THE
WONDERS OF GEOLOGY;
OR,
A FAMILIAR EXPOSITION
OF
Geological Phenomena.

BY
GIDEON ALGERNON MANTELL, LL.D. F.R.S.

HONORARY FELLOW OF THE ROYAL COLLEGE OF SURGEONS OF ENGLAND, ETC.

AUTHOR OF THE MEDALS OF CREATION, THOUGHTS ON ANIMALCULES, ETC.

Silver Coins of Edward the First, imbedded in ironstone.—Page 82

“My heart is awed within me, when I think
Of the great miracle which still goes on
In silence round me—the perpetual work
Of Thy creation, finished, yet renewed
For ever!”

IN TWO VOLUMES.—VOL. I.

SIXTH EDITION.

LONDON:
HENRY G. BOHN, YORK STREET, COVENT GARDEN.
1848.

THE COUNTRY OF THE IGUANODON. RESTORED BY JOHN MARTIN ESQ. K.I.
FROM THE GEOLOGICAL DISCOVERIES OF GIDEON MANTELL ESQ. LLD. ERS &c.

TO

BENJAMIN SILLIMAN, Esq. LL.D. M.D.

PROFESSOR OF CHEMISTRY AND GEOLOGY IN YALE COLLEGE,
NEWHAVEN, CONNECTICUT;
FOUNDER AND EDITOR OF THE AMERICAN JOURNAL OF SCIENCE;
FOREIGN MEMBER OF THE GEOLOGICAL SOCIETY OF LONDON;
ETC. ETC.

MY VERY DEAR FRIEND,

It is with the liveliest pleasure that I inscribe
anew "The Wonders of Geology" with your
distinguished name: for although we have never
met—and probably never shall meet in this world
—a friendship originating in mutual respect and
regard, and cemented by an unrestricted corre-
spondence, and an unreserved interchange of
thought and feeling, for nearly twenty years,
needs not the aid of personal intercourse to
increase its ardour, or ensure its permanence.

A 2

iv

DEDICATION.

That you may long be spared for the advance-
ment of the Sciences you have so successfully
cultivated and promoted—and for the benefit of
your countrymen whose national character your
labours have so greatly contributed to elevate and
refine—and for the delight of a large domestic
circle by whom you are alike respected and
beloved—is the fervent prayer of

Your much attached friend,

GIDEON ALGERNON MANTELL.

19, CHESTER SQUARE, PIMLICO;

London, Jan. 1848.

ADVERTISEMENT.

ALTHOUGH but a few years have elapsed since the
last edition of these volumes issued from the press,
the great advancement of Geology and the collateral
Sciences rendered it necessary to compose the entire
work anew, that the most important recent disco-
veries in Palæontology, and the new or modified views
of geological phenomena resulting from the progress
of knowledge, might be incorporated in the respec-
tive Lectures.

The time and labour required for the preparation of
the present edition have, therefore, been considerable;
and since, like all my former works, these volumes
have been composed in the intervals of arduous pro-
fessional avocations, I venture to claim indulgence
for any inaccuracies, repetitions, or omissions.

I would especially entreat the favourable consi-
deration of any author whose statements or opinions

vi

ADVERTISEMENT.

may appear in the following pages without reference, or due acknowledgment; for, in the multiplicity of subjects comprised in this edition, I am apprehensive that I may, in some instances, have inadvertently stated as original, ideas and suggestions, unconsciously derived from the works of others.

The style and arrangement of the Lectures have been retained, as it appeared inexpedient to alter the plan of a work of which ten thousand copies have been issued, and which has been republished in America, and translated into German by an eminent Professor of the University of Bonn.

To render these volumes available to the purchasers of "The Medals of Creation," a table of the references to the "Wonders of Geology" in that work, corrected for this edition, is annexed; for the two works are intended to illustrate each other; the present volumes offering a familiar exposition of the *Philosophy of Geology*, and The Medals a compendious view of the *Principles of Palæontology*.

19, CHESTER SQUARE,
PIMLICO.

# PREFACE

## TO THE FORMER EDITION.

A COURSE of Lectures delivered at Brighton, in an unsuccessful attempt to establish in that town a public museum, illustrative of the Geology, and Organic Remains, of the South-East of England, formed the groundwork of the unpretending volumes which, under the title of "THE WONDERS OF GEOLOGY," have met with so favourable a reception.

When the first edition appeared, my collection, consisting of upwards of 20,000 specimens, from which the subjects for the illustrations of the Lectures were selected, was exhibited at Brighton, by the Sussex Literary Institution, as the *Mantellian Museum*, with the view to its permanent establishment as the basis of a County Museum.

That expectation was, however, defeated; for though I would willingly have made any pecuniary

viii

PREFACE TO THE FORMER EDITION.

sacrifice, to accomplish what appeared to me so desirable
an object, yet after the death of my noble and lamented
friend, the late Earl of Egremont, the munificent
patron of the Institution,—and of the Earl of Munster,
who was an ardent supporter of the measure,—the plan
was abandoned, in consequence of the lukewarmness,
and even opposition, of some of those who had engaged
to carry out the object. I therefore, in compliance
with the suggestions of my scientific friends, disposed
of the entire collection to the Trustees of the British
Museum.

But although the main object of my labours was
thus frustrated, and the collection,—which would have
been of tenfold importance if located in the district
whence it was derived, and whose geological structure
it was designed to illustrate,—is now broken up, and
dispersed through the cabinets of our National Institu-
tion, yet many of the most interesting organic remains
are so unique, and so strikingly distinct from any
other specimens hitherto obtained, that they may be
referred to with facility, when the gallery of Organic
Remains in the British Museum shall be finally
arranged.*

I avail myself of this opportunity to record the deep
sense of obligation I feel to many excellent friends, for

* As, for example, the remains of the Wealden reptiles, the Iguano-
don, Hylæosaurus, Cetiosaurus, Swanage Crocodile, &c.; the Fishes
from the Chalk, &c.

ix

their strenuous and unremitting exertions to prevent
the dispersion of my Museum, and to establish it on a
permanent basis in my native County. And although
their efforts have proved unavailing, a time will as-
suredly come, when their endeavours to promote a
taste for scientific knowledge among the intelligent
inhabitants of Sussex will be duly appreciated, and
the failure of the attempt to secure to the County a
collection so rich in its peculiar fossil and mineral
productions, be remembered with regret.

At the suggestion of the eminent publisher with
whose imprint the work now appears, the Introduction
by Professor Silliman, appended to the American, is
prefixed to the present edition.

G. A. M.

ADDRESS TO THE READER.

GEOLOGY, beyond almost every other science, offers fields
of research adapted to all capacities, and to every condition
and circumstance in life in which we may be placed. For
while some of its phenomena require the highest intellec-
tual powers, and the greatest attainments in abstract science,
for their successful investigation, many of its problems may
be solved by the most ordinary intellect, and facts replete
with the deepest interest may be gleaned by the most
casual observer.

To the medical philosopher Geology presents peculiar
attractions for those hours of leisure and relaxation, which
are indispensable to maintain a healthy state of mind; for
it requires the cultivation and application of Chemistry,
Botany, Comparative Anatomy, Zoology, and Physiology,—
sciences which form the very foundation of medical know-
ledge. It exerts, too, the most salutary influence, by calling
forth the continual exercise of our intellectual powers; for
the desire to explain what is obscure in the natural records
of the past, induces a more accurate examination of existing
physical phenomena, and of the organization and habits of

ADDRESS TO THE READER.

xi

the living beings within the reach of actual observation. It
enforces the necessity of weighing the conflicting evidence
of apparently irreconcilable phenomena, of detecting dif-
ferences, and seeking analogies, and of generalizing and
combining an immense number of isolated facts. The mind
thus acquires the power of acute observation, of patient
investigation, and of salutary caution in drawing infe-
rences, and arriving at conclusions—habits of the first
importance in the discrimination and treatment of diseases.

And however little, in the present state of the public
mind, such qualities may be appreciated, the labour will
bring an ample reward in the self-conviction that the talents
entrusted to us have not been given in vain.

“ Better than Fame is still the toil for Fame,
The constant training for the glorious strife !”

For it should ever be borne in mind that the primary object
of every study ought to be an inward one—that of enlarg-
ing and elevating the intellect; and the direct aim of
science should be the discovery of the principles of unity,
order, and connexion, which are everywhere manifest in
the universal life of nature.

In proof that intellectual pursuits of the highest order
are not incompatible with any situation in life, I would
earnestly solicit attention to the following eloquent appeal
by one of the most enlightened statesmen of our times :—

“ Heed not the sneers and foolish sarcasms against learn-
ing, of those who are unwilling that you should rise above
the level of their own contented ignorance. Do not for a
moment imagine that you have not time for acquiring
knowledge; it is only the idle man who wants time for
every thing. The industrious man knows the inestimable
value of the economy of time, and amidst the most multi-

xii

ADDRESS TO THE READER.

farious occupations, can find leisure for rational recreation,
and mental improvement. Do not believe that the acqui-
sition of scientific knowledge will obstruct your worldly
prosperity, or that it is incompatible with your worldly
pursuits. Rely upon it, you cannot sharpen your intellec-
tual faculties, you cannot widen the range of your know-
ledge, without becoming more skilful and successful in the
business or profession in which you are engaged.”*

I may add, that by that happy connexion, whereby the
useful is indissolubly linked with the true, the exalted, and
the beautiful, science thus followed for its own sake, will
pour forth abundant overflowing streams to enrich and
fertilize that industrial prosperity, which is the conquest of
the intelligence of Man over matter.†

* Inaugural Address at the opening of the Tamworth Institution, 1841, by the Right Hon. Sir Robert Peel, Bart.

† See Introduction to Cosmos, or a Sketch of a Physical Description of the Universe; by Alexander Von Humboldt.

TABLE OF CONTENTS.

VOL. I.

<table><thead><tr><th></th><th>PAGE</th></tr></thead><tbody><tr><td>1. DEDICATION</td><td>iii</td></tr><tr><td>2. ADVERTISEMENT</td><td>v</td></tr><tr><td>3. PREFACE TO THE FORMER EDITION</td><td>vii</td></tr><tr><td>4. ADDRESS TO THE READER</td><td>x</td></tr><tr><td>5. INTRODUCTION BY PROFESSOR SILLIMAN</td><td>1-24</td></tr><tr><td>6. LECTURE I</td><td>25-122</td></tr></tbody></table>

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

xiv

CONTENTS.

<table><tr><td>7. LECTURE II. ....................................................................</td><td>PAGE</td><td>123—191</td></tr></table>

1. Introductory. 2. Extinction of Animals. 3. Law of Extinction.

4. Animals extirpated by Human Agency. 5. Apterisyx of New Zealand.

6. Moa of New Zealand. 7. Dodo of the Mauritius. 8. Irish Elk.

9. Epoch of Terrestrial Mammalia. 10. Fossil Mammalian Remains.

11. Comparative Anatomy. 12. Osteology of the Carnivora. 13. Osteology of the Herbivora. 14. Dental Organs of the Rodentia.

15. General Inferences. 16. Fossil Elephants, &c. 17. Fossil Mammalia of the valley of the Thames. 18. Fossil Elephants of other parts of England. 19. Extinct Elephant or Mammoth in Ice. 20. Mammoths of the alluvial deposits of Russia. 21. Siberia and Russia in the Mammoth epoch. 22. Mastodon. 23. Mastodons of Ava. 24. Fossil Mammalia of the Sub-Himalayans. 25. Sub-Himalayah tertiary deposits. 26. Remarkable collocation of Fossil Animals. 27. The Pampas. 28. The Sloth tribe. 29. Megatherium. 30. Mylodon.

31. Megalonyx. 32. Glyptodon. 33. Toxodon. 34. Fossil Hippopotamus, &c. 35. Dinotherium. 36. Fossil Carnivora in Caverns. 37. Cave of Gaylenreuth. 38. Försterhöhle, or Forest-cave. 39. Bone Caverns in England. 40. Diseased Bones found in Caverns. 41. Human Bones in Caverns. 42. Osseous Breccia. 43. The Rock of Gibraltar. 44. Osseous Breccia of Australia. 45. Retrospect.

8. LECTURE III. .................................................................... 192—292

1. Introductory. 2. Mineral composition of Rocks. 3. Crystallization.

4. Stratification. 5. Displaced Strata. 6. Veins and Faults. 7. Chronological Synopsis of the Strata. 8. Geology of England. 9. Alluvium and Drift of the Modern Epoch. 10. Erratic Boulders. 11. Tertiary Formations. 12. Classification of the Tertiary. 13. Fossil Shells. 14. Lithological Characters of the Tertiary. 15. Subdivisions of the Tertiary System. 16. Pliocene Deposits. 17. Miocene; the Crag. 18. Eocene, or Lower Tertiary. 19. The Paris Basin. 20. The London Basin. 21. The Isle of Sheppey. 22. Bagshot Sand. 23. Phenomena of Springs. 24. Artesian Wells. 25. The Hampshire Basin. 26. Alum Bay. 27. London Clay of Hampshire. 28. Freshwater Tertiary of the Isle of Wight. 29. Organic Remains of the Eocene Strata. 30. Amber. 31. Zoophytes of the Tertiary. 32. Shells of the Tertiary. 33. Fossil Nautilus. 34. Nummulites. 35. Rotaliæ. 36. Crustaceans and Fishes. 37. Tertiary Reptiles. 38. Tertiary Birds. 39. Fossil Mammalia of Paris. 40. Palæotheria and Anoplotheria. 41. Fossil Monkeys. 42. Tertiary Deposits of Aix. 43. Fossil Insects. 44. Fossil Fox of Æningen. 45. Fossil Fishes of Monte Bolca. 46. Tertiary Volcanoes of France. 47. Extinct Volcanoes of Auvergne. 48. Crater of the Puy de Come. 49. Mont Dore. 50. Lacustrine Strata of Auvergne. 51. Successive Epochs of Mammalia. 52. Survey of Geological Phenomena. 53. Excavation of Valleys by running Water. 54. Extinct Volcanoes of the Rhine. 55. Brown Coal Deposits; the Loess. 56. Tertiary of Europe and North America. 57. Altered Tertiary of the Andes. 58. Saliferous Deposits. 59. Retrospect. 60. Concluding Remarks.

CONTENTS.

XV

<table><tr><td>9. LECTURE IV. PART I.</td><td>PAGE</td><td>293—359</td></tr></table>

<table><tr><td>1. Introductory.</td><td>2. Formations of the Secondary Epoch.</td><td>3. Cretaceous Formation.</td><td>4. Chalk Downs.</td><td>5. Flint nodules and veins.</td><td>6. Organic remains in flint.</td><td>7. Animalcules in flint.</td><td>8. Xanthidia.</td><td>9. Middle and Lower groups of the cretaceous strata.</td><td>10. Folkstone Cliffs.</td><td>11. Cretaceous strata of Maestricht.</td><td>12. The Mosasaurus.</td><td>13. Cretaceous deposits of other countries.</td><td>14. Organic remains of the Chalk Formation.</td><td>15. Fossil vegetables.</td><td>16. Zoophytes of the Chalk.</td><td>17. Animalculites of the Chalk.</td><td>18. Chalk Rotaliæ.</td><td>19. Chalk detritus at Charing.</td><td>20. Spirolinites.</td><td>21. Crinoidea of the Chalk.</td><td>22. Star-fish.</td><td>23. Echinites.</td><td>24. Shells of the Chalk.</td><td>25. Cephalopoda.</td><td>26. The Nautilus.</td><td>27. Ammonites.</td><td>28. Turrilites and Hamites.</td><td>29. The Belemnite.</td><td>30. Crustaceans of the Chalk.</td><td>31. Fishes of the Chalk.</td><td>32. Scales of Fishes.</td><td>33. Teeth of Sharks.</td><td>34. Hypsodon and other fishes.</td><td>35. Fossil Salmon.</td><td>36. The Macropoma.</td><td>37. Beryx, and other fishes of the Chalk.</td><td>38. Reptiles of the Chalk.</td><td>39. Fossil Turtles.</td><td>40. Summary.—Tabular arrangement of Sussex Chalk fishes.</td></tr></table>

<table><tr><td>10. LECTURE IV. PART II.</td><td>360—449</td></tr></table>

<table><tr><td>1. Geology of the South-east of England.</td><td>2. Geological phenomena between London and Brighton.</td><td>3. London and Brighton Railway Sections.</td><td>4. The Wealden Formation.</td><td>5. Wealden of the Sussex coast.</td><td>6. Pounceford.</td><td>7. Tilgate Forest.</td><td>8. Ripple-marks on Wealden sandstone.</td><td>9. Subdivisions and extent of the Wealden.</td><td>10. Wealden of the North of Germany.</td><td>11. Wealden of the Isle of Wight.</td><td>12. Fossil Trees at Brook Point.</td><td>13. Wealden of the Isle of Purbeck.</td><td>14. Coves in the S.W. of Purbeck.</td><td>15. The Isle of Portland.</td><td>16. Petrified Forest of the Isle of Portland.</td><td>17. Mantelliæ.</td><td>18. Dirt-bed of the Isle of Purbeck.</td><td>19. Organic Remains of the Wealden.</td><td>20. Fossil Vegetables.</td><td>21. Fossil Cycadous Plants.</td><td>22. Clathraria Lyellii.</td><td>23. Fruits of Coniferous Trees.</td><td>24. Univalve Shells of the Wealden.</td><td>25. Bivalve Shells of the Wealden.</td><td>26. Crustaceans of the Wealden.</td><td>27. Wealden Insects.</td><td>28. Wealden Fishes.</td><td>29. Reptiles of the Wealden.</td><td>30. Fossil Turtles.</td><td>31. Marine Reptiles.</td><td>32. Crocodilian Reptiles.</td><td>33. Fossil Teeth of Crocodiles.</td><td>34. Fossil Crocodile of Swanage.</td><td>35. The Dinosaurians.</td><td>36. Megalosaurus.</td><td>37. Iguanodon.</td><td>38. Teeth of the Iguanodon.</td><td>39. The Maidstone Iguanodon.</td><td>40. Vertebræ of the Iguanodon.</td><td>41. Bones of the extremities.</td><td>42. Magnitude and proportions of the Iguanodon.</td><td>43. The Hylæosaurus.</td><td>44. Pterodactyles of the Wealden.</td><td>45. Birds of the Wealden.</td><td>46. The Country of the Iguanodon.</td><td>47. Sequence of Geological changes.</td><td>48. Retrospect.</td></tr></table>

<table><tr><td>11. APPENDIX—SUPPLEMENTARY NOTES</td><td>451—458</td></tr></table>

<table><tr><td>12. DESCRIPTION OF THE PLATES:—THE FRONTISPIECE.</td><td>461</td></tr></table>

<table><tr><td>GEOLOGICAL MAP OF ENGLAND.</td><td>462</td></tr></table>

<table><tr><td>DESCRIPTION OF PLATE II.</td><td>466</td></tr></table>

<table><tr><td>III.</td><td>468</td></tr></table>

<table><tr><td>IV.</td><td>470</td></tr></table>

<table><tr><td>13. ADDENDA.</td><td>471</td></tr></table>

<table><tr><td>14. INDEX TO VOL. I.</td><td>473</td></tr></table>

VOL. II.

<table><thead><tr><th></th><th></th><th>PAGE</th></tr></thead><tbody><tr><td>1. LECTURE</td><td>V. PART I.—The Jurassic Formation: Oolite and Lias</td><td>483—532</td></tr><tr><td>2.</td><td>V. PART II.—The Trias and Permian Formations</td><td>533—588</td></tr><tr><td>3.</td><td>VI. On Corals and Crinoidea</td><td>589—659</td></tr><tr><td>4.</td><td>VII. The Carboniferous System</td><td>660—748</td></tr><tr><td>5.</td><td>VIII. PART I.—The Devonian, Silurian, and Cumbrian Formations</td><td>749—804</td></tr><tr><td>6.</td><td>VIII. PART II.—The Volcanic, and Hypogene, or Primary Rocks</td><td>805—902</td></tr><tr><td>7. APPENDIX TO VOL. II.</td><td></td><td>903—910</td></tr><tr><td>8. DESCRIPTION OF PLATES V. and VI.</td><td></td><td>912—914</td></tr><tr><td>9. GLOSSARY</td><td></td><td>915—921</td></tr><tr><td>10. ADDENDA</td><td></td><td>923</td></tr><tr><td>11. REFERENCES IN THE MEDALS OF CREATION</td><td></td><td>925</td></tr><tr><td>12. GENERAL INDEX</td><td></td><td>927—938</td></tr></tbody></table>

THE
WONDERS OF GEOLOGY.

INTRODUCTION TO THE AMERICAN EDITION,
BY
PROFESSOR SILLIMAN.

1. OBJECT OF THE SCIENCE.—Geology is the natural history of the earth; its hills and mountains, its rivers, lakes, seas, and oceans, its fertile plains and sterile deserts—in a word, all that belongs to physical geography, is comprised in this science. Incidentally, it takes notice of agriculture and commerce, of the various improvements of civilization, and of the races and families of animated beings of both organic kingdoms, since they are all influenced, more or less, by geological phenomena. Every thing upon the globe is, therefore, connected with geology, which embraces likewise the principal physical facts and events of which our planet has been the theatre.

But the more immediate object of this science is to ascertain the structure of the earth, and the nature of the masses of which its crust is composed—the order of their arrangement—their mineral and organic contents—the proximate causes by which they were formed and deposited, and those by which they are rendered liable to future changes.

2. PRELIMINARY KNOWLEDGE.—These considerations necessarily involve a knowledge of physical laws. We must be acquainted with the chemical constitution of matter, with the combinations its elements are capable of forming, with the liabilities of the com-

B

2

THE WONDERS OF GEOLOGY.

pounds to enter into new arrangements, and with the laws which govern these changes. The mechanical laws must also be kept in view; the weight, pressure, and moving power of solids and fluids, the varieties and force of attraction; in a word, the dynamics of our globe. Nor can the subject be considered entirely apart from the planetary relations of the earth, as a member of the solar system, and of the innumerable systems which compose the stellar universe.

Those subtle agents unknown in their essence, but most manifest and potent in their effects—namely, heat, light, electricity, and magnetism, either distinct, or combined in various modifications, demand also a faithful study, that we may comprehend their manifold and unceasing effects in the economy of the earth; nor must the enveloping ocean of aerial fluid, the atmosphere, in which their energy is so largely displayed, be forgotten; both in its physical and chemical characters, it demands earnest attention. We must also know the outlines of natural history, especially of the mineral species, or, at least, of those which are, or have been, chiefly concerned in producing, by their extension or aggregation, the mountains and continents, and the entire crust of our planet, so far as it is cognizable by man. Some competent knowledge of mineralogy ought, therefore, to precede the study of geology; it is true, we may begin with a comparatively small number of the most important minerals, as our increasing acquaintance with rocks will constantly augment our familiarity with the minerals which compose them.

In like manner, as mineralogy is indispensable to the study of geology, so the other departments of natural history are auxiliary to it in a most important degree. Animals and plants, either entire or dismembered, or in fragments, are contained in almost all kinds of rocks, except the primary and the volcanic; nor can we assign the limit of organic matter even in these, for we know not how far fire, by softening or fusion, may have obliterated the organic remains that might once have been blended with materials now exhibiting no vestiges of plants or animals. Although we may not be able to mark the precise boundary beyond which organic beings do not appear, it is certain that in all geological epochs, subsequent, at least, to that of the primary rocks, animals and plants have existed in successive families; they have been created, have lived their destined periods, and by the operation of physical causes have

SILLIMAN'S INTRODUCTION.

3

perished, while new races have been called into being, and in their
turn have ceased to be, in order to give room to other families,
requiring, perhaps, new physical conditions.

Thus we travel onward in time, and upward in the order of
deposition, through races whose species are entirely extinct, until
we arrive at the periods that approximate to our own times, when
first, similar beings to those that now inhabit the earth begin to
appear, and finally to graduate into those of the present day. Now
it is obvious, that to judge intelligently of extinct races of animals
and vegetables, it is requisite to pass in review the entire organic
creation, both of ancient and modern date; not only of the ter-
restrial animals that, in early times, walked the earth, of the fishes
and amphibia that swam in the waters, of the birds, insects, and
winged reptiles that soared in the air, and of the plants that adorned
the new-born islands and emerging continents, and which, as well as
the animals, are now entombed in rocks and mountains; but, we
must be familiar, also, with the races which, at this moment, fill the
world with animation and beauty, for they are our living standards
of comparison. In short, we must be well acquainted with both
natural history and comparative anatomy.

If such be the circle of sciences preliminary or auxiliary to
geology, it may well draw from us the desponding exclamation,
Who then is sufficient for these things? We may perhaps reply, no
unassisted individual! Science is formed by the joint labours of
many minds. Different cultivators bring in the rich tribute of
the fields they have tilled and reaped, and a master-mind disposes
them in order, and draws from them the requisite conclusions to
construct a system, or, at least, to furnish its most important
elements.

3. RANK AMONG THE SCIENCES.—This very general sketch of
the relations which geology sustains to the collateral sciences, is
sufficient to evince its high dignity, and to vindicate its strong
claims to our serious attention. As a science, its date is modern;
but this is also true of all the physical sciences, among which
geology is a younger sister. Although it is rapidly advancing, and
is, therefore, not perfect, but progressive, it is still a science; and
in this sense, which of the physical sciences is perfect?* In this

* "To boast of a stability of opinion in Geology, is to boast of an extreme indolence of mind; it is to remain stationary in the midst of those who go forward."—Baron Humboldt.

B 2

4

THE WONDERS OF GEOLOGY.

respect geology is, therefore, not alone. Its ascertained facts are numerous; they are correctly observed and reported; they are skilfully classed, and a sufficient number of general as well as particular conclusions has been drawn from them to furnish the basis of a noble science. Its boundaries are daily extending, and will be extended without limit, by continued observations—its evidence will constantly accumulate, and although its theoretical speculations may change, nothing can occur to subvert the grand conclusion, that the earth has a regular structure, and that its materials have been arranged under the operation of general laws of great energy and duration, the physical expression of omniscient intelligence and omnipotent sway, guided by benevolent design, which becomes more and more apparent and convincing with every new and successful research in geology.

4. **SOURCES OF ITS EVIDENCE.**—If the inquirer ask for the source of geological evidence, it may be answered that it is derived from diligent and careful examination of the structure of the earth; and for this object our means are more ample than might at first appear.

Every artificial excavation—every well and cellar—every cut for a fort, for a common road, a railway, or a canal—every stone quarry—every tunnel through a mountain—and every pit and gallery of a mine bored into the solid earth, furnish means of perusing its interior structure. Still more do the inland precipices, and the rocky promontories and headlands along the rivers, lakes, seas, and oceans; the naked mountain-sides ribbed with strata, that bound the defiles, gorges, and valleys; the ruins accumulated at the feet of lofty pinnacles and barriers, and those that have been transported and scattered, far and wide, over the earth, present us with striking features of the internal structure of our planet.

Most of all, do the inclined strata push up their hard edges, in varied succession, and thus faithfully disclose the form and substance of the deep interior, as it exists, many miles beneath the observer's feet.

Volcanic eruptions throw up into daylight the foundations of the fathomless deep below, in the form of ejected or molten masses, or in rivers of ignited and fluid rocks, which congeal on the surface of the ground, either inflated like the scoriæ of furnaces, or in solid masses, with no visible impress of heat; and often containing very perfect and beautiful minerals, elaborated in the volcano, or dis-

SILLIMAN'S INTRODUCTION.

5

lodged from still earlier beds. In addition to the products of actual volcanoes—the igneous rocks, crystallized or deposited from fusion, both in the earliest and in many of the more modern epochs —injected among, and traversing strata of all descriptions and ages, and thus assimilated to known products of internal fire, the proper rocky masses, the granites, sienites, porphyries, serpentines, and traps, give authentic information of the unapproachable gulf of fire whence they were projected.

The internal waters that gush cool from the fountains on the land or under the sea, or those that spout in boiling geysers from the deep caverns where their imprisoned vapours accumulate explosive force; all these bring to the surface the materials of the interior, and conspire with tornadoes of gas, bursting from volcanoes and other vents, to reveal the deep secrets of the earth.

5. ITS POSITIVE UTILITY.—Geology, in addition to its inherent dignity, puts forth strong claims to regard on the ground of positive utility. Every thing reposes upon the mineral kingdom; it affords to man, directly or indirectly, all the materials of his physical comfort—all those of national wealth, and all the means of civilization. The most important of physical instruments are derived, immediately or remotely, from it, for the vegetable world, equally with the animal, rests upon this basis; whether we speak of the cedar, the oak, the lichens, or the grasses, all equally derive their support from the elements afforded by the mineral kingdom; which, in its widest sense, includes not only the solid earth, but its waters, and all its fluids—its atmosphere and all its gases. The vegetable kingdom borrows not a few elements from the mineral world; oxygen, carbon, hydrogen, and even nitrogen, and all that are indispensable to vegetable life, are found in the waters, or in the atmosphere; while other elements or compounds, adapted to particular purposes, are derived from various mineral sources; the soil, for example, affords silica, which enters into the composition of the epidermis of grasses, bamboos, equiseta, &c.; and potass and soda, derived from decomposed felspar and other minerals, pass by absorption into the juices of plants. Even animal and vegetable manures form no exception, for their elements have a similar origin, and consist almost entirely of the substances indispensable to vegetable growth.

Thus, while we explore this orb of gases, fluids, and solid rocks, we shall gain the most interesting knowledge, and much positive

6

THE WONDERS OF GEOLOGY.

advantage. Our beautiful planet is indeed worthy of our study;
it was once our cradle—it will soon be our grave,—between the
dawn and the night of life, it is the scene of our busy action, and
from it we shall rise to another state of being.

6. DISCOVERY OF USEFUL MINERALS.—Geology discloses to us the valuable minerals, and teaches us where they are likely to be found, and where research would be vain.

*Coal.*—Coal is, without doubt, wholly of vegetable origin: hundreds of species of plants have been distinguished in the coal formation, but none of these have been found living on the earth, although many of the families still exist; the recent allied species are generally of a diminutive size, in comparison with those of the coal period, and those that approach the ancient in magnitude, are chiefly found in tropical climates.

Duly informed in geology, we should never look for coal in
granite,* nor among the most ancient rocks; and in the wide inter-
vening series, a large part of the formations are excluded from the
association with this most important mineral. Slates, shales, and
limestones, charged with bitumen, afford indications of some value,
but not decisive, as bitumen is associated with many minerals that do
not belong to coal formations. The impressions of plants in the
rocks, especially those charged with bitumen, strengthen the pre-
sumption, and should we find fragments of coal scattered in the soil,
or mingled with gravel and sand in the banks and water courses, or
observe dark masses of earth, which, on close inspection, appear to
contain fine coaly matter, we may infer that beds of this combus-
tible may be near, and that it may be proper to dig or bore; and
when, at last, we find the beds of coal, they will be regularly
arranged between a roof and floor of coal-slate or shale. But it by
no means follows, that beds of shale and slate necessarily indicate
coal; those of the primary series would scarcely contain any com-
bustible, unless it were plumbago, or possibly a little anthracite.
The geological laws of coals are very strict, and a thorough
acquaintance with them is the only safeguard against fruitless
enterprises.

*Lignite*.—It is easy to mistake beds of lignite for coal: lignite,
when found in sufficient abundance, is a valuable combustible, but it

* Coal strata sometimes repose *upon* granite, (not in it,) as in France, and near Richmond, in Virginia.

SILLIMAN'S INTRODUCTION.

7

is not perfect coal; it burns with a sharp and acrid odour like the smoke of a wood fire, and is in fact wood only partially altered by inhumation. It is most abundant in the more recent geological formations, especially in tertiary sands, gravel, and clays, in which true coal has rarely been found. The trees that are buried in the recent alluvial and diluvial deposits are little altered, and are, for the greater part, referable to existing floras; sometimes they are flattened by pressure, and altered in their texture, and even partially carbonized.

*Limestone and Marble*.—Limestone, including chalk and marble, is a most useful substance. The ancient Grecian temples give decisive proof of the durability of marble; and its beauty, even after the lapse of two or three thousand years, and after innumerable aggressions by the violence of war, and the depredations of antiquaries, more destructive than the action of the elements, is in many instances not entirely destroyed. Limestone is the most important ingredient in mortar, and of great value in soils. But it is not necessary to enlarge on a subject so generally understood. It is sufficient to remark, that in the selection of limestone for architectural purposes, or as a fertilizing ingredient for soils, geological skill will often prove of great value; and in cases of high responsibility, such as those of public edifices, intended to endure to distant ages, the united services of the geologist, the stone-mason, and even the quarry-man, may well be put in requisition, for practical artists often acquire the skill to judge very correctly of the value of materials. The experience of all antiquity proves this to be true.

*Various Rocks*.—The same view may be taken of granite and sienite, and the slaty rocks of that family, of porphyries, traps, and soapstones, of sandstones and puddingstones, or breccias. All these are employed either in constructing the external walls, or in forming the interior decorations of buildings, as well as in forts, docks, bridges, quays, aqueducts, and roads; and it is of the utmost importance that time and expense should not be bestowed upon materials that are faulty, or worthless; for some kinds of sandstones, limestones, and even granites, crumble away, upon exposure to the air and the weather, and thus produce deformity and dilapidation, where everything should be solid and enduring. In general, this error may be avoided by a careful observation of the effects of time and the weather upon such masses of rocks as chance to be prominent above

8

THE WONDERS OF GEOLOGY.

the ground, and have therefore been (perhaps for ages) subjected to
those atmospherical agencies, which the finished edifice must, in its
turn, encounter.

*Metals*.—The researches for metals have ever interested mankind
in a high degree, and on no subject are they more liable to error and
imposition. Happily, the most important metal, iron, is the most
abundant. But iron ores are not always known by the uninstructed;
some of the most valuable are not attracted by the magnet, until
they have been heated in contact with carbon or hydrogen. Other
ores are so completely disguised, that they are not recognised at all
by those acquainted with the purified metals alone. This arises
from their combination with various substances, chiefly oxygen,
sulphur, acids, or arsenic, which, on account of the great change
they produce in the properties of metals, are called mineralizers.
Iron pyrites, an abundant mineral of little value, is frequently
mistaken for gold, because it is usually yellow; and this, notwithstanding
it is hard and brittle, while gold is soft and malleable, so
that a mere blow of a hammer would detect the difference. Yellow
mica has been gathered for gold dust; and silvery mica, and white
arsenical iron, have been mistaken for silver.

*Calamine*, the native oxide of zinc, has no resemblance to any metal
whatever; and *tin-stone*, the native oxide of tin, has none to that
metal; and both would be rejected by an ignorant observer. The same
may be said of the sulphuret of silver, the gray sulphuret of copper,
the chromate, molybdate, carbonate, phosphate, and sulphates of
lead, and many more. Few persons, indeed, trust themselves to
carry on great works in mining, without previously consulting professional
men; some are, however, so perverse, or blinded, as to
persist even against the best counsels, and they, of course, pay
the penalty of their folly in disappointment, and oftentimes in
utter ruin.

*Geological associations of metals*.—It is well known to geologists,
that metallic veins are rarely found in the most recent formations;
and, with the exception of iron, and of alluvial deposits of other
metals, they seldom occur in great abundance, until, in the descending
series, we approach or pass the geological epoch of coal. In the
transition rocks, certain metals abound, while others occur in the
primary, and there is no rock so old that it may not contain some
of the metals. Sound scientific views of the geological structure of
a country, will therefore serve as an important guide in the research

SILLIMAN'S INTRODUCTION.

9

for metals, and in forming a conclusion as to the probable continu-
ance, enlargement, or cessation, of metallic veins.

*Decisions of Science.*—The negative which science often pro-
nounces with entire confidence, may save many an excited mind
from delusion, and preserve for agriculture, and the useful arts of
life, the resources which might have been lavished, in reckless pro-
fusion, upon vain and unproductive mining operations. It is rarely
that metallic mines will justify the abandonment of a useful calling
in the common walks of life; even where there is abundance of
valuable ore, few individuals can, alone, afford to encounter the
enormous expense of mining, and to wait its uncertain, and, it may
be, distant and stinted returns. A good quarry of soapstone,
granite, gypsum, or sandstone, may be worth more than a mine of
gold, and such have actually been the opposite results in some
signal cases in this country. To these few instances of the import-
ance of geological knowledge to the common interests of life, many
more might be added, but these are sufficient to illustrate our argu-
ment; if, indeed, it be necessary to prove, that he who acts with
consummate knowledge proceeds with safety, walking in the full
and certain light of science, while he who adventures in the dark
has no right to expect anything but disaster and ruin.

*Geological Surveys by Public Authority.*—That there is a just
appreciation of this subject among the people of this country, is
sufficiently evinced by the geological surveys of many states and
territories, either already accomplished or in progress. More than one-
half of the States have, by public authority, instituted such surveys;
the reports which have been published evince industry, knowledge,
and skill: great progress has been made in developing the mineral
resources of the country, and in amassing stores of materials to
serve for a future digested and systematical account, both scientific
and practical, of North American geology; while, at the same time,
excellent schools are thus established, in which to form young geo-
logists by actual and responsible explorations and surveys. These
good works will, we trust, proceed, until our whole territory has
been geologically examined, when some gifted individual will give
us the grand result. In a scientific relation, these researches are
deeply interesting, and we are in this way, as well as by personal
efforts, contributing our share of materials towards the general
stock of geological knowledge.

7. SOME FEATURES IN NORTH AMERICAN GEOLOGY.—Perhaps

10

THE WONDERS OF GEOLOGY.

no country is more favoured than our own, in the nature, abundance, variety, and distribution, of the most important mineral treasures. The limits of these preliminary remarks can only present the most general summary of our geological formations, or at most, admit of nothing more than a mere sketch; but the materials for information are already abundant, and are yearly increasing, as may be seen in the various public reports, in the transactions of our learned societies, and in our journals of science.

Of the primary and transition rocks, to which we may add the coal formation and the silurian, we have immense ranges, extending in a north-easterly and south-westerly direction through the continent, and comprising most of the minerals, and many of the fossils, that are found associated with such groups in the old world.

The Alleghanies, (including many mountains having local names,) following the general bearing of N.E. and S.W., and ranging between the Mississippi and the Atlantic, form, with their branches and connected chains, the great rain-shed of the countries east and west; and rising to two, three, four, and five thousand feet and more,* give direction to the streams and rivers, that flow either into the Mississippi, the Atlantic, or the great lakes, and the St. Lawrence.

*Rocky Mountains.*—In like manner, the far more stupendous chains of the Rocky Mountains, whose loftiest peaks are reported to be between three and five miles high,† give a geological character to the regions east and west, in which directions the waters flow to the Mississippi and the Pacific, while other contributions descend to the Gulf of Mexico, and to the Northern Ocean. It is to be regretted, that in the United States proper, there are no mountain ridges, or solitary peaks, that pierce the regions of perpetual cold.

*Mount Washington.*—Mount Washington, of the White Mountain group in New Hampshire, which approaches a mile and a quarter in height, and being in 44° of north latitude, on a continent whose average temperature is many degrees below that of Europe, throws off its snowy mantle only for a short season, in July and August,

* Professor Mitchell, University of Chapel Hill, states that the top of Black Mountain, in North Carolina, is 6476 feet above the level of the ocean. See Am. Journal, vol. xxxv. No. 2.

† See Professor Renwick's Outlines of Geology.

SILLIMAN'S INTRODUCTION.

11

while it is clad in white during the remaining months of the year. Even on the first day of September, (1837,) as adventurers upon this Alpine mountain,* we were, both on its flanks and summit, involved in a wintry tempest of congealed vapour, formed into splendid groups of feathery and branching crystals, unlike to the snows of the lower regions: the driving masses came in fitful gusts, veiling in a white cloud all objects far and near; but breaking, occasionally, to admit a flood of solar light, and render visible this hoary pinnacle, and the deep gorges and valleys of the neighbouring groups of mountains.

The mountains of Essex County, State of New York, between Lake Champlain and the St. Lawrence, approach the White Mountains in altitude, but none are permanently snow-clad.

*Mountains of Central Europe*.—It is otherwise in Europe, where the grand central group of Mont Blanc, and the various Alpine mountains, rise far into the region of perpetual congelation; and Mont Blanc would pierce that region even at the equator. Thus is provided an eternal storehouse of ice and snow, over whose wintry surface the winds, rendered heavier by contact, glide into the valleys and plains of the countries at their feet, and thus temper even the warm climate of Italy, preventing the extreme vicissitudes which we experience.

But these immense natural magazines have a still more important relation to the irrigation of the vicinal countries. The melting of the snow and ice, by the heat of summer, supplies copious streams to feed the innumerable rivers that flow from these grand fountains, to almost every part of continental Europe, south of the Baltic. Thus the effects of drought are, in a great measure, prevented, while destructive mountain-floods are of rare occurrence.

From the absence of such mountains we have no permanent stores of ice and snow, and, consequently, our rivers are liable to extreme variations of altitude and force. The Ohio, in midsummer, sometimes leaves numerous fleets aground, while occasional risings, from deluging rains, swell the river to an immense flood, that spurns the barrier of the banks, inundates villages and cities, and expanding into an internal sea, rushes with wasting violence over the wide-spread meadows and farms. For this reason, hydraulic engineering is in this country attended with peculiar difficulties, both

* See Am. Jour. Science, vol. xxxiv. p. 74.

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