12

THE WONDERS OF GEOLOGY.

on account of a deficiency and an excess of water; the former
rendering the works inoperative, and the latter invading or sweeping them away.

The future civilized inhabitants of the countries near the Rocky
Mountains (excepting, of course, the immense sandy deserts, which,
near the eastern slope, emulate the sterility of Arabia and Zahara)
will enjoy advantages in many respects similar to those of Piedmont,
Switzerland, Germany, and France; and it is easy to predict, that
peculiar structures, and a peculiar state of society, will be modelled
upon the sublime physical features of those truly Alpine regions.
From this, his native land, we have too much reason to expect, that,
despite of the efforts of the benevolent to avert the impending doom,
the red man of the forest, not reclaimed to humanity, but abandoned
to his fate, will vanish before the knowledge and power, and
the still more prevailing seductions, of civilized life,—the extinguished
victim of cupidity and cruelty.

*Influence of Geological Structure on Society.*—It is perfectly appa-
rent to geologists, that the scenery of a country is not more exactly
stamped by its geological formations than are the manners and
employments of its inhabitants.

*New England.*—Thus the bleak hills and long winters of New Eng-
land being unfavourable to the most extensive and profitable agricul-
tural pursuits, while the extensive and deeply indented sea-coasts
abounding in harbours, headlands, rivers, and inlets, naturally produce
an impulse towards the ocean, conspire with the original adventurous
character of the population, to send them roving from the arctic to
the antarctic circle, till the wide world is laid under contribution
by their enterprise. The numerous streams and waterfalls furnish
the cheapest means for moving machinery, and thus manufactories
spring up, wherever, in the expressive phraseology of the inhabi-
tants, there is water-power, and steam supplies local deficiencies of
moving force. Ingenuity, conspiring with a general system of
education, is excited, under such culture, to produce numerous
inventions; and hosts of young men seek their fortunes successfully
abroad, as mechanics, seamen, traders, instructors and politicians,
and thus operate powerfully, and, we trust, beneficially, on other
communities.

*Southern States.*—The immense tracts of rich alluvium in the
southern states—the mildness of the climate—the coasts less
abounding with safe inlets, and often modified by the action of the

SILLIMAN'S INTRODUCTION.

13

existing ocean, with a population not originally commercial, give a
decided impulse to a vast agriculture, and a few great staples form
the chief reliance of the landholders. It is easy to see, that this
state of things grows out of the newer secondary, the tertiary, and
the alluvial formations, which constitute the ocean-barrier from
Staten Island to Florida, and from Florida to Texas, extending
inland toward the mountains.

*Western States.*—In the west, the boundless fertile prairies and other tracts of productive soil conspire with remoteness from the ocean, to indicate agriculture and pasturage as the main employment of the inhabitants; while exhaustless beds of coal, limestone, gypsum, and iron, and rich veins of lead and copper, and numerous and copious salt fountains, furnish means for a manufacturing, as well as an agricultural population. These pursuits occupy the greater number of the people, while many find a profitable employment in navigating those immense inland seas, the great lakes and the vast rivers, which run thousands of miles before they mingle with the ocean. This state of things is the result of the immense extent of the lower secondary and transition formations which cover the western states, sustaining portions of tertiary strata, and alluvial deposits.

While New England produces granite, marble, and other building
materials of excellent quality, Pennsylvania, with the western and
several of the southern and south-western states, supplies inex-
haustible magazines of coal, which prompt and sustain the manu-
facturing interests of this wide country, and aid its astonishing
navigation by steam; already of unexampled extent on its internal
waters, and destined at no distant day to compete, on the main
ocean, in amicable rivalry, with our parent country.

*Geological Treasures.*—Our coal formations, in richness and extent, are unrivalled in the whole world; our iron and lead are in the greatest abundance and excellence; Missouri has mountains of pure oxide of iron, that have no compeers, and there is a fair prospect that copper will also be found to abound in the West. We have great deposits of limestone and marble, of gypsum, marl, and salt, and of building stones of almost every kind; our soils are so various in quality, and in geographical position, that almost every agricultural production is obtained in abundance. It is obvious, then, that we have all the physical elements of national and individual prosperity, and that the blame will be our own, if we do not follow

14

THE WONDERS OF GEOLOGY.

them up by proper moral and intellectual culture, which, alone, can
render them sources of public and private happiness.

*Geological deficiencies—Upper Secondary.*—Of the upper secondary,
below the chalk, and above the new red sandstone, lying higher than
the coal, we have no well ascertained strata: rocks of oolite struc-
ture we may have, but it is not ascertained that we have the true
oolite of England and continental Europe, nor have we traced the
Wealden nor the Lias* with their colossal animal wonders.

*Equivalent of Chalk.*—Chalk, properly speaking, appears to be absent from the United States, but there is an equivalent to the chalk formation in vast beds of sands and marls, containing many European cretaceous fossils, between the Delaware river and the shores of New Jersey, as well as in various places in the south.†

*Absence of Volcanoes.*—The principal deficiencies in the geological formations of the United States, are in the absence of active volcanoes, and of most of the members of the upper secondary. However interesting active volcanoes, with their earthquakes and eruptions, may be to speculative geologists, the sober unscientific population of our States may well rest contented without them, satisfied to barter the sublime and terrific for quiet and safety. Although the soils formed from decomposed lava are often fertile, and the vine flourishes luxuriantly on the flanks and at the feet of the volcanic mountains of warm countries, these influences are too local to be of much importance to agriculture.

Within the United States proper, including the states and terri-
tories beyond the Mississippi, and east of the Alleghany mountains,
there is not, so far as we know, a single active volcano, nor even an
unequivocal crater of one that is dormant. It remains yet to be
decided, whether in and beyond the Rocky Mountains, quite to the
shores of the Pacific Ocean, there are any active volcanoes within
our parallels of latitude. Both north and south of our limits, there
are, on the islands and shores of the Pacific, numerous volcanoes, and
it would be strange, indeed, if there were none within our extensive
possessions on the same coast.

*Records of volcanic action in the far West.*—However this may be,
there remains no doubt that fire has done its work, on a great scale,

* It is plain that the Lias, so called, in the West, is not the Lias of England.

† See Dr. Morton's Synopsis of Organic Remains of the Green Sands of the United States, 1 vol. Svo. with plates.

SILLIMAN'S INTRODUCTION.

15

among the Rocky Mountains, and between them and the Pacific; for all our travellers attest the existence of immense regions covered with scoriæ and other decidedly igneous products, as if there had been actual and vast eruptions, within a period too short for decomposition to have reduced those tumefied and semi-vitrified masses into soil.

*Trap and Basalt.*—Regular formations of trap, and of basalt with symmetrical columns, are common among and beyond the Rocky Mountains, and the rocks of this igneous family are frequent in many parts of the old United States. They abound in New England, New Jersey, and the Carolinas, and, as usual elsewhere, they protrude their dykes among the rocks. In New England, and especially in New Hampshire, they often divide the primary rocks, cutting even granite mountains from top to bottom; branching out, in many places, with numerous veins either dying away to extinction, or, perchance, returning again to the main current after having cut off a portion of the invaded rock. The White Mountains of New Hampshire abound in such phenomena.

Similar intrusions are found in the mountains of Essex, Lake Champlain, New York, and in many other places, and the primary rocks on the coasts of Massachusetts and Maine, as well as in the interior, are wonderfully cut up by invading veins and dykes of trap, basalt, and porphyry, and even of granite itself. It appears, also, that in the state of New York, limestone and other rocks, including the primary, and not excepting granite, are traversed by intrusive trap.*

*Tertiary Formations.*—Our tertiary formations are exceedingly extensive, and are rich in fossil remains. They bound a large portion of the sea coasts south of New England, quite to the Mexican gulf, and up the Mississippi and Missouri: these oceanic deposits are also found, extending hundreds of miles into the interior from the coasts, where, as well as near the sea, they furnish, in their calcareous marls, inexhaustible resources for agriculture. Even on the shores of New England, there are marine tertiary deposits, as at Gay Head, in Martha's Vineyard, and elsewhere in that vicinity; while there are, in every part of the United States, innumerable inland deposits of fresh water tertiary.

*Boulders.*—In boulders and rocks of transport our country

* See Professor Hall, in the Geological Reports for 1838.

16

THE WONDERS OF GEOLOGY.

abounds; vast regions of older secondary and transition strata are
occupied, more or less, by ruins of primary rocks, some of them of
vast size, while the primary countries themselves, and the transition
too, are marked by their own *disjecta membra*. We are precluded
by our limits from discussing the causes of their transportation,
whether by floods, ice floes, or other motive powers. It is almost
unnecessary to remark, that pebbles, gravel, and sand, are found,
as in other countries, transported and distributed, without doubt, by
the action of water.

8. **BEAUTY AND INTEREST OF GEOLOGY AS A SCIENCE.**—In relation to the beauty and interest of Geology as a science, we can hardly trust ourselves to write, since, within our prescribed limits, we have no room, and there is little occasion to describe that which our Author has, everywhere, treated with signal ability and eloquence. It may, however, serve to engage the attention of those to whom geology is a *terra incognita*, if we, in this place, remark, that no field of science presents more gratifying, astonishing, and (but for the evidence) incredible results. It teaches us that man has been but a few thousand years a tenant of this world; for nothing which we discover in the structure of the earth, would lead us to infer that he existed at a period more remote than that assigned to him by the Scriptures. Had he been cotemporary with the animals and plants of the early geological periods, we should have found his remains, and his works, entombed along with them.

This argument forcibly impressed the mind of Bishop Berkeley a
century ago, and the following beautiful passage is cited from him
by Mr. Lyell :*—" To any one who considers that, on digging into
the earth, such quantities of shells, and in some places bones and
horns of animals, are found sound and entire, after having lain
there, in all probability, some thousands of years, it would seem
probable that gems, medals, and implements in metal or stone,
might have lasted entire, buried under ground forty or fifty thou-
sand years, if the world had been so old. How comes it then to
pass that no remains are found, no antiquities of those numerous
ages preceding the Scripture accounts of time; that no fragments
of buildings, no public monuments, no intaglios, cameos, statues,
basso-relievos, medals, inscriptions, utensils, or artificial works of any
kind, are ever discovered, which may bear testimony to the existence

* Principles, 5th Ed., vol. iii. p. 255.

SILLIMAN'S INTRODUCTION.

17

of those mighty empires, those successions of monarchs, heroes, and demi-gods, for so many thousand years? Let us look forward for ten or twenty thousand years to come, during which time, we will suppose that plagues, famine, wars, and *earthquakes*, shall have made great havoc in the world, is it not highly probable, that at the end of such a period, pillars, vases, and statues, now in being, of granite, or porphyry, or jasper, (stones of such hardness as we know them to have lasted two thousand years above ground, without any considerable alteration,) would bear record of these and past ages? Or that some of our current coins might then be dug up, or old walls, and the foundations of buildings, show themselves, as well as the shells and stones of *the primeval world*, which are preserved down to our times.”* This remarkable passage proves that the great man from whom it fell, saw the geological argument in a true light, and felt its force to such a degree as to convince him of the great antiquity of the earth, which he justly viewed, as in no way inconsistent with the comparatively recent origin of man, or with the historical account of both events contained in the Genesis. It is easy to understand how such a mind would have been convinced, warmed, and excited even to enthusiasm, by the discoveries that have burst upon us during the last fifty years.

9. **ORGANIC REMAINS.**—As we descend from the alluvial soil under our feet, through the strata, the lowest of which lies upon the granite, or the early slates, we are seldom without the records of life, in ages long past, and those records are drawn both from the animal and vegetable world.

*Early Animals.*—Shells of molluscous and testaceous animals are everywhere seen; their forms, their casts, their substance, are apparently preserved in stone, but generally converted, by the substitution of mineral matter, into true fossils. Myriads on myriads of these things are found, not merely in the superficial strata, but in the heart of the mountains, and at profound depths, forming an essential part of the solid framework of the globe.† The animals and plants are not accidental resemblances, but authentic specimens of ancient organisms, enclosed in the strata and mountains, as the materials, in mechanical or chemical suspension in the waters, concreted around them.

* Alciphron, or the Minute Philosopher, vol. ii. pp. 84, 85. 1732.

† See the list of strata formed wholly, or in great part, of organic remains, in our Author's Eighth Lecture; and in his "Medals of Creation."

C

18

THE WONDERS OF GEOLOGY.

*Fossil Fishes.*—If we descend from the strata of newest formation, to those that lie near, or upon the primary rocks, we find not only that crustaceous and molluscous animals, of various kinds, have existed in the early periods, but that fishes have occupied the waters of almost all geological ages since life began, and that among the earliest, even those that are buried beneath the coal, there were races of great size, power, and ferocity; formidable from their teeth and jaws, which had, in some species, a structure like those of reptiles; and they had forked tails with unequal flukes, which enabled them quickly to turn over on their backs before striking their prey. The fossil fishes of particular genera and species, are characteristic of particular geological formations—they extend geographically, far and wide, to distant countries, so that certain species may, if found at all, be expected in similar rocks in Europe, in America, in Asia, and Africa; and they are of every size, from inches, and fractions of an inch, to several feet. They occur either solitary—or in groups—or in fragments—or in immense shoals, like those of Monte Bolca, near Verona, in Italy, where there are several hundred species; still, scarcely a single fish of the strata that precede the most recent tertiary, is identical in species with any now existing in the waters of the globe.

*Fossil Vegetables.*—Vegetables are found in strata of nearly all geological ages, and the labours of Count Sternberg, of M. Adolphe Bronguiart, and of many other able botanists, have proved that a peculiar vegetation, adapted to the temperature, the degree of moisture, and other circumstances of the earth's successive surfaces, attended the different geological epochs.

Splendid and expensive works are now in the hands of geologists, containing exact delineations of the fossil vegetables, as far as they have been ascertained. These fossil plants are of all dimensions, from minute confervæ and lichens, to gigantic trees; their structure, from mere fragments to perfect plants, has been beautifully delineated; roots, trunks, branches and leaves, with the most delicate ramifications of the skeletons of the latter, have been examined; and in some rare cases, the more perishable organic fructification has been made out, and the fruits themselves have been identified.*

* See our Author's work, entitled "Medals of Creation," for a lucid summary of the fossil remains of animals and plants, at present known.

SILLIMAN'S INTRODUCTION.

19

*Vegetation of the Coal period.*—The most exuberant vegetation appears to have been that of the coal period, and its entombed treasures now supply the world with fuel, especially in countries where the forests are exhausted, or where economy of the modern vegetation, or preference for the results of the ancient, decides the choice.

*Varieties of the Ancient Fossil Vegetation.*—The ancient vegetation appears in many forms, as in that of lignite, of coal, and of siliceous, calcareous, and ferruginous petrifactions, still preserving the peculiar structure; and this has been made still more distinct and satisfactory, by cutting thin slices of the petrified trunks, and grinding them down until they become transparent, when the microscope reveals the internal structure, which characterizes the family. Thus, it has been made to appear, that coniferous trees of forest growth, occur in the coal formation in the south of Scotland, and the north of England; and that zamias and other palm-like trees were coeval with the chalk in the south of England. But no species of the ancient world are identical with any of the modern, and the early vegetation implies, generally, a warm and moist climate, and great fertility of production.

*Aquatic Animals.*—*Reptiles*.—The abundance of remains of animals, almost exclusively of marine species, attests the great prevalence of the ocean in the earlier geological periods, and it is not until we have passed the coal in the ascending order, that we begin to find reptiles of marine or of amphibious families, and ultimately, still higher up, of terrestrial races. With a similarity of type to the families of the present day, both the genera and species are, however, with but very few exceptions, extinct. Some were carnivorous and swam in the shallow seas, estuaries, lagoons, and bays, and preyed upon fishes, molluscous animals, and each other; some lived on land and were herbivorous; a few genera, the megalosaurus and iguanodon, for example, were colossal in size, and terrible in form, but it is probable that the latter of these terrestrial saurians was harmless and inoffensive, while the tooth of the megalosaurus would indicate a carnivorous animal, like the marine saurians. Bones of many genera and species of the reptile tribes, especially the saurians, have been found, and of some individuals, entire, or nearly perfect skeletons;—among them, several of vast dimensions have been discovered enclosed in the solid rocks,

c 2

20

THE WONDERS OF GEOLOGY.

along with their petrified and half-digested food, and with their coprolites.

*Marsupials*.—If the reptiles formed the transition from the marine animals upward, the marsupials, as they are called, were the link between the ancient reptiles and terrestrial quadrupeds. The marsupials, of which the opossum is an example, receive their young (which, when born, are still immature) into an exterior pouch or abdominal sack, and there nourish them at their paps, until they are fitted to go abroad, and to encounter the vicissitudes of their peculiar modes of life. These are the only animals hitherto found below the chalk which approximate to the proper terrestrial character. Dr. Mantell has, however, found the bones of birds in the Wealden beneath the chalk, and our own countrymen, Professor Hitchcock and Dr. James Deane, have discovered numerous tracks of bipeds, probably of birds, some of them of gigantic dimensions, in the new red sandstone of the Connecticut river.

*Fossils of the Chalk and Tertiary*.—The chalk then follows, with its immense and varied marine treasures—fuci, corals, echinoderms, mollusks, fish, reptiles, with drifted wood, &c.: and then the lower tertiary, still marine: and next, the middle tertiary, where proper and fully characterized terrestrial animals are first found in abundance. Through the remaining beds of tertiary, both marine and fresh-water, we find molluscous animals, fishes, reptiles, and vegetables, verging towards, and many identical with, those of our own times; and occasionally we discover also terrestrial animals, but mostly different from the modern; until, at last, in the diluvium and alluvium, and the most recent sedimentary and concretional formations, we discern animals and plants, still more and more like those now living, and finally graduating into perfect identity with existing races.

*No Fossil Remains of Man*.—Man, and his works, appear only in the last stages, associated with such beings as now exist, both in the animal and vegetable world. The pages of our Author will disclose the great variety and extraordinary forms, and, in many cases, colossal dimensions, unrivalled at the present time, of some of the ancient animals, the megatherium—the sivatherium—the dinotherium—the mastodon—the elephant—the hippopotamus—the rhinoceros—the cavern bear—the tiger, and many others. But in consequence of the most recent discoveries of geology, we are

SILLIMAN'S INTRODUCTION.

21

hurried from that which is stupendous and vast, to that which is inconceivably minute. The extremes of creation meet in the mineral kingdom. In the solid rocks are found both the colossal reptiles, and the microscopic infusorial animalcules. Ehrenberg has discovered that polishing slate is made up of the cases or shells of animalcules so minute, that forty-one thousand millions of them are required to fill a cubic inch, and these siliceous shields are the cause of the well-known effect of the tripoli, or rotten stone, in polishing steel, &c. An analogous constitution has been discovered in certain flint, opal, and bog iron; and extensive deposits of marl, &c., in this country, are composed of similar remains, figures of many of which have been given by Professor Bailey, in the American Journal of Science. Even the soft parts of the foraminifera have been detected in the chalk and flint of England by our Author.*

10. GENERAL REMARKS.—Such is a very general and imperfect sketch of the progressive groups of animals and plants, that have inhabited our world, have become extinct, and are, in countless myriads, entombed in the strata, and in the solid rocks. It is only on the upper surface that we discover loose and scattered boulders and fragments of rocks, and beds of gravel, sand, and detritus, the ruins of more ancient strata; in short, such accumulations of drifted and alluvial materials as we could with reason attribute to catastrophes of rising and rushing water, the deluges of geologists, or the deluge of the Scriptures; the latter, almost alone, being admitted to the contemplations of those who are uninstructed in our science. Now, it is a matter of physical demonstration, that the earth existed for many ages before Man was created; the whole course of geological investigation proves this view to be the only one that is consistent with the facts. To be convinced of its truth, it is only necessary to become thoroughly acquainted with the innumerable records of a progressive creation and destruction which the earth contains, inscribed on medals, more replete with historical truth, and more worthy of confidence, than those that have been formed by man; as much more as nature exceeds in veracity, the erring, or mendacious records of the human race.

11. CONSISTENCY OF GEOLOGY WITH THE SCRIPTURE HISTORY.—Hardly two centuries have passed since the astronomical doctrines

* See Philosophical Transactions, for 1846.

22

THE WONDERS OF GEOLOGY.

of Galileo, Kepler, and Newton, were regarded as inconsistent with the Scriptures, and therefore heretical; but although the discrepancy of the literal meaning of the Bible with the real truths of Astronomy, is still as great as ever, no one any longer hesitates to regard astronomy as giving a just view of the stupendous mechanism of the Universe;—all agree in understanding the language of the Scriptures as being adapted to the *appearances* of the heavens, of which alone, mankind in general can form any just conception, and with which alone the Scriptures are concerned. The Bible, being designed as a code of moral instruction, as a revelation of a future life, and of the sanctions that belong to that momentous subject, contains no systems of philosophy. Moral science, essentially contained in the Scriptures, is not, even there, presented in a regular form, as in human systems, but in modes more happily adapted to the actual condition and capabilities of mankind.

In relation to physics, the information contained in the Bible is only incidental. God is declared to be the Creator of the heavens and the earth,—the physical universe,—and throughout the sacred volume there are innumerable allusions to, and illustrations of, his character, as its Creator and Governor: but there is not even the most general outline of any physical science. The creation of the heavens and the earth, of the sun and the moon, are disposed of with extreme brevity, while the allusions to the geological arrangements of this planet are only such as are connected with the first appearance of its organized beings, and the emergence of the land from the original ocean.

Instruction in the sciences was not the object of the Scriptures; the physical creation was left by its Divine Author for the delightful exercise of our faculties, and to afford an inexhaustible source of mental and moral pleasure;—for application to use, to increase the power and the comforts of man—an equally unfailing fund of improvement, and for the additional illustration of the character of God; an exhaustless fountain of knowledge, mingling its streams harmoniously with those of divine revelation.

From the study of the physical creation, Man has, therefore, drawn all the natural sciences, of which Astronomy is the most sublime and splendid, while Geology yields, in this respect, only to astronomy. Neither astronomy nor geology is, however, enunciated in the Scriptures, but both are revealed in the book of Nature, and

SILLIMAN'S INTRODUCTION.

23

the astonishing truths which they unfold have been brought to
light by human research.

While, as already remarked, the science of astronomy is, in fact,
inconsistent with the *apparent* movements in the heavens, and,
therefore, with the literal and popular phraseology of the Scriptures,
which allude to physical things as they appear to the uninstructed
mind, and not as they are in reality,—geology presents not even
this discrepancy, but, on the contrary, a substantial agreement in
its facts with the Scriptures. The latter describe a physical crea-
tion of mineral matter, and a successive creation of plants and
animals, ending with man; while geology, by irrefragable demon-
strations, which nothing but a study of the earth could afford,
proves this history to be true.

The Scriptures describe a universal deluge; and geology shows
that every part of the earth is marked by the effect of such visita-
tions, occurring at one time, or at many times;—a repetition of
local deluges, or a general one, would produce similar results; and
although it may be impossible to distinguish between the accumu-
lated effects of local overflows, and a general diluvial devastation,
the surface of the earth is everywhere strewn with diluvial debris.
The Scriptures declare that there was a beginning, and geology
proves that there was a time when neither plants, nor animals, nor
man existed; but both the Scriptures and geology are silent as to
the period when the fiat of the Creator first called our earth and
the planetary systems into being. It was, doubtless, in very
remote antiquity, but the commencement is known only to Him
who has neither “beginning of years, nor ending of days.”

Thus the consistency of geology with the early Scripture history,
is susceptible of a perfect and triumphant defence, but it is not to be
found in the refinements of exegesis, nor in the forced solution of
a general deluge, which is entirely unsatisfactory, and, indeed,
impossible, as a cause of the regular formations of the earth,
immensely varied as they are, and exuberant in the relics of many
successive races of the animals and vegetables of past ages. But
this consistency is found in the regular induction from facts, in
the just understanding of time, and in its extension back beyond
the creation of man, so far as to embrace the innumerable events
that have certainly happened in the material world.

To this conclusion the religious mind is fast approaching, and

THE

WONDERS OF GEOLOGY.

---

LECTURE I.

1. Introductory.
2. Nature of Geology.
3. Harmony between Revelation and Geology.
4. Duration of geological Epochs.
5. Structure of the Earth.
6. Geographical Distribution of Animals and Plants.
7. Temperature of the Earth.
8. Nature of the Crust of the Globe.
9. Classification of Rocks.
10. Geological Mutations.
11. Connexion of Geology with Astronomy.
12. Nebular theory of the Universe.
13. Various states of the Nebulae.
14. Formation of the Solar System.
15. Gaseous state of the Earth.
16. Geology elucidated by Astronomy.
17. Aerolites.
18. Origin of Aerolites.
19. Existing geological Agents.
20. Aqueous Agency: the effects of Streams and Rivers.
21. Deltas of the Ganges and Mississippi.
22. Formation of Fluviatile Strata.
23. Ripple-marks.
24. Lewes Levels.
25. Remains of Man in modern Deposits.
26. Peat Bogs.
27. Conversion of Peat into Coal.
28. Subterranean Forests.
29. Geological effects of the Ocean.
30. The Bed of the Ocean.
31. Effects of Currents.
32. Icebergs and Glaciers.
33. Incrusting Springs.
34. Incrustations.
35. Lake of the Solfatara.
36. Marble of Tabreez.
37. Stalactites and Caverns.
38. Consolidation of loose Sand.
39. Destruction of Rocks by Carbonic Acid.
40. Carbonic Acid in Caves.
41. Consolidation by Iron.
42. Recent Limestone of the Bermudas.
43. Fossil human Skeletons.
44. Isle of Ascension.
45. Drifted Sand.
46. Formation of recent Sandstone.
47. Siliceous depositions.
48. The Geysers of Iceland.
49. Siliceous Thermal Waters of New Zealand.
50. Artificial Solution of Silex.
51. Hertfordshire Pudding-stone.
52. Effects of high Temperature.
53. Volcanic agency.
54. Subsidence and Elevation of the Temple at Puzzuoli.
55. Historical Evidence.
56. Causes of these changes.
57. Elevation of the Chilian Coast.
58. Raised Sea-beach at Brighton.
59. Elevation of Scandinavia.
60. Mutations in the relative Level of Land and Sea.
61. Retrospect.

1. INTRODUCTORY.—An eminent philosopher* has justly remarked, that in order to obtain a proper sense of the interest and importance of any science, and of the objects which it embraces, nothing more is necessary than the

* Professor Sedgwick.

26

THE WONDERS OF GEOLOGY.

LECT. I.

intent and persevering study of them; for such is the consummate perfection of all the works of the Creator, that every inquirer will discover a surpassing worth, and grace, and dignity, in that especial department of knowledge to which he may peculiarly devote his attention. Whatever walk of philosophy he may enter, that will appear to him the path which is the most enriched by all that is fitted to captivate the intellect, and to excite the imagination. Yet before we can attain that elevation from which we may look down upon and comprehend the mysteries of the natural world, our way must be steep and toilsome, and we must learn to read the records of creation in a strange language. But when this knowledge is once acquired, it becomes a mighty instrument of thought, by which we are enabled to link together the phenomena of past and present times, and obtain a domination over many parts of the natural world, by comprehending some of the laws by which the Creator has ordained that the actions of material things shall be governed.

In the whole circle of the sciences, there is none that more strikingly illustrates the force and truth of these remarks than Geology; none which offers to its votaries rewards so rich, so wondrous and inexhaustible. In the shapeless pebble that we tread upon, in the rude mass of rock or clay, the uninstructed eye would in vain seek for novelty or beauty; like the adventurer in Eastern fable, the inquirer finds the cavern closed to his entrance, and the rock refusing to give up the treasures entombed within its stony sepulchre, till the talisman is obtained that can dissolve the enchantment, and unfold the marvellous secrets which have so long lain hidden.

2. NATURE OF GEOLOGY.—To the mind that is unacquainted with the nature and results of geological inquiries, and which has been led to believe that the globe we inhabit is in the state in which it was first created, and that with

§ 3.

HARMONY WITH REVELATION.

27

the exception of the effects of a general deluge, its surface
has undergone no material change, many of the facts to be
noticed in the course of these lectures may appear almost
incredible, and the inferences drawn from their investiga-
tion be regarded as the vagaries of the imagination, rather
than as the legitimate deductions of sound philosophy. If,
therefore, it be absolutely necessary, as it unquestionably
is, that in the pursuit of knowledge of any kind, before
even experience can be employed with advantage, we must
dismiss from our minds all prejudices, from whatsoever
source they may arise, this mental purification becomes the
more indispensable in a science like Geology, in which
we meet at the very threshold with facts so novel and
astounding; facts which prove, that though man and other
living things be, as it were, but the creation of yesterday,
the earth has teemed with numberless forms of animal
and vegetable life, myriads of ages ere the existence of the
human race.

Geology may be termed the physical history of the
earth,—it comprehends the investigation of the mineral
structure of our globe, and the characters and causes of
the various changes which have taken place in the organic
and inorganic kingdoms of nature. It has been empha-
tically denominated by one of our most distinguished philo-
sophers, the sister science of Astronomy. But, relating as
it does to the history of the past, and carrying us back by
the careful examination of the relics of former ages, to
periods so remote as to startle all our preconceived opinions
of the age of our planet, the fate of its early cultivators has
resembled that of the immortal Galileo and the astronomers
of his times; and for a similar reason, namely, the supposed
discrepancy between the discoveries and inferences of this
science, and the Mosaic cosmogony.

3. HARMONY BETWEEN REVELATION AND GEOLOGY.—
There was a time when every geologist was compelled to

28

THE WONDERS OF GEOLOGY.

LECT. I.

defend himself against imputations of this kind, and it is
deeply to be regretted, that there still exists in the minds
of many well-meaning persons a prejudice against the study
of Geology, from a mistaken apprehension, lest it should
weaken our belief in the revealed word of God; for they
assume that the results of geological inquiries, and the
Mosaic account of the creation of the world, are utterly at
variance with each other. But, convinced as I am that
there never can be any collision between the doctrines of
the purest piety and those of sound philosophy, and that
prejudices have been created and perpetuated by authors,
who, falsely styling themselves geologists, have mixed up
their own vague and erroneous notions with the history of
the earth as given by the inspired writer—attempting, with
the presumption of ignorance, to account for that which
lies beyond the reach of human investigation, and to
explain it by evidence equally misapprehended and mis-
applied—I would most unequivocally assert, that a just
view of the nature and limits of geological science warrants
no such reproach. Abandoning all attempts to explain the
inexplicable, or to reconcile the irreconcilable, it confines
itself to its legitimate purpose of accumulating and inves-
tigating facts, of pointing out analogies, and indicating the
inferences to which they lead; “this is far different from
the presumption which would fain prove the truth of Scrip-
ture by physical evidence, or the weakness that would found
a system of natural philosophy on the inspired record.”

Nothing is more unwarrantable than attempts to identify
theories in science with particular interpretations of the
sacred text; and the caution of Lord Bacon, uttered a
century and a half before geology even had a name, cannot
be too often repeated. “Let no man,” said he, “upon a
weak conceit of sobriety, or an ill-applied moderation, think
or maintain that a man can search too far, or be too well
studied in the book of God’s word, or the book of God’s

§ 4.

HARMONY WITH REVELATION.

29

works—divinity or philosophy: but rather let men endea-
vour an endless progress or proficiency in both; only let
them beware that they apply both to charity and not to
arrogance—to use and not to ostentation; and again, *that
they do not unvisely mingle or confound these learnings
together.*" Deeply impressed with the necessity of strictly
obeying this admonition, I have, in all my written and oral
discourses on geology, confined myself to a simple statement
of the opinions of certain eminent philosophers and divines
on this subject—men, alike distinguished for their piety
and learning, and who have cultivated with ardour this
department of natural science, and have expressed their
conviction of its high importance and beneficial influence
upon the mind—in the hope that such evidence would be a
sufficient and direct reply to the absurd and unfounded
charges brought against geology. On the present occasion,
I shall content myself with the following extract from a
sermon by the Bishop of London: "*As we are not called
upon by Scripture to admit, so neither are we required to
deny the supposition, that the matter, without form and
void, out of which this globe was framed, may have con-
sisted of the wrecks and relics of more ancient worlds,
created and destroyed by the same Almighty Power which
called our world into being, and will one day cause it to
pass away.*"*

Thus, while the Bible reveals to us the moral history
and destiny of our race, and instructs us that mankind and
the existing races of beings have inhabited the earth but
a few thousand years, the physical monuments of our globe
bear witness to the same truth; and as astronomy unfolds
to us innumerable worlds not spoken of in the sacred
records, geology in like manner proves, not by arguments

* Sermons, by Dr. Charles James Blomfield, Bishop of London.
8vo. 1829.

30

THE WONDERS OF GEOLOGY.

LECT. I.

drawn from analogy, but by incontrovertible physical evidence, that there were former conditions of our planet, separated from each other by vast intervals of time, during which this world was teeming with life, ere the creation of man and the animals which are his cotemporaries.

4. DURATION OF GEOLOGICAL EPOCHS.—At the first step we take in geological investigations, we are struck with the immense periods of time which the phenomena presented to our view must have required for their production, and the incessant changes which appear to have been going on in the natural world. But we must remember that time and change are great only with reference to the faculties of the beings which note them; the insect of a day, contrasting its ephemeral life with that of the flowers on which it rests, would attribute an unchanging permanence to the most evanescent of vegetable forms; while the flowers, the trees, and the forests, would ascribe an endless duration to the soil on which they grow: and thus, uninstructed man, comparing his transient earthly existence with the solid framework of the world he inhabits, deems the hills and mountains around him coeval with the globe itself. But with the enlargement and cultivation of his reasoning powers, man takes a more just, comprehensive, and enlightened view of the wonderful scheme of creation; and while in his ignorance he imagined that the age and duration of this planet were to be measured by his own brief span, and arrogantly deemed himself alone the object of the Almighty's care, and that all things were created solely for his pleasures and necessities, he now becomes conscious of his own insignificance and dependence, and entertains more correct ideas of the omnipotence and goodness of his Creator. And while exercising his high privilege of being the only creature endowed with the capacity of contemplating and understanding the wonders of the natural world, he learns that most important of all

§ 5.

STRUCTURE OF THE EARTH.

31

lessons—to doubt the evidence of his senses, until confirmed by cautious and patient observation.

With these introductory remarks I proceed to the consideration of the subjects selected for the present discourse, premising, that from the magnitude and diversity of the objects embraced by geology, it is scarcely possible to offer, in the space assigned to a course of popular lectures, even an epitome of the marvels which modern researches have brought to light. This consideration, therefore, must be my apology for the concise manner in which many interesting facts will be noticed; and I would beg of you to consider that lectures of this kind can only present a general view of the philosophy of geology; that they are calculated to excite, rather than to satisfy, a rational curiosity, and cannot supersede the necessity of study, and of personal investigation.

5. STRUCTURE OF THE EARTH.—The globe we inhabit is a planetary orb, about twenty-four thousand miles in circumference, and of a spheroidal shape; its figure being such as a fluid body, made to rotate on its axis, would assume. The mean density is five times greater than that of water, the interior being double that of the solid external case. From astronomical observations, the original crust of the earth is supposed to have been a superficial coating of solidified matter, produced by the cooling of the surface of an incandescent fluid globe; and on this shell or crust have been slowly accumulated, during the lapse of innumerable ages, the rocks and strata which form the more immediate objects of geological investigation. The thickness of the solid crust of the earth is computed at from 800 to 1,000 miles, but it is not supposed that this shell is uniform in extent or density; on the contrary, it is probable that it is cavernous, and that liquid masses of mineral matter, in various states of fluidity and incandescence, are distributed throughout the interior of the globe. Some of

§ 6.

GEOGRAPHY OF ANIMALS AND PLANTS.

33

surface of the globe is fit for the habitation of man and terrestrial animals.* The area of the Pacific Ocean alone, is estimated to be equal to the entire surface of the dry land. The distribution of the land is exceedingly irregular, the greater portion being situated in the northern hemisphere, as a reference to a terrestrial globe, or a map of the world, will clearly demonstrate.

In a geological point of view, dry land is that portion of the earth's crust which is now above the level of the water, beneath which it may again disappear; and from accurate calculations it is proved, that the whole of the materials composing the present land might be distributed over the bed of the ocean, in such manner that the surface of the globe would present an uninterrupted sheet of water; thus we perceive that every imaginable distribution of land and water may have taken place, at different periods, in the earlier ages of our planet.

## 6. GEOGRAPHICAL DISTRIBUTION OF ANIMALS AND PLANTS.

—The investigation of the laws which govern the geographical distribution of animals and vegetables is highly interesting; but as my limits compel me to be brief, I must refer you to Mr. Lyell's "Principles of Geology," for a full consideration of the subject. It will be sufficient for our present purpose to state, that although it might have been expected, all other circumstances being equal, that the same animals and plants would be found in places of like climate and temperature, this identity of distribution does not exist. When America was first discovered, the indigenous quadrupeds were all dissimilar to those of the Old World. The elephant, rhinoceros, hippopotamus, giraffe, camel, horse, buffalo, lion, tiger, &c. were not met with on the new continent; while many of the American mammalia, as the llama, jaguar, coati, sloth, &c. were unknown in the old.

* Bakewell's Geology.

D

34

THE WONDERS OF GEOLOGY.

LECT. I.

New Holland contains, as is well known, a most singular assemblage of mammalia, consisting of more than forty species of marsupial animals; of which the kangaroo is a familiar example. The islands of the Pacific Ocean possess no indigenous quadrupeds, except hogs, dogs, rats, and a few bats.

The distribution of vegetable life, though perhaps more arbitrarily fixed by temperature and by local influences than that of animals, presents many anomalies. From numerous observations, however, it is supposed that vegetable creation took place in different centres, each of which was the focus of a peculiar genus or species; for many plants have a local existence, and vegetate naturally in one district alone; thus the cedar of Lebanon is indigenous on that mountain, but does not grow spontaneously in any other part of the world. It is also ascertained that certain great divisions of the vegetable kingdom are distributed over particular regions: we shall have occasion to refer to this subject in the lecture devoted to the consideration of fossil plants.

7. TEMPERATURE OF THE EARTH.—The temperature of the surface of the globe depends on the action of solar light and heat; hence the difference in the seasons, and climates of various latitudes; but there are many causes which modify the distribution of the sun's influence, and produce great local variations: under equal circumstances, however, the temperature is found progressively to diminish from the equator to the poles. There is also an internal source of heat, the cause of which has not yet been determined, but is supposed to be connected with the original constitution of our planet. It has been ascertained, by careful experiments, that below the point to which the solar influence can penetrate, there is, almost everywhere, an invariable increase of temperature, amounting to 1° of Fahrenheit for every 54 feet of vertical depth: it is therefore possible that

§ 8.

THE CRUST OF THE GLOBE.

35

at 100 miles beneath the surface of the earth, even the least fusible rocks and minerals may be in a melted state.

8. NATURE OF THE CRUST OF THE GLOBE.—The total thickness of that portion of the rocks and strata accessible to human observation, reckoning from the highest mountain peaks to the greatest natural or artificial depths, is variously estimated at from ten to fifty miles. As the earth is nearly eight thousand miles in diameter, the entire series of strata hitherto explored is, therefore, but very insignificant compared with the magnitude of the globe; bearing about the same relative proportion as the thickness of this paper to an artificial sphere a foot in diameter; the inequalities and crevices in the varnish of such a ball would, in fact, be equal in proportionate size to the highest mountains and deepest valleys.

The depth of the crust of the earth, and the greatest inequalities of its surface, as compared with its mass, are ex-

LIGN. 2.—DIAGRAM TO ILLUSTRATE THE PROPORTIONATE THICKNESS OF THE EARTH'S CRUST.

pressed in the annexed diagram.* The line from *e* to *k*, represents a depth of 500 miles; to the point *i*, 100 miles; to the line *l*, 40, forty-five miles above the surface, the supposed

* To preserve as far as possible the language and spirit of the original lectures, the references to the diagrams and specimens are retained.

D 2

36

THE WONDERS OF GEOLOGY.

LECT. I.

limit of the earth's atmosphere; and the dark line, *a, h*, a thickness of ten miles. The points *d, e, f, g*, indicate the altitude of the highest mountains in the world;* the depth of the sea is shown by the line at the extremities of the arc, *a, h*. As a thickness of 100 miles so far exceeds that of the whole of the strata that are accessible to human observation, we cannot doubt that disturbances of the earth's surface, even to ten times the depth of those which come within the scope of geological investigation, may take place, without in any sensible degree affecting the entire mass of the globe.† If these facts be duly considered, the mind will be prepared to receive one of the most striking propositions in modern geology—namely, that the highest mountains were once beneath the sea, and have been raised to their present situations by subterranean agency,— some slowly, others suddenly, but all, geologically speaking, at comparatively recent periods.

* The highest peak of the Alps, and of Europe, is Mont Blanc, which is 15,660 feet above the level of the sea—of the Andes, Chimborazo, which is 21,425 feet—and of the Himalayas, Dhwalagiri, estimated at 28,000 feet, being more than five miles of perpendicular altitude.

† To convey a general idea of the relative magnitude of the inequalities of the earth's surface, Mr. Fairholme suggests the following ingenious method. If we form a scale on the sand of the sea-shore in the proportion of an inch to a mile, we shall have a circle of 8000 inches, or 222 yards in diameter, which when marked out with small stakes, appears a very large area. Placing ourselves upon any part of this circumference, we have an opportunity of taking a just, though microscopic, view of the surface. The highest mountains in the world would be represented by a little ridge five inches high; the profound abyss of the ocean by a groove of the same depth; while the medium inequality of sea and land would not exceed one inch. To form an idea of smaller objects, we must examine an inch scale, finely graduated, by the aid of a microscope, and we shall then find that the tallest man would be about the 880th part of an inch in height—the size of the smallest animalcule observed in fluids, by the aid of the most powerful microscope.

§ 9.

CLASSIFICATION OF ROCKS AND STRATA.

37

The superficial crust of the globe is composed of numerous layers and masses of earthy substances, of which various combinations of iron, lime, and silex or flint, constitute a very large proportion; the latter forming forty-five per cent. of the whole. Those strata which have been deposited the latest, bear evident marks of mechanical origin, and are the water-worn ruins of older rocks; as we penetrate deeper, deposits of a denser character appear, which also exhibit proofs of having been formed by the action of water; but when we arrive at the lowermost accessible to observation, a crystalline structure generally prevails; and while in the upper stratified rocks, the remains of animals and vegetables are found in profusion, in the ancient crystalline masses all traces of organic forms are absent.

9. CLASSIFICATION OF ROCKS AND STRATA.—In the infancy of the science these remarkable facts gave rise to an ingenious theory, which being founded on insufficient data, has proved untenable. It will, however, be requisite briefly to explain this hypothesis, as some of the terms still employed in geological nomenclature refer to the speculations it suggested. According to this theory the mineral masses composing the earth's crust, are separable into three grand divisions or groups, as follow :—

1st. *Primitive Rocks*.—The Primitive (now termed *Primary*) rocks, are of a crystalline structure, and have evidently been brought to their present state by igneous agency; they comprise granite, sienite, porphyry, &c. These are the lowermost rocks, and constitute the foundation on which all the newer strata have been deposited; they also attain the highest elevations on the surface of the globe. They were termed primitive, because, from the entire absence of organic remains, it was inferred that they were formed before the creation of animals and vegetables; but it is now certain that granite and its associated rocks

38

THE WONDERS OF GEOLOGY.

LECT. I.

are of various ages, and it is believed are sedimentary deposits which have been altered by long exposure to a very high temperature.

2d. *Transition Rocks*.—These are super-imposed on the primary, are more or less distinctly stratified, and contain the fossilized remains of animals and plants. They received the name of *transition*, because it was assumed that they had been deposited at a period when the land and sea were passing into a state fit for the reception of organized beings. Modern researches have, however, shown that like the primary rocks, these are strata which have been altered by the effects of heat under great pressure; hence they are now termed *metamorphic*.

3d. *The Secondary Formations*.—These strata have originated, in great part, from the destruction of more ancient rocks, and have been deposited in the basins of lakes, bays, and estuaries, and in the profound depths of the ocean, by the action of rivers and seas. They abound in the mineralized remains of animals and plants; the most ancient enclosing zoophytes and shells; the next in antiquity containing, in addition, vegetable remains and fishes; those which succeed enveloping not only fishes, shells, zoophytes, plants, and insects, but also bones of numerous species of extinct marine and terrestrial reptiles, and of birds, and of a few genera of mammalia. The Chalk is the uppermost, or most recent of this class. As the secondary rocks have manifestly been formed by the agency of water, it is clear that they were originally deposited in horizontal, or nearly horizontal layers or strata, although by far the greater portion has since been broken up, and thrown in directions more or less inclined to the horizon.

For the convenience of study, this subdivision of the rocks is still retained, as will hereafter be shown. To the above groups modern geologists have added two others, namely, the *Tertiary*, and the *Alluvial Deposits*.

§ 10.

GEOLOGICAL MUTATIONS.

39

4th. *The Tertiary Strata.*—These strata lie upon, and fill up, depressions or basins of the chalk, and other secondary rocks; they consist of the detritus of more ancient beds, and of the relics of shells, plants, zoophytes, crustacea, fishes, &c.: and in them, with but one exception, the bones of mammalia first appear.

5th. *Alluvial Deposits.*—Of a later formation than the tertiary, are those irregular accumulations of alluvial or water-worn and drifted materials, which are spread over the surface of almost every country. In the newest of these beds are found remains of existing races of animals and plants, which, in the most ancient, are associated with those of extinct genera and species.

Even this slight examination of the strata affords convincing proofs of a former condition of animated nature, widely different from the present. We have evidence of a succession of periods of unknown duration, in which both the land and the sea teemed with forms of existence that have successively disappeared and given place to others; and these again to new races, more nearly related to those which now inhabit the earth, till at length traces of existing species appear.

10. GEOLOGICAL MUTATIONS.—From this view of the mineral structure of our planet we learn, at least so far as the limited powers of man can penetrate into the history of the past, that the distribution of land and water on the earth's surface has been undergoing perpetual mutation; yet, that through a vast period of time, its physical condition has not materially differed from the present. We find that the dry land has been clothed with vegetation, and tenanted by appropriate inhabitants; and that the seas and the

* The term *diluvial* is commonly employed to denote the most ancient of these deposits, and that of *alluvial* the more recent, in which existing species of animals only occur.

40

THE WONDERS OF GEOLOGY.

LECT. I.

rivers and lakes of fresh water have swarmed with living things; that at remote epochs, though animals and vegetables existed, the species were distinct from those that now abound, and the greater number fitted to live in a different climate than that which now prevails in the regions where these relics are entombed; and lastly, that in the lowest and most ancient beds, all traces of mechanical action, and of animal and vegetable organization, are absent; in other words, have either never existed, or *have been altogether obliterated*.

11. **CONNEXION OF GEOLOGY WITH ASTRONOMY.**—
Before entering upon that department of the subject to
which the term Geology is commonly restricted, it will
facilitate our comprehension of many of the phenomena
that will come under our notice, if in this place we
endeavour to penetrate the mystery that veils the earliest
condition of the earth; but this we shall in vain attempt,
if we restrict our observations to the physical phenomena
observable in our own planet. Here Geology leads to
Astronomy, and teaches us to contemplate the kindred
spheres around us for the elucidation of the early history
of the globe, and to regard the earth but as an attendant
satellite on a vast central luminary. The solar system
consists of the sun, which is a mass of solid matter sur-
rounded by a luminous atmosphere, or nebulosity; of
twelve planets, which revolve around it in various periods;
of eighteen satellites; and of numerous comets, three of
which do not pass beyond the orbits of the principal
planets. The earth is the third in distance from the sun,
and in bulk, as compared with that body, of the size of a
pea to that of a globe two feet in diameter; and it has a
satellite, the moon, which revolves round it.

Upon examining the moon with a powerful telescope, we
perceive that its surface is diversified by hills and valleys,
and presents a congeries of mountains, many of which are

§ 12.

NEBULAR THEORY OF THE UNIVERSE.

41

manifestly volcanic, lava currents being distinctly visible.
We see in fact a torn, rugged, sterile area, studded with

LIGN. 3.—TELESCOPIC VIEW OF THE MOON.

craters, and scarred by rents and chasms, and having such an aspect as we may conceive would be presented by our earth, were the pinnacles of the granite mountains un-abraded, and the valleys bare, and not covered and partially filled up by sedimentary deposits.* But there is no evi-dence of the presence of either air or water in the moon.

12. NEBULAR THEORY OF THE UNIVERSE. — In the original condition of the solar system, it is supposed that the sun was the nucleus of a nebulosity, or luminous mass, which revolved on its axis, and extended far beyond the

* See Appendix A.

42

THE WONDERS OF GEOLOGY.

LECT. I.

orbit of the most distant of the planets; these bodies having
then no existence. Its temperature gradually diminished,
and contracting by refrigeration, the rotation increased in
rapidity, and zones of nebulosity were successively thrown
off, in consequence of the centrifugal force overpowering
the central attraction: the condensation of these separated
masses constituted the planets and satellites. This view of
the conversion of gaseous matter into planetary bodies is
not limited to our own system; it extends to the formation
of the innumerable suns and worlds which are distributed
throughout the Universe; for the discoveries of modern
astronomers have shown, that every part of the realms of
space abounds in large expansions of attenuated matter,
(termed *nebulæ*,) which are irregularly reflective of light,
and of various figures, and in different states of conden-
sation, from that of a diffused luminous mass, to suns and
planets like the earth.

It must be admitted that this hypothesis is astounding,—
and we may well demand if man, the ephemeron of the
material world, can indeed measure the vast epochs which
mark the progressive development of suns and systems ?
The master minds of Laplace and Herschel have effected
this wonderful achievement, and explained the successive
changes by which it seems probable that suns and planetary
systems are formed, through the agency of the sublime
laws of the Eternal. By laborious and unremitting ob-
servations, those illustrious philosophers have demon-
strated the progress of nebular condensation, not indeed
from the appearances presented by a single nebula, (for the
process, probably, can only become sensible through the
lapse of ages,) but by observations on the almost endless
series of related contemporaneous objects that appear in
every varied state of progression, from that of a cloud of
luminous vapour, to the most dense and mighty orbs that
appear in the firmament. As the naturalist in the midst of a

§ 12.

43

forest, though unable by a glance to discover that the trees
around him are in a state of progressive change, yet per-
ceiving that there are plants in different stages of growth,
from the acorn just bursting from the soil to the lofty oak
that stands the monarch of the woods, infers, from the
succession of changes thus at once presented to his view,
the progression of vegetable life, though extending over
a period far beyond his own brief existence :—in like
manner, the astronomer, by surveying the varied conditions
of the heavenly bodies around him, can, by careful induc-
tion, determine the nature of those changes, which, as

LIGN. 4.—TELESCOPIC APPEARANCE OF VARIOUS NEBULÆ.

regards a single nebula, the human mind would otherwise
be unable to ascertain. And thus have been traced from
nebular masses of absolute vagueness, to others which pre-
sent form and structure, the effects of the mysterious law

44

THE WONDERS OF GEOLOGY.

LECT. I.

which appears to govern the stupendous celestial phenomena
that are constantly taking place.*

13. VARIOUS STATES OF THE NEBULÆ.—Some of the nebulæ appear as mere clouds of attenuated light—others as if curdling into separate masses—while many seem assuming a spheroidal figure. Others again present a dense central nucleus surrounded by a luminous halo; and a series may thus be traced, from clusters of round bodies with one or more increased points of condensation, or of central illumination, to separate nebulæ with single nuclei, and with rings, to a central disk constituting a nebular star; and finally to an orb of light with a halo like the sun!

In the comets, those nebular bodies which belong to our
own and other systems, we have evidence that even in the
most diffused state of the luminous matter, the masses
which it forms are subservient to the laws of orbicular
motion: of this fact an interesting proof is afforded by
Encke's comet (*Lign. 5*), that mere wisp of vapour, which in
a period but little exceeding three years, revolves around
the central luminary of our system.

This beautiful theory of Laplace, and of Herschel,
explains by an easy and evident process the formation of
planets and satellites, and accounts for the uniform direction
of their revolutions; and not only is it inferred that such
is the law which the Creator has established for the main-
tenance and government of the Universe, but also that upon
mechanical principles, such nebulæ must of necessity con-
solidate into planetary bodies.

* Although by the enormous powers of the telescope constructed
by the Earl of Rosse, it has been ascertained that several of Herschel's
nebulæ are clusters of stars, and it is therefore probable that other
supposed nebular masses may be brought into the same category, the
theory explained in the text will only be modified, not disproved
thereby.

§ 14.

FORMATION OF THE SOLAR SYSTEM.

45

14. FORMATION OF THE SOLAR SYSTEM.—In accordance with this hypothesis our sun is regarded as a planetary orb

LIGN. 5.—TELESCOPIC VIEW OF ENCKE'S COMET.

with a luminous atmosphere, the central nucleus of a nebu-
losity which originally extended to the extreme verge of
our planetary system. During the condensation of this
nebula the planets were successively thrown off; the most
distant, Neptune, being the first or most ancient, followed
by Uranus, Saturn, Jupiter, the five asteroids, Mars, the
Earth, Venus, and Mercury; the satellites, as distinct
worlds, being the most recent of the whole. It is inferred,
that in any given state of the rotating solar mass, the outer
portion or ring might have its centrifugal force exactly
balanced by gravity; but increased rotation would throw
off that ring, which might sometimes retain its figure, of
which we have a striking example in Saturn, and also in
the newly-discovered planet Neptune. This result, how-

46

THE WONDERS OF GEOLOGY.

LECT. I.

ever, could not take place unless the annular band were of
uniform composition, which would rarely be the case;

LIGN. 6.—TELESCOPIC VIEW OF SATURN.

hence the ring would most generally divide into several
portions, which might sometimes be of nearly equal bulk,
as in the *Asteroids*, while in others they might coalesce into
a single mass. The solar nebulæ, thus separated at various
periods, and constituting planets in a gaseous state, would
necessarily have a rotatory motion, and revolve in varying
orbits around the central nucleus; and as refrigeration and
consolidation proceeded, each body might project entire
annuli or rings, and satellites, in like manner as the sun
had thrown off the planets themselves.

In addition to the appearance of various states of attenu-
ation and of solidity presented by the nebulæ, the orbs of
our own system afford evidence of corresponding gradations
of density. The planets near to the sun are denser than
those which are more distant: thus Mercury, which is the
nearest, is the heaviest, being almost thrice as dense as the
earth; while the density of Jupiter, which is far removed,

§ 14.

47

is only one-third that of our planet; and Saturn, which,
with the exception of Uranus and Neptune, is the remotest,
is but little more than one-eighth as dense, and is supposed
to be as light as cork.*

You will at once perceive that this theory can in no
wise affect the sublime truth that the Universe is the work
of an all-wise and omnipotent Creator; " For let it be as-
sumed that the point to which this hypothesis leads us, is
the ultimate boundary of physical science—that the nearest
glimpse we can attain of the material universe, displays it
to us as occupied by a boundless abyss of attenuated matter;
still we are left to inquire how space became thus occupied
—whence originated matter thus luminous? And if we
are able to establish by physical proofs, that the first fact
which the human mind can trace in the history of the
heavens is, that ' there was light,' we are irresistibly led to
the conclusion, that ere this could take place, ' GOD SAID,
Let there be light.' "†

This theory of the condensation of nebular matter into
suns and worlds, marvellous as it may appear, will be found
on due reflection to suggest the only rational explanation
of the phenomena observable in the sidereal heavens, and
in our own globe, according to the present state of the physi-
cal sciences; while its beautiful simplicity is in correspon-
dence with the unity of design so manifest throughout the
works of the Eternal. ‡

* Introduction to Astronomy, by Sir J. F. W. Herschel. Those who feel desirous of more ample information on this subject, should consult "*Views of the Architecture of the Heavens*," by Dr. Nichol, Professor of Practical Astronomy in the University of Glasgow.

† Professor Whewell.

‡ Dr. Pye Smith, in his able commentaries on the "Relation between Scripture and Geological Science," has the following remarks upon this subject. "The nebular hypothesis, ridiculed as it has been by persons whose ignorance cannot excuse their presumption, is regarded by some of the finest and most Christian minds as in the highest degree pro-

48

THE WONDERS OF GEOLOGY.

LECT. I.

15. GASEOUS STATE OF THE EARTH.—Though it may be difficult to the unscientific inquirer to comprehend that our planet once existed in a gaseous state, this difficulty will vanish upon considering the nature of the changes to which all the materials composing the earth are constantly subjected. Water offers a familiar example of a substance existing on the surface of the globe, in the separate states of rock, fluid, and vapour; for water consolidated into ice is as much a rock as granite or the adamant, and, as we shall hereafter have occasion to remark, has the power of preserving for an indefinite period the remains of any animals and vegetables imbedded therein. Yet simply upon an increase of temperature, the glaciers of the Alps, and the icy pinnacles of the Arctic circles, disappear; and by a degree of heat still higher, would be resolved into vapour; and by other agencies might be separated into two invisible gases—

bable. If I may venture to utter my own impression, I must profess it as the most reasonable supposition, and the correlate of the nebular theory, that God originally gave being to the primordial elements of things, the very small number of simple bodies, endowing each with its own wonderful properties. Then, that the actions of those properties, in the ways which his wisdom ordained and which we call laws, produced, and is still producing all the forms and changes of organic and inorganic nature; and that the series is destined to proceed, in combinations and multiplications ever new, without limit of space or end of duration, to the eternal display of His glory.”

These remarks may be regarded as a philosophical enunciation of the hypothesis that has been termed "organic creation by law," or the formation of living beings from inorganic elements. But this theory is not, at present, substantiated, nor even sanctioned, by any unequivocal evidence: and this absence of all proof appears to me the serious and only legitimate objection to the reception of a doctrine which would explain many obscure physiological phenomena, and bring the laws of vitality into harmony with those which preside over the inorganic kingdom of nature. See the Appendix to my "Thoughts on Animals, cules;" and Westminster Review, No. XC., article "Revelations of the Microscope."

§ 16.

GEOLOGY ELUCIDATED BY ASTRONOMY.

49

oxygen and hydrogen. Metals may in like manner be converted into gases; and in the laboratory of the chemist, all kinds of matter easily pass through every grade of transmutation, from the most dense and compact to an aeriform state. We cannot, therefore, refuse our assent to the conclusion, that merely by the dissolution of the existing combinations of matter, the entire mass of our globe might pass into a gaseous or nebular condition.

16. GEOLOGY ELUCIDATED BY ASTRONOMY.—From the light thus shed by modern Astronomy upon many of the dark and mysterious pages of the earth's physical history, it appears probable that the dynamical changes which have taken place in our globe—all the transmutations of its crust revealed by geological investigations—may be referable to the operation of the one, simple, and universal law, by which the condensation of nebular masses into worlds, through periods of time so immense as to be beyond the power of human comprehension, is governed.

The internal heat of the globe—the evidence afforded by the crystalline condition of the lowermost rocks of a prevailing higher temperature in an earlier state of the earth—and the elevations and dislocations of its crust which have taken place, and are still going on—all refer to such an origin, and to such a constitution of our planet, as that contemplated by the nebular theory. Nor is the elevatory process peculiar to the earth, for Venus, Mercury, and the moon, exhibit evidence of a similar action; and in the two former the mountains are of an enormous altitude.* In a philosophical point of view, the present physical epoch of our globe "is that of the fluidity of water, which is the nebulous bed or stratum last condensed, and which exerts

* This subject is ably treated in Sir H. de la Beche's "Researches in Theoretical Geology."

E

50

THE WONDERS OF GEOLOGY.

LECT. I.

mechanical and chemical action upon the previously con-
solidated materials.”*

17. **AEROLITES.**—Intimately connected with this division of the subject, is the remarkable fact of the fall of foreign bodies, called aerolites, or meteoric stones, from the atmosphere. The specimen before us, for which I am indebted to Professor Silliman, is a fragment of a mass which fell at Nanjenoy, in Maryland, North America, a few years since. The following description of its descent, by an eye-witness, will serve to illustrate the ordinary phenomena which attend the appearance of these mysterious visitors.†

" On the 10th of February, between the hours of twelve and one o'clock, I heard an explosion, as I supposed of a cannon, but somewhat sharper. I immediately advanced with a quick step about twenty paces, when my attention was arrested by a buzzing noise, as if something was rushing over my head, and in a few seconds I heard something fall. The time which elapsed from my first hearing the report to the falling, might have been fifteen seconds. I then went with some of my servants to ascertain where it had fallen, but did not at first succeed; however, in a short time the place was found by my cook, who dug down to the stone, which was discovered about two feet below the surface. It was sensibly warm, and had a sulphurous smell: was of an oblong shape, and weighed sixteen pounds and seven ounces; it had a hard vitreous surface. I have conversed with many persons, living over an extent of perhaps fifty miles square: some heard the explosion, while others noticed only the subsequent whizzing noise in the air; all agree in stating that the sound appeared directly over their heads. The day was perfectly fine and clear. There was but one report heard, and but one stone fell, to my know-

* Dr. Nichol.

† American Journal of Science.

§ 18.

ORIGIN OF AEROLITES.

ledge; there was no peculiar smell in the air: it fell within 250 yards of my house.”*

18. ORIGIN OF AEROLITES.—Mrs. Somerville has the following interesting remarks on this subject:—“So numerous are the objects which meet our view in the heavens, that we cannot imagine a part of space where some light would not strike the eye: innumerable stars—thousands of double and multiple systems—clusters in one blaze with their ten thousands of stars—and the nebulæ amazing us by the strangeness of their forms; till at last, from the imperfection of our senses, even these thin and airy phantoms vanish in the distance. If such remote bodies shone by reflected light, we should be unconscious of their existence; each star must then be a sun, and may be presumed to have its system of planets, satellites, and comets, like our own; and for aught we know, myriads of bodies may be wandering in space, unseen by us, of whose nature we can form no idea, and still less of the part they perform in the economy of the universe. Nor is this an unwarranted presumption: many such do come within the sphere of the earth’s attraction, are ignited by the velocity with which they pass through the atmosphere, and are precipitated with great violence to the earth. The fall of meteoric stones is much more frequent than is generally believed: hardly a year passes without some instances occurring; and if it be considered that only a small part of the earth is inhabited, it may be presumed that numbers fall into the ocean, or on the parts of the land uninhabited by civilized man.—The obliquity and velocity of the descent of meteorites, the peculiar substances of which they are composed, and the explosion attending their fall, show that they are

* An analysis of this meteorite gave the following results:—Oxide of Iron, 24; Oxide of Nickel, 1.25; Silica with earthy matter, 3.46; Sulphur, a trace; = 28.71.

E 2

52

THE WONDERS OF GEOLOGY.

LECT. I.

foreign to our planet. Luminous spots, altogether independent of the phases, have been seen on the dark parts of the moon; these appear to be the light arising from the eruption of volcanoes; whence it has been supposed that meteorites have been projected from the moon by the impactus of volcanic eruption. For if a stone were projected from our satellite in a vertical line, with an initial velocity of 10,992 feet in a second—a velocity but four times that of a ball when first discharged from a cannon—instead of falling back to the moon by the influence of gravity, it would come within the sphere of the earth's attraction, and revolve around it. These bodies, impelled either by the direction of the primitive impulse, or by the disturbing action of the sun, might ultimately penetrate the earth's atmosphere and arrive at its surface. But from whatever source meteoric stones may come, it is highly probable that they have a common origin, from the uniformity, we may almost say identity, of their composition.”*

These masses present a general correspondence in their chemical composition and appearance, having (with the exception of native iron) a crystalline character internally, and externally a black slaggy crust, as in this specimen from Nanjenoy.

Obers states that aerolites have been found in tertiary and secondary strata; if so, we must conclude that before the last arrangement of the earth's surface, meteoric stones had fallen upon it.

Baron Humboldt observes that aerolites afford the only direct experimental knowledge we possess of any of the specific properties or qualities of matter not belonging to our globe. “Their direction and enormous velocity of projection (a velocity wholly planetary) render it more than probable, that these masses, enveloped in vapours and

* Connexion of the Physical Sciences, p. 423, 4th edition.

§ 19.

EXISTING GEOLOGICAL AGENTS.

53

reaching the earth in a high state of temperature, are small
heavenly bodies which the attraction of our planet has
caused to deviate from their previous path. The aspect so
familiar to us of these aerolites, and the analogy which their
composition presents to minerals contained in the crust of
the earth, is very striking. The inference to which they
point appears to me to be, that the planetary and other
masses were agglomerated in rings of vapour, and after-
wards in spheroids, under the influence of a central body ;
and that being originally integral parts of the same sys-
tem, they consist of substances chemically identical.”*

19. EXISTING GEOLOGICAL AGENTS.—Assuming then that our planet, when first called into being by the fiat of the Creator, was a gaseous mass, “without form and void,” and destined through indefinite ages to undergo mutations which ultimately rendered it a fit abode for man and the animals which are his contemporaries, we proceed to investigate the nature and effects of the agencies by which its surface is still modified.

In this division of the subject it will be my object to
explain in a clear and familiar manner some of those
physical changes which, unheeded or unappreciated, are
taking place around us; but which, operating on a large
scale, and through a long period of time, are capable of
producing effects that materially modify the earth's surface,
and give rise to results which, when viewed in the aggre-
gate, fill the uninformed mind with astonishment, and lead
it to call up imaginary convulsions and catastrophes to
explain the result of some of the most ordinary operations
of nature. As the simple lines that compose the alphabet
constitute, when placed in combination, the mighty engine
by which the master spirits of our race enlighten and

* *Cosmos*; a Sketch of a Physical Description of the Universe, by Baron Humboldt; Col. Sabine's translation.

54

THE WONDERS OF GEOLOGY.

LECT. I.

benefit mankind, so natural processes, in themselves appa-
rently inadequate to produce any important effects, become,
by their combined and continued operation, an irresistible
power, by which the dry land is converted into the bed of
the ocean, and the bed of the ocean into dry land; thus
fulfilling the universal law of nature, which subjects every
particle of matter to incessant change.

Before proceeding farther in this inquiry, I would notice
an opinion, so generally prevalent that it may possibly be
entertained by some of my readers, namely, that the pheno-
mena which will come under our consideration, have been
occasioned by the deluge recorded in Scripture. But what-
ever may have been the modifications of the earth's surface
produced by that catastrophe, they must on the present
occasion be wholly excluded from our consideration, for
the changes to which geological inquiries relate are of a
totally different character, and referable to periods long
antecedent to that miraculous event.

I have now to direct your attention to certain natural
operations which, when properly investigated, will afford
an easy explanation of facts of the highest interest and
importance, which present themselves at the first step we
take in our inquiry; will teach us how this limestone has
been formed of brittle shells, and this marble filled with
the coral to which it owes its beautiful markings—how
wood has been changed into stone, and plants and fishes
have become inclosed in the solid rock. I have to explain
to you that the ground on which we stand was not always
dry land, but once constituted the bed of the sea—that the
hills, now so smooth and rounded, and clothed with verdure,
have been formed in the profound depths of the ocean, and
may be regarded as vast tumuli, in which the remains of
beings that lived and died in the early ages of the globe are
entombed;—and that the wealds of Kent and Sussex, those
rich and cultivated districts which fill up the area between

§ 20.

EFFECTS OF STREAMS AND RIVERS.

55

the chalk hills of Sussex, Surrey, Kent, and Hampshire,
were once the delta of a river, that flowed through a
country which is now swept from the face of the earth—a
country more marvellous than any that even romance or
poetry has ventured to portray.

20. AQUEOUS AGENCY: THE EFFECTS OF STREAMS AND RIVERS.—The operations we have now to consider are produced by a substance, the most abundant in nature, and with the properties of which we are so familiar, that we but little appreciate the marvellous phenomena they present. This substance—which in one state constitutes vast islands and continents, forming masses that rival in transparency and brightness the rock crystal or the diamond, and are more durable than granite, and so sterile as to afford no sustenance, even to the simplest forms of vitality—in another condition is invisible, and separates into two gases, which supply heat and light to organic bodies;—in a third state it exists as an elastic vapour, which yields to man a power far surpassing that of the fabled wand of the magician, enabling him to cross the ocean in spite of the elements, and traverse the land with a rapidity exceeding that of any other animal;—and lastly, it appears as a fluid which is the essential support of animal and vegetable life, and covers a large portion of the surface of our globe; affording in its profound abysses a habitation for the most colossal of existing animals, and containing in each drop myriads of the minutest beings which the aided eye of man is able to descry!—such are the wonderful properties of the substance that, in its fluid state, we term *water*, and the geological effects of which we now proceed to examine.

In pursuance of this object, we will first notice the
changes produced on the surface of the land by the agency
of streams and rivers. I need not dwell on those meteoro-
logical causes by which the descent of moisture on the
surface of the earth is regulated; but will merely observe,

56

THE WONDERS OF GEOLOGY.

LECT. I.

that rivers are the great natural outlets by which the superfluous moisture of the land is conveyed into the grand reservoir, the ocean. And so exactly is the balance of expenditure and supply maintained, that all the rivers on the face of the earth, though constantly pouring their mighty floods into the ocean, do not affect its level in the slightest perceptible degree; we may therefore assume that the quantity of moisture evaporated from the surface of the sea and descending on the earth in rain and vapour, is exactly equal to the sum of all the water, in all the lakes and rivers in the world.* But though the quantity of fluid poured by the rivers into the basin of the ocean is again removed by evaporation, yet there is an operation silently and constantly going on, which becomes an agent of perpetual change. The rivulets which issue from the mountains are more or less charged with earthy particles, worn from the rocks and strata over which they flow; the united streams in their progress towards the rivers become more and more

* The quantity of water that percolates into the earth from the surface is very great. It is well known that the water in mines varies with, and depends upon, the rain falling in the districts where they are situated. Seasons of heavy rain are followed by a great increase of water in a mine, and the reverse happens from a drought. The time which elapses before the effect of these causes manifests itself varies considerably, and depends on the mineralogical character and physical features of the country. In carboniferous limestone districts the percolation of rain-water is particularly rapid, so that a heavy fall of rain will often overpower the machinery sufficient for ordinary drainage. " In two mines in Flintshire, the steam-engines, after having been increased in speed from three or four strokes per minute to the extent of their power, about five times as many, were yet incapable of preventing the water from rapidly increasing and filling the workings. In these mines there are great cross courses or faults, which can be traced several miles, and pour torrents of water into the veins; they are, in fact, channels for subterranean rivers, and the latter carry with them large quantities of sand and gravel, worn away from the rocks through which they pass."—Mr. Taylor.

§ 21. DELTAS OF THE GANGES AND MISSISSIPPI.

57

loaded with adventitious matter; and as the power of abra-
sion becomes greater, by the increase in the quantity and
density of the mass of water, a large proportion of the ma-
terials is suspended in the fluid, and carried into the sea.
If the current is feeble, much of the mud, and the larger
pebbles, will be thrown down in the bed of the river—hence
the formation of alluvial plains, as for example those in the
valleys of the Arun, the Adur, the Ouse, and Cuckmere,
in this county.* But a great quantity is transported to the
mouths of the rivers, and there forms those accumulations
of the fluviatile spoils of the land which constitute deltas;
the finest particles, however, are carried far into the sea,
and, transported by currents and agitated by the waves,
are at length precipitated into the profound and tranquil
depths of the ocean. But rivers convey not only the mud
and other detritus of the countries through which they flow;
leaves, branches of trees, and other vegetable matter, and
the remains of the animals that fall into the streams, with
shells and other exuviae, human remains, and works of art,
are also constantly transported and imbedded in the silt and
sand of the deltas and estuaries, and some of these remains
are occasionally drifted out to sea, and deposited in its
bed.

21. DELTAS OF THE GANGES AND MISSISSIPPI.—The
changes here contemplated, as they are going on in our own
island, may appear insignificant, and incapable of producing
any material effect on the earth's surface; but if we trace
the results in countries where the agents under review are
operating on a larger scale, we shall at once perceive their
importance, and that time only is required for the accu-
mulation of strata, equal in extent and alike in character
with many of those ancient deposits, which will hereafter
come under our observation.

* Sussex.

58

THE WONDERS OF GEOLOGY.

LECT. I.

From experiments made with great care, it has been ascertained that the quantity of solid matter brought down by the Ganges and carried into the sea annually, is 6,368,077,440 tons: in other words, a mass of solid materials, surpassing in size and weight sixty times that of the great pyramid of Egypt; the base of that stupendous structure covering eleven acres, and its perpendicular height being 500 feet.* The Burrampooter, another river in India, conveys annually as much earthy matter into the sea as the Ganges. The waters of the Indus, as the late Sir Alexander Burns informed me, are alike loaded with earthy materials. In the vast rivers of America, the same effects are observable; the Mississippi, which flows through twenty degrees of latitude and seven of longitude, and drains a valley 3,000 miles long and nearly 1,000 broad, brings down whole forests and immense rafts, composed of trunks and branches of trees, and drifted underwood, and transports them to its delta, which extends several hundred miles out to sea; and the basin around the embouchure of that river is becoming shallower every day, by the sole agency of the causes now under consideration. The delta of this mighty stream is computed by Mr. Lyell to be at least between 500 and 600 feet in depth, the area it covers nearly 14,000 square statute miles, and the solid matter annually added 2 billions 700 millions of cubic feet; and the period required for the formation of the deposits now composing the delta, at more than 60,000 years.†

In the sediments of these rivers, remains of the animals and plants of the respective countries are continually developed. It is therefore evident, that should the deltas become dry land, the naturalist could, by an examination of the animal and vegetable remains imbedded in the

* Lyell's Principles of Geology.

† Lecture on the Delta of the Mississippi, before the British Association, at Southampton, 1846.

§ 22.

FORMATION OF FLUVIATILE STRATA.

59

fluviatile sediments, readily determine the characters of
the fauna and flora of the countries through which the
rivers had flowed. We may here observe, that in tropical
regions, where animal life is profusely developed, and but
little under the control of man, the animal remains buried
in the deltas are far more abundant than in those of
European countries, which are thickly peopled, and in a
high state of civilization. The enterprising but unfor-
tunate Lander informed me, just before he embarked on
his last and fatal expedition to Africa, that many parts of
the Quorra, or Niger, so far as the eye could reach, teemed
with crocodiles and hippopotami; and so great was their
number, that he was often obliged to drag his boat on shore
lest it should be swamped by them.

It is unnecessary to dwell longer on these operations; it
will suffice to have shown, that by the simple effect of
running water, great destruction and extensive modifica-
tions of the surface of the land are everywhere taking
place, and at the same time fluviatile deposits are forming
on an extensive scale, and imbedding animal and vegetable
remains. Thus, in the deltas of the rivers of England are
found the bones and antlers of the deer, horse, and other
domesticated animals, associated with the trunks and
branches of trees and plants, river and land shells, human
bones, and fragments of pottery and other works of art:
while in those of the Ganges and the Nile, the remains of
the animals and vegetables of India and of Egypt are
respectively entombed.

22. FORMATION OF FLUVIATILE STRATA.—There is a
circumstance connected with these facts which it is neces-
sary here to consider. The quantity of water in streams
and rivers varies considerably at different periods of the
year; in the rainy season the rivers are overflowing, and
the waters remarkably turbid: consequently the deposits
are much greater at those periods than in the summer

60

THE WONDERS OF GEOLOGY.

LECT. I.

months, when the currents are feeble, and the rivers shallow. In that part of the stream affected by the tides, there is also a constant flux and reflux of the waters, and from this cause the sediments must, to a certain degree, be periodical. Accordingly we find the silt and sand disposed in *strata* or layers, from the partial consolidation of the surface of one bed of mud, before the superincumbent layer was precipitated upon it. Thus wherever a fresh break takes place in a bank of consolidated silt, in a delta, as for example in that of the Nile, it is easy to trace the deposits of each successive year, by means of the lighter earth on the top of each. When a portion is taken into the hand, it separates into layers; and on closely examining the edges of these, very delicate thin lines are perceptible, showing a laminated structure, like those observable in the coal-shales. Judging from these layers, the annual deposits from the Nile appear to vary considerably, but the average thickness is little more than a quarter of an inch.*

Where a river terminates in an extensive estuary, the sea throws over the layer of mud brought down by the river, a covering of sand; and frequently these alternate with the greatest regularity, the receding of the tide allowing the fresh water to deposit its mud, and the advance of the sea discharging sand and marine exuviae over the surface.

23. RIPPLE-MARKS.—And here we may notice another phenomenon. Every one must have observed, when walking by the banks of a river at low water, or on the sands of the sea-shore, that when the water has been agitated by the wind, the surface of the mud, or sand, is undulated, or furrowed over by the rippling of the waves, the marks presenting various appearances, according to the force and

* Letter to Professor Silliman from an American who visited Egypt in 1834.

§ 24.

LEWES LEVELS.

61

direction of the currents. Frequently, too, worms and molluscous animals crawl over and mark the surface with meandering lines, and ridges; and these varied characters on the sand are preserved, if a thin layer of mud happens to be deposited over them before the next advance of the waves. I shall have occasion to refer to these appearances hereafter. We may also remark that certain kinds of mollusca, or shell-fish, can only live in fresh water; others are confined to the sea; while a third class is restricted to the brackish waters of estuaries; accordingly, in the deposits under consideration, the river and estuary species are abundant, while the marine only occur as stragglers, and are comparatively rare. Land plants, and those which affect a marshy soil, as the equiseta, or mare's-tails, reeds, rushes, &c. are likewise often accumulated in such quantities as to form beds of peat.

24. LEWES LEVELS.—It will serve to impress the subject more forcibly upon our minds, if we refer to some local example of fluvio-marine deposits: and from its immediate vicinity to Brighton, I select that which occurs in the valley of the Ouse, near Lewes, which is one of several estuaries whence the sea has retired within the last eight or ten centuries. This tract is about eight miles in length from north to south, and varies in breadth from half a mile to two miles and a half. The valley is bounded by an amphitheatre of chalk hills, into which the river enters through a gorge of the Downs on the north, near Offham, and pursuing a tortuous course, flows between the towns of Lewes and The-Cliff, and discharges its waters into the sea at Newhaven. This alluvial plain is called *Leves Levels*, and is here and there flanked on the east and west by headlands, and ancient sea-cliffs; while a few insular mounds of chalk rise up through the fluviatile deposits, that have been accumulating during a long period of time. *Lign.* 7, represents a section of the valley of the Ouse, from east to west.

62

THE WONDERS OF GEOLOGY.

LECT. I.

Here we have a depression (or *basin*, as it is termed by geologists) of chalk strata, partially filled up by layers of

A. A. Silt, with river shells; B. B. Clay, with river and marine shells; C. C. Deposit with marine shells only.

indurated mud or silt, the surface of which is clothed with verdure; the bed of the river (I) is situated near the eastern chalk cliffs. By numerous sinkings through the soil, carried from the surface down to the chalk bottom, and the depth of which varied from fifteen to thirty feet, the deposits have been ascertained to be as follow :—

1. Bog-earth and peat, about five feet in thickness: formed of decayed twigs and leaves of hazel, oak, birch, &c. inclosing trunks of large trees.

2. (A. A.)—Blue clay, or indurated mud, containing several species of fresh-water shells, like those which now inhabit the river and ditches; with numerous *indusiæ*, or cases of the larvæ of a species of May-fly (*phryganeæ*) commonly termed caddis-worms. Bones of horses and deer have been found in the lower part of this bed.

* A geological section represents the internal structure of the earth on any given line, in a vertical direction; and is either, 1, *natural*, as seen in cliffs, precipices, &c.; 2, *artificial*, as in quarries, tunnels, and other excavations; or, 3, *theoretical*, when constructed from a combination of observations on the position of the strata in various distant localities.

§ 24.

SECTION OF LEWES LEVELS.

63

3. (B. B.)—Clay, containing fresh-water shells, with an intermixture of existing marine species, as the common cockle, (*cardium edule*), tellina, &c.

4. (c. c.)—Blue clay, inclosing marine shells, viz. cockles, mussels, &c. without any intermixture of fluviatile species. In this deposit a skull of the Narwhal, or sea-unicorn (*Monodon monoceros*), and of the Porpoise have been discovered.

From the nature of these sediments we learn that this valley was once an arm of the sea, and that the following sequence of physical changes has taken place :—

*First*, there was a salt-water estuary, inhabited by marine shell-fish of the same species as those now existing in the British Channel, into which cetacea occasionally entered.

*Secondly*, the inlet grew shallow, the water brackish, and marine and fresh-water shells were mingled in its blue argillaceous sediment.

*Thirdly*, the shoaling continued till fresh-water so much predestinated, that fluviatile shells, and aquatic insects, could alone exist.

*Fourthly*, a peaty swamp was formed, by the drifting of trees, and plants, from the forest of Andreadswald, which formerly occupied the entire Wealds of Sussex and the adjacent counties; and terrestrial quadrupeds were occasionally imbedded in the morass.

*Lastly*, the soil being inundated by land-floods at distant intervals only, became an oozy marsh, which has been gradually converted into a fertile tract of country.

Such are the natural changes which the river valley of the Ouse has undergone, as shown by the character of the deposits which partially fill up this depression in the chalk; and historical records confirm the geological evidence.* What further transmutations the plain of Lewes Levels is destined to undergo cannot be foretold. It may be, that

* See "A Day's Ramble in and about the Ancient Town of Lewes," 1 vol. 8vo. 1846, by the Author.

64

THE WONDERS OF GEOLOGY.

LECT. I.

some change in the relative level of the land and water
along the Sussex coast will again convert the Levels into
an arm of the sea, and the town of Lewes be once more a
port. On the other hand, the physical agents of terrestrial
change may lie dormant, and man, with the mighty powers
of nature over which science has given him control, may
include this alluvial plain in the grand line of communi-
cation that shall link together the metropolitan cities of
France and of England, and ere another century have passed
away, these now verdant pastures may be covered with
towns and cities, swarming with busy communities of the
human race.

25. REMAINS OF MAN IN MODERN DEPOSITS.—But the sediments in the river valleys often contain not only bones of deer, horse, boar, and other terrestrial animals, but also human skeletons, which are sometimes found inclosed in coffins of exceedingly rude workmanship; together with canoes,* and other relics of the early inhabitants of our

* *Ancient British Canoe.* In 1835 a canoe was discovered at the depth of several feet in a bed of silt, that filled up an ancient branch of the river Arun, at North Stoke, near Arundel. It was presented, by my noble friend the late Earl of Egremont, to the British Museum. This canoe is nearly thirty-five feet in length, four and a half wide in the centre, three feet three inches broad at one extremity, and two feet ten inches at the other; and is about two feet deep. It is formed of a single trunk of oak, which has been hollowed out and brought to its present shape with great labour: it is evidently the workmanship of a very remote period, and in all probability was constructed by some of the earliest inhabitants of our island, before the use of iron or even brass was known: the original tree must have been fifteen or sixteen feet in circumference. Three projections, left in the interior of the boat, appear to have been designed for seats; it is manifest therefore that the persons who constructed this vessel were unacquainted with the art of forming boards. This canoe is so similar to some of those which were fabricated by the aborigines of North America, when first visited by Europeans, that we can have no hesitation in concluding that it was constructed in a similar manner; namely, by charring

§ 26.

PEAT BOGS.

65

island. This human skull was dug up at a great depth in the blue silt of Beeding Levels; it was inclosed, together with the other bones of the skeleton, in a coffin of oak, which was evidently of high antiquity, being formed of four rude planks, or rather hewn trunks of trees, held together by oaken pegs. The skull is of a dark bluish-brown colour, like the bones of deer and horse found in similar deposits, an appearance attributable to an impregnation of iron; when first dug up, the interstices of the bones were filled with blue phosphate of iron. The state of the teeth is remarkable, for the crowns of the incisors are worn down almost flat, although the individual must have been in the prime of life; a fact which seems to indicate that grain, and other hard substances, constituted his customary food.

26. PEAT BOGS.—Before proceeding to the next subject, I will advert to those extensive accumulations of vegetable matter called Peat Bogs. These are morasses, covered with successive layers or beds of mosses, reeds, equiseta, rushes, and other plants that affect a marshy soil; and in particular of a kind of moss, the *sphagnum palustre*, which frequently forms a large proportion of the entire mass. The beds of peat are annually augmented by the peculiar mode of increase of the moss, which throws up a succession of shoots to the surface, while the parent plants decay, and add a new layer of soil.

The peat bogs of Ireland are of great extent: one of the mosses on the banks of the Shannon is between two and three miles in breadth, and fifty in length. Mr. Lyell remarks, that most of the peat-mosses of the North of Europe occupy

such portions of the tree as were to be removed, and scooping them out with stone instruments: no doubt this canoe belongs to the same period as the flint and stone instruments called celts, which are found in the tumuli on the South Downs.

F

66

THE WONDERS OF GEOLOGY.

LECT. I.

the areas of ancient forests of oak and pine; and that the fall of trees from the effect of storms, or natural decay, by obstructing the draining of a district, and thus giving rise to a marsh, is the origin of most of these deposits; mosses, and other marsh plants, spring up, and soon overwhelm and bury the prostrate trees; hence the occurrence of trunks and branches of oaks, firs, &c. with their fruits. De Luc states, that the sites of many of the aboriginal forests on the continent are now covered by mosses and fens, and that many of these changes are attributable to the destruction of the woods by the Romans.

A remarkable circumstance relating to peat bogs must not be omitted, namely, the occasional occurrence of the bodies of men and animals, in a high state of preservation, at a great depth. In some instances the bodies are converted into a fatty substance resembling spermaceti, and which is called *adipocire*.

27. COAL IN PEAT.—A fact of considerable geological interest is the occurrence of coal in peat bogs, since it proves that the conversion of vegetable matter into a mineral, the origin of which, but a few years since, was deemed questionable, takes place at the present time, when circumstances are favourable for the production of the bituminous fermentation. In Limerick, in the district of Maine, one of the States of North America, there are peat bogs of considerable extent, in which a substance exactly similar to *cannel coal* is found at the depth of three or four feet from the surface, amidst the remains of rotten logs of wood and *beaver-sticks*: the peat is twenty feet thick, and rests upon white sand. This coal was discovered on digging a ditch to drain a portion of the bog, for the purpose of obtaining peat for manure.* The substance is a true bituminous coal, containing more bitumen than is found in

* Dr. Jackson, on the Geology of Maine.

§ 28, 29.

SUBTERRANEAN FORESTS.

67

any other variety.* Polished sections of the compact masses exhibit the peculiar structure of coniferous trees, and prove that the coal was derived from a species allied to the American fir. It has probably been formed by the chemical changes supervening upon fir-balsam, during its long immersion in the humid peat; the circumstances under which it was placed being most favourable for that process to take place, by which, as we shall show hereafter (see *Lecture VI.),* vegetable matter is converted into coal. In the Chatham Islands, Dr. Dieffenbach observed a bed of peat, in which were layers closely resembling coal, and possessing a lustrous appearance and conchoidal fracture; while in other parts of the same layers the transition to true peat was evident.

28. SUBTERRANEAN FORESTS.—Independently of the trees imbedded in peat bogs and morasses, there are also found entire forests buried deeply in the soil; the trees having their roots, trunks, branches, fruits, and even leaves, more or less perfectly preserved. Numerous accumulations of this kind have been discovered on the coasts of England, occupying low alluvial plains, that are still subject to periodical inundations.† The trees are chiefly of the oak, hazel, fir, birch, yew, willow, and ash; in short, almost every kind that is indigenous to this island occasionally occurs. The trunks, branches, &c. are dyed throughout of a deep ebony colour by iron; and the wood is firm and heavy, and occasionally fit for domestic use; in Yorkshire, timber of this kind is sometimes employed in the construction of houses.

29. GEOLOGICAL EFFECTS OF THE OCEAN.—While the mountains, valleys, and plains of the interior of a country,

* An analysis of 100 grains gave the following results:—*Bitumen*, 72; *Carbon*, 21; *Oxide of Iron*, 4; *Silica*, 1; *Oxide of Manganese*, 2; = 100.

† See Illustrations of the Geology of Sussex, p. 288.

F 2

68

THE WONDERS OF GEOLOGY.

LECT

are undergoing slow but perpetual destruction by the combined effects of atmospheric agency, and of running water, the coasts, cliffs, and shores, are exposed to destruction from the action of the waves, and the encroachments of the sea. When the land presents a high and rocky coast, the waves, by their incessant action, undermine the cliffs, which at length fall down, and cover the shore with their ruins. The softer parts of the strata, as the chalk, limestone, marl, clay, &c. are rapidly disintegrated and washed away; while the more solid materials are broken, and rounded, by the continual agitation of the water, and give rise to those accumulations of shingle and sand which skirt the base of the sea-cliffs, and serve, in some situations, to protect the land from further encroachments. But when the cliffs are entirely composed of soft substances, their destruction is very rapid, unless artificial means be employed for their protection; which, however, in many instances are wholly ineffectual.

The encroachments of the ocean upon the land effected by this agency, often give rise to sudden and extensive inundations, and the destruction of whole tracts of country. Along the Sussex coast the inroads of the sea have been noticed in the earliest historical records; and the site of the ancient town of Brighton has been entirely swept away, the sands, and the waves, now occupying the spot where the first settlers on these shores fixed their habitations.* On low and sandy coasts, the waves drive the loose and lighter materials towards the land; and the drifted sand, becoming dry at the reflux of the tide, is carried by the wind inland, and in some situations is accumulated in such quantities as

* In my "Fossils of the South Downs," and "Geology of the South-East of England," will be found some interesting historical notices of the destruction of the Sussex coast by the inroads of the sea. These have been copied almost verbatim into several geological works, without acknowledgment or reference.

30.

THE BED OF THE OCEAN.

69

to form ranges of hills, which in their progress overwhelm
fertile tracts, and engulf churches, and even entire villages.
These sand-banks or downs, loose and fluctuating as they
are in their first stage of advancement, become under
certain circumstances stationary, and are then converted
into solid stone, by a process which we shall presently
explain.

30. THE BED OF THE OCEAN.—But the production of beach, gravel, and sand, on the shores, and the drifting of sand inland, are effects far less important than those which are going on in the profound depths of the ocean. In the tranquil bed of the sea, the finer materials, that were held in chemical or mechanical suspension by the waters, are precipitated and deposited, enveloping and imbedding shells, corals, fishes, &c. together with the remains of such terrestrial animals and vegetables as may be floated down by the streams and rivers. And, in the beautiful language of Mrs. Hemans,—

“The depths have more! What wealth untold
Far down and shining through their stillness lies!
They have the starry gems, the burning gold,
Won from a thousand royal argosies!”

“Yet more—the depths have more! Their waves have rolled
Above the cities of a world gone by—
Sand hath filled up the palaces of old,
Sea-weed o’ergrown the halls of revelry.”

“To them the love of woman hath gone down,
Dark flow their tides o’er manhood’s noble head,
O’er youth’s bright locks, and beauty’s flowery crown.”—

Yes! in these modern deposits, the remains of man, and of his
works, must of necessity be continually engulfed, together
with those of the animals which are his contemporaries.

Of the nature of the present bed of the ocean, we can of
course know but little from actual observation. Soundings,

70

THE WONDERS OF GEOLOGY.

LECT. I.

however, have thrown light upon the deposits now forming
in those depths which are accessible to this mode of inves-
tigation, and shown that in many parts immense accumula-
tions of shells and corals, intermixed with sand, gravel, and
mud, are going on. Donati ascertained the existence of a
compact bed of shells, 100 feet in thickness, at the bottom
of the Adriatic, which in some parts was converted into
marble. In the British Channel, extensive banks of sand,
imbedding shells, crustacea, &c. are in the progress of form-
ation. This specimen, which was dredged up a few miles
off Brighton, is an aggregation of sand with recent marine
shells, oysters, mussels, limpets, cockles, &c. and minute
corallines;* and this example, from the coast of the Isle of
Sheppey, consists entirely of cockles (*Cardium edule*), held
together by conglomerated sand.†

In bays and creeks, bounded by granitic rocks, the bottom
is found to be composed of micaceous and quartzose sand,
consolidated into what may be termed regenerated granite.
Off Cape Frio, on the Brazilian coast, solid masses of this
kind were formed in a few months, and in them were found
imbedded, dollars and other treasures from the wreck of a
vessel, the *Thetis*, to recover which an exploration by the
diving bell was undertaken.

31. EFFECTS OF CURRENTS.—The distribution over the bottom of the sea of the detritus brought down by rivers and streams, and of the materials worn away by the action of the waves on the shores, is principally effected by the influence of currents, which, from their regularity, permanency, and extent, may be considered as the rivers of the ocean. To this agency I can but briefly allude, and shall restrict my remarks to the Gulf-stream, which is the great current that transports the waters, and the temperature of

* Medals of Creation, vol. i. p. 375, *lign.* 87.

† Ibid. p. 377, *lign.* 88.

§ 32.

THE GULF-STREAM.

71

the tropical regions, into the climates of the north. From
the mouth of the Red Sea a current about fifty leagues in
breadth sets continually towards the south-west; doubling
the Cape of Good Hope, it assumes a north-west direction,
and in the parallel of St. Helena, its breadth exceeds 1000
miles; then taking a direction nearly east, it meets in the
parallel of 3° north, along the northern coast of Africa, with
a stream from the north; entering the Gulf of Florida,
the united currents are reflected and form the Gulf-stream,
which, passing along the coast of North America, stretches
across the Atlantic to the British Isles. At the parallel of
38°, nearly 1000 miles from the Straits of Bahama, the
water of the stream is ten degrees warmer than the air.
The course of the Gulf-stream is so fixed and regular, that
nuts and plants from the West Indies are annually drifted
to the western islands of Scotland. The mast of a man-of-war,
burnt at Jamaica, was driven ashore several months
afterwards on the Hebrides, "after performing a voyage
of more than 4000 miles under the direction of a current,
which, in the midst of the ocean, maintains its course as
steadily as a river upon the land."* The quantity and
variety of detritus transported by such currents must
be immense, and we therefore need not wonder at frequently
finding the productions of different climates associated together
in a fossil state.

32. **ICEBERGS AND GLACIERS.** From the consideration of the dynamical powers of water as a fluid, we pass to the examination of its effects when consolidated by congelation. The character of the regions of eternal ice in the Arctic circle—the floating islands and mountain ranges composed of rock-ice, which everywhere threaten with impending destruction the intrepid mariners who penetrate the desolate polar seas—the removal and transport of

* Playfair's Works, edition 1822; vol. i. p. 414.

72

THE WONDERS OF GEOLOGY.

LECT. I.

immense masses of rocks and boulders by drifting ice-floes, and the distribution of these materials in the bed of the ocean, or on the land, as the congealed water gradually melts as it approaches a milder climate—are phenomena so familiar to the English reader, from the graphic accounts which have emanated from our naval officers engaged in the arduous service of the voyages of discovery, undertaken during the present century, that it will not be necessary to dwell upon the subject.

Glaciers are sheets of ice, which form upon the tops and in the clefts and valleys of mountains, that attain such an elevation as to be within the regions of eternal snow. They are not inaptly termed, by that most charming of all philosophical travellers, Mr. Darwin, gigantic icicles. The lowest limit to which glaciers extend, depends, of course, on the height of the line of perpetual congelation, which varies in different latitudes, and is also modified by the configuration of the land. In the Alps the traveller enters the region of eternal snow at a height of from 3000 to 7000 feet; while in South America, under the equator, the snow line is equal to that of the summit of Mont Blanc.* In the Alps there are vast table-lands, of from 100 to 300 square miles, composed of solid ice, from which descend enormous masses, that slowly glide towards the lower regions, bearing with them innumerable fragments of rock. So soon as these glaciers reach the lowest limit of perpetual congelation, they melt, and the fragments of rock they contain are deposited, and form mounds and ridges of stones of all sizes, which are called moraines; these remain after all vestiges of the agent which produced them have disappeared. The difference in the character of the materials brought down by torrents and by glaciers is very manifest: for the former give rise to beds of gravel; the latter to ridges or

* Humboldt.

§ 32.

ICEBERGS AND GLACIERS.

73

heaps of boulders. The movement of the glacier from the
mountain top, arises from the softened state of the layer
of ice in contact with the surface of the earth on which it
rests; for the beautiful experiments of Professor Forbes
have shown that ice moves upon the principle of a tenacious
or viscous fluid; that is, by gravitation on an inclined
surface. The rocks forming the bases of the glaciers,
and the sides of the valleys they have traversed, are more
or less polished and grooved, from the passage of angular
masses of rock when impacted in the moving ice: the
grooves being in the direction of the movement of the
glacier.*

From careful observations on these appearances, M.
Agassiz has established characters by which, in countries
where the hills are at the present time far below the snow
line, evidence of former glaciers of great extent has been
obtained. Many indications of ancient glaciers are supposed
to occur in England and Scotland; and the accumulations
of drifted materials, containing large angular blocks, and
disposed in long banks and ridges, and the grooves and
scratches on the surface of the rocks forming the sides of
valleys and slopes of hills, which lead off from these sup-
posed moraines, are regarded by some geologists as un-
equivocal proofs of a great extent of glaciers in these
islands at a comparatively recent period: and the drift,
boulders, and superficial alluvial debris, are attributed, in
a great measure, to the agency of either icebergs or glaciers.
But the sweeping conclusion of M. Agassiz and others,
that the whole of Europe was once covered with ice, should
be received with much hesitation; and it is to be regretted
that the term "*glacial period*" has been admitted into
geological nomenclature.

* See "Etudes sur les Glaciers," par M. Agassiz; Neuchatel, 1840; and the Works and Memoirs of Prof. Forbes (in the Philos. Trans.), on the same subject.

74

THE WONDERS OF GEOLOGY.

LECT. I.

The former existence of limited glaciers in some parts of Great Britain, perhaps accompanied with a lower climatorial temperature than now prevails, appears to me the extent to which, in the present state of our knowledge, the glacial theory can be admitted as a *vera causa*, in our attempts to interpret the origin of the drift of the British islands. It may, however, be well to state, that if an elevation of the European continent to the amount of but 2000 feet were to take place, a great part of its surface would be covered with glaciers and perpetual snow, and cease to be habitable.

33. **INCRUSTING SPRINGS.**—The phenomena hitherto considered, are referable to the mechanical action of water; and the effect has been disintegration, and destruction, in the first instance, and in the second the accumulation of sediments in water-courses, and their transport into the bed of the sea. We must now refer to an operation of a totally different character—the power possessed by streams, as clear and sparkling as poet ever feigned or sung, of consolidating loose materials, of converting porous strata into solid stone, and of filling up their own channels by the deposition of calcareous matter.

That most fresh water holds a certain proportion of carbonate of lime* in solution, is well known; and also that changes of temperature, and certain other causes, will occasion the calcareous earth to be in part or wholly precipitated. The *fur*, as it is called, that lines a boiler which has been long in use, affords a familiar illustration of this fact. At the temperature of 60°, lime is soluble in 700 times its weight of water, and if to the solution a small

* *Carbonate of lime* consists of lime in combination with carbonic acid gas, which is a most abundant natural product. This gas is respirable, and when pure, will immediately suffocate an animal immersed in it, and extinguish flame.

§ 34.

INCRUSTING SPRINGS.

75

portion of carbonic acid be added, carbonate of lime is formed, and precipitated in an insoluble state. If, however, the carbonic acid be in such quantity as to supersaturate the lime, it is again rendered soluble in water; and it is thus that carbonate of lime, held in solution by an excess of fixed air, not in actual combination with the lime, but contained in the water and acting as a menstruum, is commonly found in all waters. An absorption of carbonic acid, or a loss of that portion which exists in excess, will therefore occasion the calcareous earth to be set free, and precipitated on any substances in the water, such as stones, twigs, and leaves of trees, &c. Some springs contain so large a portion of calcareous earth when they first issue from the rocks, and so speedily throw it down in their course, that advantage has been taken of the circumstance to obtain incrustations of various objects, as leaves, branches, baskets, nests with eggs, and even old wigs. The incrusting springs of Matlock and other places in Derbyshire are celebrated for such productions.* The substance deposited is termed tufa, or travertine; and in Italy, and many other countries, it constitutes extensive beds of concretionary limestone, which is often of a crystalline structure. The Cyclopean walls and temples of Pæstum, are formed of travertine. At the baths of San Filippo, in Tuscany, where the waters are highly charged with tufa, this property is applied to a very ingenious purpose. The stream is directed against moulds of medallions and other bas-reliefs, and beautiful casts are thus obtained.

34. **INCRUSTATIONS.**—As specimens of this kind are commonly, but erroneously, termed petrifactions, it will be necessary to explain their real nature. We have before us several incrustations from various places: baskets of shells,

* An account of the incrusting springs at Matlock is given in “Medals of Creation,” vol. ii. p. 940.

76

THE WONDERS OF GEOLOGY.

LECT. I.

and nests with eggs, from Derbyshire; a bird, from Knaresborough, in Yorkshire; and twigs and branches partially incrusted, from Ireland, Russia, &c.

LIGN. 8.—A TWIG INCRUSTED WITH TUFA.
*a, a, a, Extremities of the twig unchanged; b, b, b, the tufaceous crust.*

I need scarcely observe, that on breaking such specimens,
we find the inclosed substances to have undergone no
change but that of decay. In this incrustation (Lign. 8)
the twig, which is exposed in several places, is not per-
meated by stony matter, but is withered, and brittle.
Now, a true *petrifaction* is altogether of a different
nature, the substance being more or less completely
mineralized; if we break it, we find that every part of
its structure has undergone a change. Wood, for in-
stance, is often entirely transmuted into flint or chalce-
dony, and may be cut so thin, that with a powerful
lens the ramifications of the vessels and the structure of
the tissues may be seen, and from their form, and dispo-
sition, we may determine the particular kind of tree to
which the specimen belonged, although it may have been
enshrined in the stone for ages. When bone is petrified,
the same phenomena are observable; the most delicate
parts of the internal structure are preserved, and all the
cells are filled up with calcareous spar, which is oftentimes
of a different colour from that of the walls of the cells, and
thus a natural anatomical preparation of great beauty and
interest is formed.

§ 35.

LAKE OF THE SOLFATARA.

77

35. LAKE OF THE SOLFATARA.—One of the most celebrated travertine springs is the lake of the Solfatara, which lies in the Campagna between Rome and Tivoli, and is fed by a stream of thermal water that flows into it from a neighbouring pool. The water is of a high temperature, and saturated with carbonic acid gas, which, as the water cools, is constantly escaping, and keeping up an ebullition on the surface. The stream that flows out of the lake fills a canal, which is conspicuous at a distance, from the line of vapour that emanates from the water. The formation of travertine is so rapid, that not only the vegetables and shell-fish are surrounded and destroyed by the calcareous deposit, but insects also are frequently incrusted. In the beautiful specimens of travertine before us from the Solfatara, vegetable impressions are distinctly seen; the cavities in these masses have been produced by the decomposition of the vegetable matter.*

A considerable number of the edifices of both ancient and modern Rome, are constructed of travertine obtained from the quarries of Ponte Luccano, which has clearly originated from a lake of this nature. Pæstum is also built of calcareous tufa, derived from similar deposits. “The waters of these lakes,” says Sir Humphry Davy,† “have their rise at the foot of the Apennines, and hold in solution carbonic acid, which has dissolved a portion of the calcareous rocks through which it has passed; the carbonic acid is dissipated by the atmosphere, and the marble, slowly precipitated, assumes a crystalline form, and produces coherent stone. The acid originates in the action of volcanic fires on the calcareous rocks of which the Apennines are composed, and carbonic acid being thus evolved, rises to the source of the springs, and gives them their

* See Appendix B.

† Consolations in Travel; or, the Last Days of a Philosopher.

78

THE WONDERS OF GEOLOGY.

LECT. I.

impregnation, and enables them to dissolve a large quantity of calcareous matter.”

36. **MARBLE OF TABREEZ.**—In Persia, a beautiful transparent limestone, called Tabreez marble, is formed by deposition from a celebrated spring near Maragha, where the whole process of its formation may be seen. In one part the water is clear; in another dark, muddy, and stagnant; in a third it is very thick, and almost black; while in the last stage it is of a snowy whiteness. The petrifying pools look like frozen water; a stone thrown on them breaks the crust, and the water exudes through the opening; and in some states the process has proceeded so far as to admit of walking on the surface of the lake. A section of the stony mass resembles an accumulation of sheets of paper, being finely laminated; and such is the tendency of this water to solidify, that the very bubbles on its surface become hard, as if they had been suddenly arrested, and metamorphosed into stone.*

37. **STALACTITES, AND CAVERNS.**—By the infiltration of water through limestone rocks, into fissures and cavities, sparry concretions are produced on the roofs, sides, and floors of caverns. The concretionary masses which are dependent from the roof like icicles, are called *stalactites*; those which form on the floor, from the droppings of the water, are termed *stalagmites*; and when, as frequently happens, the two unite, a singularly picturesque effect is produced; the caves appearing as if supported by pillars of great beauty and variety.† Sometimes a linear fissure in the roof, by the direction it gives to the dropping of the lapidifying water, forms a perfectly transparent curtain or partition. A remarkable instance of this kind occurs in a cavern in North America, called Weyer's Cave, which is situated in the limestone range of the Blue Mountains.‡

* Morier's Travels.

† Appendix C.

‡ Appendix D.

§ 37.

STALACTITES AND CAVERNS.

79

There are also many caverns in England, celebrated for the variety and beauty of their sparry ornaments; those of Derbyshire are well known.

The Grotto of Antiparos in the Grecian Archipelago, not far from Paros, has long been celebrated. The sides and roof of its principal cavity are covered with immense incrustations of calcareous spar, which form either stalactites, depending from above, or irregular pillars rising from the floor. Several perfect columns reaching to the ceiling have been formed, and others are still in progress, by the union of the stalactite from above, with the stalagmite below. These being composed of matter slowly deposited, have assumed the most fantastic shapes; while the pure, white, and glittering spar, beautifully catches and reflects the light of the torches of the visitors to this subterranean palace, in a manner which causes all astonishment to cease at the romantic tales told of the place—of its caves of diamonds, and of its ruby walls; the simple truth, when deprived of all exaggeration, being sufficient to excite admiration and awe.*

The specimens before us will serve to illustrate these remarks: these long stony icicles are from the Isle of Portland; and these minute straws of spar are from an archway near the Chain Pier, and have been formed by the infiltration of rain through the superincumbent bed of calcareous rock. This mass of pebbles, held together by calc-spar, and containing bones and teeth of some ruminant, is from the cliffs at Kemp Town, and shows, that in periods very remote, the same process was in action along the Sussex shores. These beautiful slabs of marble are portions of stalagmites, from St. Michael's Cave, Gibraltar;

* An admirable model of part of the celebrated Cave of Adelsberg, described by Sir H. Davy, as the habitation of the *Proteus*, may be seen in the Colosseum in the Regent's Park.

80

THE WONDERS OF GEOLOGY.

LECT. I.

and this large conical mass, which has been cut through and polished to show its structure, was dug up on the summit of Alfriston Hill, in Sussex, and must have been formed in some fissure or cavern in the chalk, of which no traces now remain.

38. CONSOLIDATION OF LOOSE SAND, &c.—The changes effected by this process in strata composed of loose materials, are of still greater importance; for by an infiltration of crystallized carbonate of lime, sand is converted into sand-stone,—fragments of soft chalk are transmuted into a solid rock, as in the Coombe-rock of Brighton,—and accumulations of beach, and gravel, into a hard conglomerate, as in this example of the ancient shingle bed of the cliffs, at Rottingdean;—shells, into a building stone, as in this mass from Florida,—and the detritus of shells and corals, into limestone, as in these specimens from Bermuda. By this agency, the bones of animals are permeated with calcareous spar, and their medullary cavities lined with crystals of carbonate of lime: and clay, which has cracked by drying, has its fissures filled up, and becomes consolidated into those curious masses, called *septaria*, which, when polished, form the beautiful table-slabs for which Weymouth is celebrated.

39. DESTRUCTION OF ROCKS BY CARBONIC ACID GAS.—Although, in the instances above cited, water, by its combination with carbonic acid, occasions the solidification of loose and porous beds of detritus, yet the effect of this gas on certain rocks is that of disintegration; for by its solvent influence on the felspar, granite itself is reduced to a friable state, the quartz and mica, which with felspar constitute that rock, being set at liberty. The disintegration of granite, is a striking feature throughout extensive districts in Auvergne, especially in the neighbourhood of Clermont. In the ancient shingle of the cliffs at Kemp Town, near Brighton, blocks of granite occur which may be crumbled

§ 40.

GROTTO DEL CANE.

81

to pieces between the fingers. I have already shown you masses of pebbles held together by calcareous spar, from the same locality; we have, therefore, examples in that ancient bed, both of the conservative and disintegrating effects of carbonic acid—cementing the loose beach into solid blocks by calcareous depositions, and when in a gaseous state, or combined with water, dissolving the granite by its action on the felspar.

40. **CARBONIC ACID GAS IN CAVES.**—The escape of carbonic acid gas through fissures, into mines, wells, and caverns, is of frequent occurrence, and as the specific gravity of this gas is greater than that of atmospheric air, it forms an invisible pool at the bottom of these cavities, and its presence is seldom suspected, till shown by its deleterious effects; hence fatal accidents often happen to well-diggers and excavators from this cause; it is called choke-damp by miners.

The *Grotto del Cane*, near Puzzuoli, four leagues from Naples, has for centuries been celebrated on account of the constant evolution, from fissures in the rock, of carbonic acid gas in combination with much aqueous vapour, which is condensed by the coldness of the external atmosphere. The floor of the cavern being lower than the entrance, the gas is spread over the bottom like a pool of water, and the upper part is free from any noxious vapour; the suffocating effects of the carbonic acid is, therefore, not felt by any creature whose organs of respiration are above the level of this mephitic lake; but if a dog, or other small animal, enters the cave, it instantly falls senseless, and would expire if not speedily removed: the name of the cave is derived from the experiment being often made on dogs, for the amusement of visitors.† It is im-

* A few pounds of quicklime thrown into a well, quickly absorbs the carbonic acid gas.

† See Sandys' *Travels*; London, 1637.

G

82

THE WONDERS OF GEOLOGY.

LECT. I.

possible to fire a pistol at the bottom of the cavern; for, though gunpowder may be exploded even in carbonic acid by the application of a heat sufficient to decompose the nitre, and consequently to envelope the mass in an atmosphere of oxygen gas, yet the influence of a mere spark from steel produces too slight an augmentation of temperature for this purpose.*

41. CONSOLIDATION BY IRON.—Water charged with a large proportion of iron, acts an important part in the consolidation of loose materials, converting sand into iron-stone, and beach or shingle into a ferruginous conglomerate. On Clapham Common, and in other places in the vicinity of London, large blocks of a very compact breccia occur, being masses of chalk-flints more or less broken and rolled, cemented together by an infiltration of iron. In this example of a horse-shoe firmly impacted in a mass of pebbles and sand, from the sea-beach at Eastbourn, the cement which binds the mass is derived from the iron. Nails are frequently found in the centre of a nodule of hard sandstone formed by this process; the nail having supplied the water with the material by which the surrounding sand has become concreted into stone. I have here a cannon ball imbedded in the centre of a nodule of iron-stone, in which are several oyster shells: this specimen was dredged up off the Sussex coast, and has evidently been consolidated by the partial oxidation of the iron.

In this mass of breccia, which has been produced by a like process, are two silver pennies of Edward I; it was found in 1832, at a depth of ten feet in the bed of the river Dove, in Derbyshire. The coins are presumed to be part of the treasures contained in the military chest of the Earl of Lancaster, which was lost in this stream in 1322; the soldiers being alarmed by a sudden

* Daubeny on Volcanoes.

84

THE WONDERS OF GEOLOGY.

LECT. I.

the Thames, large masses of a firm conglomerate are occasionally dredged up, in which Roman coins, and fragments of pottery, are imbedded; the stone being formed of sand and clay solidified by ferruginous infiltration.

These specimens of oxide of iron were dug up in a marshy soil, near Bolney, in Sussex, and are of the same nature as the substance called bog-iron ore, which so frequently occurs in peat. Specimens of bog-iron are not uncommon in the superficial loam and gravel of the south-east of England. The ebony colour of the woods from Ireland, which we have already examined, has been derived from an impregnation of iron.

The consolidation of sand, gravel, and other detritus, by this agency, is taking place everywhere; on the shores of the Mediterranean; on the coasts of the West India Islands, and of the Isle of Ascension; and on the borders of the United States; thus the remains of man, at Guadaloupe—of turtles, in the Isle of Ascension—of recent shells, and bones of ruminants, at Nice—of ancient pottery in Greece—and of animal and vegetable substances, in our own country, have become imbedded and preserved.

I now proceed to notice a few instances of these simple but important operations, by which much of the solid crust of the globe is continually being renewed.

42. RECENT LIMESTONE OF THE BERMUDAS.—The shores of the Bermuda Islands afford interesting examples of this class of deposits in different states of consolidation. The sea surrounding the Bermudas abounds in corals and shells; and from the action of the waves on the reefs, and on the dead shells, the water becomes loaded with calcareous matter. Much of the detritus is transported to a distance, and subsides in the profound depths of the ocean, imbedding the remains of animals and vegetables; but a great portion is borne by the waves towards the shores, and cast up on the strand in the state of fine earth and sand. This

§ 42.

85

detritus is blown inland by the winds, and is soon con-
solidated by the percolation of water, and the infiltration
of crystallized carbonate of lime; a fine white calca-
reous stone is thus formed, which in some localities is
sufficiently compact for building. In this rock are nu-
merous shells and corals, of species which inhabit the
neighbouring seas; in some instances the large mottled
trochus, so well known to collectors both in its natural and
polished state, with all its colours preserved, is imbedded
in a pure white limestone. In many specimens the colours
are faded, and the shells very much in the state of those
found in the tertiary strata at Grignon; in others the shelly
matter is wanting, but the hard stone retains the forms and
markings of the originals. The corals are imbedded in a
similar manner; and masses occur in the limestone so like
the fossil corals of the oolite of this country, that it requires
an experienced eye to detect their real nature.

In a suite of specimens, showing the transition from
loose sand to solid rock, we have—

1. Broken shells and corals, retaining their colours.

2. Similar materials, more comminuted and completely bleached.

3. An aggregation of fine sand and white earth, broken shells, and corals.

4. Friable limestone, resembling soft chalk, and composed of comminuted corals, &c.

5. Hard limestone, of similar materials.

6. Compact limestone, enveloping shells and pebbles.

7. A fine indurated limestone, so hard as to be with difficulty broken by the hammer, inclosing a few shells and corals: this stone is employed for building.*

* On this bare calcareous rock the coffee-plant finds sufficient support, and is seen in many places growing luxuriantly, its stems shooting out from between the crevices of the stone. In the botanic gardens at Kew are several coffee-plants from Bermuda, growing on blocks of this rock.

§ 43.

FOSSIL HUMAN SKELETONS.

87

a bed of recent limestone forms a sloping bank, from the steep cliffs of the island to the sea, and is nearly all submerged at high tides. This modern rock is composed of consolidated sand, and comminuted shells and corals of species now inhabiting the adjacent seas: land shells, fragments of pottery, stone arrow-heads, carved stone and wooden ornaments, and human skeletons, are occasionally found imbedded in it. This being the first known undoubted example of the occurrence of human bones in solid limestone, excited great attention; and the fact, simple and self-evident as is its explanation, was made the foundation of many vague and absurd hypotheses.

In most instances the bones are dispersed; but a large slab of rock, in which a considerable portion of the skeleton of a female is imbedded, is preserved in the British Museum, and has been described by Mr. Konig, in a highly interesting memoir, published in the Philosophical Transactions of 1814. The annexed representation (Lign. 11) will convey an idea of this celebrated relic, which was detached from the rock at the Mole, near Point-a-Pitre.

In this specimen the skull is wanting, but the spinal column, many of the ribs, the bones of the left arm and hand, of the pelvis, and of the thighs and legs, remain. The bones still contain some animal matter, and the whole of their phosphate of lime. It is remarkable, that the fragments of the skull of this very specimen have recently been purchased for the museum at South Carolina, of a French naturalist, who brought them from Guadaloupe; and they have been described by Professor Moultrie, of the Medical College of that State. These relics consist of portions of the temporal, parietal, frontal, sphenoidal, and inferior maxillary bones, of the right side of the skull. An entire skeleton was also discovered in the usual position of burial; and another, in a sitting posture, in a softer sandstone. The bodies, thus differently situated, may have belonged to

§ 43.

FOSSIL HUMAN SKELETONS.

89

In another skeleton from Guadaloupe, now in the museum of the *Jardin des Plantes*, and represented in the last edition of Cuvier's *Théorie de la Terre*, the figure is bent, the spine forms an arc, and the thighs are drawn up as if the individual were in a sitting posture; a portion of the upper jaw, and the left half of the lower with several teeth, nearly the whole of one side of the trunk and pelvis, and a

LIGN. 12.—HUMAN SKELETON FROM GUADALOUPE.
In the Museum at Paris.

considerable portion of the upper and lower left extremities, are preserved (Lign. 12). The stone incloses terrestrial and marine shells; it is evident that the former have been drifted by streams from the interior, and the latter deposited by the sea. In the bed from which this block was extracted, were found teeth of the *Caiman* (a species of crocodile), stone hatchets, and a piece of wood, having rudely sculptured on one side a mask, and on the other the

90

THE WONDERS OF GEOLOGY.

LECT. I.

figure of an enormous frog; it is of guaiacum, but has become extremely hard, and as black as jet.*

Human skeletons have also been found in solid calcareous tufa near Santa in Peru. Bones, belonging, it is computed, to some scores of individuals, were discovered imbedded in travertine, containing fragments of marine shells which still possess colour. The bed of stone is covered by a deep vegetable soil, and forms the face of a hill crowned with brushwood and large trees, on the side of the river Santa.†

44. ISLE OF ASCENSION.—In the Isle of Ascension, which is a volcanic cone in the midst of the Atlantic, and appears to have been a dome of trachytic rocks, subsequently affording vent to lava currents, a recent deposit of conglomerate is going on. Its coasts are flanked by accumulations of concreted sand with comminuted shells, corals, echini, and fragments of lava. The specimens before us are portions of this modern rock in various states of consolidation; they are composed of corals, which still retain their colour; of shells, more or less broken; and of sand of similar materials; they also contain pebbles of trachytic and glassy lava. The shores of this island are a favourite resort of turtles, which repair thither in immense numbers, and deposit their eggs in the loose sand: the rapid conversion of the coarse calcareous banks into solid stone, occasions the frequent imbedding and preservation of the eggs; and there are specimens in the cabinet of the Geological Society, in which the bones of young turtles, just on the point of

* In the former editions of this work a notice was given of some supposed imprints of human feet on limestone, figured and described in an early volume of the American Journal of Science. These markings have since been carefully examined by Dr. Dale Owen, of New Harmony, and prove to have been sculptured by the Aborigines.

† American Philosophical Transactions for 1828, p. 283.

§ 45.

DRIFTED SAND.

being hatched, are preserved. The conglomerate of the Isle of Ascension is, as you may observe, principally composed of corals. Here we have another example of a rock formed of the calcareous skeletons of those wonderful forms of organic existence; but it is not my intention in this place to dwell on the geological changes produced by zoophytes in the formation of coral reefs, &c., as the examination of the recent and fossil corals will form the subject of a subsequent Lecture.

45. DRIFTED SAND.—We have already alluded to the encroachments on the land by the drifting of sand-banks thrown up beyond the reach of the tide, and driven by the winds inland; thus effecting the desolation of whole regions by their slow, but certain progress. Egypt instantly presents herself to the imagination, with her stupendous pyramids, the sepulchres of a mighty race of monarchs, and the wonder of the world—her temples, and palaces, once so splendid and massive, as to bid defiance to the ravages of time—her plains, and valleys, formerly teeming with abundance, and supporting a numerous population—now stripped of her ancient glories, her fairest regions depopulated, and converted into arid wastes,—her cities overwhelmed, and prostrate in the dust—and the colossal monuments of her kings, and the temples of her gods, half buried beneath the sands of the Desert!

The drifting of the sands of the Lybian desert by the westerly winds, observes M. De Luc, has left no lands capable of cultivation on those parts of the western bank of the Nile which are not sheltered by mountains; while in Upper Egypt, whole districts are covered by moveable sands, and here and there may be seen the summits of temples, and the ruins of cities which they have overwhelmed. “Nothing can be more melancholy,” says Denon, “than to walk over villages swallowed up by the sand of the Desert, to trample under foot their roofs and

92

THE WONDERS OF GEOLOGY.

LECT. I.

minarets, and to reflect that yonder were cultivated fields,
that there grew trees, that here were the dwellings of men,
and that all have now vanished. The sands of the Desert
were in ancient times remote from Egypt; and the Oases
which still appear in the midst of this sterile region, are
the remains of fertile soils which formerly extended to the
Nile.”*

In the maritime plains and valleys of Peru the same
cause is operating slowly, but with unremitting energy;
the sea-sands are marching incessantly before the trade
wind, and threaten ultimate desolation. The sand has
already surmounted the lofty hills which form the southern
boundary of the beautiful valley of Lurin, and is flowing
down in large waves over the cultivated ground. The
same phenomenon is observable on the elevated plain which
is called the Tablada, where the tops of the hills appear
like Egyptian oases, and whence the sand is pouring down
in enormous floods over the sugar plantations of San Juan
and Villa, in the valley of Rimac.†

46. FORMATION OF RECENT SANDSTONE IN CORNWALL.
—On many parts of the shores of Scotland, sand-floods
have converted tracts of great fertility into barren wastes;
and on the northern coast of Cornwall an extensive district
has been covered by drifted sand, which has become con-
solidated by the percolation of water holding iron in solu-
tion, and in some places forms ranges of low mounds, and

* See an Essay on the Moving Sands of Africa, in Professor Jamie-
son's Translation of Cuvier's Theory of the Earth, p. 375. Sir G.
Wilkinson, in his highly interesting work, questions the correctness
of these inferences, as to the extent of the sand-floods, and asserts,
that at the present time the alluvial soil is on the increase, the deposits
from the inundations of the Nile more than counterbalancing the
inroads of the sands; and that the land now capable of cultivation in
the valley of Egypt is greater than at the time of the Pharaohs.—
*Manners and Customs of the Ancient Egyptians*, vol. i. pp. 218—222.

† Blackwood's Edinburgh Magazine for March, 1839.

LECT. I.

§ 47.

RECENT SANDSTONE OF CORNWALL.

93

hills forty feet high. This sandstone is an interesting example of a recent formation, and has been described by Dr. Paris, (the distinguished President of the College of Physicians,) in one of the most graphic and instructive essays on modern deposits that has appeared in this country.* The sand has evidently been drifted from the sea by hurricanes, probably at a very remote period; it is first seen in a slight, but increasing state of aggregation, on several parts of the shore in the Bay of St. Ives. Around the promontory of New Kaye, the sandstone occurs in various degrees of induration, from that of a friable aggregate, to a stone so compact, as to be broken with difficulty by the hammer, and which is used in the construction of buildings. Upon examining the stone with a lens, it appears to be principally made up of comminuted shells; and it is worthy of remark, that the shelly particles are frequently spherical, from the previous operation of water; and some portions of the rock closely resemble the ancient limestone called *oolite*, which will hereafter come under our notice. The rocks upon which the sandstone reposes are clay-slate, and slaty limestone; and the water effecting their decomposition may have thus obtained the iron, alumina, and other mineral matters by which the loose sand has been converted into sandstone. The infiltration of water thus impregnated is a common and extensive cause of lapidification: at Pendean cove, granitic sand is gradually hardening into breccia, by this process; and in the island of St. Mary, is becoming induced by the slow action of this chalybeate.

47. SILICEOUS DEPOSITS.—Silex, or the earth of flint, a combination of the metallic base called silicon with oxygen, is a mineral, which constitutes so large a portion of the rocks and strata, that it is computed to form, either

* Appendix E.

94

THE WONDERS OF GEOLOGY.

LECT. I.

in a pure or combined state, nearly one-half of the solid crust of the globe. The flints from our chalk cliffs, the boulders and gravel on our sea-shores, and the pebbles of agate, quartz, and chalcedony, are well-known examples of the usual varieties of silex.

I scarcely need observe, that this nodule of flint, obtained from a neighbouring chalk-pit, has once been in a soft or fluid state; for there are many sharp impressions of shells, and of spines of an echinus, on its surface.* We have already seen that water impregnated with carbonic acid gas is capable of holding lime in solution, and that travertine, limestone, and other calcareous deposits, have originated from this agency; and although, even in the present advanced state of chemical knowledge, we are but imperfectly acquainted with the process by which any considerable proportion of flint can be dissolved in water, yet we have unquestionable proofs, that the solution of siliceous earth has been effected by natural processes, on a very extensive scale. At the present moment, Nature, in her secret laboratories, is still carrying on a modification of the same process; and of this fact we have remarkable instances in the Geysers of Iceland, and in the Azores, and in New Zealand. A high temperature appears necessary to enable water to hold in solution a large quantity of silex; for we find that the thermal springs of volcanic regions are the only agents by which siliceous deposits and incrustations are at present produced. The difference between the modern siliceous sinter, and the flint of the cretaceous strata, appears to be referable to the subaerial deposition of the former, and the submarine formation of the latter.

48. THE GEYSERS OF ICELAND.—The Geysers, or intermittent boiling fountains, of Iceland, have long been

* See "Thoughts on a Pebble; or, a First Lesson in Geology." Seventh edition; 1846.

LECT. I.

§ 48.

THE GEYSERS OF ICELAND.

95

celebrated for possessing this property in an extraordinary
degree; holding a large quantity of silex in solution,
and depositing it, when cooling, on vegetables and other
substances, in a manner similar to that in which travertine
is precipitated by the incrusting springs of which we have
already spoken. Iceland may be considered as a mass of
volcanic matter; the only substances not of igneous origin
in the whole island, being deposits of surturbrand, or bitu-
minous wood, in which occur leaves, trunks, and branches
of trees, with clay and ferruginous earth. These strata
support alternating beds of basalt, tufa, and lava, which form
the summit of the hill in which the vegetable remains
occur.

The Geysers, of which there are a considerable number,
are springs, or rather intermittent fountains, of hot water,
which issue from crevices in the lava. A jet of boiling
water, accompanied with a great evolution of vapour, first
appears, and is ejected to a considerable height; a volume
of steam succeeds, and is thrown up with prodigious force,
and a terrific noise like that produced by the escape of
vapour from the boiler of an engine. This operation con-
tinues sometimes for more than an hour, when an interval
of repose of uncertain duration succeeds, after which the
same phenomena are repeated. If stones are thrown into
the mouth of the cavity from which the fountain has issued,
they are ejected with violence after a short interval, and
again jets of boiling water, vapour, and steam, appear in
succession. The eruptions of the "great Geyser," wit-
nessed by Sir G. S. Mackenzie,* were preceded by a sound
like the distant discharge of heavy ordnance, and the ground
shook sensibly; the sound was rapidly repeated, when the
water in the basin, after heaving several times, suddenly

* Travels in Iceland, in the summer of the year 1810, by Sir George Steuart Mackenzie, Bart.

solid
s, the
les of
les of

or fluid
and of
seen
apable
stone,

in this
state
painted
of flint
roofs,
ed by
the
s still
of this
of Ice-
high
in so-
thermal
which
c pro-
sinter,
refer-
e sub-

ior in-
been

ology."

LECT. I.

§ 48.

THE GEYSERS OF ICELAND.

97

basin of the “great Geyser” is an irregular oval, about fifty-six feet by forty-six, formed of a mound of siliceous deposits about seven feet high; the channel through which the water is ejected being sixteen feet in diameter at the opening, but contracting to ten feet lower down; its perpendicular depth is estimated at sixty feet.

Sir G. S. Mackenzie has proposed an ingenious explanation of these phenomena, which the diagram in the preceding page will serve to illustrate. It is supposed that the water from the surface percolates through crevices (Lign. 13, a,) into a cavity in the rock (b), and heated steam, produced by volcanic agency, rises through fissures in the lava beneath (c, c). The steam becomes in part condensed, and the water filling the lower part of the cavity (d) is raised to a boiling temperature, while vapour under high pressure occupies the upper part of the chasm. The expansive force of the steam becomes gradually augmented, and at length drives the water up the fissure or pipe (e), and a boiling fountain with jets of vapour is produced; this continues playing till all the water in the reservoir is expended, when the steam itself escapes with great violence, till the supply is exhausted.*

The siliceous concretions formed by these springs cover an extent of four leagues. M. Eugene Robert states, that this curious formation may be seen passing by insensible gradations from a loose friable state, the result of a rapid deposition, to the most compact and transparent masses, in which impressions of the leaves of the birch-tree, and portions of the stems, are distinctly perceptible, presenting the appearance of the agatized woods of the West Indies. Rushes, and various kinds of mosses, converted into a white siliceous rock, in which the minutest fibres are preserved, also occur; but on the margin of the Geysers, from the

* Travels in Iceland, p. 229.

H

98

THE WONDERS OF GEOLOGY.

LECT. I.

splashing of the water, the depositions resemble large cauliflowers; and on breaking these masses, vegetable impressions are often discovered. Numerous thermal springs occupy the valley in the interior of the island, in the midst of which the Geysers are situated; it is evident that these waters rise from deep crevices, in which they have been heated by volcanic fires. The rivers proceeding from the springs often resemble milk in appearance, owing to the argillaceous bolé which they take up in their passage among the siliceous concretions: such are the white rivers of Olassai. Mount Hecla, like all the mountains of Iceland, is entirely covered with snow, and no smoke appears on its summit. Accumulations of rolled masses of obsidian and pumice-stone form a layer on the flanks of the mountain, thirty feet thick; stems and branches of the birch-tree occur in the midst of this bed; they are the remains of the ancient forests of the island, which the volcanic eruptions have entirely extirpated.*

49. SILICEOUS THERMAL WATERS OF NEW ZEALAND.—The phenomena under review are being effected at the present moment, on a much grander scale, in the volcanic districts of New Zealand. The principal volcanic mountain of that country is Tongariro, which has an elevation of 6200 feet above the level of the sea. Its crater is a quarter of a mile in diameter, and very deep; the sides are precipitous, and in some places overhanging, and the entire area is always covered with steam. From this crater streams and torrents of boiling water and vapour, highly charged with silex, are constantly issuing forth, and, flowing down the flanks of the mountain in cascades and torrents, empty themselves into lakes near its base, and deposit in their course siliceous sinter in great abundance, incrusting leaves, branches, and other extraneous substances. The whole of the surrounding

* Bulletin de la Société Géologique de France.

§ 49.

VOLCANIC PHENOMENA IN NEW ZEALAND.

99

country for several miles, is studded with lakes and pools, and fountains of hot and boiling water; and groups of mud ponds, or stufas, occur in considerable numbers. Some of the boiling torrents of the mountain find their way to the delta of the river Waikato, and cover a space of two miles square with an assemblage of thermal springs. The surface of this area appears to be only a thin crust of pumice and a friable sulphureous earth, with chalcedonic and siliceous incrustations, spread over volcanic caverns.

The most stupendous of these boiling pools is partly surrounded by a cliff sixty feet high, which is oxidized, corroded, and undermined from the effects of the heated vapours, which are continually issuing forth in jets. At the base of this cliff the pond is constantly boiling with a white foam, and throwing up fountains eight or ten feet high, with great noise and violence. Silex is thrown down by the boiling waters in the state of stalagmitic concretions, and this deposit resembles in colour and solidity the flint of the English chalk. This generally insoluble mineral is here held in solution by the alkaline elements and very high temperature of the water.

"Another and still more striking example of a thermal lake," observes Dr. Dieffenbach, from whose interesting work on New Zealand the preceding notice is taken, "is that of Rotu-Mahanu. Imagine a deep lake of a blue colour surrounded by verdant hills, and in this lake several islets, some showing the bare rocks, while others are covered with shrubs; while on all of them steam issues from a hundred openings between the green foliage without impairing its freshness. On the opposite side is a flight of broad steps of the colour and aspect of white marble with a rosy tint from siliceous incrustations, over which flowed a cascade of boiling water into the lake. A part of this lake is separated from the rest by a ledge of rocks, forming

H 2

100

THE WONDERS OF GEOLOGY.

LECT. I.

a lagoon in a state of ebullition, which discharges its
waters into the Rotu-Mahanu.”*

These modern siliceous formations are facts of great
interest and importance; for they prove, in the clearest
manner, that the most insoluble and refractory substance
may be reduced to a liquid state, and again become con-
solidated, and assume numerous modifications, merely by
the agency of thermal waters; hence the envelopment of
the delicate corals, shells, &c. which are so abundant in
chalk flints, is readily explained.

50. ARTIFICIAL SOLUTION OF SILEX.—The natural
processes above described, have been successfully imitated
in a series of experiments, conducted with great sagacity
by Mr. Jeffery, with the view of determining whether
silex is soluble in heated water, without the presence of
alkalies, or other chemical agents. The following is a
concise account of these important experiments.

A large boiler, used for vitrifying brown stone-ware,
was heated by four exterior furnaces, each six feet long
and five wide. Between each of these furnaces and the
kiln a deep pit was made, and filled to a height of three feet
with water, which was renewable from without. Some fels-
pathic and siliceous minerals were placed in the direction
of the current just within the kiln; and upon some of the
arches a few earthenware vessels were placed, that any
action upon them might be observed. Below a full red
heat but little effect was perceived; but at a temperature
above that of fused cast-iron, a rapid solution of mineral
matter took place; this heat was continued for ten hours.
When the kiln was opened, more than a hundred-weight
of mineral matter had been dissolved and carried away in
the vapour. The wall was eaten away, and presented a
corroded and unglazed surface, like loaf-sugar partially

* Dr. Dieffenbach's New Zealand.

§ 51.

HERTFORDSHIRE PUDDING-STONE.

101

melted by water: and there was no appearance of the smooth glazed surface, which invariably attends the action of an alkali on a siliceous substance. Some of the earthenware vessels were partially eaten through; but on the uppermost arch, where the heat was only a full red, a curious phenomenon appeared; the articles there had received, exterior to their own glazing, and loosely incrusting it, a complete frosted siliceous coating, having the appearance of a candied surface. This was evidently a precipitation from the vapour; in fact, a hoar-frost of silex. There was from half an ounce to an ounce on each vessel, and altogether several pounds were thus precipitated; but by far the greater part of the vapourized mineral was, as might be expected, carried away by the current, and dissipated in the air. This powerful action was apparently entirely due to the presence of water; there being at all times the same quantity of alkali present in the fuel, whatever that might have amounted to, without producing such an effect. The experiment is conclusive as to the solvent power of water at a very high temperature on silica, and siliceous rocks; for the action cannot be attributable to the alkalies, because, under precisely similar conditions, the experiment failed when there was no water; and besides, each pound of alkali would have had to dissolve forty pounds of silica. Mr. Jeffery has in fact performed, on a small scale, the same operation which is incessantly going on in the volcanic regions of Iceland and New Zealand, and established the potency of heated water and vapour to effect the solution of silex.*

51. HERTFORDSHIRE PUDDING-STONE.—We have before us numerous examples of conglomerates formed by carbonate of lime; in other words, aggregations of pebbles,

* See an account of Mr. Jeffery's experiments in Reports of the British Association of Science, for 1840.

102

THE WONDERS OF GEOLOGY.

LECT. I.

sand, shells, and corals, cemented together by calcareous spar; and others by ferruginous infiltrations: but this specimen is a congeries of rounded flint pebbles, imbedded in a siliceous paste. This conglomerate is commonly called Hertfordshire pudding-stone, and was formerly in much request with lapidaries; for the cement being as hard and solid as the pebbles themselves, the stone admits of being cut and polished into a great variety of ornaments. The formation of this rock must have resulted from a stream of siliceous matter having flowed through a bed of gravel, and cemented the pebbles into a solid mass, while those portions which the liquid flint did not reach, remained as loose water-worn materials.

But there are many very hard sandstones composed entirely of siliceous granules, which appear to have been formed simply by the effect of great pressure, there being no cementing medium; the rock, when broken, appearing like the fractured surfaces of fine sugar.*

It is not my intention in this lecture to dwell on the silicification† of the remains of animals and plants; it will

* A consolidation of this kind can be produced artificially. In the experiments made for the trial of the strength of gunpowder, leathern bags filled with sand are put into the mortar which is to receive the cannon ball, propelled by the powder from another gun at the distance of only fifty feet. The sand is frequently compressed by the percussion of the ball, into a mass of sandstone, sufficiently firm to remain solid and bear handling; and this sandstone is perfectly free from any cement. The consolidating power of great pressure has lately been ingeniously applied to various purposes; among others, to the formation of tesseræ from porcelain earth, and of graphite or plumbago, fit for the finest pencils, from the rubble of rejected ore formerly thrown by as useless. This rubble is reduced to an impalpable powder, and then subjected to great pressure in moulds, and the most pure graphite is the result: this prepared mineral is now generally employed for the best lead pencils.

† Petrifaction by flint.

§ 52.

EFFECTS OF HIGH TEMPERATURE.

103

suffice to remark, that in silicified wood the most minute
vegetable structure may often be detected, although the
specimens will strike fire with steel; and that the most
delicate and perishable animal tissues are often preserved
in flint.

52. EFFECTS OF HIGH TEMPERATURE.—The phenomena presented to our notice in this investigation of the Geysers of Iceland, and other natural solutions of silex in thermal waters, lead to the consideration of another agent in the transmutations that take place in the crust of the globe. It must be obvious to every intelligent mind, that beds of loose and porous materials can have acquired hardness and solidity only by one of the following processes; namely, either by matter dissolved in a fluid, and afterwards deposited among the porous masses in the manner just described; or by the reduction of the materials by heat into a state of softness or fusion, and their subsequent conversion, by cooling, into a solid mass.* Fire, or to speak more correctly, a high temperature, however induced—whether by electromagnetic influence, or by central or medial sources of heat—and water, are therefore the chief agents by which the mineral masses composing the crust of our planet have been and are still being modified. We have already seen how vast are the changes which result from the effects of water; we must now take a rapid survey of the influence which caloric is capable of exerting; an influence far more universal and varied than we may at first be prepared to expect.

The expansive power which heat exerts on most substances, and its conversion of the most solid and durable bodies, first into a fluid, and lastly into a gaseous state, are phenomena so familiar as to require no lengthened comment. But the effects of heat are found to vary according to the circumstances under which bodies are submitted to its influence; hence the changes induced by high temperature

* Playfair.

104

THE WONDERS OF GEOLOGY.

LECT. I.

beneath great pressure, are totally different from those effected by fire on the surface, under the ordinary weight of the atmosphere. A familiar example will serve to illustrate my meaning. Chalk consists of lime combined with carbonic acid; and as, for agricultural and other economical purposes, it is desirable to have the lime in its pure state, the chalk, or limestone, is exposed to a great heat, in kilns erected in the open air, until all the carbonic acid gas is dissipated, and the stone is said to be burnt into quicklime. In the specimens before us the same substance is seen in the state both of chalk and lime. It may readily be conceived, that if this operation were conducted beneath such a degree of pressure as would prevent the escape of the gaseous elements, the formation of quicklime would not take place; the chalk would be fused, and the carbonic acid, released from its present relation with the calcareous particles, would enter into other combinations, and the mass when cooled, be wholly different from the product of the lime-kilns, formed by the same agency in the open air. Experiments have proved that this opinion is correct. Sir James Hall exposed pounded chalk to intense heat, under great pressure, and it was fused, not into lime, but into crystalline marble: even the shells inclosed in the chalk underwent the same transmutation, yet preserved their forms.* That analogous changes have been effected by natural operations we have abundant proof; but in this stage of our inquiry it is only necessary to remark, that where ancient streams of lava have traversed chalk, the latter invariably possesses a crystalline structure. We shall hereafter find, in accordance with the philosophical theory of Dr. Hutton, that all the ancient

* From a table drawn up with due caution by Sir James Hall, it is proved that under a depth of the sea, not exceeding one-third of a mile, chalk would be converted into a crystalline limestone, and that at a depth of little more than a mile it would be in a state of fusion, provided there were no refrigerating causes in action.

§ 53.

VOLCANIC AGENCY.

105

strata have been more or less modified by heat, acting under great pressure and at various depths; and that the present position and direction of the rocks composing the crust of the globe, have been produced by the same cause.* The Huttonian theory, indeed, offers a satisfactory explanation of a great proportion of geological phenomena, and enables us to solve many of the most difficult problems in the science; and it is but an act of justice to the memory of its illustrious founder, and of his able illustrator, Professor Playfair, to state that this theory, corrected and elucidated by the light which modern discoveries have shed upon the physical history of our planet, is that embraced by the most distinguished modern geologists.

53. VOLCANIC AGENCY.—Of the activity and power of the agent to which these remarks more immediately refer, the currents of melted rocks, called lavas, ejected through crevices and fissures of the earth, accompanied with evolutions of heat and vapour, afford the most striking proofs; and the volcano, with its frequent concomitant the earthquake, have in all ages excited the terror and astonishment of mankind. It would be foreign to the design of this discourse, to dwell upon the nature and causes of volcanic action. Dr. Daubeny,† Mr. Scrope,‡ and others, have published highly interesting treatises on the subject; and Mr. Lyell has given an admirable sketch of volcanic phenomena. § I will only advert to the increased temperature of the earth in proportion as we descend from the surface towards the interior, and the profound depths from which thermal waters take their rise, as tending to support the opinion, that volcanic eruptions are occasioned by causes

* See Playfair's Illustrations of the Huttonian Theory, vol. i. p. 33, et seq. Edin. 1822.

† Daubeny's Lectures on Volcanoes, 1826.

‡ Scrope's Considerations on Volcanoes, 1825.

§ Principles of Geology, vol. ii.

106

THE WONDERS OF GEOLOGY.

LECT. I.

which are constantly in action in the interior of the globe. We shall hereafter have occasion to demonstrate that dislocations of the strata, and elevations of the bottom of the ocean, and subsidences of the land, and eruptions of melted mineral matter, have taken place from the earliest periods within the scope of geological inquiries.

The expansive power of caloric, even in ordinary circumstances, is very considerable, as is shown by the instrument called a *pyrometer*, which illustrates a fact continually presented to our notice, namely, the expansion of a bar of metal by heat, and its contraction, by cooling, into its original dimensions. The expansion of solid bodies by heat, when effected on a large scale, gives rise to many interesting phenomena. The careful experiments made by Colonel Totten, on the expansion of granite, marble, and other rocks, by variations of temperature, have shown that the mere expansion, or contraction, of extensive beds of these materials, will account for the elevation and subsidence of considerable tracts of country, and explain many analogous phenomena.*

54. SUBSIDENCE AND ELEVATION OF THE TEMPLE OF JUPITER AT PUZZUOLI.—One of the most interesting examples of local elevation and subsidence, apparently resulting from this cause, is that afforded by the remains of the celebrated temple of Jupiter Serapis, at Puzzuoli.

These ruins are situated on the northern shore of the Bay of Baiæ, at no great distance from the Solfatara, and consist of the remains of a large building of a quadrangular form, seventy feet in diameter; the roof of which was supported by twenty-four granite columns, and twenty-two of marble, each formed of a single stone. Many of the pillars are broken and their fragments strewed about the pavement, but three remain standing, and on them are

* American Journal of Science, vol. xxii.

§ 54.

107

inscriptions, not traced by the Greeks or Romans, but by
some of the simplest forms of animal existence, which have
here left enduring records of the physical changes that have

LIGN. 14.—REMAINS OF THE TEMPLE OF JUPITER SERAPIS, AT PUZZUOLI
(From Mr. Lyell's Principles of Geology.)

taken place on these shores, since man erected the temple
in honour of his imaginary gods. The surface of the columns,
the tallest of which is forty-two feet in height, is smooth
and uninjured to an elevation of about twelve feet from the
pedestal, where a band of perforations, nine feet wide,
made by marine boring mussels (*modiola lithophaga*), com-
mences; and above this, that is, at the height of twenty-one
feet from the pedestal, these cavities disappear. The hollows,
many of which still contain shells, sand, and microscopic
shields, are of an elongated elliptical shape, and are so
numerous and deep, as to prove unquestionably that the

108

THE WONDERS OF GEOLOGY.

LECT. I.

pillars were submerged in sea-water, the base and lower portions having been protected from the depredations of the boring shells by accumulations of rubbish and tufa; while the upper parts projected above the waters, and consequently were beyond the reach of the *lithodomi*.\* The platform of the temple is now about one foot below high-water mark; and the sea, which is only forty yards distant, penetrates the intervening soil. The upper part of the band of perforations is now at least twenty-three feet above the level of the sea; and yet it is evident that the columns were once immersed in salt water for a long period. It is equally clear that they have since been elevated to their present height, and yet have maintained their erect position, amid the extraordinary changes to which they were subjected; thus incontrovertibly proving, that the relative level of the land and sea, on that part of the Mediterranean coast, has changed more than once since the Christian era; each movement, both of subsidence and elevation, having exceeded twenty feet.† And there, at the present moment—

> "Those lonely columns stand sublime,
> Flinging their shadows from on high,
> Like dials, which the wizard Time
> Had raised to count his ages by!"—MOORE.

55. HISTORICAL EVIDENCE. — Fortunately, historical evidence throws some light on the respective dates of the most considerable changes of level, that the area on which the temple is situated has undergone. From inscriptions recording the embellishment of the temple by Septimus Severus and Marcus Aurelius, we learn that the building was entire, and occupied its original position, in the third century. In 1198 the eruption of the volcanic lake of the Solfatara took

* *Lithodomi*, from *lithos*, stone, and *demo*, to build.

† For a full account of the phenomena, see *Principles of Geology*, vol. ii. p. 268.

§ 56.

109

place, and was accompanied by earthquakes; a subsidence of the coast followed, and sunk the temple to a depth that submerged the columns in water to a height above the band of perforations. This state of things must have continued till the beginning of the sixteenth century; for the flat district called La Starza, on which the temple stands, is described by contemporary observers as being covered by the sea in 1530. Eight years afterwards earthquakes were very frequent and violent along that part of the Neapolitan coast, and on the 29th of September a volcanic eruption suddenly burst forth, and threw up, in a single night, a mound of pumice and ashes 450 feet high, and a mile and a half in circumference; and which still remains, and is called Monte Nuovo. During this catastrophe the coast on the north of the Bay of Baiæ was permanently elevated to the height of twenty feet, and formed a tract 600 feet in breadth, including the area occupied by the ruins of the temple, which were also elevated above the reach of the water, several of the columns retaining their original position.* These interesting relics of antiquity appear to have been wholly neglected till 1750, when the shrubs and weeds with which they were overgrown and concealed were removed, and the earth accumulated in the court of the temple cleared away. For the last thirty or forty years a slow subsidence of this coast appears to have been going on, and the floor of the temple is now often under water.†

56. CAUSES OF THESE CHANGES.—Professor Babbage attributes the tranquil elevation and depression of the temple, to the contraction and expansion of the strata on which it was built; the sources of volcanic action in the sur-

* Professor James Forbes of Edinburgh, on the historical evidence relating to the elevations and subsidences of the Temple of Jupiter at Puzzuoli, and of the adjacent coast.—*Brewster's Edinburgh Journal of Science*, vol. i. second series.

† See a letter addressed to the author by Mr. Hullmandel, Appendix, F.

110

THE WONDERS OF GEOLOGY.

LECT. I.

rounding country being very numerous, and a hot spring still existing on the land-side of the ruins. The change of level is therefore easily accounted for, by supposing the temple to have been built on the surface, when the rocks beneath were expanded by the effects of a high temperature, and that they subsequently contracted by slow refrigeration. When this contraction had reached a certain point, if a fresh accession of heat from the neighbouring volcano took place and increased the temperature of the strata, they would again expand, and thus raise the ruins to their present level.

Mr. Babbage carries out these views to explain the elevation of continents and mountain ranges, assuming the following facts as the basis of his theory :—

1st. As we descend below the surface of the earth, the temperature increases.

2dly. Solid rocks expand by being heated, but clay and some other substances contract.

3dly. Rocks and strata of dissimilar characters present a corresponding difference as conductors of caloric.

4thly. The radiation of heat from the earth varies in different parts of its surface; according as it is covered by forests, mountains, deserts, or water.

5thly. Existing atmospheric agents, and other causes, are constantly changing the condition of the surface of the globe.

Thus wherever a sea or lake is filled up by the wearing down of the adjacent lands, new beds are formed, conducting heat much less quickly than the water; while the radiation from the surface of the new land will also be different. Hence, any source of caloric, whether partial or central, which previously existed below that sea, must increase the temperature of the strata underneath to a much higher degree than before, because they are now protected by a bad conductor;* and their expansion must therefore

* Sir John Herschel observes, that this process is precisely similar to that by which a great coat, in a wintry day, increases the feeling of

§ 56.

BAY OF NAPLES.

111

elevate the newly-formed deposits above their former level;
—thus the bottom of an ocean may become a continent.
The whole expansion, however, resulting from the altered
circumstances, may not take place until long after the filling
up of the sea; in which case its conversion into dry land
will result partly from the accumulation of detritus, and
partly from the elevation of the bottom. As the heat now
penetrates the newly-formed strata, a different action may
be induced, the beds of clay or sand may become consoli-
dated, and instead of expanding, may contract. In this case,
either large depressions will occur within the limits of the
new continent, or after another interval, the new land may
again subside, and form a shallow sea. This sea may be
again filled up by a repetition of the same processes as before;
—and thus alternations of marine and fresh-water deposits
may occur, having interposed between them the productions
of the dry land.*

To review the physical changes which have taken place
around the Bay of Naples would prove highly interest-
ing, but my limits will only permit me to observe, that
whole mountains have been elevated on the one hand, and
temples and palaces submerged beneath the sea on the
other. In our sister island we have evidence of former
changes of a like nature, and which are alluded to by our
inimitable lyric poet, in the following beautiful lines:—

“On Lough Neagh's banks as the fisherman strays,
When the clear cold eve's declining,
He sees the round towers of other days
In the wave beneath him shining!

warmth; the flow of heat outwards being obstructed, and the surface
of congelation removed to a distance from the body by the heat thereby
accumulated beneath the new covering.

* Proceedings of the Geological Society, March 1834.

112

THE WONDERS OF GEOLOGY.

LECT. I.

"Thus shall memory often, in dreams sublime,
Catch a glimpse of the days that are over;
Thus, sighing, look through the waves of time
For the long faded glories they cover!"—MOORE.

57. ELEVATION OF THE COAST OF CHILI.—One of the most remarkable modern instances of the upheaval of an extensive tract of country, is that recorded by the late Lady Calcott, (then Mrs. Maria Graham,) as having been produced by the memorable earthquake which visited Chili in 1822, and continued at short intervals till the end of 1823. The shocks were felt through a space of 1,200 miles, from north to south. At Valparaiso, on the morning of the 20th of November, it appeared that the whole line of coast had been raised above its level; an old wreck of a ship, which could not previously be approached, was now accessible from the land; and beds of oysters, not before known in that locality, were brought to light. "When I went to examine the coast," says Lady Calcott, "although it was high-water, I found the ancient bed of the sea laid bare and dry, with oysters, mussels, and other shells, adhering to the rocks on which they grew: the fish being all dead, and exhaling the most offensive effluvia. It appeared to me, that there was every reason to believe the coast had been raised by earthquakes at former periods, in a similar manner; for there were several layers of beach, consisting of shingle mixed with shells, extending in parallel lines to the shore, to the height of fifty feet above the sea."*
Part of the coast thus elevated consists of granite; subsequent observations have proved that the whole of the country was raised, from the foot of the Andes to far out at sea; the supposed area over which the elevatory movements extended, being about 100,000 square miles; a space

* Geological Transactions, vol. i. second series.

ECT. I.

§ 58.

RAISED SEA BEACH AT BRIGHTON.

equal in extent to half the kingdom of France. Mrs. Somerville mentions, that a further elevation to a considerable extent has also taken place along the Chilian coast, in consequence of the violent earthquake of 1835.

58. RAISED SEA BEACH AT BRIGHTON.*—Examples of such changes occur in almost every part of the world, and there is perhaps no considerable extent of country, which does not afford some proof, that similar physical mutations have taken place in modern times. And although we have not a temple of Serapis on our shores, yet the cliffs from Brighton to Rottingdean afford unquestionable evidence that the relative level of land and sea, has undergone great changes within, to speak geologically, a comparatively recent period. The cliffs along the coast, from New Shoreham to Rottingdean, are composed of layers of chalk rubble, with flints slightly rolled, and interspersions of clay and loam; the whole being an accumulation of water-worn materials, deposited at some very remote period in an estuary or bay of the sea. The base of the cliffs, to the height of a few feet, consists of the chalk strata, which may be seen at low water extending far out to sea, being covered here and there by shingle and sand. Between the chalk and the superincumbent mass above described, is a bed of rolled chalk-flints, pebbles, and sand, with boulders of granite, porphyry, and other rocks, foreign to the south-east of England; in fact, a sea beach, formed in the same manner as the present bed of shingle which skirts the base of the cliffs. Among the pebbles of this ancient beach, are rolled masses of chalk and limestone, full of perforations made by boring shells; here are several specimens, with cavities

* The geological character of the cliffs at Brighton, and the occurrence of bones of elephants and other mammalia in those beds, were first described in my “Fossils of the South Downs,” 1822.

I

114

THE WONDERS OF GEOLOGY.

LECT. I.

similar to those made in the chalk-rock by the recent
*pholades* and *mytili*.

These strata, which must have been deposited beneath
the waves, now constitute a line of lofty cliffs, extending for
miles along the sea-coast. The annexed diagram (*Lign.* 15)

LIGN. 15.—ELEVATED STRATA AND BEACH AT BRIGHTON, EAST OF KEMP TOWN.

A, Elephant bed; B, Ancient bed of shingle; C, the Chalk; D, Terrace of Chalk beneath the ancient sea-beach.

represents a vertical section, as seen in those places where
the inroads of the sea have extended to the chalk strata, and
the face of the ancient cliff is exposed, the newer deposits
being shown in profile from south to north; these consist
of the following :—

1. (A), Chalk rubble, loam, &c., obscurely stratified; this deposit, from its containing many teeth and bones of elephants, I have named the Elephant bed; it constitutes the upper three-fourths of the cliffs.

2. (B), Shingle, or sea beach and sand, several feet above high-water mark. This ancient shingle, which from the inroads of the sea extends in the cliffs beyond Kemp Town but a short distance inland, is constantly found beneath the loam and clay, several hundred yards north of the shore, in the western part of Brighton. In wells sunk in the Western road, the shingle bed was reached at the depth of fifty-four feet.

§ 58.

RAISED SEA BEACH AT BRIGHTON.

115

3. (c), The undisturbed chalk, which forms a sloping cliff, inland, behind the elephant bed (A) and shingle (B), passes under the latter, and appears as a terrace at the foot of the present cliffs (D).*

These appearances demonstrate the following sequence of changes in the relative level of the land and sea on the Sussex shores :—

*First.* The chalk terrace on which the ancient shingle rests, was on a level with the sea for a long period; and the beach was formed, like the modern shingle, by the action of the waves on the then existing chalk cliffs. The rolled condition of the materials, and the borings of the *lithodomi*, prove a change of level as decidedly as do the bands of perforations in the columns of the temple of Jupiter at Puzzuoli.

*Secondly.* The whole line of coast, with the shingle (B), was submerged to such a depth, as to admit of the deposition of the uppermost strata (A).

*Lastly.* The cliffs were raised to their present elevation, and at this period the formation of the existing sea beach commenced.

Here, then, we have unquestionable evidence that the Sussex shores have been subjected to changes similar to those produced by earthquakes on the Chilian coast.

A phenomenon of a like nature, but of a far more ancient period, is observable at Castle Hill, near Newhaven, about eight miles east of Brighton; there, immediately beneath the turf, is a regular sea beach with oyster-shells, many feet in thickness, forming the summit of the chalk cliffs, 150 feet above the level of the sea.

Near Bromley in Kent, and Reading in Berkshire, similar accumulations of pebbles and oyster-shells are to be found. Elevated beds of shingle, of comparatively recent

* See Geology of the South-East of England, p. 30; Fossils of the South Downs, p. 277; Medals of Creation, vol. ii. p. 913.

I 2

116

THE WONDERS OF GEOLOGY.

LECT. I.

epochs, occur likewise on the shores of the Frith of Forth,
and along the eastern and western coasts of England.

59. ELEVATION OF SCANDINAVIA.—Having thus ad-
duced a few striking proofs of the mutations which the
land has undergone in past times, we are led to inquire—
is this change still going on? is the alternate subsidence
and elevation of the land the effect of a law of nature,
established from the commencement of the present condition
of our planet, and destined to continue in action while its
physical constitution remains the same? We may unhesi-
tatingly reply in the affirmative, for there are innumerable
proofs that this law has been in constant action from the
earliest periods; and I now proceed to adduce an instance
in which the elevation of a whole country is actually taking
place, unsuspected by the busy multitude which inhabit its
towns and cities, and known only by the researches of the
natural philosopher. I allude to Scandinavia, which is
slowly and visibly rising, from Frederickshall, in Sweden,
to Abo, in Finland, and even, perhaps, as far as St. Peters-
burgh; while the adjacent coast of Greenland is suffering a
gradual depression. The state, therefore, is one of oscilla-
tion, the waters appearing to sink at Torneo, and to retain
their former level at Copenhagen.

The opinion that Sweden is in this state of change, is no
new idea; it was long since entertained by Celsius, and
other Swedish philosophers.* Mr. Lyell, who has twice

* Celsius remarks, "that several rocks on the shores of the Baltic, which are now above the water (A.D. 1730), were, not long before, sunken rocks, and dangerous to navigators; one especially, which, in the year 1680, was on a level with the surface of the water, is twenty and a half Swedish metres above it. From an inscription, near Aspô, in the Lake Melar, which communicates with the Baltic, engraved, as is supposed, above 500 years ago, the land appears to have risen no less than thirteen Swedish feet."—*Playfair's Illustrations of the Huttonian Theory*, p. 436, edit. 1822.

§ 59.

ELEVATION OF SCANDINAVIA.

117

visited Scandinavia within the last few years, with the
view of determining this interesting question, expresses
himself fully convinced that certain parts of Sweden are
undergoing a gradual rise, to the amount of two or three
feet in a century; while other tracts, farther to the south,
appear to have experienced no movement.* He surveyed
the shores of the Bothnian Gulf, between Stockholm and
Gefle, and on the western coasts of Sweden, districts par-
ticularly alluded to by Celsius. Upon examining the
marks cut by the pilots, under the direction of the Swedish
Academy of Sciences, in 1820, the level of the Baltic, in
calm weather, was found to be several inches lower than
the marks, and from two to three feet below those made
seventy or a hundred years ago. Similar results were
obtained on the side of the ocean, and in both districts the
testimony of the inhabitants agreed with that of their
ancestors, as recorded by Celsius. On the shores of the
Northern Sea, there are banks of recent shells, at various
heights, from 10 to 200 feet; and on the side of the Both-
nian Gulf, between Stockholm and Gefle, there are deposits
containing fossil shells of the species which now inhabit the
brackish waters of that sea. These occur at different eleva-
tions, from one to a hundred feet, and sometimes extend
fifty miles inland. Some of the shells are marine, and
others fluviatile; the marine species are identical with
those now living in the ocean, but are small in size, and
never attain the average dimensions of those which live
in water sufficiently salt to enable them to reach their full
development. The specimens before us were collected by
Mr. Lyell at Uddevalla, in Sweden, from the summit of
cliffs twenty feet above the level of the sea; they consist
of marine species, which still inhabit the neighbouring
waters.

* Philosophical Transactions. Principles of Geology, Fifth Edition,
vol. ii. p. 286.

218

THE WONDERS OF GEOLOGY.

LECT. III.

which it was placed.* In this point of view, fossil shells
become objects of the highest importance to the geologist,
since they are frequently the only indications of the circum-

* There is, however, a source of error that cannot always be guarded against: great changes are produced in shells by merely local influences, and these are often mistaken for specific distinctions. Professor E. Forbes, whose investigations have so beautifully elucidated many of the phenomena relating to the submarine distribution of the mollusca, and other aquatic animals, affirms that many parts of the sea are too deep to admit of the existence of any animals or vegetables; and therefore, that deposits of vast thickness, in which no organic remains can occur, may be forming in those profound abysses at the present time.

He remarks, that the absence of fossils in any marine stratum, is no proof that when the bed was deposited, there might not have existed above it a sea teeming with life. Now, admitting to the full extent the facts and inferences adduced by this accomplished naturalist, in proof of the intimate relation existing between the depth of water and the mineral character of the sea-bottom, and the prevailing species and genera of mollusca; and entirely concurring in the opinion that the absence of fossils in any strata, ought not to be admitted as proof that the waters which deposited them were destitute of living things, yet I cannot admit as a corollary from these premises, that very deep sea deposits must necessarily be destitute of organic remains. The materials, whether organic or inorganic, that are carried into the ocean by streams and rivers, and the detritus of the cliffs and coasts transported by the powerful currents which traverse the entire area of the ocean, and the sediments which accumulate in the most profound abysses, may imbed organic remains, equally with those which are deposited in shallower waters (*see* p. 70). With the exception of those strata in which the local conditions prove that the shells, corals, &c. lived and died on the areas where their remains are imbedded, the prevalence or absence of fossil remains appears to have principally depended on the influence of submarine currents, tidal waves, &c. Nothing is more common than to find over vast regions a like intermixture of shallow and deep-water species and genera,—as rostellariæ, turritellæ, melaniæ, mussels, &c. collocated with ammonites and nautili, fishes, radiaria, &c. that when living inhabited geographical zones of very different depth: and this, too, not only in littoral beds, but likewise in strata, which, from the absence of gravel, sand, and other alluvial detritus (as in the white chalk), we must infer to have been deep sea deposits. We have, then,

§ 14.

CHARACTERS OF THE TERTIARY.

219

stances under which deposits were accumulated.* I return
from this digression to the consideration of the phenomena
presented by the several groups of the tertiary formations.

14. LITHOLOGICAL CHARACTERS OF THE TERTIARY STRATA.—The predominating characters of the tertiary system are alternations of marine beds with those of lacustrine and freshwater origin. A large portion of the beds is arenaceous, with intervening strata of clay and marl. Shingles, the remains of ancient sea-beaches, abound in some localities, and often occur as a conglomerate or puddingstone, as in Hertfordshire (p. 101); or as a ferruginous breccia, as at Castle Hill, near Newhaven, on the Sussex coast.† The ruins of the Chalk are everywhere recognizable in the immense beds of water-worn flints, which contain shells and zoophytes peculiar to the cretaceous system. Large erratic boulders and blocks of crystalline sandstone are of frequent occurrence on the chalk downs, and have probably been derived from the upper beds of the Bagshot sand. In the vicinity of Brighton, blocks of ferruginous breccia are scattered over the surface of the Downs, and masses of quartzose sandstone, of a saccharine structure, occur at Falmer, and in Stanmer Park: some years since there was a large rock of this stone in Goldstone Bottom, near Brighton.

In most of the gravel beds around London there are
numerous blocks of siliceous breccia and conglomerate. In
some of the tertiary series limestone predominates, and
alternates with sands and marls of great variety and
brilliancy of colour; beds of gypsum, and siliceous nodules
resembling the flints of the chalk, also occur. Such are

no conclusive evidence that the so-called *azoic* strata were formed
before the existence of animated beings, or that any beds of later
data, destitute of fossils, were deposited in deeper water than many of
the fossiliferous deposits.

* See Medals of Creation, vol. i. p. 363.

† Geology of the S. E. of England, p. 55.

220

THE WONDERS OF GEOLOGY.

LECT. III.

the leading lithological features of this system of deposits, which we will now examine more in detail.

The distribution of the tertiary strata over Europe, appears to be in areas more or less well defined. In our own Island, there are the basins of London and Hampshire, which probably were originally united; and the remains of other series of beds in Yorkshire, Norfolk, Suffolk, Essex, &c. The metropolis of France is situated within the confines of a tertiary area; and in the southern and northern provinces of that country, there are extensive tracts of similar deposits. In Auvergne, they are associated with lavas and scoriæ of ancient volcanic eruptions, and constitute a district of unrivalled geological interest. In the Sub-Apennines, they are largely developed; and in other parts of Sicily and Italy they insensibly pass into vast beds of modern origin, which are still in progress of formation.

In the United States, tertiary marls, clays, and sands, are spread over considerable areas, between the Alleghany mountains and the Atlantic, resting upon sands and marls belonging to the chalk formation. In Maryland and Virginia, there are extensive deposits of this class, remarkable for their organic composition, as we shall hereafter have occasion to notice.

15. SUBDIVISIONS OF THE TERTIARY SYSTEM. — The divisions of the Tertiary system, adopted by geologists, are concisely expressed in the following synopsis.*

* See Mr. Lyell's Elements of Geology, vol. i. p. 284.

§ 16.

UPPER TERTIARY, OR PLIOCENE.

221

II. MIOCENE;
or
Medial Tertiary.

Strata containing from
twenty to thirty per
cent. of extinct species
of shells. The tempe-
rature of the sea, as in-
dicated by the shells, of
a sub-tropical character.

The *Crag* of the ma-
ritime parts of Es-
sex, Suffolk, and
Norfolk. Faluns
of the Loire. Beds
in the Val d'Arno.

III. EOCENE;
or
Lower Tertiary.

Marine and freshwater de-
posits; the recent spe-
cies of shells amounting
to scarcely more than
five per cent. The pre-
vailing forms indicate a
marine temperature al-
most equal to that of the
existing tropical seas.

The series of de-
posits, comprised
in the tertiary
basins of London,
Hampshire, Paris,
and the Nether-
lands.

16. UPPER TERTIARY, OR PLIOCENE.—From the large proportion of recent species of shells which occur in the pliocene strata, the beds have all the characters of a modern aggregate, as in the extensive and beautiful collection from Palermo before us, for which I am indebted to the liberality of the Marquess of Northampton.

They are from a range of hills, which rises to an elevation of about 200 feet above the level of the Mediterranean, immediately behind Palermo. These hills are in a great measure composed of coarse limestone, made up of friable shells, which are frequently in an admirable state of preservation; in some examples preserving even their markings and natural polish. The elegant and picturesque manner in which they are occasionally grouped renders them objects of great beauty and interest. These fossils, with but few exceptions, are of species still living in the adjacent sea; a proof that when the limestone was formed, the same condition of the basin of the Mediterranean existed as at present, and that it was unin-

222

THE WONDERS OF GEOLOGY.

LECT. III.

fluenced by the elevation of that portion of its ancient
bed, which now forms the range of hills.

In other parts of Sicily, limestone, blue marl, beds of
shelly calcareous breccia, and gypseous clay occur, inter-
mingled with volcanic products. In the *Val di Noto*
there is a remarkable assemblage of these deposits, which
is thus described by Mr. Lyell :—*

"The rising grounds of the Val di Noto are separated from the cone of Etna, and the marine strata on which it rests, by the plain of Catania, which is elevated above the level of the sea, and watered by the Simeto. The traveller passing from Catania to Syracuse, by way of Sortina and the valley of Pentalica, may observe many deep sections of these modern formations, rising into hills from one to two thousand feet in height, and entirely composed of sedimentary strata, with recent shells; these are associated with volcanic rocks. The whole series of strata, exclusively of the volcanic products, is divisible into three principal groups. 1. The *uppermost*, compact limestone in laminated strata, with recent shells; total thickness, from 700 to 800 feet. 2. Calcareous sandstone, with schistose limestone. 3. Laminated marls and blue clays."

The above groups contain shells and zoophytes of the same
species as those from Palermo just noticed. The large
scallop (*Pecten jacobæus*), which at the present day is pro-
fusely strewn on the Sicilian shores, is abundant, and
beautifully preserved in the compact limestone; associated
with immense numbers of very minute foraminifera, of
species that now swarm in the waters of the Mediterra-
nean. Leaves of plants and stems of reeds are of frequent
occurrence.

The Apennines, which extend through the Italian
peninsula, are flanked, both on the side of the Adriatic
and the Mediterranean, by the Sub-Apennines, a low range
composed of tertiary marls, sands, and conglomerates, some

* Principles of Geology, vol. iii. p. 388.

§ 17.

MIOCENE, OR MIDDLE TERTIARY.

223

of which were cotemporaneous with the Crag, while others belong to a more ancient epoch. These beds have resulted from the waste of the secondary rocks, of the Apennines, which were dry land before these strata were deposited.

17. MIOCENE, or MIDDLE TERTIARY.—*The Crag*. The miocene are defined as strata containing but a small proportion of recent species of shells, seldom exceeding 20 or 30 per cent.; but there are exceptions to the rigid application of this rule in many of the strata comprised in the middle tertiary. Near Bordeaux, and in Piedmont, Hungary, and other parts of the continent, groups of miocene strata occur, and have been described by Mr. Lyell, and other geologists.*

In England a very interesting assemblage of pliocene and miocene strata is spread over considerable areas, along the maritime parts of the eastern counties, Essex, Suffolk, and Norfolk,—and is called the *Crag*; a provincial term, signifying gravel. These beds extend along the coast forty or fifty miles, and form a tract which in some parts is ten or twelve miles in breadth (*see* Plate I.). The foundation rock of that part of England is the white chalk, which is more or less covered by the London eocene clay, on which the lower Crag is superimposed. The Crag strata consist of loam, clay, sand, and gravel, containing beds of marine shells and corals; many of the layers being wholly made up of shelly and coralline detritus. In the upper part of the series there are intercalations of fluviatile deposits; and over all a bed of silt, containing mammalian remains, which insensibly blends with the superficial alluvium of the country.

Mr. Edward Charlesworth, to whom belongs the merit of having first accurately investigated and interpreted the zoological characters of the Crag, and pointed out the

* See Elements of Geology, vol. i. chap. xiv.

224

THE WONDERS OF GEOLOGY.

LECT. III.

natural groups of this series, has established the following subdivisions of the deposits that occupy the eastern coast of England :—

1. *Coralline* or *lowermost Crag*. A series of calcareous and marly strata, loose white sands, layers of shells and corals, and concretionary bands of stone. It abounds in shells, echini, sponges, and corals, (especially of the genus *Fascicularia*), and these occur in so perfect a state as to indicate that they lived and died on the spot; for many of the sponges and corals are in the upright position in which they grew. This group is upwards of twenty feet in thickness, and extends along the coast of Suffolk, over an area of twenty miles in length and three or four in breadth.

2. *Red* or *Norfolk Crag*. So named from its deep ferruginous colour. It consists principally of quartzose sand, with comminuted and waterworn shells, corals, bones and teeth of fishes, and other fossil remains. These beds, when occurring in the same locality, are invariably superimposed on the Coralline Crag. They attain a thickness of upwards of forty feet, and abound in marine shells, especially numerous species of *Murex*, *Buccinum*, and *Fusus*; among the latter is the *Fusus contrarius*, (so named because the spiral convolutions pass from the right to the left, instead of in the opposite and ordinary direction,) a well-known shell, formerly in great request among collectors.*

3. *Mammaliferous*, or *fluvio-marine Crag*. Sandy loam, and clay, more or less charged with shelly detritus; it occurs in certain localities at Southwold, Norwich, Cromer, &c. and contains bones and teeth of several extinct mammalia, associated with those of existing and indigenous species.

4. Insulated patches of lacustrine beds with mammalian remains. Above the whole of these deposits, is the usual alluvial sediment and drift, in which are vast numbers of bones and teeth of Elephants and other pachyderms, including a species of Mastodon, and the Irish Elk.†

* See Parkinson's Organic Remains of a former World; vol. iii. pl. 6, fig. 5.

† Of the Mastodon thirteen teeth have been found. More than thirty years since, tusks of mammoths, horns of Bos and Aurochs, and antlers of the Irish Elk, from near Walton Nase, in Essex, were sent to me by G. B. Greenough, Esq.

§ 17.

MIOCENE, OR MIDDLE TERTIARY.

225

To complete this slight sketch of the geology of the district, we
may observe that there are some insulated patches of lacustrine
silt and clay, containing extinct mammalian remains, asso-
ciated with those of living indigenous species; these strata
appear to be post tertiary.

The Coralline-crag has yielded to the researches of
Mr. Searles Wood and others, upwards of 400 species of
shells; numerous corals; teeth of several fishes of the
Shark family, some of large size (*Carcharias megalodon*);
teeth of Eagle-rays (*Miliobatis*); and ear-bones (*otolithes*)
of the Sperm-whale, and other cetaceans. The corals
are of unknown genera, and the echinoderms, of which
there are sixteen species, are distinct from any in the
adjacent seas.

From the Red Crag, nearly 300 species of shells have
been obtained, of which about one-half also occur in the
lower Crag. The number of extinct (or more properly,
*unknown*) species, is about 30 per cent, in the former,
and 20 per cent. in the latter group. Microscopic shells
of foraminifera are abundant. Terebratulæ of great size
are often met with; specimens six inches long have been
obtained by Mr. Charlesworth.

The Mammaliferous Crag has evidently originated in
deposits of silt and sand, brought down from adjacent
land by a river, or streams of fresh water, into a creek
or bay in which marine detritus was accumulating.
With numerous marine shells, it contains some fluviatile
and terrestrial species; and in it have been found teeth of
the Mastodon, Ursus spelæus,† and other contemporaneous
fossil mammalia.

The uppermost beds appear to be entirely lacustrine or
fluviatile, for they contain fresh-water shells and bones
and teeth of land quadrupeds; comprising those of field-

* Medals of Creation, vol. ii. p. 603.

† Mag. Nat. Hist. vol. iii. p. 450.

Q

226

THE WONDERS OF GEOLOGY.

LECT. III.

mice, rat, and beaver; and the large extinct form of the
latter, that occurs in the mammoth drift of Russia (the
*Trogontherium*, see ante, p. 154); a portion of the jaw of
an opossum, and bones of unknown species of water-mole,
deer, roebuck, monkey, and bat.*

The passage of the mammaliferous crag into the alluvium,
is in many places so imperceptible, that no line of chrono-
logical separation can be drawn; and our previous remarks
on the deposits of the valley of the Thames, render farther
comment unnecessary.

18. EOCENE, OR LOWER TERTIARY DEPOSITS.—I now proceed to the consideration of the *Eocene*, or those tertiary strata which are of the highest antiquity, and occupy basins or depressions of the chalk, where that formation constitutes the fundamental rock of the country. Every step of our progress will now be replete with increased interest, and the relics of new and extraordinary forms of being will appear before us. I shall pass rapidly over the stratigraphical character of these rocks, that our attention may be more fully directed to the organic remains which they inclose.

I will first describe the geographical distribution and
general characters of a few of the principal groups, and
the more remarkable fossil animals and plants; and then
survey those regions of central France, of the Rhine, and
of South America, which have been the scenes of active
volcanoes during the tertiary epoch.

It may be regarded as a singular coincidence, that the
capitals of Great Britain and France are located on strata
of the same geological age. Paris is situated on a vast
alternation of marine and fresh-water beds, lying in a de-
pression of the chalk; the latter forming the boundary of
the area in which the city is placed. London also is built

* At Ostend, near Bacton, Norfolk; see Medals of Creation, vol. ii. pp. 859—867. Professor Owen has figured and described the most important of these relics in "British Fossil Mammalia."

§ 18.

EOCENE, OR LOWER TERTIARY.

227

on clays, sands, and shingles, filling up a basin of cre-
taceous strata, the margin of which skirts the area of the
tertiary on the south, but leaves it open to the sea on the east.
In Hampshire, and on the northern part of the Isle of Wight,
a series of contemporaneous lacustrine beds, with inter-

LIGN. 33.—TERTIARY BASINS OF PARIS, LONDON, AND HANTS.

(From Mr. Webster's Map; Geol. Trans. Vol. II.)

spersions of marine deposits, in like manner rests upon the
Chalk. The relative situation and comparative extent of
these three basins are shown in the map (Lign. 33); and

LIGN. 34.—SECTION FROM HERTS, TO SENS, IN FRANCE.

(From Mr. Lyell's Elements of Geology.)

1, 1, Tertiary; 2, 2, Chalk; 3, 3, Greensand; 4, 4, Wealden.

The shaded sites of London and Paris, and of part of Hants and the Isle of Wight, indicate the tertiary deposits.

the ideal section (Lign. 34), from Hertfordshire across the
British Channel, to Sens in France, explains the position

Q 2

228

THE WONDERS OF GEOLOGY.

LECT. III.

of the London and Paris basins, and the underlying chalk
and wealden deposits.

19. THE PARIS BASIN.—The Paris basin is from east to west about 100 miles in extent, and 180 from north-east to south-west; the greatest total thickness of the beds, or in other terms, the depth passed through to reach the chalk, amounts to several hundred feet.

The strata, commencing with the lowermost, or most
ancient, present the following characters :—

1. *The lowermost.* Chalk flints, broken, and partially rolled, sometimes conglomerated into ferruginous breccia.*

2. *Plastic clay, and sand.* Strata of clay and sand, with fresh-water shells, drifted wood, lignite, leaves, and fruits; with bands of limestone containing marine shells.

3. *Siliceous limestone, or Calcaire grossier*; with fresh-water and terrestrial shells and plants, and a coarse, marine, compact limestone, passing into calcareous sand, and abounding in marine shells.—These beds often alternate, and are considered by M. Constant Prevost to be contemporaneous formations; the marine strata having been formed in those parts of the basin which were open to the sea, and the fresh-water limestone, by mineral waters poured into the bay from the south; the Continent being situated then, as now, to the south, and the ocean to the north. Layers of *miliolite* limestone,† almost entirely composed of microscopic shells of foraminifera, occur in this part of the basin.

4. *Gypseous marls, and limestones*; with bones of terrestrial animals, and fluviatile shells. These are supposed to have been discharged by a river which flowed into the gulf; the gypsum being precipitated from water holding sulphate of lime in solution, in the same manner as the travertine or calcareous tufa, of which we have already spoken (p. 74).

5. *Upper marine formation,* consisting of marls, micaceous and quartzose sand, with beds of sandstone abounding in marine shells.

* A layer of this kind is very common on our South Downs, immediately under the turf.

† So called from its inclosing immense quantities of a minute shell, named *Miliola*.

§ 20.

THE LONDON BASIN.

6. *Upper fresh-water marls*, with interstratified layers of flint, containing seed-vessels of aquatic plants (*Charæ*, p. 86), and animal and vegetable remains. These beds are attributed to lakes and marshes, which existed after the marine sands had filled up the basin.

From this rapid sketch, we perceive that the strata which occupy the Paris basin have been produced by a succession of changes, that readily admits of explanation by the principles enunciated in the previous lectures. Here we have an ancient gulf of the chalk, which was open to the sea on one side, while on the other it was supplied by rivers charged with the spoils of the country through which they flowed, and that carried into the sea the remains of animals and plants, with fresh-water shells; and there were occasional introductions of mineral waters. Changes in the relative level of the land and sea took place, and thus admitted of new accumulations upon the previous deposits; lastly, the country was elevated to its present altitude above the sea. Mutations of this kind, as we have already seen, are in progress at the present moment, and afford a satisfactory elucidation of these interesting phenomena. I reserve for the present any remarks on the fossils of the Paris basin, and pass to the examination of synchronous strata in our own Island.

20. THE LONDON BASIN.—The tertiary deposits on which the metropolis of England is situated are spread over a considerable area, which is bounded on the south by the North Downs, and extends on the west beyond High-elm Hill, in Berkshire. It is flanked on the north-west by the Chalk hills of Wiltshire, Berkshire, Oxfordshire, Buckinghamshire, and Hertfordshire. On the east it is open to the sea; the Isle of Sheppey, situated in the mouth of the Thames, being an outlier of the same deposits.* These beds extend

* See Mr. Webster's paper in the Geolog. Trans. vol. ii.; and Conybeare and Phillips's Geology of England and Wales.

230

THE WONDERS OF GEOLOGY.

LECT. III.

over Essex, a considerable part of Suffolk, Epping and Hainault forests, the whole of Middlesex, and a portion of Bucks. The tertiary deposits comprised in this series are subdivided as follows :—

*Bagshot Sands, and Bracklesham Clays*;—sands, sandstones and foliated marls, and concretionary masses of siliceous sandstones; with a medial group of argillaceous beds.

*London Clay*;—a tenacious blueish-black clay, with layers of septaria, intercalated sands, shingles and conglomerates.

With the first division, Mr. Prestwich places the *Bracklesham clay*; and with the latter the *Bognor rocks*: beneath the whole are the mottled clays of Alum Bay, and the *Newhaven* and *Woolwich* beds, all of which are included in the term *Plastic clay*.

The site of the metropolis and its environs consists of the London clay, which abounds in marine remains, and constitutes the great mass of the materials that fill up this ancient gulf of the ocean. Immediately upon the chalk, however, there are thick beds of sand and mottled clay, called Plastic clay (from the *Argile plastique* of the Paris basin), in which fresh-water shells, plants, and drifted wood are found in some localities. In other instances, layers of green sand lie upon the chalk, which at Reading contain immense quantities of oyster shells: a similar accumulation of shells occurs near Norwood, and at Headley in Surrey, a few miles from Reigate. At Bromley, in Kent, there is an extensive bed of oyster-shells with pebbles of chalk-flints interspersed, the whole being cemented together by a calcareous deposit into a remarkable shell conglomerate, which is in much request for grottoes and ornamental rock-work.

The London clay is found immediately beneath the gravel which so generally constitutes the subsoil of the metropolis; it is of great extent, and varies from 300 to 600 feet in thickness. The blue clay produces a dark, tough soil, with occasional intermixtures of green and ferruginous sands, and variegated clays. It abounds in

§ 20.

THE LONDON BASIN.

231

layers of spheroidal nodules of indurated argillaceous limestone, internally traversed by veins of calcareous spar, that radiate from the centre to the circumference. From the appearance of septa or partitions which this character confers, these concretions are called *Septaria*: shells and other organic remains frequently form the nuclei of these nodules, which are used in prodigious quantities for cement. Many other argillaceous strata contain concretionary spheroids of this kind: beautiful specimens are obtained from the Lias, and Oxford clay, and are cut and polished for tables and other articles. The septaria are commonly disposed in horizontal lines, and lie at unequal distances from each other. Brilliant sulphuret of iron abounds in the clay, and permeates the septaria and many of the organic remains. Crystallized sulphate of lime, or selenite, is also common in these and other argillaceous strata. The cuttings through Highgate Hill, to form the archway; the excavations in the Regent's Park; and, more recently, the tunnels carried through a part of the same ridge of clay at Primrose Hill, in the line of the Birmingham railroad; and the cuttings of other railways, and the explorations, by wells, over the whole area around London, have brought to light such prodigious quantities of organic remains, that the fossils of this deposit are almost universally known. The late Mr. Sowerby called early attention to these productions, the first plate in his *Mineral Conchology* being devoted to the nautili and other shells of the London basin. Immense numbers of marine shells of extinct species; crabs, lobsters, and other crustaceans; teeth of sharks, and of many other genera of fishes; bones of crocodiles, turtles, serpents and birds; leaves, fruits, stems of plants, and rolled trunks of trees perforated by boring shells;—occur throughout these strata, but are located in greater abundance in some spots than in others. The clay and gravel pits at Woolwich, on the

232

THE WONDERS OF GEOLOGY.

LECT. III.

banks of the Thames, are full of fresh-water univalve
shells; and at Plumstead, Bexley, and other places, marine
bivalves occur in clay, and in indurated argillaceous lime-
stone.*

21. THE ISLE OF SHEPPEY.—The Isle of Sheppey is entirely composed of the London clay, and the thickness of the beds is upwards of 550 feet. It has long been celebrated for its organic remains; and I may observe, that the discovery of seed-vessels and stems of plants in pyritous clay, in a visit which I made to Queenborough, when a youth, tended to confirm my early taste for geological researches. The cliffs on the north of the island are about 200 feet high, and consist of clay abounding in *septaria*, which are washed out of the cliffs by the action of the sea, and collected for cement. The organic remains are, however, unfortunately so strongly impregnated with pyrites, that the collector often finds the choicest fossil fruits in his cabinet, like the fabled apples of the Dead Sea, one moment perfect and brilliant, and the next decomposed and fallen to pieces, leaving only an efflorescent sulphate of iron. A solution of isinglass in spirits of wine, applied as a varnish, is one of the best preservatives. The same species of animal and vegetable remains that are found in the blue clay of the metropolis, are also met with in profusion in the Isle of Sheppey.†

Fruits, seed-vessels, with stems and branches of trees, of
a tropical character, probably drifted by currents into the
gulf of the London basin, occur in such abundance and
variety in the Isle of Sheppey, that the existence of a group
of spice islands at no great distance, seems necessary to ac-
count for so vast an accumulation of vegetable productions.
The seed-vessels are referable to several hundred species ;
some are related to the Cardamom, Date, Areca, Cocoa,

* Messrs. Wetherell and Edwards have fine collections of the
Highgate fossils.

† See Medals of Creation, vol. i. p. 175.

§ 22.

ISLE OF SHEPPEY.

233

Cotton-plant, Bean, Cucumber, Acacia, Pepper, &c.* The wood found in the Sheppey clay, is generally in the state of a pyritous lignite, with the ligneous fibres and circles of growth well defined; it is often veined with brilliant pyrites, and the fissures and cavities are frequently filled with that mineral. It is rarely that any considerable mass of this wood is found free from the ravages of a species of teredo, resembling the recent *Teredo navalis*, or *borer*, which inhabits the seas of the West India islands. The shelly tubes sometimes remain, but their cavities, as well as the perforations in the wood, are more or less filled up with pyrites, indurated clay, argillaceous limestone, or calcareous spar; and specimens, when cut and polished, exhibit interesting sections of these meandering channels. In these specimens, which I collected in 1811, from the cuttings of the canal in the Regent's Park, the structure of the wood, and the form of the shells, are beautifully displayed.†

22. BAGSHOT SANDS AND CLAYS.—At Highgate and Hampstead, Purbright and Frimley Heaths, in Surrey, and on Bagshot Heath, extensive beds of siliceous sands, with a middle group of clays and marls occur, but they contain very few traces of organic remains; the fossils hitherto observed are principally casts of shells of Bracklesham species. In cutting through the summit of Goldsworth Hill, four miles north of Guildford, on the line of the London and Southampton railway, teeth and other remains of several genera of fishes were discovered; the teeth of sharks, and the palates of rays, were the most numerous. Teeth of the saw-fish (*Pristis*), and of several new genera of cartilaginous fishes, were also collected.‡

* See Figures and Descriptions of the Fossil Fruits of the London Clay; by I. S. Bowerbank, Esq. F.R.S.

† For a particular account of the Island and its fossils, see “Ex-cursion to the Isle of Sheppey;” in Medals of Creation, vol. ii. p. 897.

‡ See Geology of the Isle of Wight, p. 84.

234

THE WONDERS OF GEOLOGY.

LECT. III.

The boulders and masses of sandstone, which are abundant in some of the chalk valleys, and on the flanks of the Downs, and are called *Sarsden-stone*, or *Druid sandstone*, from being the principal material employed in the construction of Stonehenge, and other Druidical monuments, have been derived from the lower Bagshot sands. In many of the wastes and unproductive heaths around London, the arenaceous deposits of this group form the subsoil; and they constitute that picturesque spot, Hampstead Heath, and cap Highgate Hill and the adjacent heights. The beds of shingle associated with the sands, have unquestionably been derived from the ruins of the chalk formation.*

23. NATURE OF SPRINGS.—From the alternation of sands and other porous strata with stiff impervious clays, throughout the London basin, the metropolitan district is favourable for obtaining water by means of the borings termed Artesian wells, by which means perennial fountains are made to rise from the natural reservoir in the lowermost beds of sand. The nature of these wells is easily explained. The descent of moisture from the atmosphere upon the earth, and its escape into the basin of the ocean by the agency of streams and rivers, were noticed in the first lecture. The rain falling on a gravelly or porous soil, descends through it, till its progress is arrested by a clayey or impervious stratum, which thus forms a natural tank that receives the water, and a subterranean reservoir or pool will be the result,

* Mr. Prestwich, whose indefatigable and able researches have largely contributed to establish correct views of the natural groups of which the British tertiary consist, regards the Bagshot sands as a triple series; arenaceous strata constituting the upper and lower, and argillaceous beds the middle division: to this last he refers the blue clay of Bracklesham, Southampton, Barton, &c. However this maybe, the geological character of the eocene system of the London and Hampshire basins, is that of an extensive marine formation, with a few intercalations of fluviatile deposits in the lower groups, and passing into a freshwater and lacustrine condition in the upper.

§ 24.

ARTESIAN WELLS.

235

according to the direction and configuration of the over-
lying bed of clay. This state of things will continue, till,
by an increased supply, the water rises above the level of
the basin or channel, and either overflows, or escapes
through fissures in the rocks, to another level. If the
course of the waters be subterranean, the beds of slightly
coherent stone are worn away, and chasms or caverns are
formed; hence the underground rivers and streams, of
great extent, which occur in many places (p. 56); but if the
water find its way to the surface, a spring bursts forth.
This is the nature of all springs, except those which arise
from very great depths, such for example as the thermal
waters of many countries; these probably originate from
the condensation of steam, evolved through fissures by
volcanic agency. Streams impregnated with the mineral
substances contained in the strata through which they flow,
are called mineral waters. Those in the tertiary strata
near Epsom, contain sulphate of magnesia, whence the
name of Epsom salt, given to this substance wherever it
occurs.*

24. **ARTESIAN WELLS.**—But pervious strata frequently alternate with others which are not so; and they, likewise, form basins, the areas of which are partially filled with clay, through which water cannot pass: in such a case it is obvious, that the sands beneath the clay, fed by the rain which descends on the uncovered margin of the basin, must constitute a reservoir, and the water gradually accumulate beneath the central plateau of clay, whence it cannot escape. If this bed of clay be perforated, either by natural or artificial means, the water must necessarily rise to the surface, and may be thrown up in a jet to a considerable height, which will depend on the level of the fluid in the subterranean reservoir; such is the phenomenon observable in the

* See my notes on the Geology of Surrey, in Brayley's History of that county.

236

THE WONDERS OF GEOLOGY.

LECT. III.

Artesian wells around London. Argillaceous strata are generally found to be dry within, and the blue clay confines the water contained in the sands beneath; the engineer therefore perforates the clay, introduces tubes, and taps the natural tank, and the imprisoned waters rush to the surface; by this method perennial fountains have been formed at Tooting, Hammersmith, Fulham, &c.*

The wells sunk into the London clay (*Lign. 35, 1, d, d,*) do

LIGN. 35.—PLAN OF THE ARTESIAN WELLS NEAR LONDON.

1. The London clay.

2. Plastic clay and sand.

3. The chalk.

a, b, b, Borings that reach the chalk. c, c, Wells in the plastic clay. d, d, Wells in the London clay.

not yield pure water; but the sandy strata alternating with the clays, afford a supply, the quantity and quality of which depend on the nature of the rock. The borings which reach the sands of the plastic clay (*Lign. 35, 2, c, c,*) furnish good soft-water; but the wells that extend to the chalk (*Lign. 35, 3, a, b, b,*) obtain the most copious springs, the water often rising to the surface in a perennial fountain.†

* Consult Dr. Buckland's Bridgewater Essay, p. 561; and an admirable Essay on Artesian Wells, in the Mining Journal, conducted by H. English, Esq. F. G. S.

† As the white chalk, into which the Artesian borings in London are generally carried some twenty or thirty feet, is not a retentive rock, but on the contrary is so porous that not a natural pool or lake is to be found throughout the chalk districts, except under some peculiar local conditions, a few words must be added, to explain this anomaly. The *chalk-marl*, which is the first retentive bed of any considerable extent in the cretaceous formation, lies at a depth of many hundred feet beneath the bottom of the London basin, and therefore could not, in ordinary conditions, form a reservoir that could be reached by artificial means, if the strata were either horizontal,

§ 25.

THE HAMPSHIRE BASIN.

237

The wells in London vary in depth from 100 to 600 feet;
but the total thickness of the clay in some places is estimated
at nearly a thousand feet. The most remarkable instance
of success in obtaining a perennial fountain from a deep
source, by the process of boring above described, is the
Artesian well at Grenelle, near Paris, which was carried
through the entire series of the tertiary and cretaceous
strata, down to the green sand; a depth of 1,800 feet!
The water rises in a powerful column to the height of
thirty feet above the highest part of Paris, and has a
temperature of 91° Fahrenheit, being sufficiently hot for
warming greenhouses, &c.

25. THE HAMPSHIRE BASIN.—The London basin does not present an alternation of marine and fresh-water deposits, like that of Paris ; but in Hampshire and the Isle of Wight, there is an extensive suite of tertiary, composed of fresh-water clays, sands, and limestones, associated with marine strata. This series extends over a considerable district. On the east, a small outlier of the lower beds of plastic clay appears at Castle Hill, near Newhaven, in Sussex ;* and to the west of Brighton, the London clay rises to the surface, and forms the subsoil between the Downs and the sea-shore. The inland boundary of these tertiary strata stretches by Chichester, Emsworth, and Southampton, to Dorchester ; and the London clay is

or lying inclined in a direction from the central plateau of London;
but the chalk forms a deep gulf or excavation, in which the Lon-
don clay is situated, and thus the drainage from the surrounding
chalk hills flows into the centre of the basin, and furnishes an almost
inexhaustible reservoir. I need not add, that attempts to obtain
water by Artesian borings in any chalk district, where the strata are
horizontal or inclined, will fail, unless the beds immediately upon
the *chalk-marl* could be reached. The borings for water near South-
ampton exemplify these remarks. See my *Geology of the Isle of
Wight*, p. 81.

* Geology of the South-East of England, p. 53.

238

THE WONDERS OF GEOLOGY.

LECT. III.

spread over the whole area of the New Forest and the
Trough of Poole, being flanked by the chalk on the north,
north-east, and north-west, and open to the sea on the
south. The Isle of Wight, though now separated from the
main land, is a disrupted mass of the formations of the
south-east of England; the chalk basin having been broken
up, and the cretaceous strata, with the superimposed sands,
clays, and gravel, thrown in many instances into a vertical
position. This phenomenon is strikingly displayed at the
north-west extremity of the island, at Alum Bay, and in
the eastern, at Culver Cliff and Whitecliff Bay.

26. ALUM BAY.—Alum Bay, so called from the alum,
formerly extracted from the decomposing pyrites with
which the clay abounds, is well known to the visitors of
the Isle of Wight. This sketch (Lign. 36) conveys a
general outline of the bay; a, represents the vertical chalk;
b, b, the tertiary strata, consisting of sands and clays of an

LIGN. 36.—ALUM BAY, ISLE OF WIGHT; FROM THE WEST.
a, Chalk strata, nearly vertical. b, b, Vertical Tertiary strata.

infinite variety of colour. The appearance of these cliffs is
thus graphically described by Mr. Webster, whose memoir

§ 27.

LONDON CLAY OF HAMPSHIRE.

239

on the strata above the English Chalk, formed a new era
in British Geology, and raised our tertiary series to an im-
portance equal to that of the Paris basin.

"The clays and sands of Alum Bay afford one of the most interest-
ing natural sections imaginable. They exhibit the actual state of the
strata above the chalk, before any change took place in the position
of the latter. For, although the beds of which they are composed are
quite vertical, yet, from the nature and variety of their composition,
and the regularity and number of their alternations, no one who views
them can doubt that they have suffered no change, except that of
having been moved with the chalk from a horizontal to a vertical
position. These sands and clays present every variety of colour of
green, yellow, red, crimson, ferruginous, white, black, and brown."

27. LONDON CLAY OF THE HAMPSHIRE BASIN. — The London clay extends over the greater portion of the area of the Hampshire basin, its peculiar fossils abounding in many localities. Castle Hill, near Newhaven, which has been already mentioned as an isolated portion of the lower series of plastic clay, is made up of sands, marls, and clays, with beds of oyster-shells and shingle; these deposits form the upper part of the hill, and rest upon the chalk of which the lowermost fifty feet of the cliff are composed.* The *subsulphate of alumine*,† a mineral peculiar to this locality, occurs in the ochraceous clay which is in immediate contact with the chalk. Selenite, or crystallized gypsum, abounds in the marls; and there is a layer of surturbrand, or lignite, a few inches thick, containing impressions of dico-tyledonous plants.‡ The clays abound in marine and fresh-water shells; some of the layers being aggregations of compressed shells, held together by argillaceous earth.§ The

* See Geology of the South Downs, p. 261.

† British Mineralogy, Tab. 499. Geology of the South-East of England, p. 56.

‡ Fossils of the South Downs, Pl. viii. figs. 1, 2, 3, 4.

§ Two species of *Potamides*, and one of *Cyclas*, (both fresh-water genera,) are the prevailing forms.

240

THE WONDERS OF GEOLOGY.

LECT. III.

oyster-bed, where pebbles enter into the composition of the concreted masses, closely resembles the Bromley conglomerate (p. 230). I have collected a few teeth of sharks, but no other vestiges of fishes have been observed. At Chimting Castle, near Seaford, on the eastern escarpment of the valley of the Ouse, olive-green sand, and a ferruginous conglomerate of chalk-flints, lie upon the chalk; proving the further eastward extension of the tertiary beds along the Sussex coast.*

To the west of Brighton, the London clay is perceived near Worthing, emerging from beneath the alluvium which, as we have already seen, contains remains of elephants. At Bognor, an arenaceous limestone, full of the usual shells of the London clay,† constitutes a group of low rocks, which in another century will probably have entirely disappeared. The beauty and variety of the shells, particularly of the nautili, and of the perforated fossil wood, render these organic remains objects of considerable interest.

In the blue clay at Bracklesham Bay, on the western coast of Sussex, and at Stubbington, fossil shells may be obtained at low-water in profusion;‡ and Hordwell and Barton Cliffs, in Hampshire,§ have long been celebrated for similar fossils; shells from these localities are to be found in almost every collection of organic remains.

28. FRESH-WATER TERTIARY STRATA OF THE ISLE OF WIGHT.—The peculiarity of the Isle of Wight eocene strata as compared with those of London, consists in the

* Geology of the South-East of England, p. 62.

† Fossils of the South Downs, p. 271.

‡ Bracklesham Bay, on the western coast of Sussex, is bounded by a low cliff composed of blue clay, and green sand, full of fossil shells, fishes' teeth, and other remains. For a particular account of this productive tertiary locality, see “Excursion to Bracklesham Bay,” in my Medals of Creation, vol. ii. p. 902.

§ These cliffs are fully described in my Geology of the Isle of Wight, chap. v. p. 164.

§ 29. FRESH-WATER STRATA OF THE ISLE OF WIGHT.

lacustrine and fluviatile character of the upper series of deposits, which is superimposed on marine strata identical with those of Bracklesham. These fresh-water beds consist of marls, sands, and limestones, containing abundance of river and lacustrine shells, and a few bones and teeth of mammalia, of some of the extinct genera of the Paris basin. This series is spread over the northern districts of the Island, forming the coast-line from Whitecliff Bay, to Headon Hill in Alum Bay. The relative position of the fluviatile and marine eocene strata, is shown in Lign. 37: strata, the equivalents of the Bognor rocks,

Fig. 1. Fresh-water strata of Headon Hill. 2. Vertical marine strata of Alum Bay. 3. Nearly vertical beds of Chalk.

London clay, Bracklesham clay, and Bagshot sands, appear in a vertical position throughout the entire extent of Alum Bay, from the white chalk (3), to the foot of Headon Hill (a); and are succeeded by the fresh-water deposits (1). The limestones abounding in fluviatile shells (see Lign. 39), are quarried at Binstead near Ryde, and at Calbourn, and Shalfleet; and may be seen in various places along the northern coast. Bones of turtles and crocodilian reptiles, are sometimes met with.*

29. ORGANIC REMAINS OF THE EOCENE STRATA; FOSSEL PLANTS.—So numerous are the relics of the inhabitants

* These strata, and the most interesting fossils hitherto discovered in the Isle of Wight, are so fully described and illustrated in my recent work, "Excursions round the Isle of Wight, &c.," that I beg to refer to that volume for more ample information.

R

242

THE WONDERS OF GEOLOGY.

LECT. III.

of the ancient lands and waters entombed in the strata
we have thus cursorily surveyed, that I can only offer
a very brief account of the organic remains. I will
select a few of the fossils of the Paris basin as typical of
the zoology of the older tertiary epoch, and notice such
others from British localities, as may be requisite for the
elucidation of the subject.

Dicotyledonous wood occurs in considerable abundance,
in the state of large trunks and branches, which appear to
have been drifted far out to sea, and are full of perforations
inclosing shells of boring mollusca. The strata around Lon-
don, and in the Isle of Sheppey, abound in specimens of this
kind. Leaves and stems of palms have been found in the
Paris basin, and in the Isle of Sheppey, &c. ; and the trunk
of a tree related to the palm, nearly four feet in diameter,
at Soissons. Fruits belonging to trees allied to the Areca,
pine, fir, cocoa-tree, &c. have been discovered in several
localities. The abundance of fruits of numerous genera
belonging to hot climates, that are accumulated in the Isle
of Sheppey, has already been mentioned (ante, p. 232).
Beds of lignite or brown coal, occur at Bovey Tracey in
Devonshire,* and in various parts of France, the Nether-
lands, &c.

30. AMBER.—The beautiful substance so remarkable for
its electric properties, Amber, is a production of the teri-
tiary epoch, and is highly interesting in a geological point of
view, from its containing insects and other organic bodies.
The Amber in common use is chiefly obtained from sub-
marine beds of lignite in Prussia, and along the coast of the
Baltic; this substance being washed up by the action of
the sea, and drifted on the shore. It is a fossil resin, the
product of an extinct species of pine (Pinus succinifer).
Insects, spiders, small crustaceans, leaves, and fragments

* See Medals of Creation, vol. i. p. 84.

§ 31.

AMBER.

of vegetable tissue, are imbedded in some of the masses. Upwards of 800 species of insects have been observed; most of them belong to species and even genera that appear to be distinct from any now known; but others are nearly related to indigenous species, and some are identical with existing forms, that inhabit more southern climes.

The forests of Amber-pines were in the south-eastern part of what is now the bed of the Baltic, in about 55° north latitude, and 37°—38° east longitude. The different colours of amber are derived from local chemical admixture. The amber contains fragments of vegetable matter, and from these it has been ascertained that the amber-pine forests contained four other species of pine, and several Cypresses, Yews, and Junipers, with Oaks, Poplars, Beeches, &c.; altogether forty-eight species of trees and shrubs; constituting a flora of a North American character. There are also some ferns, mosses, fungi, and liverworts.*

31. **Zoophytes.**—Polyparia, or corals, and other zoophytes, abound in some of the marine strata, but the species are not very numerous in the British series. Several kinds of turbinolia, caryophyllia, fungia, and other corals, are figured and described by authors. I have a few specimens from Grignon, presented to me by the late Baron Cuvier. The modern tertiary (those of Palermo for example) abound in various kinds of flustra and sponges. The coralline strata of the Crag are almost wholly made up of a few forms of *Tubuliporidae* (p. 224).

An elegant small *Astrea* has recently been found at Bracklesham in Sussex, by Mr. Bowerbank. Some of the tertiary strata of North America abound in corals.†

* Professor Göppert: Geol. Proc. 1845.

† Geol. Journal, No. 4, p. 495; Report on the Corals from the Eocene and Miocene of North America, by Mr. Lonsdale.

R 2

246

THE WONDERS OF GEOLOGY.

LECT. III.

few species of shells. The whole of these forms must be familiar to you, as they belong to genera which swarm in our present seas. The *Cypræa*, or Cowry (Lign. 38, fig. 1), and the *Ancilla*, or Olive (fig. 2), are well-known types. The *Cerithium* (fig. 4), belongs to a genus most abundant in the sands of the Paris basin, and is remarkable for the elegance and variety of the fossil species, which exceed by three times in number their living analogues. The *Cerithium giganteum* attains a considerable magnitude. Some masses of the Bognor rock are almost wholly composed of a species of *Pectunculus*, (fig. 8.) The *Ampullaria* (fig. 7) is abundant at Grignon, and commonly in a beautiful state of freshness.

It has already been observed, that the shells of fresh-water mollusca possess characters by which they may be distinguished from marine species. This small selection (Lign. 39) from the fresh-water beds of Paris will serve to illustrate this remark. The general appearance of these shells will remind you of certain kinds which inhabit our ponds and rivers; particularly the large thin snail (*Limnæa*,* fig. 5), and the discoidal shell (*Planorbis*, figs. 6, 7, 8); while figs. 3 and 4, (*Cyclostoma*), resemble a species that inhabits the banks of lakes. At Headon Hill, Binstead, Calbourne, &c. in the Isle of Wight, the clays and limestones are full of fresh-water shells.

33. FOSSIL NAUTILUS.—Several species of Nautilus are found in the tertiary strata at Highgate, Sheppey, and Bognor; those inclosed in the septaria, or indurated argillaceous nodules, of the London clay, possess considerable beauty, and admit of being cut into sections, which admirably

* The *Limnæa* and *Planorbis* are generally joint inhabitants of our pools and streams. They are pulmoniferous, that is, possess air-breathing organs; hence they are obliged frequently to rise to the surface of the water to respire the air.—See Plate I. of my *Geology of the Isle of Wight*: in that work the name of the first genus is erroneously printed *Limneus*.

§ 34.

FOSSIL NAUTILUS.

display the internal structure of the original. I shall defer
an explanation of the mechanism of these shells to the sub-
sequent lecture, when other genera of the same order will
come under our notice. The large splendid species (*Nau-
tilus imperialis*) of which hundreds of specimens have been
collected from the cuttings at Highgate Tunnel, and the
recent railway excavations, is figured in Sowerby's Mineral
Conchology; a work which contains coloured representa-
tions of a great number of the British tertiary shells. I will
only particularize a rare and elegant species, discovered by
Mr. Wetherell, of Highgate, which is here figured of the
natural size.

LIGN. 40.—NAUTILUS ZICZAC, FROM THE LONDON CLAY, PRIMROSE HILL.

(In the cabinet of Mr. Wetherell.)

Fig. 1. Side view. Fig. 2. Front view.

This shell is remarkable for the peculiar character of the
septa or divisions, as expressed in the specific name ; the
siphunculus extends along the inner margin. The septa
are distinctly seen, in consequence of the external layer of
the shell having been destroyed by decomposition.

34. NUMMULITES : AND OTHER FORAMINIFERA. — The fossils called *Nummulites* (from their resemblance to a coin) belong to those extremely minute forms of molluscous animals which are termed *Foraminifera*, from the shells of most of the genera being perforated all over with openings or foramina.

§ 36.

NUMMULITES OF THE PYRAMIDS.

249

sections of the inclosed shells. The Nummulites are widely
diffused through the ancient tertiary deposits, and form
entire chains of calcareous hills. They constitute immense
beds in the Alps and Pyrenees, and are not confined to the
tertiary, but occur also in some of the secondary formations.
The blue clay at Bracklesham and Stubbington, and the
calcareous sandstone of Emsworth and Bognor, in Sussex,
abound in Nummulites.

In North America, the eocene limestone of Suggsville,
which forms a range of hills 300 feet in height, is entirely
composed of lenticular bodies, supposed to be related to
this genus.* In some parts of France, beds of nummulitic
limestone of great extent and thickness occur, and are
referable either to the lowermost group of the tertiary
formations, or the uppermost of the cretaceous.

35. ROTALIÆ—Many of the foraminifera have cham-
bered shells, so like that of the Nautilus, that but for their
perforated surface, they might be taken for embryotic
cephalopoda. The animals of these polythalamia (many-
chambered shells), have, however, no relation whatever to
the nautilus, but are of a very simple structure, as we shall
explain in the next lecture, when treating of the Rotaliæ
of the chalk. These animalcules swarm in many of the
tertiary strata; in the annexed sketch (Lign. 42) are
shown two specimens adhering to a very characteristic
shell (Vermetus) of the Bognor sandstone. The marine
sands of the Paris basin are, in some localities, so full of
microscopic forms, that a cubic inch of the mass contains
upwards of sixty thousand foraminifera.†

36. CRUSTACEANS AND FISHES.—Of the higher order of
crustaceans, as the Crabs, Lobsters, &c., many species are

* Nummulites Mantelli of Dr. Morton. I have not been able to detect the nummulitic structure in these fossils. See Synopsis of the Organic Remains of the Cretaceous Group of North America. Philadelphia, 1834.

† Medals of Creation, vol. i. p. 221.

250

THE WONDERS OF GEOLOGY.

LECT. III.

found in the London Clay, and other tertiary deposits;
the greater number are extinct, or at least unknown to

LIGN. 42.—FOSSIL SHELLS, FROM THE LONDON CLAY, AT PRIMROSE HILL.
(Collected and described by Mr. Wetherell.)

Fig. 1. Two specimens of *Vermetus Bognoriensis*; natural size.

2 and 3. Portion of the same magnified, to show more distinctly two minute *Rotaliæ* which adhere to them.

2\* Magnified views of the smaller Rotalia, seen in profile, and laterally.

3\* The same of the larger specimen.

naturalists. As the external configuration of the shell or
crustaceous covering of these animals, is conformable to the
soft parts it incloses and protects, the form and size of the
principal viscera, as the heart, stomach, &c. may be ascer-
tained from the markings impressed on the case; and thus
the character of a fossil species, and its relation to living
types, may be determined by the experienced zoologist,
from an examination of the carapace and other parts
of the shell. Many very beautiful fossil crabs and
lobsters have been collected from the clay in the Isle of
Sheppey;* some of which are figured and described by
Mr. Parkinson,† and M. Brongniart.‡ In the tertiary

* Medals of Creation, vol. ii. p. 530.

† Organic Remains of a Former World, vol. iii.

‡ Histoire Nat. Crust. Foss. pl. viii. figs. 5 and 6,

§ 36.

CRUSTACEANS AND FISHES.

251

limestone of Malta a species of Crab occurs in great per-
fection, as exemplified in the specimen before us (*Lign.* 43).
The minute crustaceans, termed *Cyprides*, which swarm in
our pools, lakes, and streams of fresh water, are abundantly
distributed in some of the tertiary fluviatile deposits.*

LIGN. 43.—FOSSIL CRAB, FROM MALTA—(half the natural size).
(Cancer Macrochelus.)

*Fishes of the Tertiary Epoch.* The fishes that have been collected from the various groups of tertiary strata, comprise many hundred species, belonging to all the existing orders and families; but some of the most ancient forms either do not occur, or are but feebly represented.† Nearly two hundred species are figured and described by M. Agassiz in his splendid work on fossil fishes; of which between forty and fifty belong to the universally distributed family, the Sharks. Teeth of various genera of this voracious tribe, are found in abundance in numerous British localities.‡ In the Crag, teeth of enormous size (*Carcharodon*) are often met with; and the same species occurs in the tertiary of Maryland. The teeth of several genera of

* Medals of Creation, vol. ii. p. 119.

† See Genealogical table of the class Fishes, in M. Agassiz's "Re-
cherches sur les Poissons Fossiles."

‡ Medals of Creation, vol. ii. p. 623.

252

THE WONDERS OF GEOLOGY.

LECT. III.

the Ray family, abound in the clay of Bracklesham, Hordwell, and the Isle of Sheppey. The jaws, covered with their dental plates, or teeth, of several species of the Eagle-rays* (*Miliobatis*) occur in the same localities: and the maxillary bones, with their tubercles, of those extraordinary fishes, the *Chimæroids*, have been found in a remarkably fine state of preservation, at Bracklesham Bay, Highgate, Isle of Sheppey, &c.†

The swarms of fishes in the strata of Monte Bolca, and at Aix in Provence,‡ have been already alluded to: and our limits will not admit of a more extended notice; but I may add, that a gigantic *Torpedo* has been discovered at Monte Bolca. The only existing species of fish known in a fossil state is the little *Mallotus villosus*, which inhabits the shores of Iceland, of which fossil specimens occur in nodules of indurated marl or clay, along the coasts of that island.§

As a concise expression of the Ichthyology of the tertiary epoch, it may be stated that the fossil fishes approach in their characters to the living genera, but all the species are extinct. The newer tertiary, as the Crag, contain genera common in tropical seas, as the large sharks (*Carcharias*) and Eagle-rays, &c. In the eocene or most ancient, as the London and Paris basin, Monte Bolca, &c., one third of the Ichthyolites belong to extinct genera.||

37. REPTILES OF THE TERTIARY EPOCH.—The reptiles of the Tertiary, like the mammalia, fishes, and other classes of animals, more nearly approach the recent types, than the fossil reptilians of the more ancient strata. All the orders now existing have representatives in the deposits of this epoch. In the London Clay, remains of Alligators, Crocodiles, and Serpents, have been found in many localities; and of the Turtles or Chelonians, detached bones of terrestrial

* Medals of Creation, vol. ii. p. 629.

‡ Ibid. p. 587.

|| Ibid. p. 670.

† Ibid. p. 619.

§ Ibid. p. 670.

§ 38.

FOSSIL BIRDS.

253

Tortoises, and fresh-water and marine Turtles; many entire
specimens of the carapace and plastron, have been obtained
from Sheppey, and Harwich. Some beautiful examples
have also been met with in the Isle of Wight.* The
lower jaw of an Alligator (*A. Hantoniensis*) with the teeth,
was found in Hordwell Cliff;† and in the clay near Lym-
ington I discovered many bones of a crocodile (*Crocodilus
Spenceri*):‡ Lady Hastings

has obtained a perfect skull,
and other parts of the skeleton
of a Crocodile, from the same
locality.

In the eocene strata of
India, Dr. Falconer found,
with the colossal tortoise (p.
164), bones of other tortoises,
and gavials, that could not
be distinguished from those
of species now inhabiting In-
dia. The lacustrine deposit
of Œningen (p. 263), has
yielded specimens of a large
extinct species of Salaman-
der.

38. FOSSIL BIRDS. — In
the gypseous building-stone
of Montmartre, M. Cuvier

found many bones possessing characters peculiar to those
of birds; and after much research he was enabled to
determine several fossil species, related to the pelican,
sea-lark, curlew, woodcock, buzzard, owl, and quail.
In some examples there are indications of the feathers,

* Geology of the Isle of Wight, p. 112.

† London Journal of Geology and Palæontology, plate 2.

‡ Geology of the Isle of Wight, p. 163.

LIGN. 44.—FOSSIL BIRD, FROM
MONTMARTRE.

254

THE WONDERS OF GEOLOGY.

LECT. III.

and even of the air-tubes. Sometimes the skeleton is wanting, and a pellicle of a dark brown substance alone points out the configuration of the original (*Lign.* 44). Not only are the skeletons and feathers of birds found in the tertiary strata, but even the eggs of aquatic species occur in the lacustrine limestone of Auvergne; these have probably been formed in loose calcareous debris along the borders of the lakes, in like manner as the eggs of turtles incrusted in the modern travertine, on the shores of the Isle of Ascension (p. 90).

39. FOSSIL MAMMALIA OF PARIS.—We have next to consider the fossil remains of the mammalia, whose skeletons were entombed in the mud of the waters which formerly occupied the site of the metropolis of France, and the surrounding country. The gypsum quarries which are spread over the flanks of Montmartre had long been known to afford fossil bones; but though specimens occasionally attracted the notice of the naturalists of Paris, and collections were formed, no one appears to have suspected the mine of wonders which the rocks contained, till the curiosity of Baron Cuvier was awakened by the inspection of a large collection of these bones, after he had successfully applied the laws of comparative anatomy to the investigation of the fossil elephants and mammoths. He had previously paid but little attention to the partial accounts of fossil bones found in the vicinity of Paris, although in 1768, M. Guettard had figured and described many bones and teeth.

M. Cuvier now, however, perceived that a new world was open to his researches, and he soon obtained an extensive collection, and found himself, to use his own expression, in an ancient charnel-house, surrounded by a confused mass of mutilated skeletons of a great variety of animals. To arrange each fragment in its proper place, and restore order to these heterogeneous relics, seemed at first a hopeless task; but a knowledge of the immutable laws by which the

256

THE WONDERS OF GEOLOGY.

LECT. III.

The examination of the fossil teeth at once showed that the animals were herbivorous, the enamel and ivory being disposed in the manner already explained (p. 141); the crown of the tooth is composed of two or three simple crescents, as in certain pachydermata; thus differing from the ruminants, which have double crescents, and each four lines of enamel. Following out the inquiry, Cuvier at length ascertained that a great proportion of the bones and teeth, belonged to two extinct genera of pachyderms, related to the tapir, rhinoceros, and hippopotamus.

Every one is familiar with the forms and habits of the two last animals; but the Tapirs are not so well known; they are a family of pachyderms confined to Sumatra and South America. The Malay Tapir, a stuffed specimen of which may be seen in the British Museum, sometimes attains eight feet in length, and six in circumference. It has a flexible proboscis, a few inches long; its general appearance is heavy and massive, resembling that of the hog. The eyes are small, the ears roundish; the skin is thick and firm, and covered with stout hair, and the tail short. It inhabits the banks of lakes and rivers, and has been observed to walk under water, but never to swim.

40. PALÆOTHERIA, AND ANOPLOTHERIA.—It is unnecessary to enter at large on the structure and habits of the animals to which these remains belonged; for even the forms of these extinct beings must be familiar to the reader, as Cuvier's restorations of their living lineaments, are to be found in every popular work that treats of the ancient inhabitants of our globe.

The *Anoplotheria* are remarkably distinguished by having feet with but two toes, as in the ruminants, and are the most ancient form of bi-hoofed animal known in a fossil state. They had an uninterrupted dental system, the teeth being placed in a continuous series, as in man, without any interval between them. The *A. commune* (*Lign.* 45, *fig.* 4),

§ 40.

PALÆOTHERIA AND ANOPLOTHERIA.

257

was eight feet long, and of the height of a wild boar, but of
a more elongated shape; it had a long and thick tail, which
must have enabled it to swim with facility, like the Otter;
the structure of the teeth indicates that it browsed on
grass like the horse. The *A. gracile* (*Lign.* 45, fig. 1), so
named from its elegant proportions, was of the size and
form of the Gazelle, and must have lived after the manner
of the deer and antelopes.

The *Palæotheria* resembled the Tapirs in the form of
the head, and in having a short proboscis, but their molar
teeth were more like those of the Rhinoceros; their fore-
feet had but three toes, instead of four as in the Tapirs.
Upwards of eleven species, varying from the size of the
Rhinoceros to that of the Hog, have been discovered in the
tertiary strata of France. The *P. magnum* (*Lign.* 45, fig. 2),
was of the magnitude of a horse four or five feet high, with a
massive head and proboscis, and short extremities. The
*P. medium* was one-sixth smaller than the American
Tapir, but had longer and slighter legs and feet. The
*P. minus* (fig. 3) was an elegant creature as large as the
Roebuck, with light and slender limbs.

Numerous other genera of extinct mammalia have been
discovered in the eocene strata, and their characters deter-
mined by Baron Cuvier. Some are related to the animals
we have just described; as the *Anthracotherium*, (so
named from the discovery of its remains in the anthracite,
or lignite of Cadibona,) which held an intermediate place
between the hog and hippopotamus. Six or seven species
of carnivora, an opossum, a squirrel, dormouse, &c. have
also been found in the Paris basin. In England, remains
of several species of Palæotheria, Anoplotheria, and other
characteristic genera, have been discovered.*

In the miocene strata of Touraine and of Darmstadt,

* See Prof. Owen's British Fossil Mammalia; and my Geology of the
Isle of Wight, p. 115.

S

258

THE WONDERS OF GEOLOGY.

LECT. III.

remains of the above extinct mammalia, and of the mastodon, are found associated with those of existing genera.

41. FOSSIL MONKEYS.—The illustrious Cuvier, when commenting on the extraordinary fact, that among the innumerable relics of the mammalia which peopled the continents and islands of our planet during the tertiary ages, no traces of man or of his works occur, emphatically observed, that it was a phenomenon not less surprising, that no remains of the quadrumanous tribes, which rank next

LIGN. 46.—PORTION OF THE LOWER JAW OF A MONKEY; FROM EOCENE SAND AT KINGSTON, NEAR WOODBRIDGE.*

(Magnified two diameters.)

Fig. 1.—The outer side of the tooth and jaw.

2.—View of the specimen from above, showing the upper surface of the crown of the tooth.

3.—View of the inner side.

to the human race in physical conformation, should have been discovered; and that the circumstance was the more remarkable, because the majority of the mammalia found in the drift, and tertiary deposits, have their congeners at the present time in the warmest regions of the globe; in those intertropical climates where the existing quadrumana

* From the Magazine of Nat. Hist. vol. iii. p. 447.

§ 41.

FOSSIL MONKEYS.

259

are almost exclusively located.* At length proofs were
obtained, and almost at the same time in France, India,
South America, and England, of the existence of this order
of animals during the most ancient tertiary epochs.

The fossil remains are referable to four modifications of
the existing types of quadrumana. Those from France
belong to an animal of the Ape tribe; those from England
to the *Macacus*; the Indian fossils to a species of the long-
limbed and tailed monkeys, of which the Negro monkey is
an example; and the relics from South America to a gigan-
tic Capuchin monkey.†

The British specimens (Lign. 46), were found in a bed
of eocene sand, at Kyson or Kingston, a few miles east
of Woodbridge in Suffolk.‡

* Discours sur les Révolutions, p. 171.

† THE QUADRUMANA OR MONKEYS.—These animals come nearest to man in the form and proportion of their skeleton, and of their separate bones; in the general disposition of their muscular system, and its adaptation for a semi-erect position of the body; in their great cerebral organization, the perfection and equable development of their senses; their intellectual capacity, and complicated instincts. These most elevated of all inferior animals are fitted to select, obtain, and digest the succulent ripe fruits of trees, and are destined to inhabit the rich and shady forests of tropical climates. They leave to the squirrels and the sloths the buds and leaves; to the ponderous elephant and rhinoceros the branches and the stem; and to the beavers, and other rodentia, the hard bark of the trees. Their delicate organization is adapted only for the richest products of the vegetable kingdom; and the soft and nutritious quality of their food is suitable to the broad enamelled crowns of their molar teeth, which are studded with rounded tubercles: their stomach is simple. With a high cerebral and muscular development, corresponding with their elevated rank in the scale of beings, and the position of their food, they are the most agile and sportive of all mammalia; and they are provided with prehensile organs at every point; their teeth, tail, feet, and hands assist in their agile movements, and in their boundings from branch to branch, and from tree to tree.—Dr. Grant's Lectures on Comparative Anatomy.

‡ See Prof. Owen's British Fossil Mammalia, and my Medals of Creation, vol. ii. p. 863.

s 2

260

THE WONDERS OF GEOLOGY.

LECT. III.

42. TERTIARY STRATA AT AIX.—A group of strata remarkable for its organic remains, occurs near Aix, a town in Provence, which is situated upon a thick deposit of tertiary conglomerate. The series on the northern side of the valley consists of—1. Tertiary breccia, the lowermost bed, which forms the site of the town of Aix. 2. Marl, with fishes and insects. 3. Gypsum and gypseous marls, containing fishes and insects, leaves of palms, and other plants, and fresh-water univalve and bivalve shells, particularly a species of *cyclas*, in great abundance.* 4. Fresh-water limestone. To the south, extending towards Toulon, are lacustrine strata of red marl, with compact limestone

LIGN. 47.—FOSSIL FISH, FROM AIX.
(Smerdis minutus.)

inclosing shells, gyrogonites, &c ; still farther to the south,
beds of grey fresh-water limestone appear ; and at Fuveau,
a series of blue limestones, shales, and coal, is exten-
sively worked. Fresh-water shells, and seed vessels of
*Charæ* with other vegetable remains, occur in abundance
in the coal-beds and intermediate layers of shale.

* The *Cyclas* inhabits lakes and marshes, and therefore denotes the lacustrine origin of the deposits.

262

THE WONDERS OF GEOLOGY.

LECT. III.

Formation of Aix, in Provence,” by Mr. Lyell, and Sir R. I. Murchison.*

All the insects belong to existing genera, and only one species is aquatic.† The anterior *tarsi* are generally obscure, or distorted; but in some specimens the claws are visible, and the sculpture, and even a degree of local colouring, are preserved. The nerves of the wings in the *Diptera*, and the pubescence on the head, are distinctly seen. Several of the beetles have the wings extended beyond the *elytra*, as if they had fallen into the water while on the wing, and had made an effort to escape by flight. M. Marcel de Serres has enumerated nearly seventy genera of insects, and a few *Arachnides*, or spiders. The most curious fact is, that some of the insects are identical with species which now inhabit Provence. It seems probable that these insects were brought together from different localities by floods, and mountain streams; yet, as Mr. Curtis observes, all of them might have inhabited moist and shady forests. The laminated marls contain also the coverings of the fresh-water crustacean, called *Cypris*, which swarms in our pools and stagnant waters, and must be familiar to all who have seen the exhibition of the oxy-hydrogen microscope; living cyprides being commonly shown, and appearing somewhat like the head and feet of a flea protruding from an oval case or shield, and swimming by means of their fine *cilia*, which resemble pencils of hair. These crustaceans shed their cases annually, and the surface of the mud spread over the bottoms of lakes is often covered with their relics. The marls of Aix, as well as of many other fresh-water formations, abound in fossil *Cyprides*, which oftentimes constitute entire seams or thin layers.

The seed-vessels of the *Chara*, a common plant in our ditches and ponds, also occur in profusion; they were

* Jameson's Edinburgh Journal, for 1829.

† Principles of Geology, vol. iii. p. 211.

§ 44.

FOSSIL FOX OF ŒNINGEN.

263

formerly supposed to be shells, and from their peculiar structure received the name of *gyrogonites*, which they still bear, although their real nature has long since been ascertained.* In conclusion, Mr. Lyell observes, "that this tertiary series differs essentially from that of the London and Paris basins. The great development of regular beds of blue limestone and shale, the quality and appearance of the coal, and the thickness of the compact grey, brown, and black argillaceous limestones and sandstones, give them the aspect of the most ancient of our secondary rocks; and it is only by the peculiar species of fluviatile and lacustrine shells, the seed-vessels of the charæ, &c. that the comparatively recent date of the whole group is demonstrated."

44. FOSSIL FOX OF ŒNINGEN.—Among the tertiary lacustrine formations of the Continent, there is one so much celebrated for its organic remains as to require a passing notice. Œningen, near Constance, has for centuries been known to contain fossil remains of great beauty and interest. A short but graphic memoir by Sir R. Murchison,† presents in a few lines the history of this ancient lake. The Rhine, in its course from Constance to Schaffhausen, flows through a depression of a tertiary marine formation, known by the name of *Molasse*, which forms hills on both sides of the river, of from 700 to 900 feet in height. In a depression or basin of this molasse, is a series of strata composed of marls, and cream-coloured, fine-grained, fetid limestone, with laminated white marl-stone, forming a total thickness of thirty or forty feet. In the marl-stone, leaves and stems of plants, insects, shells, crustacea, fishes, turtles, a large aquatic salamander, birds, and a perfect skeleton of an animal allied to the common Fox, have been

* See Medals of Creation, vol. i. p. 187; or Geology of the Isle of Wight, p. 109.

† Geological Transactions, 1832, vol. iii. p. 277.

264

THE WONDERS OF GEOLOGY.

LECT. III.

discovered. This last fossil was purchased by Sir R. Murchison, for whom I developed it, and removed the stone with which all the bones were thickly encrusted, so as to expose the entire skeleton, which differs but slightly from that of the recent species; it is figured and described in the Geological Transactions for 1832.*

A tortoise, three feet in length, with the cranium and bones of the neck, tail, and of three of the pats, well preserved, has since been discovered. Sir R. Murchison concludes

* Although there were certain obvious differences between some parts of the skeleton, and the corresponding bones of the existing species of Fox with which I had the means of instituting a comparison, I did not feel myself warranted in affirming the fossil to be specifically distinct from all known recent vulperine forms; an opinion in which Mr. Clift entirely concurred; I therefore simply designated it the *Fossil Fox of Œningen*. M. Meyer, however, from my figures and descriptions only, has deemed it right to impose the name of *Canis palustris*; and subsequently Professor Owen, from detecting a few slight discrepancies upon a rigorous comparison of the fossil with recent congenerous forms, has referred it to a new genus; and the fossil, which cost me so many nights of patient dissection to develop, is now enrolled in the annals of science as the *Galecynus Œningensis* of Prof. Owen. See Geol. Journal, vol. iii. p. 55. It has been shrewdly remarked, by a celebrated anonymous author, that such is palæontological refinement now-a-days, that an extra plication of enamel in the tooth of a fossil pachyderm, or an additional notch on the tooth of a carnivore, is sufficient to obtain a specific and even sub-generic name for that animal, and constitute its origin a separate creation! If this be admitted, the fixity of species must soon be deemed a chimera.

A late eminent naturalist observed, "that the laws of correlation, though so admirable in the results of their application to extinct forms, must still be admitted with great caution, and some limitation: for the proportions of many animals vary greatly, from age and other circumstances. Thus, the legs of a colt are relatively much longer than those of the adult horse; and were we to conclude from the extreme size of the internal condyle of the arm-bone of the *Orycteropus*, that the claws of that animal are equally developed with those of others of the same order, the conclusion would be erroneous."—*Harlan's Medical and Physical Researches*, Philadelphia, 1835.

§ 45.

FOSSIL FISHES OF MONTE BOLCA.

265

that these fresh-water deposits are the contents of a lake, belonging to the newer tertiary epoch; and that the period of their formation must have long preceded the present condition of the country, for they contain some unknown species of animals, and the Rhine has worn a channel through them to the depth of several hundred feet.

45. FOSSIL FISHES OF MONTE BOLCA.—Another interesting assemblage of tertiary strata is exposed in the celebrated quarries of Monte Bolca, that are situated on the borders of the Veronese territory, about fifty miles NN.W. of the lagunes of Venice. These deposits form part of a range of hills of moderate elevation; volcanic deposits abound in the neighbouring Vicentin, and the summit of the hill at Monte Bolca is capped with basalt.* This hill is principally composed of argillaceous and calcareous strata, with beds of a cream-coloured fissile limestone, which readily separates into laminæ of moderate thickness, and abounds in fishes in the most beautiful state of preservation. They are all compressed flat, but the scales, bones, fins, and even the muscular tissue remain; their colour is a deep brown, thus admirably contrasting with the limestone in which they are imbedded. Several hundred species are contained in these quarries, and thousands of specimens have been collected; according to M. Agassiz, all the species, though related to the recent, are extinct.† From the immense quantities which occur in so limited an area, it seems probable that the limestone in which they are imbedded was erupted into the ocean in a fluid state by volcanic agency; and that the fishes were thus suffocated, and surrounded by the calcareous mass. Nor is this hypothesis without support, for on the appearance of a volcanic island in the Mediterranean, a few years since, hundreds of dead fishes were seen putrid and floating in the waters; and it

* Organic Remains of a Former World, vol. iii. p. 247.

† See Recherches sur les Poissons Fossiles.

266

THE WONDERS OF GEOLOGY.

LECT. III.

cannot be doubted that shoals of fishes may at the same
time have been enveloped in the volcanic matter at the
bottom of the sea, and become compressed and preserved;
and when the mud which envelopes them is consolidated,
and the bed of the Mediterranean elevated above the
waters, these fishes may resemble the ichthyolites of Monte
Bolca.*

46. TERTIARY VOLCANOES OF FRANCE.—In the former
lecture I alluded to volcanic action as still in activity, and
as having been equally energetic in more ancient periods;
and there is abundant proof, that during the immense lapse
of time comprehended between the earliest and the latest of
the tertiary formations, the internal fires of our globe were
not dormant. We have already had occasion to remark
how rarely the former geographical relations of a country
are preserved, and that though we may be able to pronounce
with certainty that this spot was once dry land,—that
yonder flowed a river,—that here is the bed of an ancient
sea,—yet we can seldom determine the limits of the one, or
trace the boundaries of the other. But there is one re-
markable exception—a district, where the most striking
geological revolutions have taken place, and yet the area
of those changes still maintains its ancient physical geo-
graphy—that district is Auvergne, a province in central
France.

Nearly a century since, two French academicians, MM.
Guettard and Malesherbes, on their return from an explo-
ration of Vesuvius, arrived at Montelimart, a small town
on the left banks of the Rhone, where Faujas St. Fond, a
distinguished naturalist, was sojourning. These savans
were struck with the remarkable character of the pavements
of the streets, which were formed of short joints of basaltic
columns, placed perpendicularly in the ground; and upon
inquiry they found the stones had been obtained from the

* See Lecture VIII.

§ 46.

TERTIARY VOLCANOES OF FRANCE.

267

neighbouring mountains of the Vivarais. This information
induced them to survey the country; and upon arriving at
Clermont, the capital of Auvergne, a town with about 30,000
inhabitants, they were satisfied that the whole region was
of volcanic origin; for in the vicinity of that town they
discovered consolidated currents of lava, black and rugged
as those of Italy, extending uninterruptedly into the plains
below, from some conical hills of scoriæ, which still pre-
served the form of craters.* "To those who now visit
central France, and see everywhere unequivocal marks of
volcanic agency,—the numerous hills formed entirely of
loose cinders, porous and diversified as if just thrown from
a furnace, and surrounded by plains of rugged lava, on
which even the lichen refuses to vegetate,—it appears
scarcely credible, that previously to the last half century,
no one had thought of attributing these marks of desolation
to the only power in nature capable of producing them.
This, however, is perfectly natural, and not without ex-
amples. The inhabitants of Herculaneum and Pompeii
built their houses with the lava of Vesuvius, ploughed up
its scoriæ and ashes, and ascended its crater, without dream-
ing of their proximity to a volcano which was to give the
first proof of its energies by burying them beneath its erup-
tions; and the Catanians regarded as a fable all mention of
the former activity of Etna, when, in 1669, half their town
was overwhelmed by its lava currents."†

* Recherches sur les Volcans éteintes du Vivarais: par M. Faujas St. Fond. Paris, 1778.

† Geology of Central France, by G. Poulett Scrope, Esq. F.R.S., 1827. In 1815, Professor Playfair visited Auvergne, and concisely, but graphically, described the volcanic phenomena there exhibited. Mr. Bakewell, in 1823, drew attention to this remarkable district in his " Travels in the Tarentaise, by Robert Bakewell, Esq." 2 vols. 8vo. 1823; and subsequently Dr. Daubeny, Messrs. Scrope, Lyell, and Murchison, have severally published highly interesting memoirs on the geological phenomena of Auvergne.

268

THE WONDERS OF GEOLOGY.

LECT. III.

47. **EXTINCT VOLCANOES OF AUVERGNE.** (Plate II.)—
The country which is the site of these extinct volcanoes is
about 220 miles south of Paris, and forms a vast plain,
situated in the department of the Limagne d'Auvergne.
It is so remarkable for its fertility, that it is called the
Garden of France; a quality attributable to the detritus of
the volcanic rocks, which enters into the composition of the
soil. It is inclosed on the east and west by two parallel
ranges of gneiss and granite. Its average breadth is
twenty miles, its length between forty and fifty, and its
altitude about 1,200 feet above the level of the sea. The
surface of this plain is formed of alluvial deposits, com-
posed of granitic and basaltic pebbles, and boulders, re-
posing on a substratum of limestone. Hills, of various
elevations, composed of calcareous rocks, are scattered
over the plain; and the river Allier flows through the
district, over beds of limestone and sandstone, except where
it has excavated a channel to the foundation-rock of
granite. The hills formed of calcareous alluvial deposits,
are the remains of a series of beds, which once constituted
an ancient plain, at a higher elevation than the present.
Many are surmounted by a crest or capping of basalt, to
which their preservation is probably attributable; others
have escaped destruction from being protected by hori-
zontal layers of a durable limestone, which I shall pre-
sently describe.

We have, then, as the ground-plan of the district, an
extensive plain, chequered with low hills of fresh-water
limestone, which are capped with compact lava (Pl. II.
fig. III); the boundaries of this tract being formed of
ranges of primary rocks, 3,000 feet in altitude. To the
westward the limestone disappears, and a plateau of granite
rises to a height of about 1,600 feet above the valley of
Clermont, being 3,000 feet above the level of the sea.
This supports a chain of volcanic cones and dome-shaped

§ 48.

CRATER OF PUY DE COME.

269

mountains, (Pl. II. fig. II.) about seventy in number, varying in altitude from 500 to 1,000 feet from above their bases, and forming an irregular range nearly twenty miles in length, and two in breadth. The highest point of this range is the Puy* de Dome, which is 4,000 feet above the level of the sea (Pl. II. fig. II), and is composed entirely of volcanic matter ; it possesses a regular crater, 300 feet deep, and nearly 1,000 feet in circumference. Many of these cones retain the form of well-defined craters, and their lava currents may be traced as readily as those of Vesuvius. The Puy de Pariou is a most perfect example: it is a cone covered with fine turf, both on the ascent and within the crater; the latter is a mile in circumference, and very deep, sloping downwards at an angle of 30°. From the lower part of the cone a current of lava, which is still rugged and black, has issued; and the plain is covered with scoriæ and volcanic cinders, which are exposed to the depth of twenty feet, in the ravines made by the winter torrents.

48. CRATER OF PUY DE COME.—One of the most remarkable cones is the Puy de Come, which rises from the plain to the height of 900 feet; its sides are covered with trees, and its summits present two distinct craters, one of which is 250 feet in depth. A stream of lava may be seen to have issued out from the base of the mountain, which at a short distance, from having been obstructed by a mass of granite, has separated into two branches; these can be traced along the granitic platforms, and down the side of a hill into an adjacent valley, where they have dispossessed a river of its bed, and constrained it to work out a fresh channel between the lava and the granite of the opposite bank. Another cone rises to the height of 1,000 feet above the plain, having a crater nearly 600 feet in vertical

* Puy is the name given in this province to an insulated conical hill.

270

THE WONDERS OF GEOLOGY.

LECT. III

§ 49.

depth, and a lava current, which first falls down a steep declivity, and then rolls over the plain in hilly waves of black and scorified rocks. In one part of this volcanic group is a circular system of cones, apparently the product of several rapidly succeeding eruptions. " The extraordinary character of this scene impresses it for ever on the memory; for there is, perhaps, no spot, even among the Phlegræan fields of Italy, which more strikingly displays the characters of volcanic desolation.* Although the cones are partially covered with wood and herbage, yet the sides of many are still naked; and the interior of their broken craters, rugged, black, and scorified, as well as the rocky floods of lava with which they have loaded the plain, have a freshness of aspect, such as the products of fire alone could have so long preserved, and offer a striking picture of the operation of this element in all its most terrible energy."† The accompanying sketches‡ will illustrate these remarks.

*Plate II. fig. III.* A view of the environs of Clermont. In front is a basaltic peak, crowned by the Castle of Montrognon; and beyond are basaltic platforms (indicated by the dark lines of shade) on hills of limestone. The town is seen in the plain or basin, which has been excavated by diluvial agency, since the deposition of the strata which form the surrounding hills. In the distance is the primary escarpment, forming part of the boundary of the volcanic district.

*Fig. II.* Part of the southern volcanic chain of Puys, exhibiting the broken craters of Chaumont; from the bases of several the cooled lava currents still remain as when they issued. Mont Dome appears in the distance.

* Plate II. represents a part of this chain of extinct volcanic rocks; with Mont Dome in the distance.

† Scrope's Geology of Central France.

‡ The delineations are reduced from the elaborate and beautiful drawings of Mr. Scrope.

§ 49.

MONT DORE.

271

This region affords, too, a striking illustration of the erosion of the surface of a country by alluvial action. The thickness of the volcanic mass is between 300 and 400 feet; it is composed of two distinct beds of basalt, separated by a layer of scoriæ and volcanic fragments. Many portions, both of the upper and lower beds, are made up of well-defined, vertical, polygonal columns. The streams of lava to which these plateaux belong, have been traced for more than thirty miles; they rise in a narrow ridge across the primitive heights, and then spread over, and lie comformably upon, the secondary formations. The limestone beneath the basalt is, in some places, covered with vegetable soil, containing a common species of terrestrial shell (*Cyclostoma elegans*). The nearly horizontal disposition of the basalt, its columnar structure, and position on the limestone, into which it has injected veins and dikes, render it, as Mr. Scrope observes, very analogous to the ancient volcanic rocks of Ireland, which will be described in a future Lecture.

49. MONT DORE (Pl. II. fig. 1). In the same province there is another remarkable system of extinct volcanoes connected with the Puy de Dome. While in the district I have just described, the primitive soil is only partially obscured by the volcanic products, in Mont Dore, the granitic foundation, over an area of many miles in extent, is entirely covered by them, and the erupted masses attain a considerable elevation. Mont Dore is a mountainous tract, the highest portion of which is about 6,000 feet in altitude.* It consists of a group of seven or eight rocky summits, which form a zone a mile in diameter, the whole consisting of a succession of beds of volcanic origin. It is deeply channelled by two principal

* Pl. II. fig. 1. is a profile of Mont Dore as seen from a distance, from a sketch by M. Constant Prevost: the dotted outline shows the form of the cone when in activity; a ground plan of the broken crater is annexed.

272

THE WONDERS OF GEOLOGY.

LECT. III.

valleys, and furrowed by many minor water-courses, all
originating near the central eminence, and diverging
towards every point of the horizon. The beds of which
this group is composed, consist of scoriæ, pumice-stone,
trachyte, and basalt; these rocks dip off from the central
axis, and lie parallel to the sloping flanks of the mountain,
as is the case in Etna, the Peak of Teneriffe, and all other
insulated volcanic mountains. There is no crater; all
vestiges having been destroyed since the extinction of its
fires; but streams of lava may be traced, in elevated peaks,
over a gorge which occupies the very heart of the mountain,
and they extend to a distance of many miles. A remarkable
natural section, worn by a cascade, at a short distance
from the baths of Mont Dore, exhibits the following beds
in a descending series:

1. Porphyritic trachyte; a volcanic rock, 160 feet in thickness.

2. Arenaceous tufa. 3. Columnar basalt. 4. Breccia, made up of volcanic fragments, cemented together by tufa. 5. Thick beds of basalt. 6. White ferruginous tufa, enveloping fragments of granite, basalt, &c., and traversed by veins of the overlying basalt.

I may add, that the volcanic vents of central France are
evidently of very different ages; some being of immense
antiquity, while others are of comparatively recent origin,
for they have exploded through the oldest beds of basalt;
but even the most modern belong to a very remote period.

50. FRESH-WATER STRATA OF AUVERGNE.—This district presents a series of alternations of fresh-water limestones, with basalt, scoriæ, and other volcanic productions, based on a foundation of granite and gneiss. These beds occur in the following order, beginning with the lowest or most ancient:—

1st. Clay, sand, and breccia, without organic remains.

2d. Limestone and calcareous marl, in strata nearly horizontal; about 900 feet thick. These are entirely of fresh-water origin, for they abound in shells of the genera *potamides*, *helix*, *planorbis*, and *limnæa*, which are known to inhabit lakes and rivers. Some

§ 50.

273

of the beds contain bitumen; others are entirely made up of the cases of the Caddis-worm (*Indusia tubulata*), cemented together by calcareo-siliceous matter. (This specimen, which was in the cabinet of Faujas St. Fond, displays the characters of this remarkable concrete: it consists of the tubes or cases of the larvae of a species of *phryganea*, or may-fly.) These cases, which are formed by the adhesion of shells to the outer surface of the silken case secreted by the insect, are abandoned by the animal when its metamorphosis is completed, and layers of them may often be seen in our ditches and lakes. The fossil cases have been cemented together by calcareous infiltration, and form a compact stone, which is employed for building. The attached shells are so minute, that often more than a hundred are affixed to a single case; and a cubic inch of the limestone includes ten or twelve tubes. If, says Mr. Scrope, we consider that repeated strata, of five or six feet in thickness, almost entirely composed of these fossils, once extended over the whole plain of the Limagne, occupying a surface of many hundred square miles, we may have some idea of the countless myriads of minute beings which lived and died within the bosom of that ancient lake.

In the limestones, associated with land and fresh-water shells, and remains of terrestrial plants, are bones of species of palæo-therium, anoplotherium, lagomys, marten, dog, rat, tortoise, crocodile, serpent, and birds; the lava currents that have flowed over the strata have produced but little change in the organic remains. This series comprises beds of gypseous and laminated marls, with intercalations of siliceous limestone, containing impressions of lacustrine and river shells. In some localities, the fresh-water limestone has an intermixture of volcanic matter, and presents the characters of a sediment slowly and tranquilly deposited in a lake, into which ashes, and fragments of rocks and scoriae, were projected by a neighbouring volcano; while some beds appear to have been formed by a violent intrusion of volcanic products.

3d. Immense beds of basalt, scoriae, &c., spread over the tabular masses of fresh-water limestone, and often capping the summits of the lower hills. (Pl. II. fig. 111.)

4th. Sand and diluvial gravel, containing bones of the mastodon, elephant, hippopotamus, rhinoceros, tapir, horse, boar, hyena, bear, dog, beaver, hare, &c.: with these are associated lignite, and other vegetable remains. Some of the beds of limestone abound in seed-vessels of charæ; and the laminated clays contain fishes, with leaves and stems of reeds and other plants.

T

274

THE WONDERS OF GEOLOGY.

LECT. III.

There are several incrusting springs in Auvergne, largely impregnated with carbonic acid, which have deposited immense quantities of calcareous tufa. These issue from fissures in the granite and gneiss rocks that form the base of the whole territory, and are spread over the volcanic foci whence these mineral waters, in all probability, originate; numerous thermal springs also occur throughout the district.

51. **SUCCESIVE EPOCHS OF MAMMALIA.**—The fossil remains of mammalia found in the sedimentary deposits of the volcanic region of Auvergne are very numerous, and comprise many of the most ancient species of the Paris basin, as well as those of existing ones. They are separated by Mr. Lyell,* and other eminent observers, into three groups;—

I. Mammalian remains from the fresh-water strata overlying the granite; these comprise bones of Palæotheria, Anoplotheria, and other Cuvierian pachyderms, associated with extinct species of Rhinoceros, Horse, Deer, &c.; this is the most ancient group.

II. Bones of Mastodon, Hippopotamus, Elephant, Horse, Tapir, Elk, Antelope, and many other terrestrial quadrupeds, all supposed to be extinct forms; associated with existing species of fresh-water shells. These are from the lacustrine deposits, which are separated from the above by ancient lava currents (basalt).

III. Fossil bones from the beds of sandy marl, and alluvial debris. These are referable to small Rodents (Lagomys), and nearly fifty species of other existing mammalia; as Mouse, Squirrel, Hare, Marten, Dog, Cat, &c.; Hog, Ox, Deer, and Horse; Frogs, Lizards, Snakes, and Birds; of the latter, even the eggs are occasionally found.

52. **SUMMARY OF THE GEOLOGICAL PHENOMENA OF AUVERGNE.**—In the calcareous and siliceous limestones of Auvergne, and their associated laminated marls, gypsum, lignite, and conglomerate, we have a general analogy with the older fresh-water tertiary formations of Paris; the shells and plants being similar, and the quadrupeds of the same genera. And if we suppose the

* See Proceedings of the Geol. Soc. 1845, p. 75.

§ 52. GEOLOGICAL PHENOMENA OF AUVERGNE.

275

Paris basin to have been elevated above the water during the active state of neighbouring volcanoes, and that successive streams of lava flowed over its sedimentary deposits, we should have a series of phenomena resembling those of Auvergne; with the exception, that the presence of marine remains would denote that the basin had been filled with salt water, and communicated with the sea. The facts submitted to our notice appear to establish the following sequence of physical events.

1st. The elevation, after the deposition of the secondary limestones, of the whole area of the primary rocks which form the foundation of central France.

2dly. A period of tranquillity, during which fresh-water lakes occupied the irregular hollows of the district; the neighbouring country being inhabited by palæotheria, anoplotheria, and other extinct mammalia, whose bones, together with the relics of the then existing vegetation, and the shells of mollusca, became enveloped in the tranquil depositions that were going on in the lacustrine basins.

3dly. Another elevation of the district took place, a new system of lakes was established, and the country was again clothed with forests, and was inhabited by deer, oxen, rhinoceroses, and hyenas, many of whose skeletons became imbedded in the sediments of the waters.

4thly. The volcanoes became active; explosions took place through hundreds of vents; trachyte and basalt were ejected, and in some places pierced the fresh-water deposits, while in others they overspread them with sheets of lava. Vegetation still flourished, and the remains of plants were entombed in the volcanic products.

5thly. Another period of tranquillity—the rivers and other water-courses, dammed up or deranged by the lava currents, formed new channels, and accumulated beds of gravel, sand, and clay. Deer, horses, oxen, &c., with hyenas and other carnivora, inhabited the district; having for contemporaries terrestrial mammalia of species which exist in Auvergne at the present time. Volcanic eruptions succeeded, and continued till a comparatively recent period.

Lastly. Streams and rivers of later date, and which still effect the drainage of the country, began to wear away channels through

T 2

276

THE WONDERS OF GEOLOGY.

LECT. III.

the beds of lava and limestone to the primary rocks beneath,
and intersect the country with valleys and ravines, spreading
over the ancient beds a thick covering of alluvial soil.*

53. EXCAVATION OF VALLEYS BY STREAMS AND RIVERS.
—There is no district which exhibits in more striking cha-
racters the erosive power of running water, than Auvergne.
In many places the basalt is columnar, like that of Staffa,
and the Giants' Causeway; and one range, on the banks
of the Ardêche, forms a majestic colonnade 150 feet in
height, extending a mile and a half along the valley which
has been channelled out by the river that flows at its base.

Mr. Scrope's description of this process is highly graphic. " The bed of the Ardêche is strewed with basaltic boulders, pebbles, and sand, originating from the destruction of the columnar ranges. In some of the volcanic cones the beds of basalt may be traced issuing from the crater and following the inequalities of the valley, just as a stream of lava would flow down the same course at the present time. Yet these ancient currents have subsequently been corroded by rivers which have worn through a mass of rock 150 feet in height, and formed a channel even in the gneiss rocks beneath, since the lava first flowed into the valley. In another spot, a bed of basalt, 160 feet high, has been cut through by a mountain stream, and very beautiful columnar masses are exposed. The vast excavations effected by the erosive power of water along the valleys which feed the Ardêche, since their invasion by lava currents, prove that even the most recent of these volcanic eruptions belong to an era incalculably remote."

54. EXTINCT VOLCANOES OF THE RHINE.—I have dwelt
* This account of the volcanic phenomena of Auvergne, is an abstract
of the interesting Essays of Messrs. Bakewell, Scrope, Lyell, Mur-
chison, Dr. Daubeny, Dr. Hibbert, MM. Croiset, Jobert, Robert, and
Bertrand-Roux. Mr. Scrope's work cannot be perused, even by the
general reader, without deep interest.

§ 54.

so long on the Phlegræan fields of Auvergne, that but a
brief space can be afforded to another group of tertiary
volcanoes. Every one who has ascended the Rhine, will
remember where

"The castled crag of Drachenfels,
Frowns o'er the wide and winding Rhine,"

forming one of the Siebengebirge, or Seven Mountains,
whose majestic and graceful forms suddenly burst on the

LIGN. 49.—THE DRACHENFELS.

sight, rising from the level plains on the right bank of the
river, to an altitude of nearly 1,500 feet. These picturesque
objects belong to a group of extinct volcanoes; while, on
the opposite side of the river, the Eifel, with its crater
covered with scoriæ and cinders, and lava currents still dis-
tinctly visible, attest the wide area over which those ancient
fires once extended. Unlike the district we have just
noticed, the foundation rock of the country is an ancient
sedimentary deposit, consisting of coarse red sandstone and
slate, thrown into a highly inclined position. Through

278

THE WONDERS OF GEOLOGY.

LECT. III.

these beds the volcanic eruptions, consisting of trachyte, basalt, and other modifications of trap rocks and scoriae, have forced their way. The basalt is black, and very compact, and breaks into sharp fragments; it is frequently columnar, and the separate hexagonal pillars are made use of for posts and pavements, in the adjacent towns. Such, says Mr. Horner,* is the profusion of basaltic pillars, that the walls of the town of Linz are wholly built of these materials, placed on their sides, with the ends projecting outwards. The streets are paved with the smaller columns set on end, thus forming a miniature representation of the Giants' Causeway; and the same volcanic product forms a large proportion of the walls of Bonn and Cologne. The secondary strata are covered by a series of tertiary deposits, consisting of sand, sandstone, clay, and lignite; constituting what is termed a *brown coal formation*. Upon these deposits is an extensive layer of gravel, which is covered by a deep bed of loosely coherent sandy loam, or mud, provincially termed *Loess*. This fine earthy detritus, which contains recent species of terrestrial and fresh-water shells, forms the subsoil of the vast plains in which Bonn and Coblentz are situated, and extends as far as the falls of Schaffhausen.

### 55. BROWN COAL FORMATION.
—As the usual condition in which bituminized vegetable matter occurs in the tertiary formations, is well exemplified in the brown coal, or *lignite*, of the Rhine, it will be instructive to examine the characters of this deposit somewhat in detail; for we shall thereby obtain data which will prepare us for the investigation of the ancient carboniferous system. This formation, which is spread over a great extent of country on both sides of the river, consists of clay, sand, sandstone, conglomerates, clay and ironstone, with lignite, or bituminized wood, of

* On the Geology of the Environs of Bonn, by Leonard Horner, Esq. F.R.S. Geological Transactions, vol. iv. 1836.

§ 55.

BROWN COAL FORMATION.

various qualities, disposed in distinct beds, and intermixed
with argillaceous matter. The breadth of the ridge of low
hills, formed by this assemblage of strata on the left bank of
the Rhine, is from three to five miles, its elevation varying
from 50 to 200 feet.

The lignite occurs in the following states :—1. A black
earthy and pulverulent substance. 2. Concretionary masses,
with leaves and fragments of wood. 3. Wood in various
degrees of bituminization, and of shades of colour from a
light-brown to jet-black. 4. Very finely laminated masses
of bituminous matter and clay, of a dark chocolate colour,
and separating into elastic flakes, as thin as paper, whence
its name *papierkohle*; this substance is so highly bitumi-
nous as to burn with a bright flame. The wood is gene-
rally in small fragments, but stems of large trees, some-
what compressed, occasionally occur; in some instances the
trees are imbedded in an upright position, having the
roots attached, and the stems passing through several beds
of lignite. In many examples the wood is so little changed,
that, like the timber of our peat-bogs, it is employed in
building; in others it is highly pyritous, that is, impreg-
nated with sulphuret of iron, like the fossil vegetables of the
Isle of Sheppey.

Mr. Horner is of opinion that there were extensive fresh-
water lakes, in the sediments of which trees and plants,
drifted by land-floods, were engulfed; and that volcanic
eruptions were simultaneously going on, in the same manner
as in the modern submarine volcanoes. There is a great
fault, or dislocation, in this brown coal formation, which he
suggests may be attributed to a powerful and sudden volcanic
explosion, that probably occasioned the elevation of the Sie-
bengebirge, and raised up that portion of the coal-beds which
reposes on the flanks of those peaks. The gravel covering
the lignite, must have been strewn over the plain previously
to this elevation, for it is found on both sides of the river at

280

THE WONDERS OF GEOLOGY.

LECT. III.

a great height, and not in the intermediate plain. These
inductions are so evident as to require no comment.

The ancient alluvial deposit called the *Loess*, is a fine
loam, containing fresh-water and land shells of many
existing species; a few bones of the horse and mammoth,
are the only mammalian remains that have been discovered.*
From the extensive distribution of this bed, and its occur-
rence at various elevations—in some instances on the flanks
of mountains 1,200 feet above the level of the sea, at others
spread out over the gravel of the vast plain of the Rhine—
it is inferred, that although the *loess* has been deposited
since the existing system of the hills and valleys of the
country, yet great changes must have subsequently taken
place in the physical geography of the district; and
Mr. Lyell states that there is reason to conclude, that
since the deposition of this fluviatile loam, all the land
between Switzerland and Holland has suffered a subsidence,
and a subsequent elevation, to the amount of many hundred
feet.

56. OTHER TERTIARY STRATA OF EUROPE, NORTH AMERICA, &c.—It has already been mentioned, that strata referable to the period comprehended between the uppermost secondary formations and the human epoch, occur throughout Europe; presenting in some instances well-defined groups, with marked boundaries, and in others, vast areas, over which the deposits are irregularly spread. The geographical relations of the tertiary strata to the existing lands and seas, is an interesting subject of inquiry, but on which my limits forbid me to enter.† I may, however, observe, that Europe must have possessed many of its most striking physical characters at the commencement of the eocene period; and that its present configuration has been produced by the conjoint effect of successive mutations in

* Principles of Geology, vol. iv. p. 33.

† Mr. Lyell's Principles of Geology should be consulted.

§ 56.

TERTIARY STRATA OF NORTH AMERICA.

281

the relative level of land and water, during the deposition
of the marine and fresh-water strata, reviewed in this
discourse.

In North America the researches of Dr. Morton, Professor
Vanuxem, Mr. Lyell, and other observers, have shown that
in the territories of the United States eocene and miocene de-
posits extend over a great part of Maryland, along the coast
of New York and New England, and occur in New Jersey,
Delaware, Long Island, &c. The tertiary beds of Maryland
consist of limestone, clay, sand, and gravel, and abound in
the usual eocene shells; some of which are identical with
European tertiary species of *turritella, venericardia, fusus,
ancilla, &c.* The remains of a large cetaceous animal,
(named *Zeuglodon* from its deeply cleft teeth) are found
in great numbers in the American eocene deposits.*

*Infusorial marls of Virginia.* The towns of Richmond and Petersburg in Virginia, are built on strata of siliceous marls, which extend over considerable tracts of country, and have an aggregate thickness of more than twenty feet. These marls, whose organic composition was first detected by Professor W. Rogers, are of the older tertiary (miocene or eocene) formations. The investigations of Dr. Bailey have shown, that these earths are almost wholly made up of the siliceous cases, or shields, of infusorial animalcules, termed *Navicula, Gaillonella, Actinocyclus, Coscinodiscus, &c* : the latter especially predominate, two or three species forming a large proportion of this aggregation of minute organisms. The *Coscinodisci* (or sieve-like discs) are elegant saucer-shaped shells, elaborately ornamented with hexagonal spots disposed in curves, and resembling the engine-turned sculpturing on a watch; they vary in size from 1-100th to 1-1000th of an inch in diameter. If but a few grains of the Richmond earth are prepared for the microscope, all the varieties above specified are generally

* See Medals of Creation, vol. ii. p. 826.

282

THE WONDERS OF GEOLOGY.

LECT. III.

displayed, so largely is this marl composed of the skeletons or shields of animalcules; in fact, very few inorganic particles enter into its composition.*

57. ALTERED TERTIARY STRATA OF THE ANDES.—But striking as are the proofs already adduced of elevations and subsidences, and other effects of volcanic agency during the tertiary period, they sink into comparative insignificance, when contrasted with the enormous changes which have taken place in the great mountain chains of South America, during the same geological epoch. From the observations of Mr. Charles Darwin, we learn that an extensive tertiary system, analogous to that of Europe, skirts both flanks of the primary rocks which form the southern chain of the Andes; the latter having suffered a certain degree of elevation before the deposition of the former. These strata, which are of great thickness and extent, are separable into two groups; the lowermost beds, like those of Auvergne, repeatedly alternate with lavas, and thus denote the commencement of the eruptions of the ancient craters. Over these are accumulations of porphyritic pebbles, covered, at elevations of many hundred feet, by beds of shells of recent species; and the sides of the mountains appear like a succession of sea-beaches, which have been slowly and tranquilly lifted up. The altered character of the tertiary deposits within the influence of the igneous products,—the conversion of beds of loose pebbles into solid, compact rocks,—and the occurrence of metalliferous veins in strata of comparatively modern origin,—are facts so powerfully exemplifying the geological principles enunciated in the former lectures, that though this discourse has extended to a great length, I cannot omit Mr. Darwin's graphic description of these phenomena, as originally communicated in a letter to Professor Henslow, of Cambridge, dated Valparaiso, March 1835.

* See the Article "*Fossil Animalcules*," in Medals of Creation, vol. i. pp. 224—228.

§ 57.

TERTIARY STRATA OF THE ANDES.

283

"You will have heard of the dreadful earthquake of the 20th February. I wish some of the geologists, who think the earthquakes of these times are trifling, could see how the solid rocks are shivered. In the town there is not one house habitable; the ruins remind me of the drawings of the desolated eastern cities. We were at Valdivia at the time, and felt the shock very severely. The sensation was like that of skating over very thin ice, that is, distinct undulations were perceptible. The whole scene of Conception and Talesana is one of the most interesting spectacles we have beheld since we left England. I was much pleased at Chiloe by finding a *thick bed of recent oyster-shells capping the tertiary plain*, out of which grew large forest trees. I can prove that both sides of the Andes have risen in this recent period to a considerable height. Here the shells were 350 feet above the sea. On the bare sides of the Cordilleras, complicated dykes and wedges of variously coloured rocks are seen traversing, in every possible form and shape, the same formation, and thus proving by their intersections a succession of violences. The stratification in all the mountains is beautifully distinct, and, owing to a variety of colouring, can be seen at great distances. Porphyritic conglomerates, resting on granite, form the principal masses. I cannot imagine any part of the world presenting a more extraordinary scene of the breaking up of the crust of the globe, than these central peaks of the Andes. The strata in the highest pinnacles are almost universally inclined at an angle from 70° to 80°. I cannot tell you how much I enjoyed some of the views; it is alone worth coming from England to feel at once such intense delight. At an elevation of from ten to twelve thousand feet there is a transparency in the air, and a confusion of distances, and a stillness, which give the sensation of being in another world. The most important and most developed formation in Chili is the porphyritic concrete. From a great number of sections, I find it to be a true coarse conglomerate or breccia, which passes by every step in slow gradation to a fine clay-stone porphyry; the pebbles and cement becoming porphyritic, till at last all is blended in one compact rock. The porphyries are excessively abundant in this chain, and at least four-fifths of them, I am sure, have been thus produced from sedimentary beds in situ. The Uspellata range is geologically, although only six or seven thousand feet high, a continuation of the grand eastern chain. It has its nucleus of granite, consisting of beds of various crystalline rocks, (which I have no doubt are subaqueous lavas,) alternating with sandstone, conglomerates, and white aluminous beds, like decomposed felspar, with many other curious varieties of sedimentary deposits. In an escarpment of compact greenish sandstone,

284

THE WONDERS OF GEOLOGY.

LECT. III.

I found a small wood of petrified trees in a vertical position; or rather, the strata were inclined about 20° or 30° to one point of the trees, and 70° to the other; that is, before the tilt, they were truly vertical. The sandstone consists of many horizontal layers. Eleven of the trees are perfectly silicified, and resemble the dicotyledonous wood which I found at Chiloe and Conception; the others, from thirty to forty in number, I only know to be trees from the analogy of form and position; they consist of snow-white columns of coarsely crystallized carbonate of lime. The largest trunk is seven feet in circumference. They are all close together, within one hundred yards, and about the same level; no where else could I find any. It cannot be doubted that the layers of fine sandstone have quietly been deposited between a clump of trees, which were fixed by their roots. The sandstone rests on lava; is covered by a great bed, apparently about one thousand feet thick, of black augite lava; and over this there are at least five grand alterations of such rocks, and aqueous sedimentary deposits, amounting in thickness to several thousand feet. According to my view of these phenomena, the granite, which forms peaks of a height probably of 14,000 feet, has been fluid in the tertiary epoch; strata of that period have been altered by its heat and are traversed by dykes from the mass, and are now inclined at high angles, and form regular or complicated anticlinal lines. To complete the climax, these same sedimentary strata and lavas are traversed by very numerous true metallic veins of iron, copper, arsenic, silver, and gold, and these can be traced to the underlying granite. A gold mine has been worked close to the clump of silicified trees!"

58. TERTIARY SALIFEROUS DEPOSIT.—Not only coal, but even extensive beds of rock salt occur in the tertiary system. The celebrated salt mines of Galicia, of which M. Boué* has given an interesting description, belong to this epoch. The deposit is nearly 3000 yards long, 1066 broad, and 280 yards deep. The upper part of the mine consists of green salt, with nodules of gypsum in marl. The salt contains in some places lignite, bituminous wood, and shells. In the lower division are beds of arenaceous marls, with lignite, impressions of plants, and veins of salt; coarse sandstone, with vegetable remains; aluminous and

* Journal de Géologie.

§ 59.

RETROSPECT.

gypseous shale, and indurated calcareous marl, with sulphur, salt, and gypsum.

59. RETROSPECT.—So numerous and varied have been the phenomena presented to our notice, that a comprehensive retrospect is necessary, in order to obtain a correct idea of the highly interesting deductions resulting from this general survey of the tertiary formations.

In the newer tertiary, or pliocene, including the mammalian epoch of the last lecture, the fossil remains in the alluvial deposits afford incontestible proof that the mammoth, mastodon, hippopotamus, dinotherium, elk, and other colossal animals of extinct species and genera, together with birds, reptiles, and carnivora, inhabited such districts of our continents as were then above the waters; while the older tertiary, or eocene, inclose the bones of land animals, principally pachyderms, approximating to certain races that now exist in the torrid zone, but which belong to extinct genera. The seas and lakes of that remote epoch occupied areas, the greater part of which is now dry land; and rocks and mountains, hills and valleys, streams and rivers, diversified the surface of countries which have since been either destroyed, or entirely changed; and whose past existence is only revealed by the deposits that were accumulated in the lakes and deltas, by streams and rivers. The ocean abounded in mollusca, crustacea, and fishes, of which a large proportion is referable to extinct species. Crocodiles, turtles, birds, and insects, were contemporary with the palæotheria, and anoplotheria; and animal organization, however varied in certain types, presented the same general characters as in modern times; the extinction of species and genera being then, as now, in constant activity. The vegetable world also contained the same great divisions; there were forests of oak, elm, and beech; of firs, pines, and other coniferous trees; palms, tree-ferns, and the principal groups of our modern floras; while the water, both salt and fresh, teemed with the few

286

THE WONDERS OF GEOLOGY.

LECT. III.

and simple forms of vegetable structure peculiar to that
element.

The state of the inorganic world is not less manifest : the abrasion of the land by streams and rivers,—the destruction of the sea-shores by the waves, and the formation of beach and shingle,—the desolation inflicted by volcanic eruptions,—all these operations were then, as now, in activity. The bed of an ancient sea, containing myriads of the remains of fishes, crustacea, and shells, now forms the site of the capital of Great Britain; and accumulations of tropical fruits and plants, with remains of crocodiles, serpents, turtles, and birds, drifted by ancient currents from other climes, constitute islands in the estuary of the Thames; while the sediments of inland seas, lakes, and gulfs, teeming with the skeletons of beings which are blotted out from the face of the earth, compose the country around the metropolis of France.

Notwithstanding that the changes in the relative level of the land and sea during this epoch were numerous and extensive, one region still preserves traces of its original physical geography; and though the earthquake has rent its mountains to their very centre—though hundreds of volcanoes have again and again spread desolation over the land—and inundations and mountain torrents have excavated valleys, and chequered the plains with ravines and water-courses—yet the grand primeval features of that country remain; and we can trace the boundaries of its ancient lakes, and the successive changes which its surface has undergone, from the first outbreak of its volcanoes, to the commencement of the present state of repose. The lowermost lacustrine deposits in Auvergne, which are spread over the foundation rocks of gneiss and granite unmixed with igneous productions, mark the period antecedent to the volcanic era; while the intrusions of lava and scoriæ in the superincumbent strata, denote the first erup-

§ 59.

RETROSPECT.

287

tions of Mont Dome. The succeeding period of tranquillity
is recorded in characters alike intelligible. The slow
deposition of calcareous mud—the incrustation of successive
generations of aquatic insects, crustacea, mollusca, and
infusoria—the imbedding of the bones of mammalia, birds,
and reptiles—the accumulation of lignite and other vegeta-
ble matter—are data from which we may restore the ancient
country of Central France.

It was a region encircled by a chain of granite moun-
tains, watered by numerous streams and rivulets, and
possessing lakes of vast extent. Its soil was covered with
luxuriant vegetation, and peopled by palæotheria, anoplo-
theria, and other terrestrial mammalia; the crocodile and
turtle found shelter in its marshes and rivers; aquatic
birds frequented its fens, and sported over the surface of
its lakes; while myriads of insects swarmed in the air, and
passed through their wonderful metamorphoses in the
waters. In a neighbouring region,* herds of ruminants
and other herbivora, of species and genera now no more,
with birds and reptiles, were the undisturbed occupants of
a country abounding in palms and tree-ferns, and having
rivers and lakes, with gulfs which teemed with the inhabi-
tants of the sea; but to this district the fiery torrents of
the volcano did not extend. But to return to Auvergne;
a change came over the scene—violent eruptions burst
forth from craters long silent—the whole country was laid
desolate—its living population was swept away—all was
one vast waste, and sterility succeeded to the former
luxuriance of life and beauty. Ages rolled by—the mists
of the mountains and the rains produced new springs, tor-
rents, and rivers—a fertile soil gradually accumulated over
the cooled lava currents and the beds of scoriæ, to which
the sediments of the ancient lakes, borne down by the
streams, largely contributed. Another vegetation sprang

* The Paris basin.

828

THE WONDERS OF GEOLOGY.

LECT. III.

up—the mammoth and mastodon, with enormous deer and oxen, now quietly browsed in the verdant plains—other changes succeeded—those colossal forms of life in their turn passed away, and at length the earlier races of man-kind took possession of a country, which had once more become a scene of fertility and repose.

To those who have favoured me with their attention through this discourse, it cannot be necessary to aver, that the successive changes in organic and inorganic nature thus rapidly portrayed, are supported by proofs so incontrovertible, and traced in characters so intelligible, as to constitute a body of evidence with which no human testimony can compete. It is true that the time required for this succession of events must have extended over an immense period; but time and change are great only in relation to the beings which note them, and every step we take in geology shows the folly and presumption of attempting to measure the operations of nature by our own brief span. “There are no minds,” says Mr. Scrope, “that would for one moment doubt that the God of Nature has existed *from all eternity*; but there are many who would reject as preposterous, the idea of tracing back the history of *His works* a million of years. Yet what is a million, or a million of millions of years, when compared to eternity?”*

Germany presents us with an interesting series of analogous changes, effected in a later era. The outburst of the now extinct volcanoes of the Rhine, the accumulation of fluviatile silt over the plains, and the subsequent elevation of the whole country, show that these physical mutations were not confined to a single region or period.

In the Andes, the enormous disruptions and elevations of the most ancient as well as modern deposits, teach us, that through a long lapse of ages, the volcanic fires of South America have acted with intense energy; and yet more,

* Geology of Central France.

§ 60.

CONCLUDING REMARKS.

289

that the melting and transmutation of loose materials into compact rocks, the conversion of incoherent strata into solid stone, and even the sublimation of gold and other metals into fissures and veins, are phenomena which have taken place since our seas were peopled by mollusca of existing species. The importance of these extraordinary and interesting facts will be rendered more obvious in a subsequent lecture.

60. CONCLUDING REMARKS.—In conclusion, it will be useful to inquire, even though some repetition may be incurred, what are the legitimate inferences from the facts that have been placed before us, as to the condition of our globe and its inhabitants during the tertiary epoch? Was there, as some have supposed, an essential difference in the constitution of the earth?—was its surface more covered with lakes and marshes than now?—and did animal life more abound in those types, which are suitable to a lacustrine condition?—or have such conclusions been drawn from a partial view of the phenomena, and do the facts only warrant the inference, that certain regions which are now dry land, were in ancient times submerged beneath the sea, or covered by vast lakes; and that there may have existed contemporaneously, as great an extent of dry land as at present, in areas now buried beneath the ocean?—In the fossilized remains of the population of the tertiary lands and waters, we find all the grand types of the existing faunas—terrestrial, lacustrine, and marine mammalia—herbivora, carnivora, birds of every order, and of numerous species and genera—reptiles, fishes, crustacea, insects, zoophytes, and even those living atoms, the infusoria—in short, all the leading divisions, and subdivisions of the animal creation. In the vegetable world the same general analogy is maintained; and as all these varied forms of being required corresponding physical conditions, we have at once conclusive evidence that the general constitution of the earth,

U

290

THE WONDERS OF GEOLOGY.

LECT. III.

and the correlation between the organic and inorganic kingdoms of nature, during the tertiary epoch, were essentially the same as at present. Dry land and water, continents and islands, existed then, as now,—their geographical distribution may have varied,—the temperature in certain latitudes may have been much higher,—fertile countries may have occupied areas now covered by water, and marshes and fens have prevailed in regions now arid and waste; but the same agents of destruction and of renovation were then in as constant activity as at present. It is true that immense numbers of large mammalia lie buried in regions where such creatures could not now find subsistence, and in latitudes where the climate is at this time unsuitable to such forms of organization. But some of these apparent anomalies may be explained by the fact, that the alluvial beds in which these remains occur cannot have been the sites of the dry land on which these extinct beings existed; they are the sediments of ancient lakes—the deltas of former rivers—the estuaries of seas—they are formed of the detritus of the land transported from a distance, and spread over areas then submerged beneath the waters. If the Gulf-stream annually strews the shores of the Hebrides with the fruits of torrid climes, the currents of the ancient seas must have produced analogous results; and in our attempts to interpret past changes, it must not be forgotten that they have most probably been produced by causes similar to those which are still in action. I do not question the assumption, that some of the countries containing these fossil remains, may have enjoyed a milder climate during the tertiary ages than at present; or that in still more ancient periods there may not have prevailed a much higher temperature; but it appears to me, that the variation of climate which a change in the relative distribution of the land and water would occasion, as suggested by Mr. Lyell,*—and a difference in the radiation of heat

* Principles of Geology, vol. i. chap. vii.

§ 60.

CONCLUDING REMARKS.

291

from internal sources, as explained by Sir J. Herschel and Mr. Babbage,—may account for all the phenomena of this nature, which our examination of the tertiary formations has revealed.

The occurrence of groups of animals of the same families, in certain districts, is in strict conformity with the distribution of living species in regions not under the control of man. Thus when ancient France presented a system of lakes, animals fitted for such physical conditions found there the means of subsistence—when the vast plains and forests of America were adapted for colossal mammalia, there the mastodon and the mammoth obtained food and shelter—and when the former continent of Europe swarmed with herbi-vora, the carnivorous tribes, as the lion, the tiger, and the hyena, obtained the support which their habits and economy required.

One striking feature in the events that have passed in review before us, is the immense scale on which the extinction of species and genera seems to have been effected: but it must be remembered, that our observations have extended over periods of vast duration, and that we have been contemplating the aggregate effects of a law, which even in modern times has produced, and is still producing, great and important modifications in the system of animated nature. In our attempts to penetrate the mystery which veils the early scenes of the earth's physical history, by a reference to the effects of the laws which now govern the organic and inorganic kingdoms of nature, the caution of the illustrious philosopher Playfair, should be ever present to our minds:—“If existing causes appear to be inadequate to the effects produced, it may be only that, in respect to man, their movements are too slow to be perceived. The utmost portion of the progress to which human experience can extend, is evanescent in comparison of the whole, and must be regarded as the momentary increment of a vast

U 2

292

THE WONDERS OF GEOLOGY.

LECT. III.

progression, circumscribed by no other limits than the
duration of the world. Time performs the office of inte-
grating the infinite small parts of which the progression is
made up—it collects them into one scene, and produces
from them an amount far greater than any that can be
assigned from human observation.” *

Thus the tertiary epoch displays to us a state of the
globe replete with life: the physical constitution of the
earth's surface, and the condition of the land and sea, being
adapted to the habits and economy of beings of the same
types of organization as those which exist at the present time.
In the most ancient periods certain forms of life prevailed,
and gradually became extinct, and were succeeded by others
which in their turn also passed away; and in tracing the
varying types of vitality from the earliest ages, we perceive
a gradual approach to the present condition of organic
nature, in the contemporaneous existence of extinct forms
with those which now exist; the grand line of separation
between the present and the past being the creation of the
human race. From that era, in proportion as Man has
extended his dominion over the earth, many races of animals
have been either exterminated, or modified, by his caprices
or necessities; and it cannot be doubted, that in the lapse
of a few thousand years, vast changes will be effected by
human agency alone, in the geographical distribution and
relative numerical proportion of many of the existing genera
and species of animals.

* Illustrations of the Huttonian Theory.

LECTURE IV.

PART I.

1. Introductory. 2. Formations of the Secondary Epoch. 3. Cretaceous Formation.

4. Chalk Downs. 5. Flint nodules and veins. 6. Organic remains in flint.

7. Animalcules in flint. 8. Xanthidia. 9. Middle and Lower groups of the cretaceous strata. 10. Folkstone Cliffs. 11. Cretaceous strata of Mæstricht.

12. The Mosasaurus. 13. Cretaceous deposits of other countries. 14. Organic remains of the Chalk Formation. 15. Fossil vegetables. 16. Zoophytes of the Chalk. 17. Animalculites of the Chalk. 18. Chalk Rotaliæ. 19. Chalk detritus at Charing. 20. Spirolinites. 21. Crinoidea of the Chalk. 22. Star-fish.

23. Echinites. 24. Shells of the Chalk. 25. Cephalopoda. 26. The Nautilus.

27. Ammonites. 28. Turrilites and Hamites. 29. The Belemnite. 30. Crustaceans of the Chalk. 31. Fishes of the Chalk. 32. Scales of Fishes. 33. Teeth of Sharks. 34. Hypsodon and other fishes. 35. Fossil Salmon. 36. The Macropoma.

37. Beryx, and other fishes of the Chalk. 38. Reptiles of the Chalk. 39. Fossil Turtles. 40. Summary.—Tabular arrangement of Sussex Chalk fishes.

1. INTRODUCTORY.—The knowledge we have acquired from our investigation of the phenomena described in the previous lectures, will materially facilitate our geological progress, by enabling us to comprehend the former effects of those physical agencies, by which the surface of the earth has been perpetually renovated, and maintained in a suitable condition for the existence of successive races of animated beings.

The elevation of the beds of seas and rivers, and their conversion into fertile countries—the submergence of islands and continents beneath the waters of the ocean—the rapid formation of conglomerates from shells and corals on the sea-shore—the accumulation of beach and gravel, and

294

THE WONDERS OF GEOLOGY.

LECT. IV.

the inhumation of animals and vegetables—the slow deposition of sediments by lakes and rivers—the imbedding of innumerable generations of insects, and the formation of limestone from their almost invisible skeletons—the construction of solid stone out of fragments of bones and rocks, shivered by earthquakes—the engulfing in estuaries and inland seas, of land animals, birds, and reptiles—the conversion of organic and inorganic substances into rock, from the infiltration of flint and lime by thermal waters—the transmutation of submerged forests into coal and lignite—the destructive and conservative effects of volcanic eruptions—the consolidation of sand, gravel, and clay, into indurated masses by heat—and the production of metal-liferous veins of gold and silver—all these phenomena have passed in review before us, although our inquiries have extended through periods which, however vast and remote in relation to the records of our race, are but brief and modern in the physical history of our planet.

The geological events previously described, though forming a connected series, may be divided into periods, each of which is marked by certain zoological characters; namely, 1st. The *Modern*, or *Human Epoch*; 2d. The *Elephantine*, characterized by the preponderance of large pachydermata; 3d. The *Palæotherian*, in which animals allied to the tapirs prevailed, and Europe presented a system of gulfs and lakes.

2. FORMATIONS OF THE SECONDARY EPOCH.—We proceed to the consideration of an antecedent epoch,—that which comprehends the Secondary Formations. Hitherto our attention has been principally directed to deposits confined within comparatively limited areas, as the basins of lakes, gulfs, estuaries, and inland seas; and the superficial accumulations of drifted materials, produced by the action of torrents, rivers, icebergs, glaciers, inundations, &c. We have now arrived on the shores of that ocean, of whose spoils the

§ 2.

295

existing islands and continents are principally composed; the fathomless depths of the ancient seas are spread before us, and the relics of innumerable myriads of beings which lived and died in their waters, and became entombed in their profound abysses, remain, like the mummies of ancient Egypt, the silent yet eloquent teachers of their own eventful history.

A reference to the Tabular Synopsis (p. 200), will show that the secondary formations constitute ten principal subdivisions; viz. the *Cretaceous*, *Wealden*, *Oolitic* and *Liassic*, *Triassic*, *Permian*, *Carboniferous*, *Devonian*, *Silurian*, and *Cumbrian* systems, each containing littoral, and oceanic deposits; sandstones having been formed amidst the agitated waters of the sea shores; clays in tranquil bays and gulfs; and limestones in deep water. I purpose, in the present discourse, to explain the geological characters of the first two of the series, namely, the **CHALK** and the **WEALDEN.**\* The former is composed of rocks that have been accumulated in the depths of a sea of great extent; the latter, of the sediments of a vast delta; the one affording a striking illustration of the nature of *oceanic*, and the other of *fluviatile* deposits. As both the Chalk and the Wealden are fully developed in the south-east of England, the phenomena about to be described may be readily examined, and collections of the peculiar fossils of these formations obtained, with but little trouble.†

\* The term Wealden is derived from the German *Wald*, signifying a Wood or Forest. The *Weald* of Sussex was formerly an impenetrable forest, called *Anderida* by the Romans, and *Andreadswald* by the Saxons.

† Since the earlier editions of this work, the Author's extensive collection of the Fossils of the south-east of England has been purchased by the Trustees of the British Museum. A brief compendium of its contents was published by the Sussex Royal Institution, under the title of "Descriptive Catalogue of the Mantellian Museum at Brighton," 8vo. Brighton, 1836: fifth edition.

296

THE WONDERS OF GEOLOGY.

LECT. IV.

3. THE CRETACEOUS OR CHALK FORMATION.—The pure white limestone called *Chalk*, is known to every one; but in the nomenclature of geology, the term is applied to a group of deposits very dissimilar in lithological composition, but agreeing in the nature of the organic remains which they contain, and evidently referable to the same geological epoch. The series essentially consists of green and ferruginous sands, clays, marls, and grey and white limestones, abounding in marine remains. With this explanation it will be convenient to employ the term in its extended sense. The Chalk Formation comprises the following principal subdivisions :—

<table><tr><td>1. Upper chalk, with flints</td><td></td><td>Craie blanche of the French Geologists.</td></tr><tr><td>2. Lower chalk, without flints</td><td></td><td>Craie tufée.</td></tr><tr><td>3. Firestone,</td><td>Chalk marl</td><td></td></tr><tr><td></td><td>Upper green sand, or Glauconite</td><td>Glaucée crayeuse.</td></tr><tr><td>4. Galt, or Folkstone marl</td><td></td><td></td></tr><tr><td>5. Greensand, or Shanklin, or Lower-green-sand</td><td></td><td>Glaucée sableuse.</td></tr><tr><td></td><td></td><td>Terrain Néocomien.</td></tr></table>

The *Chalk* is generally white, but in some countries is of a deep red, and in others of a yellow colour; nodules and veins of flint occur in the upper division, but seldom in the lower chalk of England. The *Marl* is an argillaceous limestone, which is very constantly found underlying the chalk; the lower beds contain a large intermixture of green sand, and form a coarse calcareous sandstone, called *Firestone*. The *Galt* is a stiff, dark blue clay, abounding in shells, which, as in most argillaceous beds, retain their pearly investment unimpaired in lustre. The *Greensand* is a triple alternation of sands and sandstone with clays; with beds of chert and fuller's earth in some localities.

On the Continent the cretaceous deposits are largely developed; and taken as a whole, the chalk formation may be described as extending over a great part of the south-east of

§ 3.

THE CRETACEOUS FORMATION.

297

England, Northern France, Germany, Denmark, Sweden, European and Asiatic Russia, and of the United States of North America. Over this vast extent, the organic remains present certain general characters, sufficiently precise to determine the nature of the deposits. Whether imbedded in pure white limestone, coarse sandstone, blue clay, loose sand, or compact rock, the fossils consist, for the most part, of species of the same genera of shells, corals, sponges, echinites, belemnites, ammonites, and other marine animal exuvæ; fishes, reptiles, wood, and plants. The white chalk strata extend along a great part of the Hampshire, Sussex, and Kentish coasts; the precipitous headland of Beachy Head, and the cliffs at Dover are well known; these natural sections exhibit the manner in which the beds have been displaced, and thrown into various inclined positions.*

Along the southern coast of the Isle of Wight, the entire series comprised in the Cretaceous formation is exposed to view; and the characters and relations of the various deposits may be studied with facility, either on the south-eastern or south-western coasts of the "beautiful island." The white chalk strata, thrown into a nearly vertical position, and boldly displayed, on the east at *Culver Cliff*, and on the west at the *Needles*, traverse the island from east to west; being covered on the north by tertiary deposits. In Sandown Bay, the strata have an anticlinal position,† and on each side the axis of elevation, the several members of the Chalk, namely the greensand, galt, firestone, marl, and chalk, appear in their

* See The Fossils of the South Downs, or Illustrations of the Geology of Sussex, 1 vol. 4to. with 42 plates. Geology of the South-East of England, 1 vol. 8vo. Medals of Creation. Geology of the Isle of Wight.

† *Anticlinal:* a term applied to strata which incline or dip towards each other, or from a central axis, like the ridge-tiles on the roof of a house.

298

THE WONDERS OF GEOLOGY.

LECT. IV.

natural order of succession. A similar section is seen
in Compton Bay; while along the Undercliff, fallen masses
of the upper beds, intermingled with detritus, form the
ruinous cliffs of that picturesque tract; and beyond, at
Black-gang and Atherfield, the greensand series constitutes
the line of coast; the Wealden forming the cliffs in Brixton
and Brook bays; but the details of this interesting district
are so fully given in my recent work,* that I need not
enter at length upon the subject.

4. **CHALK DOWNS.**—The features of a chalk district are very peculiar, when the surface has not been broken up for tillage, or is not concealed by dense woods and forests. The rounded summits of the hills clothed with short verdant turf—the smooth undulated outlines of the Downs, unbroken save by the sepulchral mounds of the early inhabitants of the country—the coombes and furrows, ramifying and extending into the deep valleys which abruptly terminate at the base of the hills, and appear like dried up channels of rivulets and streams, though free from all traces of alluvial debris; thus bearing the impress of physical operations of which the agents that produced them have long since passed away—are phenomena that must be familiar to every one who has travelled over the downs of the south-east of England. These features are restricted to the hilly districts where the *white-chalk* forms the subsoil, and have resulted from the peculiar nature of the sedimentary detritus of which the strata comprised in the upper division of the cretaceous system are composed. For where the lower group of clays, marls, sands, and sandstones approaches the surface and forms the subsoil, the country is broken and diversified, and the landscape presents a striking contrast with the down scenery.

* Geological Excursions round the Isle of Wight and along the adjacent Coast of Dorsetshire, 1 vol. 8vo. with numerous illustrations, sections, map, &c. H. G. Bohn, London, 1847.

§ 4.

CHALK DOWNS.

299

The upper division of the cretaceous system is composed of beds of a very peculiar white limestone, varying in thickness from a few inches to several feet. In the *Upper Chalk* there are numerous parallel rows of siliceous nodules, termed flints, disposed in irregular distances from each other; and in some places sheets or seams of flint are intercalated between the chalk strata, and extend over considerable areas. The chalk is also traversed by vertical and diagonal veins of flint. The only metallic substances are oxide of manganese, in the state of dendritic or arborescent markings; and oxides and sulphurets of iron. Iron-pyrites frequently constitutes the casts of shells, echini, &c.—the surface of the mineral retaining sharp imprints of the external characters of the original.

The white chalk is composed of lime and carbonic acid; and a microscopical analysis proves it to be a mere aggregation of shells and corals, so minute that upwards of a million are contained in a cubic inch of the rock; the

LIGN. 50.—CHALK-DUST; highly magnified, seen by reflected light.

a, a. Rotaliæ. b. Textilariæ.

(From "Thoughts on a Pebble.")

amorphous particles appear to be the detritus of similar structures, and not a chemical precipitate. The appearance of a few atoms of chalk-dust, under a highly magnifying power, is shown in this figure (Lign. 50). These organisms are the

300

THE WONDERS OF GEOLOGY.

LECT. IV.

calcareous cases and shells of the animalcules termed *Fora-
minifera,* which swarm in inconceivable numbers in our
present seas, and are daily and hourly contributing to the
amount of sediment now accumulating in the bed of the
ocean.

5. FLINT NODULES AND VEINS.—The *flints* (as the siliceous nodules are generally termed) occur in horizontal rows or layers, generally parallel with the lines of stratification of the chalk, but placed at unequal distances from each other. They are of all sizes, from that of a small nut to masses several feet in circumference. But besides these parallel beds, there are sheets of flint intercalated between the chalk strata, and covering areas, often many miles in extent. These continuous layers are termed tabular flint; they are seldom more than two or three inches in thickness, and veins and threads of silex frequently ramify from them into the fissures of the surrounding chalk. This tabular flint is generally solid throughout, but sometimes incloses a layer of chalky matter, full of the usual minute organisms of the chalk. Vertical and diagonal veins of flint filling up crevices and fissures in the rock, and traversing both the strata of limestone and any sheets of tabular flint that may be interposed, are of common occurrence; these prove that the lower beds were consolidated, and had subsequently been fissured, before the superimposed strata were deposited, and the streams of siliceous matter flowed over them.

The nodules and veins of flint that are so abundant in
the upper chalk, have probably been produced by the
agency of heated waters and vapours. The perfect fluidity
of the siliceous matter before its consolidation, is proved
not only by the sharp moulds and impressions of shells, &c.
retained by the flints, but also by the presence of numerous
organic bodies in the substance of the nodular masses, and
the silicified condition of the sponges and other zoophytes

* Medals of Creation, vol. i. p. 228.

§ 6.

ORGANIC REMAINS IN FLINT.

301

which swarm in some of the cretaceous strata. For though silex or the earth of flint is insoluble in boiling water, its solution, as we have previously stated (p. 93), readily takes place in vapour heated to a temperature above that of fused cast-iron (p. 100); and similar effects are being produced at the present moment by the thermal waters of active volcanoes (p. 98).

The temperature to which water may be raised, depends on the presence or absence of air; for it has been proved by direct experiment that water deprived of air may be heated to 275° of Fahrenheit, under the ordinary pressure of the atmosphere, without exhibiting any symptoms of ebullition. The solvent power of water on rocks containing silex may, therefore, be fully adequate to produce all the phenomena presented by the siliceous nodules, veins, dikes, &c. of the chalk formation; and our chalk flints may possibly have originated from the quartz of granitic and other plutonic rocks, dissolved in heated water, and erupted into the basin of the ancient chalk ocean.

6. ORGANIC REMAINS IN FLINT.—In many instances the organic remains in chalk flints are simply incrusted by silex: such is the state of numerous sponges which are as it were invested by the flint, and have their pores and tubes filled by the same material; the original tissue appearing as a brown earth. In other examples the sponge has been enveloped by a mass of liquid silex, and subsequently perished; in this manner have been formed those hollow nodules, which on being broken present a cavity containing only a little white powder, or some fragments of silicified sponge: while in other instances the cavity is lined with quartz or chalcedony. It frequently happens that only part of the zoophyte is permeated by silex, while the other portion is in the state of a friable calcareous earth impregnated with the chalk.

Sponges and other organic bodies often form the nuclei

302

THE WONDERS OF GEOLOGY.

LECT. IV.

of flint nodules, and the original substance of the fossil
is generally silicified, and the most delicate internal
structure preserved. In other instances the inclosed or-
ganisms have undergone no change, but appear as if
immersed and preserved in a semi-transparent medium;
such is the state in which foraminiferous shells, corals, &c.
often occur. An exquisite example of this kind was
discovered by the Marquess of Northampton, in a chalk
flint from Brighton; in polished slices of this specimen,
numerous branches of delicate corals (*Pustulopora, Rete-
pora, Idmonea, &c.*) and foraminifera, appear as perfect
and unaltered as if imbedded in glass.

But there are innumerable flint nodules which exhibit
no traces of spongeous structure; and veins, dikes, and
sheets of tabular flint, that may be regarded as pure, and
free from organic remains, excepting such as must inevitably
have become entangled and imbedded in a stream of mineral
matter flowing over a sea-bottom. Wood which has been
perforated by lithodomi, and silicified, is not scarce; and
confervæ and fuci are sometimes found floating, as it were,
in the liquid silex. Bones of reptiles and fishes are often
impacted in a mass of flint; but in only one instance have
I observed that the silex has permeated the osseous
structure.

7. ANIMALCULES IN FLINT.—For the most part, the
minute shells of the chalk and flint are filled with amorphous
mineral matter; but in many examples, as I have ascer-
tained by direct experiment,† the soft parts or body of the
animalcule remain in the shell; sometimes completely silici-
fied, but in others in the state of *dried animal membrane,*
like the ink-bag of the cuttle-fish in lias, the soft parts of

* Medals of Creation, vol. i. p. 284.

† See my observations "On the Fossil Remains of the soft parts of *Foraminifera*, discovered in the chalk and flint of the S. E. of England." Philosophical Transactions, 1846, part iv.

§ 7.

ANIMALCULES IN FLINT.

303

cephalopoda in clay, and the capsule of the eye and membranes of the stomach in certain fishes of the chalk.* In the flints such specimens are by no means rare, and from the semi-transparency of that mineral, are easily detected under the microscope. The annexed figure (Lign. 51)

LIGN. 51.—THE SHELL OF A ROTALIA, CONTAINING THE FOSSILIZED REMAINS OF THE BODY OF THE ANIMAL; IN FLINT (highly magnified).†

represents the body of a *Rotalia*, in its shell, imbedded in flint; the original is invisible to the naked eye, but under a good microscope its structure is beautifully defined; the

* I would refer the general reader, who is not conversant with the various conditions in which the remains of vegetables and animals occur in the mineral kingdom, according to the circumstances under which they were originally imbedded, and the chemical changes they may have subsequently undergone, to my remarks "*On the Nature of Fossils or Organic Remains,*" Medals of Creation, vol. i. chap. iii. See also "*Instructions for the collecting of Fossils,*" vol. ii. p. 885.

† Specimens of the Rotaliæ, Xanthidia, and other minute fossil organisms of the chalk and flint, may be obtained of Mr. Topping, the well-known microscopic artist, No. 1, York Place, Pentonville Hill, London. See Medals of Creation, vol. i. pp. 78, 244, for "*Instructions how to prepare Fossils for the Microscope.*"

304

THE WONDERS OF GEOLOGY.

LECT. IV.

folds of the membrane in the cells being as obvious as in a specimen obtained from the sea.

The shells of the Rotaliæ and Textilariæ in the chalk, also contain the desiccated soft parts of the animalcules unmineralized; and by dissolving the chalk and shells in weak hydrochloric acid, and immersing the residue in a transparent medium (*Canada balsam*), the tissues are as distinctly seen as in the recent state. I shall again refer to this subject when treating of the organic remains of the cretaceous system. In this place, however,

I would call your attention to an ex-
quisite example of the preservation
of the soft parts of an animalcule in
flint. The fossil here delineated (*Lign.*
52) was discovered by my friend the
Rev. J. B. Reade,* a gentleman well
known for his accurate microscopic
investigations. It is evidently a coral,
from the cell of which a polype pro-
truded, when it became enveloped in
the fluid silex: with the exception of
the tentacula, which appear either to
have perished, or to have collapsed
so as not to be distinguishable, the
form and structure of the original are
admirably preserved.

LIGN. 52.
A CORAL-POLYPE, in flint,
(magnified 500 diameters).

8. XANTHIDIA.—The minute microscopic spherical bodies, to which Ehrenberg has given the name of *Xanthidia*, from the supposition of their analogy to the spores of certain kinds of *Desmideæ*,† are so abundant in the flints, that I must briefly notice them in this place. These fossils occur both in the chalk and flint; and though generally

* Rector of Stone, Bucks.

† *Desmideæ:* a group of organisms of doubtful affinity; being considered by some naturalists as vegetable, by others as animal structures.

§ 8.

XANTHIDIA IN FLINT.

305

silicified, have been detected unmineralized in the chalk, and
as flexible as the soft parts of the rotaliæ.*

The fossil Xanthidia, (the true nature of which is,
I think, still problematical,) are hollow globular or spherical
bodies, beset with spines or tubular processes, which, in
many species, are fimbriated at the extremities, and vary
considerably in number and length. Some species (*Lign.
53*), have these appendages very long, and their extremities

patulous and fimbriated. In
a rare species (discovered
by my son), the spines are
short, equal, and relatively
thick (*Lign. 54, fig. 5*); in
others they are interme-
diate in length, proportions,
and number (as in *Lign. 54,*
*fig. 4, 6*). The manner in
which these bodies occur in
the flint, is shown in the
example figured in *Lign.
54*; which is a thin chip
containing five Xanthidia,
that was broken off at ran-
dom from a nodule. The
specimen is represented of

the natural size in *fig. 1*; slightly magnified as seen by
transmitted light in *fig. 2*; and under a higher power in
*fig. 3*; the fragment having been previously rendered
as transparent as glass by immersion in Canada balsam.

LIGN. 53.—XANTHIDIUM PALMATUM.
(Drawn by Rev. J. B. Reade; magni-
fied 500 diameters.)

* The Xanthidia were first discovered in this state by Mr. Deane, of Clapham, an able microscopic observer, to whom I am indebted for my choicest specimens of the soft parts of Rotaliæ. See Philos. Trans. 1846, p. 466.

X

306

THE WONDERS OF GEOLOGY.

LECT. IV.

*Figs. 4, 5, 6, represent the three best defined specimens highly magnified.*

LIGN. 54.—XANTHIDIA IN FLINT.

(By Reginald Neville Mantell.)

Fig. 1. A thin, transparent, chip of flint; natural size.

2. The same magnified, viewed by transmitted light.

3. More highly magnified.

4. *Xanthidium ramosum*; one of the animalculites seen in the previous figures, magnified 300 diameters.

5. *Xanthidium Reginaldi*; from the same group: a very rare species.

6. Another variety of Xanthidium ramosum.

9. MIDDLE AND LOWER GROUP OF THE CHALK FOR- MATION.—Beneath the Chalk with flints, is a series of strata of equal thickness, termed the *Lower Chalk*, in which no flints are met with in England, except in a few localities; in some places on the Continent, however, nodules

* The Xanthidia which occur in the English chalk flints, were first noticed and figured by the Rev. J. B. Reade, in the Annals of Nat. Hist. 1838; they have since been made the subject of an elegant memoir, published in the Transactions of the Microscopical Society of London, vol. i. p. 77, by H. Hopley White, Esq. of Clapham. A specimen from chalk, by Mr. Deane, is figured in Philos. Trans. 1846, Pl XXI. fig. 1.

§ 11.

FOLKSTONE CLIFFS.

309

part (Lign. 55). Eastware Bay, near Folkstone, is celebrated for the beauty and variety of the Galt fossils, which are constantly being washed out of the cliff by the action of the sea.

This series may be traced with more or less distinctness around the denudation of the Wealden, encircling the freshwater strata. The lowermost member, the Greensand, rises into more importance towards the west; and in Surrey, Hampshire, and western Sussex, forms a line of bold hills, which runs parallel with the chalk downs, and rivals them in altitude; a valley of galt generally intervenes between the sand and chalk, as at Reigate. Along the Kentish coast the three natural subdivisions of the greensand are clearly defined. The upper, or Shanklin sand series, is chiefly made up of ferruginous sands, with ironstone and concretions of chert, and dark clays in the lower part. The middle group is marked by the prevalence of green and grey sand, with bands of calcareous sandstone and cherty limestone, called Kentish rag. The lowermost, or Atherfield series, consists principally of sandy argillaceous beds, with layers of concretionary limestone, containing numerous peculiar fossils. The Shanklin and Atherfield deposits are so named from localities in the Isle of Wight where they are developed in great thickness and extent.*

In the north-east of Ireland the greensand constitutes an important feature; on the Continent it is found accompanying the upper members of the chalk formation, and is well displayed in Saxony, and along the Alps and Carpathian mountains.

11. CRETACEOUS STRATA NEAR MAESTRICHT.—In the valley of the Meuse there is a series of strata, the uppermost beds of which contain many shells that occur also in the tertiary; these deposits pass downwards into lime-

* See my Geology of the Isle of Wight for details; chap. vi.

310

THE WONDERS OF GEOLOGY.

LECT. IV.

stones with numerous flint nodules, and cretaceous fossils;
and these imperceptibly blend with the pure white chalk at
the bottom. These strata are well shown on the banks of
the Meuse, and fossils may be obtained in abundance from
the extensive quarries, which have been worked for ages.
St. Peter's Mountain, in which these excavations are
situated, is a cape or headland between the Meuse and
the Jaar, formed by the extremity of a range of hills which
bounds the western side of the river valley. The moun-
tain commences at the distance of a mile south of Maes-
tricht, and extends in a direction towards Liège for about
three leagues; it presents an almost perpendicular escarp-
ment towards the Meuse. A section of the hill affords the
following succession of strata :—

1. Lowermost : *White chalk*, with layers of flint nodules.

2. Chalk, very hard and gritty.

3. *Calcareous freestone*, and beds of loosely aggregated sand, of a yellow fawn colour, abounding in fossils. Numerous layers of flint occur throughout the entire series, having the usual characters of the siliceous nodules of the chalk.

The Maestricht freestone is so extremely soft in the
quarry, that it may easily be cut with a knife, but it
hardens and becomes of a lighter colour by exposure to the
air.* The beds of limestone have a total thickness of
about 500 feet. Excavations have for centuries been
carried on in the strata of freestone, and from the immense
quantities of stone removed, extensive caverns and galleries
now traverse the heart of the mountain. Shells, corals,

* The avidity of collectors has induced the quarrymen to practise an ingenious fraud upon strangers : teeth and bones of the horse, boar, &c. are carefully imbedded in blocks of the limestone while it is soft; and when the stone becomes hard, the specimens are offered for sale as genuine fossils from the quarries; the deception may be detected by immersing them in water.

§ 12.

THE MOSASAURUS.

311

crustacea, teeth of fishes, and other marine remains, occur
in profusion; with wood perforated by lithodomi, and the
bones of a large and very remarkable reptile.*

12. THE MOSASAURUS; OR FOSSIL REPTILE OF THE MEUSE.—The occasional discovery of bones and teeth of an unknown animal in the limestone, had long since directed the attention of naturalists to the quarries of St. Peter's Mountain. In 1770 M. Hoffmann, who was forming a collection of organic remains, had the good fortune to

LIGN. 56.—REMAINS OF THE MOSASAURUS.

Discovered at Maestricht, by M. Hoffmann, in 1770; now in the Museum at Paris
(Four and a half feet by two and a half.)

discover a specimen, which has conferred additional interest
on this locality. Some workmen, on blasting the rock in
one of the caverns of the interior of the mountain, perceived,

* See Hist. Nat. de la Montagne de St. Pierre, by Faujas St. Fond, 1 vol. 4to. with splendid engravings, and numerous figures of the fossils that have been discovered in the quarries of St. Peter's Mountain.

312

THE WONDERS OF GEOLOGY.

LECT. IV.

to their astonishment, the jaws of an enormous animal
attached to the roof of the chasm. The discovery was
immediately made known to M. Hoffmann, who repaired
to the spot, and for weeks presided over the arduous task
of separating from the rock the mass of stone containing
these remains. His labours were at length repaid by the
successful extrication of the specimen, which he conveyed
in triumph to his house. Unfortunately, the Canon of the
Cathedral which stands on the mountain, claimed the fossil
in right of being lord of the manor, and succeeded, by a
most unjust and expensive law-suit, in obtaining this pre-
cious relic. It remained in his possession for years, and
Hoffmann died without regaining his treasure, or receiving
any compensation. The French Revolution broke out, and
the armies of the Republic advanced to the gates of Maes-
tricht; the town was bombarded, but by desire of the
committee of savans, who accompanied the French troops,
the artillery was not allowed to play on that part of the
city in which the celebrated fossil was known to be con-
tained. In the meanwhile the Canon, shrewdly suspecting
why such peculiar favour was shown to his residence,
concealed the specimen in a secret vault; but when the
city was taken, the French authorities compelled him to
give up his ill-gotten prize, which was immediately trans-
mitted to the Jardin des Plantes, at Paris, where it still
forms one of the most striking objects in that magnificent
collection.

The model of this specimen in my museum* was pre-
sented to me by Baron Cuvier; it consists of the jaws,
teeth, palate-bones, vertebræ, and os quadratum; a bone
possessed by some reptiles, and in which the auditory cells
are contained. There are some fine portions of jaws with
teeth of the Mosasaurus in the British Museum. The
original was a reptile, holding an intermediate place between

* Now in the British Museum.

§ 13. CRETACEOUS STRATA OF OTHER COUNTRIES.

the *Monitor* and *Iguana*, about twenty-five feet long; it was furnished with a tail of such construction, as must have rendered it a powerful oar, enabling the animal to stem the waves of the ocean, of which Cuvier supposes it to have been an inhabitant.

In the English chalk a few remains of this reptile have been met with. I collected three vertebræ from the upper chalk near Lewes, many years since;* and have recently obtained a caudal vertebra from Kemp-town, near Brighton; the latter is partially invested with flint, which has consolidated around it without obscuring its essential characters.

Some teeth, from North America, collected by Dr. Morton of Philadelphia, appear to be of the same species as those from Maestricht, and afford additional proof of the extension of the waters of the chalk ocean over the area now occupied by the Atlantic, and part of the dry land of North America.†

13. CRETACEOUS STRATA OF OTHER COUNTRIES.—In the north of France the same characters predominate; but in the south, the group is more or less calcareous throughout; and the lower division, which is the representative of our greensands and clays, consists of calcareous beds, with white limestone and tufaceous marlstone.

In Central and Eastern Germany the entire system is more siliceous, calcareous matter being very sparingly distributed. In Saxony it consists of siliceous sandstone—conglomerates, chert, and ferruginous sand and sandstone—calcareous grit containing the well known galt shell, *Inoceramus concentricus*—and calcareous rock with hamites, scaphites, terebratulæ, and plagiostoma; the uppermost strata yielding a siliceous building stone.

* Fossils of the South-East of England, p. 146.

† See Dr. Morton's Synopsis of the Cretaceous Strata of the United States.

314

THE WONDERS OF GEOLOGY.

LECT. IV.

In Russia the white chalk is finely developed in the southern steppes of the Don Cossacks;* and Artesian wells have been carried to a depth of 630 feet through these strata, without indicating any change of rock. The chalk at Uspensk lies in hollows of the carboniferous system, and contains many well known English cretaceous shells. In the royal collection at Warsaw are echinoderms and shells from the Polish chalk, identical with our common species: even the *Choanites Königi* occurs in the flints, as in those of the South Downs.† Sir R. Murchison observed true chalk on the banks of the river Ural, the extreme boundary of the Russian Empire. On the Volga the white chalk passes through a group of clay-stones and shales, into tertiary eocene strata. The surface of the chalk of Russia is no where eroded as in Western Europe.

In North America, the deposits which appear to be the equivalents of the lower members of the British series, contain numerous fossils of the cretaceous types, and a few species which are identical. The chalk strata of New Jersey, that intervene between the Alleghany mountains and the Atlantic, resemble the sandy and argillaceous beds of our galt and greensand. The overlying tertiary consist of marly clays, and variously coloured sands, with green particles, as in the bottom of the London clay near Reading. Such is for the most part the character of the series in New Jersey: and further south, in Maryland and Virginia, the eocene strata are as full of green particles as the cretaceous, and can only be distinguished by their fossils, and geological position. ‡

* Geology of Russia, vol. i. p. 265. All the remarks relating to the Geology of Russia are derived from Sir R. I. Murchison's work.

† Medals, vol. i. p. 264.

‡ See Mr. Lyell's Remarks on the Cretaceous Strata of New Jersey, in his Travels in North America. Also Prof. Rogers's Address to the Association of American Geologists. 1844.

§ 14. ORGANIC REMAINS OF THE CHALK FORMATION.

14. ORGANIC REMAINS OF THE CHALK FORMATION.—
I would remind the reader, that the numerous groups of
strata comprised in the cretaceous system, are to be
regarded as an ancient ocean-bed ;—a vast accumulation
of sedimentary deposits, more or less consolidated by sub-
sequent chemical changes, that was formed in the profound
depths of the sea, in periods of unfathomable antiquity.
This mass is made up of inorganic and organic materials :
the former consist of the debris of the cliffs and shores which
encompassed the ancient sea; of the spoils of islands and
continents brought into the ocean by floods and currents of
fresh water; and of mineral deposits thrown down from
chemical solutions: the *organic substances* are the durable re-
mains of animals and plants which lived and died in the ocean,
and of fluviatile and terrestrial species that were transported
from the land by rivers and their tributaries. The whole
forms such an assemblage of sedimentary deposits as
would probably be presented to observation, if a mass of
the bed of the Atlantic, 2000 feet in thickness, were elevated
above the waters, and became dry land; the only essential
difference would be in the generic and specific characters of
the imbedded animal and vegetable remains.

The fossils of the cretaceous formation are exceedingly
numerous, and offer examples of all the usual forms of
marine existence except Cetaceans, of which no vestiges
have as yet been found in strata older than the eocene.

Particular genera and species appear, however, to be
restricted to certain subdivisions of the system; thus, in the
white chalk, there are many species of shells that do not
occur in either of the other groups. The marl and galt also
have peculiar fossils, and the greensand abounds in shells and
zoophytes, that are wanting in the upper series of deposits.
The genera and species of the mollusca must therefore have
varied during the period of the deposition of the chalk ;
some kinds prevailed at the commencement of the forma-

316

THE WONDERS OF GEOLOGY.

LECT. IV.

tion, and became extinct, or at least no longer inhabited the same parts of the ocean at a subsequent epoch; while other forms appear for the first time.

The state of preservation in which the fossils occur, varies according to the lithological composition of the strata. The shells, corals, echinites, &c. of the white chalk, are generally transmuted into carbonate of lime having a spathose structure; their cavities are commonly filled with chalk, flint, or sulphuret of iron; in many instances they are hollow, and lined with crystals of carbonate of lime. The softer zoophytes are often silicified, and there is scarcely a flint nodule in which their remains may not be traced. The bones of the reptiles and fishes, and the coverings of the crustaceans, are in a friable state, and stained with sulphuret of iron. The teeth and scales of the fishes possess a high polish, and are more or less permeated by ferruginous infiltrations. Wood occurs in the state of lignite in the clays and sands, and in brown friable masses in the chalk, which quickly decompose upon exposure to the air; but when enveloped in flint, the structure is silicified, and well preserved;* like the fossil wood of the tertiary, it has evidently been drifted, and is perforated by teredines and other boring animals; the fissures are often filled with brilliant pyrites.

In the *Galt*, the nacreous covering of the shells is commonly preserved, and the ammonites and nautili of Folkstone rival in beauty the shells of the London clay, and like them are subject to decomposition.

The *Greensand* fossils in the cherty sandstones are often silicified; and the whetstone pits of Devonshire are celebrated for the beauty and variety of the chalcedonic shells, star-fish, &c. with which they abound. In the sands, limestones, and argillaceous strata, the shells are for the most part well preserved.

* Medals of Creation, vol. i. p. 168.

§ 15.

FOSSIL VEGETABLES.

317

The organic remains of the cretaceous system already known, amount to many hundred species. The most striking zoological character, is the abundance of echinites, belemnites, and ammonites: the latter are the shells of an extinct race of cephalopoda, that appears for the last time in the chalk; no traces of the existence of a single species having been discovered in the tertiary, or any newer formations. My collection, consisting of many thousand fossils from the chalk of England and America, displays the usual genera and species of zoophytes, corals, shells, echinites, star-fish, crinoidea, crustacea, fishes, and reptiles; together with many that are exceedingly rare, and some unique. I will illustrate this subject by a selection of a few examples.*

15. FOSSIL VEGETABLES.—The marine flora of the chalk, as I have already remarked, offers but little variety: a few species of *Fuci*, and *Confervæ*, are the only instances that have come under my notice. One species of *Fucus*, (*Fucoides Targionii*, Lign. 57,) abounds in the malm rock of Western Sussex, particularly at Bignor, formerly the seat of my late friend, John Hawkins, Esq.; almost every fragment of the rock is marked with its meandering forms. *Confervæ* are occasionally found in the flints, and very rarely in the chalk.† Plants allied to *Zostera* occur in the chalk of the Isle d'Aix. Drifted wood abounds in the line of junction between the galt and greensand. In the Kentish rag, near Maidstone, there have been discovered

* I would refer the reader to my Medals of Creation, for details of the most important organic remains of the chalk; and to Mr. Morris's catalogue of British fossils, for lists and references of all the published species. Figures and descriptions of British chalk fossils are given in my Fossils of the South Downs, Wonders of Geology, and Geology of the South-East of England; in Mr. Sowerby's Mineral Conchology, Mr. Lyell's Elements of Geology, and Parkinson's Organic Remains of a Former World.

† *Confervites Woodwardii*; Medals of Creation, vol. i. p. 104.

318

THE WONDERS OF GEOLOGY.

LECT. IV.

fir-cones (*Abies Benstedi*), coniferous wood, petioles of the *Clathraria*, and the stem of a plant allied to *Dracæna*.

The *Coniferæ* (cone-bearing, as the Larch) appear to have constituted the principal feature in the flora of the country,

LIGN. 57.—FUCUS IN MALM-ROCK; FROM BIGNOR PARK, SUSSEX.

(Fucoides Targionii.)

whose rivers and streams flowed into that part of the chalk ocean that is accessible to observation in England. All the wood I have met with, whether in the white chalk, firestone, galt, or greensand, is coniferous; and most of it possesses the structure of the *Araucaria*, or Norfolk Island pine. Several pine or fir cones have been found, but all of small size.

Of those peculiar coniferous plants, the *Zamia* and *Cycas*, many remains have been collected. A beautiful elongated cone of a *Zamia* was obtained some years since, near Willingdon, in Sussex, from a bed of greensand, which abounds in coniferous wood.*

In the chalk marl at Bonchurch, in the Isle of Wight, a remarkable specimen of the summit of a stem of the

* It is figured in Geol. Proc. 1843, as *Zamites Sussexiensis*. See Medals of Creation, *Fossil Coniferæ*, vol. i. p. 165.

§ 16.

FOSSIL ZOOPHYTES.

319

*Clathraria*, with the petioles attached, has been discovered; as this plant essentially belongs to the flora of the Wealden, its description will be given in a subsequent section of this discourse.

A few imperfect specimens of an oval compressed fruit, have been found in the chalk near Lewes, and in Kent. This fruit, so far as can be judged from the examples known, appears to have been a compound berry, having, like the mulberry, the seeds imbedded in a soft pulpy mass.*

16. FOSSIL ZOOPHYTES.—The soft and flexible zoophytes are so exceedingly numerous in the flints, that but few nodules are destitute of traces of sponges, and other kinds of amorphozoa and porifera. In the white chalk, corals are comparatively rare; but the Maestricht beds contain them in great abundance. There are certain layers of a very friable earthy chalk in the cliffs along the Kentish coast, and especially near Dover, that abound in very delicate and beautiful species of numerous small corals; as *Retepora*, *Pustulopora*, *Millepora*, *Idmonea Comptoniana*, &c.† A small *Caryophyllia* (*Lign. 58, fig. 3*) is common in the English chalk; a species of *Turbinolia* (*Lign. 58, figs. 1, 2*) in the galt; and of *Astræa* in the greensand. Specimens have been collected of several other genera; but the absence of the large madrepores and stony corals is a remarkable fact, corroborating the evidence derived from other sources, that the white chalk was deposited in the profound

* I have named this fruit *Carpolithes Smithiæ*, in honour of Mrs. Smith of Tunbridge Wells; a lady of consummate skill in the dissection of chalk fossils, and most ardent and liberal in the promotion of palæontological science. Medals of Creation, vol. i. p. 196.

† Medals of Creation, vol. i. p. 284. I have a splendid mass, from Dover, of retepora and pustulopora, covering a surface of chalk, six inches by four; the chalk itself wholly consisting of an aggregation of polythalamian shells; it was collected by Mrs. Smith, of Tunbridge Wells. Specimens of these chalk corals may be obtained of the dealer, W. Griffiths, of Dover, and 91, Tooley-street, London.

320

THE WONDERS OF GEOLOGY.

LECT. IV.

abyss of an ocean; for the economy of the living corals
fits them to live only in waters of moderate depths. It
would be tedious and uninstructive to place before you

LIGN. 58.—CORALS FROM THE CHALK FORMATION.

Fig. 1. *Turbinolia Königi* from the galt: the fossil is attached to the marl by the disk, the base lying uppermost and exposed. 2. The upper surface of *Turbinolia Königi*, imbedded in galt. 3. *Caryophyllia centralis*, from the chalk near Lewes. 4. *Fungia* in limestone, from Maestricht. 5. *Gorgonia*, from Maestricht.

lists of the scientific names by which the zoophytes of
the chalk are known to naturalists; it will suffice to
observe, that the more delicate forms, as flustra, millepora,
cellepora, retepora,\* &c. are very abundant: and in some
localities of the greensand, as, for example, the quarries at
Faringdon, in Berkshire, the strata literally swarm with
various species of spongia, siphonia, &c.;† the nature of
these fossils will be explained in a subsequent lecture.

\* See Medals of Creation, vol. i. p. 284.

† Ibid. p. 256.

§ 17.

ANIMALCULITES OF THE CHALK.

321

There is a fossil zoophyte (*Choanites Königi*) which is well known to collectors of Sussex pebbles by the name of *petrified sea-anemone*, from its supposed resemblance to the living Actinia (*Pl. VI. fig. 11*); but the original was a very different creature. From an extensive suite of specimens, I have ascertained that it was of a pyriform shape, with a central opening, from which numerous tubes radiated; and these are oftentimes exquisitely preserved in flint. The external surface frequently exhibits the remains of crucial spines, similar to those possessed by the recent alcyonia.*

Certain polypiferous zoophytes (*Ventriculites*) are exceedingly numerous in the chalk near Lewes and Brighton; and being often preserved partly in chalk and partly in flint, give rise to most interesting specimens, which throw light on the segregation of silex from the thermal streams holding that mineral in solution, which were periodically erupted into the calcareous sediments of the chalk ocean.†

17. ANIMALCULITES OF THE CHALK.—Under this head I will notice some of the minute organisms of the cretaceous system. The term animalculites, though not strictly applicable to all the microscopic fossil *Infusoria*, may be conveniently employed to designate the remains of animalcules of the most simple structure; and *polythalamia*, to denote the chambered shells of the foraminifera; as rotalia (p. 249), textilaria, &c.‡

The *Foraminifera* are marine animals, of low organization, and, with but few exceptions, extremely minute; in an ounce of sea-sand between three and four millions

* Thoughts on a Pebble, pl. 1 & 2. Medals of Creation, vol. i. p. 264.

† See Medals of Creation, vol. i. p. 274.

‡ Want of space compels me to refer the reader for many details on this subject, to my “*Notes on a Microscopical Examination of Chalk and Flint*,” in the *Annals of Nat. Hist.* 1845.

Y

322

THE WONDERS OF GEOLOGY.

LECT. IV.

have been enumerated. The body consists of uniform granules, inclosed in a skin or membrane, having one or more cavities or digestive sacs. These animals appear, in fact, to be merely polypes protected by shells; some have a single cell (*Orbulina*): others consist of several cells, disposed in a conical or cylindrical direction (*Nodosaria*). Another family has the shell discoidal like the nautilus, and divided by cells; these are the *polythalamia*, properly so called, of which there are many genera, distinguished by peculiarities in the aperture, disposition of the septa or partitions, and direction of the spire and volutions: to this group belong the Rotalia, Rotalina, Cristellaria, &c. All these forms swarm in infinite multitudes in the present seas, and were not less abundant in the ancient ones. The Nummulites of which we have already spoken (p. 248), have also living representatives (*nummulina* of M. D'Orbigny). The distinguishing character of these shells consists in the numerous perforations by which they are traversed, and which in the living state afforded exit to minute filaments or processes.*

18. **CHALK ROTALIÆ.**—In the *Rotaliæ*, which are the most abundant cretaceous forms, the body of the animal is inclosed within the shell, and occupies all the chambers; and the perforations, which are numerous, admit of the exsertion of the soft transparent feelers or pseudo-podia, which are the instruments of motion. The shell of the rotalia, therefore, though presenting the general form of that of the nautilus, is essentially different: for in the latter the body of the animal is wholly contained in the outer chamber, and the internal compartments are successively-quitted empty dwellings; whereas, in the polythalamian, all the cells are filled by the soft parts of the animalcule contemporaneously. When the shell, which is calcareous, is removed by weak hydrochloric acid, the body is exposed,

* See Medals of Creation, vol. i. p. 232.

§ 18.

CHALK ROTALIÆ.

323

and is seen to extend to the innermost chamber ; and there
is a connecting tube which occupies the place of the
siphuncle of the nautilus, for the digestive sacs in the cells
are united by the intestinal canal; minute infusoria which
the animal has swallowed, may sometimes be detected in
these receptacles. The annexed figure, *Lign.* 59, represents
a recent marine polythalamian deprived of its shell.

LIGN. 59.—The body of a recent foraminiferous animalcule: the shell having been dissolved by acid. From the North Sea, off Cuxhaven.

(Nonionina Germanica, of Ehrenberg;)
Magnified 200 diameters.

In some of the sacs (a, a,) Naviculæ and other infusoria swallowed by the animal are visible. From Ehrenberg's *Memoirs*.

A comparison of this figure, with the specimen in flint
(*Lign.* 51, p. 303), will show the close analogy between them.

The soft parts of these foraminifera occur, not only in the
flint, but in the white chalk : and by subjecting the latter
to the action of dilute hydrochloric acid, the bodies of the
rotaliæ may sometimes be detected, as distinct in form, as
in this recent specimen from the sea (Lign. 59). I must refer
to my observations on this subject in the Philosophical
Transactions (for 1846, part iv. p. 465), for further particulars
of this remarkable fact. The Rotaliæ and Textilariæ are the
prevalent foraminifera in the English chalk : and the same

Y 2

324

THE WONDERS OF GEOLOGY.

LECT. IV.

species swarm in our seas, and are abundant in the sandy clays which are spread over great part of Cambridge-shire, Lincolnshire, &c. Mr. Williamson of Manchester, and Mr. Smith of March, have sent me specimens of this sand, principally made up of these shells, with those of *Lagenula, Spiroloculina, &c.*\*

The common generic forms of the English chalk, and some of the species, have been found in the cretaceous strata throughout Europe, Asia, and America. From numerous localities of America I have obtained, through the liberality of Dr. Bailey,† earths largely composed of these fossils. Mr. Lyell has figured, from the cretaceous beds of New Jersey, a Rotalina and Cristellaria, identical with English species.‡

19. CHALK DETRITUS AT CHARING.—I must conclude this notice of the cretaceous polythalamia, by directing attention to a remarkable deposit, first observed by W. Harris, Esq. of Charing, Kent, to whom I am indebted for an extensive suite of the prevalent species. Near Charing, there is a bed about a foot thick of chalk detritus, consisting of white sandy tenacious clay, spread over the outcrop, or exposed surface of the firestone; and which has evidently originated from the action of water on the unconsolidated chalk of the neighbouring downs, before the surface of those hills was protected by a covering of vegetable soil. This debris is largely made up of shells of numerous kinds of

* See a highly interesting paper on Foraminifera from the Levant, Boston, and Charing, by W. C. Williamson, Esq. in vol. viii. of the Manchester Literary and Philosophical Society, 1847.

† Dr. W. Bailey, Professor of Chemistry in the U. S. Military Academy of West Point, New York, a gentleman eminently distinguished for his scientific attainments, has elaborately investigated the fossil infusoria and foraminifera of the United States, and published the result of his researches in several successive numbers of the American Journal of Science.

‡ Geol. Proc. for 1845-6, p. 4.

§ 46.

THE COUNTRY OF THE IGUANODON.

443

the prevailing atmospheric condition of the country may
also be drawn from the undulated surfaces of the sand-
stones, and from the fossil trees. In the former we have
proof, that when the land of reptiles existed, the water was
rippled by the breezes, which then, as now, varied in
intensity and direction in a brief space; by the latter,
that in certain situations the wind blew from a particu-
lar quarter for a great part of the year, and that the
mean annual temperature was as variable as in modern
times. From what has been advanced, it must not, how-
ever, be supposed, that the country of the Iguanodon
occupied the site of the south-east of England; and that
the animals and terrestrial plants of the Wealden, lived and
died near the spot where their relics are entombed. For,
with the exception of the shells and crustaceans, which
probably inhabited the delta, all the fossil remains bear
marks of having been transported from a great distance.
But though three-fourths of the bones we discover have
been broken and rolled,—the teeth detached from their
sockets,—the vertebrae and bones of the extremities, with
but very few exceptions, disjointed, and scattered here and
there,—the stems and branches of the trees torn to pieces,
and deprived of their foliage,—there is no intermixture of
sea-shells, nor of beach or shingle; these remains have
been subjected to abrasion from river currents, but not to
attrition from the waves of the ocean. The gigantic limbs
of the large reptiles could not have been dissevered from
their sockets without great violence, except by the decom-
position of their tendons from long maceration in water;
and if the latter had been the sole cause, we should not
find the bones broken and separated, but lying more or less
in juxtaposition, like the skeletons of the Plesiosauri in the
Lias. The condition in which these fossils occur, proves
that they were floated down the river with the rafts of
trees, and other spoils of the land, till, arrested in their

444

THE WONDERS OF GEOLOGY.

LECT. IV.

progress, they sank down, and became imbedded. The
phenomena here contemplated cannot, I conceive, be satis-
factorily explained upon any other grounds; and the
source of the mighty stream which flowed through the
country of the Iguanodon must, therefore, like that of
the Mississippi, have been hundreds, perhaps thousands,
of miles distant, from the delta accumulated in the course
of ages at its mouth.

Such was the country of the Iguanodon—a country,
which language can but feebly portray, but which the
magic pencil of a Martin, by the aid of geological research,
has rescued from the oblivion of the past, and placed before
us in all the hues of nature, with its appalling dragon-
forms, its forests of palms and tree-ferns, and the luxuriant
vegetation of a tropical clime.*

47. SEQUENCE OF GEOLOGICAL CHANGES.—Let us now
review the sequence of those stupendous changes, of which
our examination of the geological phenomena of the south-
east of England has afforded such incontrovertible evidence.
From the facts brought before us, we learn that at a period
incalculably remote, there existed in the northern hemi-
sphere an extensive island or continent, possessing a climate
of such a temperature, that its surface was clothed with
coniferous trees, arborescent ferns, and plants allied to the
Cycas and Zamia; and that the ocean which washed its
shores was inhabited by turtles, and marine lizards of
extinct genera. This country suffered a partial subsidence,
which was effected so tranquilly, that many of the trees
retained their erect position, and the cycadous plants, and
a considerable layer of the vegetable mould in which they
grew, remained undisturbed. In this state an inundation
of fresh water covered the country and its forests, and depo-
sited upon the soil and around the trees a calcareous mud,

* See the Frontispiece; an engraving on steel, from an original
painting by John Martin, Esq., K. L.

§ 47.

445

which was gradually consolidated into limestone; thermal streams, holding flint in solution, percolated the mass, and silicified the submerged trees and plants.

A further subsidence took place, floods of fresh water overwhelmed the petrified forest, and heaped upon it accumulations of detritus, which the streams and rivers had transported from the land. The country traversed by the rivers, like that of the submerged forest, enjoyed a tropical climate, and was clothed with palms, arborescent ferns, and cycadæ; it was tenanted by gigantic herbivorous and carnivorous reptiles, and its waters abounded in turtles, and various kinds of fishes, crustaceans and mollusca. The bones of the reptiles, the teeth and scales of the fishes, and the stems, leaves, and seed-vessels of the trees and plants, were brought down by the streams, and imbedded in the mud of the delta, beneath which the petrified forest was now buried.

This state continued for an indefinite period—another change took place—the Country of Reptiles with its inhabitants was swept away, and the delta, and the fossil trees with the marine strata on which they grew, subsided to a great depth, and formed part of the bottom of a profound ocean; the waters of which teemed with numberless zoophytes, shells, and fishes, of species long since extinct. Periodical intrusions of thermal streams charged with silex, gave rise to layers and veins of nodular and tabular flint, and occasioned the silicification of the organic remains subjected to their influence.

This epoch, which was of long duration, was succeeded by elevatory movements, by which the bottom of the deep was broken up, and large areas were slowly upheaved; and as the elevation continued, the deposits which had accumulated in the depths of the ocean approached the surface, and were exposed to the action of the waves. These masses of cretaceous strata now began to suffer

446

THE WONDERS OF GEOLOGY.

LECT. IV.

destruction, and the delta of the Country of the Iguanodon gradually emerged above the waters; and finally, the petrified forest of the Oolite rose in the midst of the sea, and became dry land. At length, some portions of the elevated strata attained an altitude of several hundred feet, and a group of islands was formed; but in the basins or depressions beneath the waters, sediments derived from the disintegration of the sea-cliffs were deposited. Large herbivorous mammalia now inhabited such portions of the former oceanbed as were covered with vegetation sufficient for their support; and as these animals died, their bones became enveloped in the accumulations of mud and gravel, which were forming in the bays and estuaries.

This era also passed away—the elevatory movements continued—other masses of the bed of the chalk ocean, and of the wealden strata beneath, became dry land—and at length those more recent deposits containing the remains of the herbivorous mammalia which were the last tenants of the country. The oak, elm, ash, and other trees of modern Europe, now sprang up where the groves of palms and tree-ferns once flourished—the stag, boar, and horse, ranged over the plains in which were entombed the bones of the colossal reptiles—and finally, *Man* appeared, and took possession of the soil.

At the present time, the deposits containing the remains of the mammoth and other extinct mammalia, are the sites of towns and villages, and support busy communities of the human race; the Huntsman courses, and the Shepherd tends his flocks, on the elevated masses of the bottom of the ancient chalk ocean*—the Farmer reaps his harvests upon the cultivated soil of the delta of the Country of the Iguanodon†—and the Architect obtains from beneath the petrified forest, the materials with which to construct his temples

* The South Downs.

† The Wealds of Kent and Sussex.

§ 48.

RETROSPECT.

447

and his palaces :*—while from these various strata, the Geologist gathers together the relics of the beings that lived and died in periods of unfathomable antiquity, and of which the very types have long since been obliterated from the face of the earth, and endeavours by these natural memorials to determine the nature and succession of those physical revolutions, which preceded all human history and tradition.

48. RETROSPECT.—Such is a plain enunciation of the results of our investigations; but I will embody these inductions in a more impressive form, by employing the metaphor of an Arabian writer, and imagining some higher intelligence from another sphere to describe the physical mutations of which he may be supposed to have taken cognizance, from the period when the forests of Portland were flourishing, to the present time.

"Countless ages ere man was created," he might say, "I visited these regions of the earth, and beheld a beautiful country of vast extent, diversified by hill and dale, with its rivulets, streams, and mighty rivers, flowing through fertile plains. Groves of palms and ferns, and forests of coniferous trees, clothed its surface; and I saw monsters of the reptile tribe, so huge that nothing among the existing races can compare with them, basking on the banks of its rivers, and roaming through its forests; while in its fens and marshes, were sporting thousands of crocodiles and turtles. Winged reptiles of strange forms shared with birds the dominion of the air, and the waters teemed with fishes, shells, and crustacea.—And after the lapse of many ages I again visited the earth; and the country, with its innumerable dragonforms, and its tropical forests, all had disappeared, and an ocean had usurped their place. And its waters teemed with nautili, ammonites, and other cephalopoda, of races now extinct; and innumerable fishes and marine reptiles.

* The Isle of Portland.

448

THE WONDERS OF GEOLOGY.

LECT. IV.

—And thousands of centuries rolled by, and I returned,
and, lo! the ocean was gone, and dry land had again ap-
peared, and it was covered with groves and forests; but
these were wholly different in character from those of the
vanshed Country of the Iguanodon. And I beheld, quietly
browsing, herds of deer of enormous size, and groups of
elephants, mastodons, and other herbivorous animals of
colossal magnitude. And I saw in its rivers and marshes
the hippopotamus, tapir, and rhinoceros; and I heard the
roar of the lion and the tiger, and the yell of the hyena and
the bear.—And another epoch passed away, and I came
again to the scene of my former contemplations; and all
the mighty forms which I had left had disappeared, the face
of the country no longer presented the same aspect: it was
broken into islands, and the bottom of the sea had become
dry land, and what before was dry land had sunk beneath
the waves. Herds of deer were still to be seen on the
plains, with swine, and horses, and oxen; and bears and
wolves in the woods and forests. And I beheld human
beings, clad in the skins of animals, and armed with clubs
and spears; and they had formed themselves habitations in
caves, constructed huts for shelter, and inclosed pastures
for cattle, and were endeavouring to cultivate the soil.—
And a thousand years elapsed, and I revisited the country,
and a village had been built upon the sea-shore, and its in-
habitants supported themselves by fishing; and they had
erected a temple on the neighbouring hill, and dedicated it to
their patron saint. And the adjacent country was studded
with towns and villages; and the downs were covered with
flocks, and the valleys with herds, and the corn-fields and
pastures were in a high state of cultivation, denoting an
industrious and peaceful community.—And lastly, after an
interval of many centuries, I arrived once more, and the
village was swept away, and its site covered by the waves;
but in the valley and on the hills above the cliffs a beautiful

§ 48.

RETROSPECT.

city appeared;* with its palaces, its temples, and its thousand
edifices, and its streets teeming with a busy population in
the highest state of civilization; the resort of the nobles of
the land, the residence of the monarch of a mighty empire.”†

* Brighton.

† The concluding portion of these remarks refers to the changes that have taken place on the Sussex coast, during the historical era. Before the Conquest, the greater part of the then little fishing town of Brighthelmston (Brighthelm's-town), or Brighton, was situated below the cliffs, on a terrace of beach and sand, now covered by the waves. The Church, dedicated to St. Nicholas, the patron saint of fishermen, was placed on an eminence, that it might serve as a land-mark. The inroads of the sea led to the erection of buildings on the high ground, and their progressive encroachment gradually diminished the area of the ancient town, till at length a sudden inundation, but little more than a century ago, swept away the houses, fortifications, and inclosures that remained.ª The sea has, therefore, only resumed its former position at the base of the cliffs; the site of the old town having been an ancient bed of shingle, abandoned for ages by the ocean, perhaps contemporaneously with the retreat of its waters from the valley of the Ouse. Should the advancement of the sea be progressive, Lewes Levels (ante, p. 61) may again become an estuary, and the town of the Cliff, and the hamlet of Landport, regain the characters from which their names were derived. See A Day's Ramble in and about the ancient town of Lewes: by the Author. 1846.

ª Illustrations of the Geology of Sussex, p. 292. Geology of the South-East of England, p. 23. Dallaway's Western Sussex, vol. i. p. 55.

G G

# APPENDIX.

## SUPPLEMENTARY NOTES.

A. Page 41.—THE SURFACE OF THE MOON.—The moon is the only planetary body placed sufficiently near us, to have the inequalities of its surface rendered distinctly visible with the telescope. Attendant on the earth, and having nearly the same density, we may reasonably infer that the mineral substances of which it is composed do not differ essentially from those on the surface of our own planet. If, as is most probable, the moon is surrounded by an atmosphere, it must be very clear and low, for it scarcely occasions a sensible refraction of the rays of light when it passes over the fixed stars. Many of the dark parts of the moon, particularly the part called *mare crisium*, appear to be covered with a fluid, which is probably more transparent than water, as the forms of the rocks and craters are seen beneath it, but not so distinctly as in the lighter parts of the moon's surface. To examine the moon with a reference to its external structure, the defining power of the telescope should be of the first quality, sufficient to show the projections of the outer illuminated limb, as distinctly as they appear when the moon is passing over the disk of the sun during a solar eclipse. With such a telescope, and a sufficient degree of light and of magnifying power, almost every part of the moon's surface appears to be volcanic, containing craters of enormous magnitude and vast depth: the shelving rocks, and the different internal ridges within them, seem to mark the stations at which the lava has stood and formed a floor during different eruptions; while the cones in some of the craters resemble those formed within modern volcanoes. The largest mountain on the southern limb of the moon, like the largest volcanic cone on the earth, Chimborazo, has no deep crater on its summit. There are indeed the outlines of the crater, but it is nearly filled

G G 2

452

WONDERS OF GEOLOGY.

VOL. I.

up; while from the foot of this lunar mountain, streams of lava diverge in different directions, to the distance of six hundred miles. The longest known current of modern lava on the earth is in Iceland, and extends sixty miles; but the volcanoes in that island bear no proportion to those of the moon in magnitude.—Mr. Bakewell.

B. Page 77.—THE LAKE OF THE SOLFATARA.—"Its temperature was, in the winter, in the warmest parts, above 80 deg. of Fahrenheit, and it appears to be pretty constant; for I have found it to differ a few degrees only, in January, March, May, and the beginning of June; being therefore nearly twenty degrees above the mean temperature of the atmosphere, it must be supplied with heat from a subterraneous source. Kircher has detailed in his *Mundus Subterraneus* various wonders respecting this lake, most of which are unfounded; such as that it is unfathomable, that it has at the bottom the heat of boiling water, and that floating islands rise from the gulf. It must certainly be very difficult, or even impossible to fathom a source which rises with so much violence from a subterraneous excavation; and at a time when chemistry had made small progress, it was easy to mistake the disengagement of carbonic acid for an actual ebullition. The floating islands are real, but neither the Jesuit nor any of the writers who have since described this lake, have had a correct idea of their origin, which is exceedingly curious. The high temperature of this water, and the quantity of carbonic acid that it contains, render it peculiarly fitted to afford a pabulum or nourishment to vegetable life; the banks of travertine are every where covered with reeds, lichens, confervæ, and various kinds of aquatic vegetables. At the same time that the process of vegetable life is going on, the crystallization of the calcareous matter which is every where deposited, in consequence of the escape of carbonic acid, likewise proceeds, and gives a constant miliness to what from its tint would otherwise be a blue fluid. So rapid is the vegetation, owing to the decomposition of the carbonic acid, that even in winter, masses of confervæ and lichens, mixed with deposited travertine, are constantly detached by the currents of water from the bank, and float down the stream; which being a considerable river, is never without many of these small islands on its surface. They are sometimes only a few inches in size, and composed merely of dark green confervæ, or purple or yellow lichens; but, occasionally, are even several feet in diameter, and contain seeds and various species of common water-plants, which are usually more or less incrusted with marble. There is, I believe, no place in the world where there is a

APPENDIX.

453

more striking example of the opposition or contrast of the laws of animate and inanimate nature—of the forces of inorganic chemical affinity, and those of the powers of life. Vegetables, in such a temperature, and every where surrounded by food, are produced with a wonderful rapidity; but the crystallizations are formed with equal quickness, and are no sooner produced than they are destroyed together. Notwithstanding the sulphurous exhalations from the lake, the quantity of vegetable matter generated there, and its heat, make it the resort of an infinite variety of insect tribes; and even in the coldest days in winter, numbers of flies may be observed on the vegetables surrounding its banks, or on its floating islands. Their larvæ may also be seen there, sometimes incrusted and entirely destroyed by calcareous matter, as well as the insects themselves; and various species of shell-fish that are found amongst the vegetables which grow and are destroyed in the travertine on its banks. Snipes, ducks, and other water-birds, often visit these lakes, probably attracted by the temperature and the quantity of food in which they abound; but these usually confine themselves to the banks, as the carbonic acid disengaged from the surface would be fatal to them, if they ventured to swim upon it when tranquil. In May 18—, I fixed a stick on a mass of travertine covered by the water, and examined it in the beginning of the April following, for the purpose of determining the nature of the depositions. The water was lower at this time; yet I had some difficulty, by means of a sharp-pointed hammer, in breaking the mass which adhered to the bottom of the stick; it was several inches in thickness. The upper part was a mixture of light tufa and leaves of confervæ; below this was a darker and more compact travertine, containing black and decomposed masses of confervæ; in the inferior part, the travertine was more solid, and of a grey colour, but with cavities which I have no doubt were produced by the decomposition of vegetable matter. I have passed many hours, I may say days, in studying the phenomena of this wonderful lake; it has brought trains of thought into my mind connected with the early changes of our globe; and I have sometimes reasoned from the forms of plants and animals preserved in marble in this thermal source, to the grander depositions in the secondary rocks, where the zoophytes or coral polypes have worked upon a grand scale, and where palms and vegetables, now unknown, are preserved with the remains of crocodiles, turtles, and gigantic extinct saurians, which appear to have belonged to a period when the whole globe possessed a much higher temperature. I have likewise often been led, from the remarkable phenomena surrounding me in that spot, to compare the works of man

454

WONDERS OF GEOLOGY.

VOL. I.

with those of nature. The baths, erected there nearly twenty cen-
turies ago, present only heaps of ruins, and even the bricks of which
they were built, though hardened by fire, are crumbled into dust;
whilst the masses of travertine around, though formed by a variable
source from the most perishable materials, have hardened by time;
and the most perfect remains of the greatest ruins in the eternal city,
such as the triumphal arches and the Colosseum, owe their duration to
this source.

How marvellous are those laws by which the humblest types of
organic existence are preserved, though born amidst the sources of
their destruction, and by which a species of immortality is given to
generations floating, as it were, like evanescent bubbles on a stream
raised from the deepest caverns of the earth, and instantly losing what
may be called its spirit in the atmosphere!"—*Sir Humphrey Davy's*
*Last Days of a Philosopher.*

C. Page 78.— CAVERNS.—One of the most common appearances in limestone caverns, is the formation of what are called stalactites, from a Greek word signifying distillation or dropping. To explain these, a brief description of the mode of their production will be necessary. Whenever water filters through a limestone rock, it dissolves a portion of it; and on reaching any opening, such as a cavern, oozes from the sides or roof, and forms a drop, the moisture of which is soon evaporated by the air, and a small circular plate of calcareous matter remains; another drop succeeds in the same place, and adds, from the same cause, a fresh coat of incrustation. In time, these successive additions produce a long, irregular, conical projection from the roof, which is continually being increased by the fresh accession of water, loaded with calcareous or chalky matter; this is deposited on the outside of the stalactite already formed, and trickling down, adds to its length by subsiding to the point, and evaporating as before; precisely in the same manner as, during frosty weather, icicles, which are stalactites of ice, or frozen water, are formed on the edges of the eaves of a roof. When the supply of water holding lime in solution is too rapid to allow of its evaporation at the bottom of the stalactite, it drops to the floor of the cave, and drying up gradually, forms, in like manner, a stalactite rising upwards from the ground, instead of hanging from the roof; this is called, for the sake of distinction, stalagmite.

It frequently happens, where these processes are uninterrupted, that
a *stalactite* hanging from the roof, and a *stalagmite* formed imme

APPENDIX.

455

diately under it from the superabundant water, increase till they
unite, and thus constitute a natural pillar, apparently supporting the
roof of the grotto; it is to the grotesque forms assumed by stalactites,
and these natural columns, that caverns owe the interesting appear-
ances, described in such glowing colours by those who witness them
for the first time. One of the most beautiful stalactitic caverns in
England is at Clapham, near Ingleborough. In the Cheddar Cliffs,
Somersetshire, there has lately been discovered a similar cave, richly
encrusted with sparry concretions.—See *Medals of Creation*, vol. ii.
p. 931.

D. Page 78.—WEYER’S CAVE.—This cave is situated in a ridge of
limestone hills, running parallel to the Blue mountains. A narrow
and rugged fissure leads to a large cavern, where the most grotesque
figures, formed by the percolation of water through beds of limestone
present themselves; while the eye, glancing onward, watches the dim
and distant glimmers of the lights of the guides—some in the recess
below, and others in the galleries above. Passing from these recesses,
the passage conducts to a flight of steps that leads into a large cavern
of irregular form, and of great beauty. Its dimensions are about thirty
feet by fifty. Here the incrustations hang just like a sheet of water
that has been frozen as it fell; there they rise into a beautiful stalac-
titic pillar, and yonder compose an elevated seat, surrounded by sparry
pinnacles. Beyond this room is another, more irregular, but more
beautiful; for besides having sparry ornaments in common with the
others, the roof overhead is of the most admirable and singular for-
mation. It is entirely covered with *stalactites*, which are suspended
from it like inverted pinnacles; and they are of the finest material, and
most beautifully shaped and embossed. In another apartment, an
immense sheet of transparent *stalactite* which extends from the roof
to the floor, emits, when struck, deep and mellow sounds, like those of
a muffled drum. Farther on is another vaulted chamber, which is
one hundred feet long, thirty-six wide, and twenty-six high. Its walls
are filled with grotesque concretions. The effect of the lights placed
by the guides at various elevations, and leaving hidden more than they
reveal, is extremely fine. At the extremity of another range of
apartments, a magnificent hall, two hundred and fifty feet long, and
thirty-three feet high, suddenly appears. Here is a splendid sheet of
rock-work, running up the centre of the room, and giving it the aspect
of two separate and noble galleries; this partition rises twenty feet
above the floor, and leaves the fine span of the arched roof untouched.

456

WONDERS OF GEOLOGY.

VOL. I.

There is here a beautiful concretion, which has the form and drapery
of a gigantic statue; and the whole place is filled with stalagmitical
masses of the most varied and grotesque character. The fine per-
spective of this room, four times the length of an ordinary church,
and the amazing vaulted roof spreading overhead, without any
support of pillar or column, produce a most striking effect. In
another apartment, which has an altitude of fifty feet, there is at one
end an elevated recess, ornamented with a group of pendant stalactites
of unusual size, and singular beauty. They are as large as the pipes
of a full-sized organ, and ranged with great regularity; when struck,
they emit mellow sounds of various keys, not unlike the tones of
musical glasses. Other cavities, profusely studded with sparry incrus-
tations, extend through the limestone rock. The length of this extra-
ordinary group of caverns is not less than one thousand six hundred
feet.—Abridged from "A Narrative of a Visit to the American
Churches;" by Drs. Reed and Matheson. See also, an interesting
Narrative of "A Tour to the Caves in Virginia," by the late Dr.
Harlan, Medical and Physical Researches, p. 404.

E. Page 93.—RECENT FORMATION OF SANDSTONE.—"A sandstone occurs in various parts of the northern coast of Cornwall, which affords a most instructive example of a recent formation; since we here actually detect Nature at work in converting loose sand into solid rock. A very considerable portion of the northern coast of Cornwall is covered with calcareous sand, consisting of minute particles of comminuted shells, which, in some places, has accumulated in quantities so great, as to have formed hills of from forty to sixty feet in elevation. In digging into these sand hills, or upon the occasional removal of some part of them by the winds, the remains of houses may be seen: and in places, where churchyards have been overwhelmed, a great number of human bones may be found. The sand is supposed to have been originally brought from the sea by hurricanes, probably at a remote period. At the present moment, the progress of its incursion is arrested by the growth of the *arundo arenacea*. The sand first appears in a slight but increasing state of aggregation on several parts of the shore in the bay of St. Ives; but, on approaching the Gwythian river, it becomes more extensive and indurated. On the shore opposite Godrevy Island, an immense mass of it occurs, of more than a hundred feet in length, and from ten to twenty in depth, containing entire shells and fragments of clay-slate; it is singular that the whole mass assumes a striking appearance of stratification. In some places

APPENDIX.

457

it appears that attempts have been made to separate it, probably for
the purpose of building, for several old houses in Gwythian are built
of it. The rocks in the vicinity of this recent formation in the bay of
St. Ives, are greenstone and clay slate, alternating with each other.
The clay slate is in a state of rapid decomposition, in consequence of
which large masses of the hornblende rock have fallen in various
directions, and given a singular character of picturesque rudeness to
the scene. This is remarkable in the rocks which constitute Godrevy
Island. It is around the promontory of New Kaye, that the most
extensive formation of sandstone takes place. Here it may be seen
in different stages of induration, from a state in which it is too friable
to be detached from the rock upon which it reposes, to a hardness so
considerable that it requires a very violent blow from a sledge to break
it. Buildings are here constructed of it; the church of Cranstock is
entirely built with it; and it is also employed for various articles of
domestic and agricultural uses. The geologist who has previously
examined the celebrated specimen from Guadaloupe, will be struck
with the great analogy which it bears to this formation. Suspecting
that masses might be found containing human bones, if a diligent
search were made in the vicinity of those cemeteries which have been
overwhelmed, I made some investigations in those spots, but, I regret
to add, without success. The rocks upon which the sandstone reposes
are alternations of clay slate, and slaty limestone. The inclination of
the beds is SS.W., and at an angle of 40°. Upon a plane formed by
the edges of these strata, lies a horizontal bed of rounded pebbles,
cemented together by the sandstone which is deposited immediately
above them, forming a bed of from ten to twelve feet in thickness, and
containing fragments of slate, and entire shells; and exhibiting the
same appearance of stratification as that noticed in St. Ives Bay.
Above this sandstone lie immense heaps of drifted sand. But it is on
the western side of the promontory of New Kaye, in Fishel Bay, that
the geologist will be most struck with this formation; for here no
other rock is in sight. The cliffs, which are high, and extend for
several miles, are entirely composed of it; they are occasionally inter-
sected by veins and dykes of breccia. In the cavities, calcareous
stalactites of rude appearance, opaque, and of a grey colour, hang
suspended. The beach is covered with disjointed fragments, which
have been detached from the cliffs above, many of which weigh two
or three tons."—*From a Memoir by Dr. Paris, in the Transactions of
the Royal Geological Society of Cornwall.*

458

WONDERS OF GEOLOGY.

VOL. I.

F. Page 109.—ON THE SUBSIDENCE OF THE COAST AT PUZZUOLI.
*Letter from C. Hullmandel, Esq. to the Author.*—“ Most travellers merely pass through Puzzuoli in their way to Baia, and few being acquainted with the Neapolitan dialect have had the opportunities which I enjoyed, of conversing with the natives upon the subject. In the year 1813, I resided for four months in the Capuchin convent of Puzzuoli, which is situated between the road from Naples, and the sea, at the entrance of the town of Puzzuoli. In the Capuchin convents the oldest friar is called ‘il molto reverende;’ and the one who then enjoyed the title in this convent was 93 years old. He informed me that when he was a young man, the road from Naples passed on the seaward side of the convent; but that from the gradual sinking of the soil, the road was obliged to be altered to its present course.

“ While I was staying at the convent, the refectory, as well as the entrance gate, were from six inches to a foot under water, whenever strong westerly winds prevailed so as to cause the waters of the Mediterranean to rise. Thirty years previously, my old informant stated, such an occurrence never took place. In fact, it is not probable that the builder of the convent would have placed the ground-floor so low as to expose it to inundations, as it now is. Moreover, the small wharf at Puzzuoli, like the convent, is constantly under water when westerly winds prevail; here again it is evident that the original constructors of the wharf never intended it to be in this state. These facts appear to prove that the gradual subsidence of the soil has been going on for many years, and is still in actual progress, and corroborate the opinion derived from the appearances observable on the columns of the Temple of Jupiter Serapis, that the country has been subjected to alternate elevations and subsidences.”

“*London, November, 1839.*”

DESCRIPTION OF THE FRONTISPIECE.

(See page 444.)

A PICTORIAL ILLUSTRATION OF THE COUNTRY OF THE IGUANODON, FROM THE GEOLOGICAL DISCOVERIES OF THE AUTHOR.

BY JOHN MARTIN, ESQ. K.L.

THE mode of induction by which the geologist and comparative anatomist are enabled to ascertain the form and structure of animals and plants which no longer exist on the face of the earth, and even the nature of the countries which they inhabited, is explained in the preceding pages. From the materials furnished by the researches of the Author in the Wealden formation of the south-east of England, the eminent painter of "BELSHAZZAR'S FEAST," (Mr. John Martin,) composed the striking picture that forms the frontispiece of this Work.

The data upon which the restorations are founded are described in the Fourth Lecture, Part II. (see p. 360). The painting represents a country clothed with a tropical vegetation, peopled by colossal reptiles, and traversed by a river, which is seen to empty itself into the sea, in the distance. Oolitic rocks form the heights and cliffs with which the landscape is diversified. The vegetation consists of the trees and plants whose fossil remains have been discovered in Tilgate Forest, namely, arborescent ferns, clathrariæ, and coniferous trees; while the lesser species are distributed over the foreground.

The reptiles comprise the Iguanodon (p. 422), Hylæosaurus (p. 435), Megalosaurus (p. 421), Crocodiles (p. 415), and Turtles (p. 410). An Iguanodon attacked by a Megalosaurus and Crocodile, constitute the principal group; in the middle distance an Iguanodon and Hylæosaurus are preparing for an encounter; a solitary Pterodactyle, or flying reptile (p. 438), with its wings partly expanded, forms a conspicuous object in the foreground; while Tortoises are seen crawling on the banks of the river. Ammonites and other shells of the Portland oolite, which is the foundation rock of the country, are strewn on the shore.

DESCRIPTION OF THE GEOLOGICAL MAP OF ENGLAND.

PLATE I.

THIS map, or rather ground plan, is necessarily on too small a scale to afford more
than a very general idea of the geographical distribution of the principal groups of
strata over England, in accordance with the chronological synopsis in Lecture III.*

A summary of the general features of the country is given in page 207, which it is
unnecessary here to repeat; but it may be interesting to offer a slight sketch of
what may be termed the Geology of the shores of England. With this view, if we
start on an imaginary cruise from the north, beyond Berwick, and proceed along the
eastern, south-eastern, and southern coasts, to the Land's-End, and then sail along
the western shores till we reach the Solway Firth, the following geological
phenomena will successively be presented.

The border country of England and Scotland consists of *Silurian* deposits, with a
tract of *Devonian* north of Berwick, in which fossil fishes have been met with.
From Berwick to Shields, the *Carboniferous* system, comprising the *Mountain*
*limestone*, *Coal*, and *Millstone grits*, forms the Northumberland coast; a few
insulated masses of plutonic rocks (*Trap*) appearing here and there; as for example,
at Bamborough Castle, and Dunstanborough. From near Tynemouth to Hartlepool,
the *Magnesian limestones* of the *Permian* system appear; thence to Redcar, the
*Trias* deposits, in which the embouchure of the river Tees is situated, form the shore.

The coast of the north riding of Yorkshire, composed of *Lias* and *Oolite*, is now
reached; a tract that includes Whitby, in the neighbourhood of which place are
high cliffs of Lias, abounding in fossils of great variety and interest; as for example,
Ichthyosauri and other reptiles: jet, wood, and numerous shells. In the continuance
of this coast to Scarborough and Speeton, the *Great Oolite*, *Coral-rag*, *Oxford clay*,
and other members of the Oolite appear, containing organic remains in profusion;
and along this shore are exposed the intercalated *fluvio-marine* strata, full of cyclo-
duous plants, ferns, &c. lignite, and coal. Thence to Flamborough Head, the
*Greensand*, *Speeton clay*, and *Red chalk* emerge, and finally, the *White chalk*, of
which the high cliffs of the promontory consist. From this part of Yorkshire, the
coast boundary is chiefly made up of the alluvial deposits of Holderness; and along
the maritime district of Lincolnshire, till we reach Norfolk, of low cliffs, of gravel,
and marine detritus; covered in many places by drift, containing mammalian re-
mains. The chalk range of Norfolk extends to the sea on the north, from Thornham
to Blakeney; and at Cromer is capped by mammaliferous Crag.

The tertiary strata of Norfolk are for the most part obscured along the coast by
drift and alluvial debris, in which great numbers of the teeth and bones of
mammoths, and other extinct mammalia, have been discovered. At Happisburg,
numerous bones of elephants have been met with; in the Crag cliffs near South-
wold, the teeth of *Mastodon longirostris* have been found.

* For convenience the Silurian and Cumbrian deposits are denoted by the same number (8) and colour.

DESCRIPTION OF THE PLATES.

463

At Aldborough, the *Coralline Crag* appears inland; and in the cliffs at Bawdsey and Felixstow, the *Red Crag*\* is seen overlying the *London clay*; and a fine section is exhibited at Walton Naze, south of Harwich. At Clacton, there is a post-tertiary deposit, containing freshwater shells, and mammalian remains.

We now approach the embouchure of the Thames, which lies in a trough of London or eocene clay; certain localities, as the Isle of Sheppey, the cliffs in Herne Bay, &c. abounding in fruits and other vegetable remains, which are associated with marine shells, and bones of mammalia, birds, reptiles, scales and teeth of fishes, &c.

The North Foreland of the chalk range of Kent is next passed, the coast being flanked by vertical cliffs of the Cretaceous formation to Dover. The grey chalk appears at the base of Shakspeare's Cliff; and the lower members of the series, the *Firestone, Galt, and Greensand*, at Folkstone and Hythe; the cliffs in Eastware Bay abound in Galt fossils.

The low alluvial district of Romney marshes now skirts the sea-shore, to near Winchelsea; this town and Rye being situated on mounds of Wealden strata, that rise through the silt of the surrounding marsh lands.

We now pass along the eastern extension of the Wealden denudation on the Sussex coast; the Wealden sands and sandstones, with alternating clays and shales, constituting the range of cliffs that stretches, with but little interruption, from the east of Hastings to Bexhill; and in which the usual fossils occur in considerable abundance.

Accumulations of shingle now bound the bay formed by Pevensey levels, which is guarded by numerous martello towers, and the Wealden strata are wholly concealed. Near Southbourn, on the north of the South Downs, the Greensand, Galt, and Firestone, reappear; and are surmounted by the White chalk, which abruptly rises into the promontory of Beachy Head. A bold line of chalk cliffs, interrupted only by a few valleys, through which the rivers from the interior discharge their waters into the sea, now stretches along the coast towards Brighton; where, to the extent of three or four miles, the cliffs consist of detritus, containing bones of elephants, whales, horses, deer, and other mammalia. At the embouchure of the river Ouse, which flows into the sea from Lewes, the chalk cliffs forming the western headland of Newhaven harbour, are capped by tertiary eocene strata.

To the west of Brighton, the coast is for the most part low; the foundation rock of the district, the chalk, seldom rising into view; and thick beds of alluvial covering, with eocene strata beneath, form the tract on the south of the Downs, through western Sussex, and the adjacent maritime district of Hampshire.

The Sussex coast at Bognor, is skirted by a few low rocks of calciferous sandstone, abounding in eocene tertiary shells: and in Bracklesham bay, a bank of London clay and sand has yielded numerous organic remains of great interest.

We now sail round the eastern termination of the Isle of Wight, and perceive on the north the tertiary strata in Whitecliff bay, abutting against the vertical chalk of Culver Cliff. Rounding the promontory, we enter Sandown bay, where the Wealden beds rise in an anticlinal position from under the cretaceous strata. The ruinous chalk escarpment of the Undercliff is next passed, and we enter another bay of the Wealden, at Brixton, Brook, and Compton; and again meet with bold precipices of chalk at Freshwater Gate and the Needles; and vertical eocene strata in Alum Bay.

Pursuing our westward course, we see the distant coast of Hampshire, by Hord-

\* Through an oversight, the term "Norfolk" has been affixed as a synonym to the *Red Crag*, in page 224; but Mr. Charlesworth informs me, that neither the *Red nor Coralline Crag* occurs in any part of the county of Norfolk.

464

WONDERS OF GEOLOGY.

VOL. I.

well and Christchurch, formed of freshwater and marine tertiary deposits; and entering Studland Bay, perceive the vertical chalk cliffs of Handfast point. Coasting along the Isle of Purbeck, the different members of the cretaceous and wealden formations are seen in various parts of this sinuous and indented line of coast; in some places forming the entire cliffs; in others surmounting the Kimmeridge clay and Portland oolite; and we pass by the little Coves in the south-west of the Island, in which the strata of the Chalk, Wealden, and Oolite, appear in a vertical position.*

Rounding the insulated mass of *Oolite* that forms the Isle of Portland, we reach the Dorsetshire coast, which is here composed of beds of the *Inferior oolite*. These deposits are succeeded near Lyme Regis by cliffs of *Lias*; which the researches of the late Miss Mary Anning, and Mr. Hawkins, have rendered so celebrated; the remains of Ichthyosauri, Plesiosauri, and other reptiles, with numerous shells, crinoidea, and plants, excelling in beauty and variety, those of any other English locality.

The Lias is succeeded on the west by Triassic strata; and these, after a short interruption of greensand, reappear and continue by Sidmouth, Exmouth and Teignmouth to near Babbicombe, where the *Devonian*, or *Old Red deposits*, first emerge: beautiful coralline marbles are quarried near Babbicombe.

The coasts of Devonshire and Cornwall, with but few interruptions, are made up of the different members of the Devonian system; Silurian strata occurring in a few localities. *Mica* and *Chlorite schists*, form the promontory at Start Point; *Serpentine* and *Diallage rock*; the Lizard; and *Granite*, the Land's-End. From Plymouth to Falmouth is the grand region of copper ores; the country consisting of slaty rocks (termed *Killas*), and limestones, traversed by porphyritic (provincially called *Elvan*) dikes, with protrusions of granitic rocks. Intrusions of *Trap* are frequent all over this part of England; at St. Ives, the cliffs are composed of this igneous product.

The western shores of Cornwall present similar phenomena; and throughout this sea-coast, elevated terraces of beach or shingle are numerous, proving the frequent alteration in the relative level of sea and land, which have here taken place.

Along the west coast of Devonshire, beds of the Carboniferous system appear; the shales are often highly contorted, and occur in the state of indurated slate, provincially called *culm*: they contain shells, and many of the usual species of coal plants.

In north Devonshire, the Devonian system reappears; and at Ilfracombe there are beds of limestone and calcareous slates, full of shells and corals. If we pass up the Bristol Channel, as far as Watchet, we find a line of Lias cliffs, abounding in shells and reptilian remains.

But it would extend this notice to too great a length, were I to point out every interesting locality within view, in our voyage along the western coasts of England: it must, therefore, suffice to mention only the most striking geological phenomena.

Crossing to the opposite Welsh coast, mountain limestone, capped by Lias, appears at Nash Point, and near Dunraven; and in Swansea and Carmarthen bays, we perceive the great South-Wales coal-measures fully developed; the promontory of Worm's Head, which lies between the bays, being composed of Devonian strata and Mountain limestone. Near Tenby, the cliffs are formed of carboniferous deposits, very much contorted: and beyond, at St. Goven's Head, beds of mountain

* The details of the geology of the coasts of the Isle of Wight and Purbeck, are given in my Geology of the Isle of Wight.

DESCRIPTION OF GEOLOGICAL MAP.

465

limestone appear under similar conditions. In Milford Haven, which is chiefly flanked by Devonian rocks, Silurian deposits appear near St. Ann's Head; and there are numerous isolated masses of Trap: Ramsey Island, and St. David's Head, also consist of these igneous rocks.

We now enter Cardigan Bay, which is formed in the lower division of the Silurian system. The strata consist for the most part of slates with characteristic fossils, which are associated with contemporaneous and intrusive igneous rocks. Mica and chlorite schists, form the cliffs on the southern headland of Caernarvon Bay, and similar rocks occur in the Menai Straits, and at Holyhead; with interspersions of Devonian, Silurian, and Carboniferous strata. Along the coast of Denbighshire, the Upper Silurian strata reach the coast, and are succeeded by Carboniferous and Triassic deposits.

Crossing the embouchure of the river Dee, which is situated in the Coal-measures, the Triassic system of Cheshire appears at Birkenhead. Marine detritus and alluvium obscure the regular strata along this part of the Lancashire coast; until beyond Lancaster Bay, where Upper and Lower Silurian strata, and Mountain limestone appear.

At St. Bees Head, the coast exhibits coal-measures, covered by *Permian* deposits; and at Whitehaven and Workington, the sea-shores are entirely composed of carboniferous strata, the beds of coal being worked far under the sea. At Maryport, the magnesian limestone of the Permian system forms the cliffs. We now enter the Solway Firth, and terminate this rapid sketch of the geological phenomena exhibited by the coasts of England.

H H

ADDENDA TO VOLUME I.

NEBULAR THEORY OF THE UNIVERSE, *page* 41.—The following remarks by one of the most eminent philosophers of our times, are appended, with the view of showing, that although the nebular theory cannot be regarded as having any pretensions to be considered as a philosophical theory supported by direct observations, yet as suggestive of the effects of a law by which it seems propable the sidereal Universe is governed, it is deserving the highest consideration :—

“Should the powers of an instrument such as Lord Rosse's telescope, succeed in demonstrating the starry nature of the regular elliptic nebulæ which have hitherto resisted such decomposition, the idea of a *nebulous matter*, in the nature of a shining fluid, or condensible gas, must, of course, cease to rest on any support derived from actual observations in the sidereal heavens, whatever countenance it may still receive in the minds of cosmogonists from the tails and atmospheres of comets, and the zodiacal light in our own system. But though all idea of its ever being given to mortal eye, to view aught that can be regarded as an outstanding portion of primeval chaos, be dissipated, it will by no means have been even then demonstrated that among those stars so confusedly scattered, no aggregating powers are in action, tending to draw them into groups, and insulate them from neighbouring clusters; and, speaking from my own impression, I should say, that in the structure of the Magellanic Clouds, it is really difficult not to believe we see distinct evidences of the exercise of such a power.—Much has been said of late of the nebulous hypothesis as a mode of representing the origin of our own planetary system. An idea of Laplace, of which it is impossible to deny the ingenuity, of the successive abandonment of planetary rings, collecting themselves into planets by a revolving mass gradually shrinking in dimensions by the loss of heat, and finally concentrating itself into a sun,

472

ADDENDA.

has been insisted on with some pertinacity, and supposed to receive
almost demonstrative support from considerations to which I shall
presently refer. I am by no means disposed to quarrel with the
nebulous hypothesis even in this form, as a matter of pure speculation,
and without any reference to final causes; but if it is to be regarded
as a demonstrated truth, or as receiving the smallest support from any
observed numerical relations which actually hold good among the
elements of the planetary orbits, I beg leave to demur. If we go on
to push its application to that extent, we clearly theorize in advance
of all inductive observation.”—*Address to the British Association held
at Cambridge, in June 1845; by Sir J. F. W. Herschel, Bart.*

OLBERS ON AEROLITES, *page* 52.—The statement in the text is
erroneous. Olbers expressly comments on the *non-discovery* of meteor-
olites in tertiary and secondary strata, and inquires whether from the
absence of fossil meteoric stones we are to infer that previous to the
last and present arrangement of the earth’s surface, no Aerolites had
fallen upon it; though, according to Schriebers, it is probable that
the phenomenon now occurs not less than 700 times annually?—*See
Humboldt’s Cosmos, translated by Col. Sabine.*

Masses of native iron containing *nickel*, have however been discovered
in Northern Asia in an auriferous deposit, at a depth of 40 feet: and
also in the Carpathian mountains; and these masses are very like
undoubted meteoric stones.

There is a fine collection of Aerolites, admirably arranged by Mr.
König, in the gallery of minerals of the British Museum.

CHARING CHALK DETRITUS, *page* 324.—Since this notice was
printed, Mr. Harris has favoured me with a more particular description
of this interesting deposit. The village of Charing is situated on the
bed of detritus, which in many places is twelve feet thick. Mr. Harris
has obtained from it most of the species of Foraminifera which occur in
the chalk and in the tertiary strata of the Paris Basin. *Cytherinæ*
(marine crustaceans allied to the fresh-water Cyprides, *ante*, p. 405,)
abound in the detritus, and also in the neighbouring chalk and chalk-
mari. From the abundance of small land and fresh-water shells
associated with these cretaceous forms, Mr. Harris infers that the
neighbouring dry land was clothed with vegetation before this local
drift was formed.

INDEX TO VOLUME I.

A.

ACANTHIAS, fossil spines of, 342.

*Acrognathus boops*, 347, 352.

Adriatic, bed of, 70.

Aerolites, 50, 472.

_________ of Nanjenoy, 50.

_________ origin of, 51.

_________ Olbers on, 472.

_________ Humboldt, Baron, on, 52.

African Elephant, teeth of, 143.

Agassiz, M. on fossil fishes, 340.

_________ glaciers, 73.

Aix, fossils of, 252 (see 260).

_________ insects, 262.

*Alethopteris elegans*, 394.

*Alligator Hantoniensis*, 253.

Alluvial deposits, 39, 208.

Alum Bay, 241, 238.

Alumine, subsulphate of, 239.

Amber, 243.

American Cretaceous formations, 314.

_________ Tertiary __________, 281.

Ammonites, 334.

_________ *communis*, 334.

_________ *Mantelli*, 330.

_________ *Sussexiensis*, 330.

Andes, tertiary strata of, 282, 288.

Animals, extinction of, 125.

_________ extirpated by man, 126.

Animalculites in chalk, 334.

_________ flint, 302.

_________ soft parts of fossil, 303.

Anoplotherium, 256.

Anthracotherium, 257.

Antiparos, grotto of, 79.

Apteryx of New Zealand, 128.

Araucaria, fossil, 381.

Archæoniscus Brodei, 405.

Artesian wells, 235.

_________ of Grenelle, 237.

_________ London, 236.

Ascension, Isle of, 91.

_________ fossil turtles of, 91.

Ashburnham strata, 374.

Asiatic Elephant, teeth of, 143.

Astronomy in relation to Geology, 49.

Ava, mastodons of, 159.

*Aulolepis typus*, 348, 352.

Auroch, fossil, 173,

Auvergne, geology of, 267.

_________ fresh-water strata of, 272.

_________ mammalia fossil of, 274.

_________ extinct volcanos of, 269.

_________ review of geological phenomena of, 274.

B.

Babbage, Professor, on the elevation of land, 109.

Bacon, Lord, quoted, 29.

Bailey, Dr. W. on fossil Infusoria, 281.

Bagshot sand, 230, 233.

Bakewell, Mr. on the Moon, 451.

Balcomb, wealden strata at, 364.

Bay of Baiæ, 108.

_________ Naples, 111.

Bays in the Isle of Purbeck, 383.

Beach, raised, at Brighton, 113.

_________ Chili, 112.

Bead conglomerate, 83.

Bears, fossil, of the caverns, 177.

_________ femur of, 185.

Bed of the Adriatic, 70.

_________ British channel, 70.

_________ ocean, 69.

Belemnites in Chalk, 336.

*Belemnitella mucronata*, 336.

Bermuda limestone, 84.

Bensted, Mr., Iguanodon remains discovered by, 427.

Berkely, Bishop, quoted, 16.

Beryx in Chalk, 346.

_________ radians, 350.

_________ Lewesiensis, 351.

Big-bone Lick, 157.

Bignor, fossil fuci of, 318.

Bishop of London, quoted, 29.

Birds' feet, characters of, 145.

_________ fossil bones of, 440.

Bognor rocks, 240.

Boiling springs, 98.

Bonchurch, fossil plants of, 396.

Bone conglomerate, 185.

_________ microscopical examination of, 440.

Bonn, geology of, 278.

474

INDEX TO VOLUME I.

Bornholm, Isle of, 376.

Boulders, erratic, 209.

Bowerbank, Mr., on structure of bones, 440.

Bracklesham Bay, 240.

Brighton, 449.

______ cliffs, 114.

______ raised beach at, 113.

______ coast, mutations of, 449.

British Channel, bed of, 70.

Brodie, Rev. P., on fossil Insects, 407.

Bromley, fossil oysters of, 115, 230.

Brook Point, Isle of Wight, 378.

Brown coal of the Rhine, 278.

Byron, Lord, quoted, 122.

C.

Calcott, Lady, on the coast of Chili, 112.

Canoe, Ancient British, in silt, 64.

Carbonate of Lime, 195.

Carbonic acid gas in caves, 81.

Carboniferous system, 204.

Carnivora, fossil in caves, 174.

______ osteology of, 138.

Carpolithes Smithiæ, 319.

Castle Hill, Newhaven, 115, 239.

Cautley, Major, on the Sub-Himalayans, 161.

Caverns, 78, 454.

______ ossiferous, 174.

______ of the Brazils, 178.

______ England, 179.

______ Gaylenreuth, 175.

______ Kirkdale, 180.

______ Kent's Hole, near Torquay,

181. human remains, in, 181, 184, Cetiosaurus, 412.

Cervus megaceros, 132.

Cestracion, or Port Jackson Shark, 341.

Chalk, composition of, 299.

______ crinoida of, 326.

______ formation, 201, 296.

______ fossils of, 315.

______ animalcules of, 321, 324.

______ fishes, 338, 357.

______ reptiles, 353.

______ shells, 329.

______ zoophytes, 319.

Chalk-marl, 307.

Charing, chalk detritus at, 324, 472.

Charlesworth, Mr. on the Crag, 323.

______ Mosasaurus, 353.

Chili, elevation of the coast of, 112.

Chimæra, fossil, 343.

Classification of fishes, 340.

______ tertiary strata, 215.

______ rocks, 37.

______ formations, 200.

Clathraria Lyellii, 395, 396.

Coal in peat-bogs, 66, 67.

Coal in tertiary, 242, 260, 278.

______ of the Wealden, 292.

Coins in conglomerates, 82, 84.

Colombia river, submerged forest in, 390.

Colossal fossil Turtle, 164.

Colossochelys Atlas, 164.

Comparative anatomy, 137.

Coniferæ, fossil, 379, 386, 394, 399.

Conglomerates, osseous, 185.

______ of Gibraltar, 186.

______ with beads, 83.

______ coins, 82, 84.

Consolidation of sand, 80, 102.

______ by iron, 82.

Coprolites, 346.

Coralline Crag, 224.

Cornwall, recent limestone of, 92.

Country of the Iguanodon, 442.

Crab, fossil of, Malta, 251.

Crag, deposits of, 223.

______ Charlesworth, Mr. on, 223.

______ Wood Searles, Mr. on, 225.

Craufurd, Mr., on fossils from Ava, 159.

Cretaceous formations, 296.

______ of America, 314.

______ England, 296.

______ Russia, 314.

Crinoida of the Chalk, 326.

Crust of the earth, 31, 35.

Crustaceans of the tertiary, 249.

______ Chalk, 337.

______ Wealden, 405.

Crystallization, 195.

Ctenoid fishes, 340.

Cumbrian System, 205.

Currents, effect of, 70.

Cuvier, principles of palæontology by, 138.

Cuvierian pachyderms, fossil, 255.

Cycadous plants, fossil, 387, 396.

Cyclos of the Wealden, 404.

Cycloid fishes, 340.

Cyclura carinata, 436.

Cyprides, fossil, 251, 405.

D.

Darwin, Chas. Esq. on the Pampas, 165.

______ Andes, 282.

Davy, Sir H., on the Solfatara, 452.

Deane, Henry, Mr. on Xanthidia, 305.

Delta of the Ganges, 57.

______ Mississippi, 58.

______ Nile, 60.

______ Wealden, 370.

Dercetis elongatus, 349, 352.

Dermal bones of Goniopholis, 417.

______ Hylæosaurus, 436.

______ spines 437.

Detritus at Charing, 324, 472.

Devonian System, 204.

Dew, James, fossil sculptor, 163.

Didus ineptus, 130.

INDEX TO VOLUME I.

475

Dieffenbach, Dr. on Tongariro, 99.

Diluvium, 39.

Dinkel, M. drawings by, 346.

Dinornis or Moa, 129.

Dinosaurs, 419.

Dinotherium, 173.

Dirt-bed of Portland, 387.

Purbeck, 389.

Swindon, 390.

Disintegrated granite, 80.

Displaced strata, 197.

Dodo, 130.

Drachenfels, 277.

Drift, 200, 208.

of Scandinavia, 211.

at Muswell Hill, 213.

sand of Egypt, 91.

Cornwall, 93.

Peru, 92.

Druid sandstone, 234.

Dunker, Dr. W. on the Wealden of Germany, 377.

Duration of Geological Epochs, 30.

Durlstone Bay, 382.

E.

Earth, appearance of, from space, 32.

crust of, 31, 35.

gaseous state of, 48.

internal heat of, 31.

structure of, 31.

Echinites of the Chalk, 327, 328.

Edentata, fossil, 165.

Egerton, Sir P. on Wealden fishes, 409.

Chimæroid —, 343, 429.

Egypt, drifted sands of, 91.

Elasmotherium, 154.

Elephants, fossil, 147.

teeth of, 142.

in ice, 151.

of Brighton Cliffs, 114,

150.

the Thames, 149.

the Norfolk coast,

150.

Elephas primigenius, 160.

Elevation of the coast at Brighton, 113.

of Chili, 112.

temple at Puzzuoli, 106.

Scandinavia, 116.

Elk, Irish, fossil, 132.

Encke's comet, 45.

Endogenites erosa, 394.

England, geology of, 207.

geological map of, 462.

Eocene deposits, 216, 220, 226.

Epoch of terrestrial mammalia, 134.

Erratic boulders, 209.

Evaporation, amount of, 56.

Excavation of valleys, 276.

Existing geological agents, 53.

Expansion of rocks by heat, 106.

Extinct volcanoes of Auvergne, 466.

the Rhine, 276.

Extinction of animals, 125, 127.

F.

Fairholme, Mr. on the earth's surface, 36.

Faults in rocks, 199.

Feet of birds, structure of, 145.

Femur of Bear, 185.

of Iguanodon, 431.

Firestone, or Upper greensand, 307.

Fishes, fossil, arrangement of, 339.

cretaceous, 338, 357.

of Aix, 26¹.

Monte Bolca, 265.

the Wealden, 407.

scales of, 340.

Fitton, Dr. Geology of Hastings, by, 367, 369.

on the Strata below the Chalk, 386.

Fleming, Dr. on the Mammoths, 153.

Flint nodules and veins, 300.

fossils in, 301.

Fluviatile strata, formation of, 59.

Fluvio-marine deposits, 197.

Folkstone Cliff, 308.

Foraminifera, 247.

of the Chalk, 300, 321.

Charing, 324, 472.

soft parts of, in flint, 323.

Forest Ridge of Sussex, 361.

fossil, at Brook Point, 379.

Portland, 387.

Forfarshire, lacustrine strata of, 86.

Fossil Birds, 253, 440.

coniferous plants, 399.

Crustaceans, 249, 337, 405.

Echinoderms, 327.

Elephants, 143, 147.

Fishes, 260, 265, 356, 407.

Fox of Œningen, 263.

Human skeletons, 86.

Insects, 262.

Ivory, 148.

Mammalia, 136.

of Paris, 254.

the Thames, 149.

Auvergne, 274.

Nautili, 246.

Reptiles of the Chalk, 354.

Wealden, 409.

shells, 216.

tertiary, 244.

chalk, 329.

Wealden, 400, 403.

Fossil Fauna of the Sewalik hills, 161.

Fossils of the Isle of Sheppey, 232.

476

INDEX TO VOLUME I.

Fresh-water tertiary strata, 240.
shells, 245.

Wealden shells, 400.

Frontispiece of Vol. I. described, 444,
461.

G.

Galicia, salt mines of, 284.

Galt, 296, 307.

Ganges, delta of, 57.

Ganoid fishes, 340.

Gaseous state of the earth, 48.

Gavials, fossil, 414.

biconvex vertebræ of, 419.

Geographical distribution of animals, 33,
Geological epochs, 134, 200.

effects of the ocean, 67.

Map of England, 462.

Mutations, 39.

Geology, nature of, 26.

of Central France, 267.

England, 207.

S. E. of England, 360.

in relation to Astronomy, 40.

harmony with Scripture, 27.

Germany, Wealden of, 377.

Geysers of Iceland, 94, 96.

Gibraltar, rock of, 186.

Glaciers, 72.

Agassiz, M., on, 73.

Forbes, Prof., on, 73.

Glaris, fossil fish of, 352.

Glytodon, 171.

Gneiss system, 206.

Goniopholis crassidens, 414.

Gorgonia, fossil, 320.

Granite, disintegrated, at Brighton, 80.

Auvergne, 80.

Granitic system, 206.

Grant, Dr., on Quadrupana, 259.

Grantham, G. Esq., bead conglomerate
by, 83.

Grays in Essex, fossils of, 149.

Greensand, 308, 309.

Grotto of Antiparos, 79.

Del Cane, 81.

Guadaloupe, human skeletons of, 86.

Gulf stream, 70.

H.

Hall, Sir. J. I., experiments of, 104.

Hamites, 335.

Hampshire, basin of, 237.

Handfast Point, 382.

Harris, W. Esq., on Charing chalk-
detritus, 324, 473.

Hastings, Geology of, 369.

Lady, fossil crocodile of, 253.

sands, 374.

Headon Hill, 241.

Heat, internal, of the earth, 34.

Hemans, Mrs., quoted, 69.

Herbivora, structure of teeth, 141.

Herbivorous reptiles, 422.

Herschel, Sir J. F. W., on the nebular
theory, 471.

Hertfordshire breccia, 101.

High temperature, effects of, 103.

Himalayah fossils, 161.

Hippopotamus, fossil, 171.

Hoffman, M., discovery of Mosasaurus,
312.

Hopkins, W. Esq., on the interior of the
earth, 32.

Hordwell, fossil reptiles of, 253.

Horn of Iguanodon, 431.

Horner, Leonard, Esq., on the geology
of Bonn, 278.

Horse, fossil, 172.

Horsham, strata at, 372.

Hullmandel, Mr., on the Temple at
Puzzuoli, 109, 457.

Human bones in caves, 182, 184.

Epoch, 200.

fossil skeletons, 86, 88.

of Guadaloupe, 86.

Peru, 90.

skeleton in alluvium, 65.

Humboldt on meteorolites, 52.

Huttonian Theory, 105.

Hybodus, 409.

Hyena, fossil, 181.

Hylæosaurus, 435, 470.

dermal bones and spines,

437.

tooth of, 438.

Hypogene rocks, 206.

Hypsodon Lewesiensis, 343.

I.

Icebergs, 71, 211.

Iceland, geysers of, 94.

Ichthyology, fossil, 339

Ichthyolites of the Chalk, 356.

Jeffery, Mr., on the solution of silex, 100.

Iguana, 423.

Iguanodon, 422.

caudal vertebræ of, 426.

country of, 443.

form and size of, 433.

femur of, 432.

horn of, 431.

jaw of, 426.

of the Isle of Wight, 432.

Maidstone, 427.

teeth of, 423.

Incrustations, 75.

Incrusting springs, 74.

Indusia tubulata, 273.

Infusoria, fossil, of Virginia, 281.

INDEX TO VOLUME I.

477

Inoceramus, 331.

Insects, fossil, 261, 406.

Ireland, Greensand of, 309.

Irish Elk, 132.

Isle of Ascension, 91.

— Man, fossil els of, 134,

— Portland, 383.

— Purbeck, 381.

— Sheppey, 232.

— Wight, Geological Excursions round, 241.

— fossil forest of, 379.

— tertiary strata, 238, 241.

— Wealden strata, 378.

Jupiter Serapis, temple of, 106.

Jurassic formation, 202.

Ivory, fossil, 148.

K.

Kaup, M., discovery of the Dino-
therium, 174.

Kentish rag, 429.

— Iguanodon found in, 427.

Kent's Hole, near Torquay, 181.

Kirkdale Cavè, 179.

Konig, Charles, Esq., on fossil human
skeleton, 87.

Kyson, or Kingston, fossil monkey of,
259.

L.

Lacustrine deposits, 86, 263.

— of Æningen, 263.

— Limestone, 86.

Lagomys, 187.

Lake of Solfatara, 77, 452.

— Tabreez, 78.

Laminated strata, 197.

Langton Green, Wealden fossils of, 406.

Law of extinction of animals, 125.

Lecture I. 25—122.

— II. 123—191.

— III. 192—292.

— IV. Part I. 293—359.

— II. 360—449.

Leith Hill, 362.

Lepidotus of the Wealden, 408.

Leptolepis, 409.

Level of land and sea, mutations of, 118.

Lewes Levels, 61.

Lias system, 202.

Lickey quartz rock, 212.

Lignite of the Rhine, 279.

— Wealden, 392.

Loess of the Rhine, 278, 280.

Lonchopteris Mantelli, 393.

London Basin, 229.

— Artesian Wells of, 236.

— Clay, 231.

— of Hants, 239.

London, section from, to Brighton, 362.
— railway, 363.

Lulworth Cove, 384.

Lyell, Mr., on the elevation of Sweden,
116.

— geology of Aix, 262.

— Auvergne, 262.

— Forfarshire, 274.

— Loess of the Rhine, 58.

— the Siberian fossil mam-
moths, 153.

— tertiary systems of, 215.

— the Sibirische Fossilien, 215.

— Val di Noto, 222.

M.

Maestricht, strata of, 309.

— Mosasaurus of, 310.

Machiorodus latidens, 182.

Mackenzie, Sir G., on Iceland, 95.

Macrauchenia, 171.

Macropoma Mantelli, 345.

Macrorhynchus Myeri, 417.

Magnesian limestone system, 203.

Maidstone Iguanodon, 427.

Mallotus villosus of Iceland, 252.

Mammalia, fossil, 136, 149, 161, 163, 224,
254.

— tertiary, 254.

— of Auvergne, 273.

— Paris, 255.

Mammaliferous Crag, 224.

Mammoths of England, 148.

— North America, 156.

— Russia, 154.

— Siberia, 153.

— teeth of, 143.

Man, fossil remains of, 86.

Mantell, R. N. Mr., Xanthidia in flint,
306.

Mantellæ of Portland, 388.

Map, Geological of England, 462.

Marble, Purbeck, 403.

— Sussex, 402.

— Tabreez, 78.

Martin, John, Esq., painting by, 444.

Marsupite, 326.

Maryland, tertiary strata of, 281.

Mastodon, 157, 159.

— of America, 156.

— Ava, 159.

— the Crag, 224.

— Sewalik hills, 161.

— angustidens, 159.

— elephantoides, 160.

— giganteus, 157.

Megalonyx, 169.

Megalosaurus, 421.

Megatherium, 167.

478

INDEX TO VOLUME I.

Metamorphic rocks, 206.

Meteorolites, 50, 472.

Mica-schist system, 206.

Miliobatis, fossil, 252.

Mineral composition of rocks, 194.
elementary, 194.

Miocene, 216, 220, 223.

Mississippi, delta of, 58.

rafts of, 58.

Moa of New Zealand, 129.

Mollusca, 217.

Monkeys, fossil, 258.

Molluskite, 402.

Mont Dore, 271.

Monte Bolca, 252 (see 265).
Nuovo, 109.

Montmartre, quarries of, 254.

Moon, telescopic appearance of, 41.
Mr. Bakewell on, 451.

Morris, Mr., on fossil mammalia, 149.

Catalogue of British fossils
by, 149.

Morton, Dr., Synopsis of American
Cretaceous formation, 313.

Mosasaurus, 311.

of America, 313.

English chalk, 313.

Mount Hecla, 98.

Washington, 10.

Mountains, heights of, 36.

Murchison, Sir R. I., on the geology of
Aix, 262.

geology of
Russia, 126.

Chalk of
Russia, 314.

strata at
Œningen, 263.

Scandin-
vian drift, 211.
Siberian

Mammoths, 156.
Silurian system of,
205.

Muswell Hill drift, 213.

Mylodon, 168.

memoir on, by Prof. Owen, 168.

N.

Nature of Geology, 26.

Nautilus of the Chalk, 333.

tertiary, 246.

elegans, 333.

imperialis, 247.

zigzag, 247.

Nebular theory, 41, 471.

Nebulæ, various states of, 44.

Neritina Fittoni, 401.

Newhaven, tertiary strata of, 115.

New Red Sandstone, 203.

New Zealand, Apteryx of, 128.

boiling streams of, 98.

New Zealand. extinct birds of, 129.

Nile, deposits of, 60.

Nonionina Germanica, 323.

Norfolk Island Pine, fossil, 381.

Northampton, Marquess of, tertiary
shells by, 221.

fossil co-
rals discovered by, in flint, 302.
Spirolinites,
325.

Nummulites, 247.

O.

Ocean, geological effects of, 67.

Œningen, fossil fox of, 263.

Olbers on Aerolites, 472.

Old Red Sandstone, 204.

Oolitic formation, 202.

Osmeroides, 344, 347.

Osseous breccia, 185.

of Australia, 188.

Osteology of the carnivora, 138.

herbivora, 141.

rodentia, 143.

Ostrich-like birds, fossil, 129.

Organic remains in flint, 301.

of the Chalk, 315.

Wealden, 391.

Owen, Prof., on dermal spines of the
Hylæosaurus, 436.

fossil birds' bones, 440.

South American fossil
mammalia, 171.

History of British fossil
mammalia, 151, 174, 183, 185, 227, 257.

Report on fossil rep-
tiles, 420.

Oyster bed, fossil, of Bromley, 115.

P.

Pagurus Faujasii, 338.

Palæontology, principles of, 138.

Palæotherium, 256.

Palæornis Cliftii, 442.

Palæozoic deposits, 203.

Palermo, fossils of, 221.

Paludinæ of the Wealden, 401, 403.

Pampas, The, structure of, 164.

Paris basin, 288.

Paris, Dr., on a recent formation of sand-
stone, 93, 455.

Parish, Sir W., fossil edentata disco-
vered by, 164.

Peat bogs, 65.

with coal, 66, 67.

Petit, M., on alluvial deposits, 215.

Petrified forest of Portland, 386.

Philippi on tertiary strata of Italy, 215.

Pine-trees fossil, 380.

INDEX TO VOLUME I.

479

Placoid fishes, 340.

Plagiostoma, 331.

Playfair, Prof., on Siberian Mammoths,
153.

_________ geological epochs, 292.

Plesiosaurus of the Wealden, 412.

_________ chalk, 354.

Poecileleuron, 417.

Polype in flint, 304.

Polyptychodon, 354.

Portland, Isle of, 383.

_________ petrified forest of, 385.

Pounceford, 370.

Pliocene deposits, 216, 220.

Plutonic rocks, 206.

Prestwick, Mr., on London basins, 230,
234.

Primary rocks, 37.

Primitive rocks, 37.

Principles of Palaeontology, 138.

Pterodactyles of the Chalk, 354.

_________ Wealden, 438.

Pudding-stone of Hertfordshire, 101.

Purbeck beds, 352, 374.

_________ Isle of, 381.

_________ marble, 375, 403.

_________ wealden of, 381.

Puy de Come, 269.

_________ Dome, 269.

_________ Pariou, 269.

Puzzuoli, temple of, 106.

Pyramids, nummulites of, 248.

Q.

Quadrumana, fossil, 258.

Quorra, Lander on the, 59.

R.

Raft, fossil, in the Isle of Wight, 379.
_________ of the Mississippi, 58.

Raised beach at Brighton, 113.

Raphiosaurus, 354, 418.

Railway section to Brighton, 363.

Recent Limestone of Cornwall, 92.

_________ Bermuda, 84.

Reade, Rev. J. B., animalcules in flint,
304, 305.

Red crag, 224, 225.

Rein-deer, fossil, of the Isle of Wight,
173.

Reptiles of the Chalk, 353.

_________ Wealden, 409.

Retrospect of Lect. I. 119.

_________ Lect. II. 189.

_________ Lect. III. 285.

_________ Lect. IV. 447.

Rhine, extinct volcanoes of, 276, 288.

Rhinoceros, fossil, 171.

_________ in ice, 152.

Richmond, Virginia, Infusorial earth of,
281.

Ripple marks, 60, 372.

Rippled sandstone, 372.

Rock of Gibraltar, 186.

Rocks, arrangement of, 37, 200.

_________ composition of, 194.

_________ expanded by heat, 196.

_________ Primary, 37.

_________ Secondary, 38.

_________ Transition, 38.

Rocky mountains, 10.

Rodentia, structure of teeth, 143.

Rogers, Prof., on Richmond earth, 281.

Römer, M., on the Wealden, 377.

Rosse, Earl of, telescope of, 44, 472.

Rotaliæ fossils, 249, 303.

_________ of the chalk, 321.

_________ soft parts of, 323.

Rotu-Mahanu in New Zealand, 99.

Running water, effects of, 55.

Russia in the mammoth epoch, 155.

_________, Geology of, by Sir R. Murchison,
126.

S.

Sacrum of the Dinosaurians, 420.

_________ Gavial, 419.

St. Peter's Mountain, 310.

Saliferous tertiary deposits, 284.

Sand consolidated by pressure, 102.

Sandstone, ripple-marks on, 372.

Sarsden stone, 234.

Saturn, telescopic view of, 46.

Scales of fishes, 339.

Scandinavia, elevation of, 116.

Scandinavian drift, 211.

Scaphites, 335.
Sea, encroachments of, in Sussex, 68.

Secondary epochs, 201, 294.

_________ formations, 295.

_________ rocks, 38.

Section of Alum Bay, 241.

_________ at the baths at Mont Dore, 272.

_________ Brook Point, 378.

_________ from London to Brighton, 362.

_________ Isle of Wight,
364.

_________ near Folkstone, 308.

_________ in the Isle of Portland, 386.

_________ of Lewes Levels, 62.

_________ of mammoth alluvium, 155.

_________ in Tilgate Forest, 372.

Sepia, 332.

Sewalik hills, fossils of, 161.

Shells of the Chalk, 329.

_________ fossil, 216.

_________ tertiary, 244.

_________ of the Wealden, 400.

Sheppey, Isle of, 232, 233.

Siberia, alluvial deposits of, 154.

_________, in the mammoth epoch, 155.

480

INDEX TO VOLUME I.

Siberia, Mammoths of, 153.

Siebenbirge of the Rhine, 277.

Siliceous solution, artificial, 100.
springs and streams, 93.

Silliman, Prof., Introduction by, 1.

on Coal, 6.

Geology of America, 9.

fossil fishes, 18.

plants, 18.

reptiles, 19.

marble, 7.

metals, 8.

Mount Washington,

10.

Silver coins in breccia, 82.

Silurian System, 205.

Sivatherium, 163.

Skeletons, human fossil, 86.

Sloth tribe, 165.

Smerdis minutus, 260.

Smith, Mrs., fossils by, 319.

—, Rev. Dr. Pye, quoted, 47.

Solar System, 40, 45.

Solfatara, Lake of, 77, 452.

South-east of England, Geology of, 360.

Sowerby's Mineral Conchology, 231.

Sphenopteris Mantelli, 393.

Spherulites Mortoni, 331.

Species of Echinites, 329.

Spines, dermal, of Hylæosaurus, 437.

Spirolinites, 325.

Springs, nature of, 234,

—, thermal of Iceland, 98.

—, New Zealand, 98.

Stalactites, 78, 454.

Stalagmites, 78.

Star-fishes of the Chalk, 327.

Stone, Wealden strata at, 390.

—, Insects, fossil, 407.

Strata, Chronological Synopsis of, 200.

Streams and rivers, effects of, 55.

Streptospondylus, 414.

Structure of the Earth, 31.

Struthious birds, 132.

Studland Bay, 381.

Sub-Apennines, 222.

Sub-Himalayah fossils, 161, 163.

Submerged forest, 390.

Subterranean forest, 67.

—, rivers, 56.

Subsulphate of alumine, 239.

Sussex coast, changes in, 449.

—, marble, 403.

Swanage Bay, 381.

—, fossil crocodile, 415.

Swindon, dirt-bed at, 390.

T.

Tabular flint, 300.

Tabreez marble, 78.

Teeth of Cestracion in Chalk, 341.

—, Elephants, 142.

Teeth of Fishes, fossil, 341.

—, Goniopholis, 414.

—, Hylæosaurus, 438.

—, Iguanodon, 424.

—, Mammoths, 143.

—, Mastodon, 157.

—, Megalosaurus, 421.

—, Rodents, 143.

—, structure of, 142.

Temple at Puzzuoli, 106.

Tertiary birds, 253.

—, crustaceans, 249.

—, epoch, 200.

—, fishes, 251.

—, formations, 39, 200, 213, 220.

—, fossils, 241.

—, mammalia, 254.

—, reptiles, 252.

—, shells, 244.

—, saliferous deposits, 284.

—, Volcanoes of Auvergne, 268.

—, strata of the Andes, 282.

—, Aix, 260.

—, America, 281.

—, Monte Bolca, 265.

—, zoophytes, 243.

Terrestrial Mammalia, epoch of, 134.

Thames, fossil mammalia of, 149.

Thetis frigate, wreck of, 70.

Tilgale Forest, 371.

Toganrog, section at, 155.

Topping, Mr., microscopic artist, 303.

Torpedo fossil, 252.

Torquay, Cave near, 181.

Totten, Colonel, experiments of, 106.

Toxodon, 171.

Travertine, 77.

Transition rocks, 38.

Triassic formations, 203.

Trotter, Robert, Esq., fossils by, 408, 416, 430.

Trionyx Bakewelli, 411.

Trogontherium, 154.

Turbinolia Konigi, 320.

Turrilites, 335.

Turtles, 410.

—, fossil of the Chalk, 355.

—, Wealden, 410.

Tusks of Mastodon, 159.

U.

Unio Valdensis, 404.

Upright fossil trees, 386, 389.

V.

Val di Noto, 222.

Valley of the Thames, fossils of, 149.

Valleys formed by running waters, 276.

Ventriculites, 321.

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