another, presses and
plunges onward in reckless haste. Imagine the many encounters during a
single season between one set of the terrestrials only, the saurians;
of the class, there are the remains of the megalosaurus, the great
saurian—of the geosaurus, the land saurian—of the hylæosaurus, the forest
saurian—of the teleosaurus, the perfect saurian,—all fitted with jaws
and teeth, most cruelly bent on mischief, and restrained by no brotherly
sympathies when accident or bold defiance bring them in the way of each
other. The fell onslaughts of generous man, tribe against tribe, clan
to clan, nation to nation, for some inconceivable nothing or unintended
provocation, recorded within the brief historical epoch, may reconcile
one to a picture of the irrationals similarly engaged, and throughout
periods of time sufficient for the deposition of the entire oolitic
series, before which the rule of earthly dynasties shrinks into utter
insignificance.