Geology for Beginners ... comprising a familiar explanation of Geology, and its associate sciences, etc

Front matter

GEOLOGY FOR BEGINNERS. L O X 1> 0 N* : PR1VTEP BT SCHl'LTE AMI CO., 13, POI.AXD STREET. -i-itia, p.* or -nf.PTri.r... ms.luHM M ,,. i i** i GEOLOGY FOR BEGINNERS, BY G. F. RICHARDSON, F.G.S. OF silt BRITISH MUSEUM. Memnonium or Head of Rameses in the British Museum showing the Passage of Greenstone into Syenite.— Page 162. "It cannot be too extensively known that nature is vast and knowledge limited, and that no individual, however humble in place or acquirement, need despair of adding to the general fund."— HUGH MILLER, ON THE OLD RED SANDSTONE. LONDON: HIPPOLYTE BAILLIERE, 219, REGENT STREET. FOMIGN BOOKSELLER TO THE ROYAL SOCIETY, AND TO THE ROYAL COLLEGE OP SURGEONS IN LONDON. PARIS: J. B. BAILLIBBE, LIBRAIRE RUE DE L'£COLE DE MfiDBClNE. 1842. GEOLOGY FOR BEGINNERS, COMPRISING A FAMILIAR EXPLANATION OF GEOLOGY, AND ITS ASSOCIATE SCIENCES MINERALOGY, PHYSICAL GEOLOGY, FOSSIL CONCHOLOGY, FOSSIL BOTANY, AND PALÆONTOLOGY.

INCLUDINO DIRECTIONS FOR FORMING COLLECTIONS AND GENERALLY CULTIVATING THE SCIENCE, WITH A SUCCINCT ACCOUNT OF THE SEVERAL GEOLOGICAL FORMATIONS. BT G. F. RICHARDSON, F.G.S. OF THE BRITISH MUSEUM, TRANSLATOR OF THE LIFE AND WRITINGS OF K&RNER, AUTHOR OF SKETCHES IN PROSE AND VERSE, &C, &C LONDON: HIPPOLYTE BA1LLIERE, 219, REGENT STREET, FOREIGN BOOKSELLER TO THE ROYAL SOCIETY, AND TO THE ROYAL COLLEGE OF SURGEONS IN LONDON. PARIS: J. B. BAILLIERE, LIBRAIRE, RUE DE L'*_COLE DE MEDECINE. 1842. TO JOHN HENRY DUKE OF RUTLAND, K.G. &C, &C, &C. ONE OF THE TRUSTEES OF THE BRITISH MUSEUM, AND A LIBERAL DONOR TO THE SCIENTIFIC COLLECTIONS OF THAT ESTABLISHMENT, THE FOLLOWING PAGES ARE, BY PERMISSION, MOST RESPECTFULLY INSCRIBED BY HIS GRACE'S MOST OBEDIENT AND MOST DEVOTED SERVANT, G. F. RICHARDSON.

Preface

The motives which have induced the author to prepare this production for the public are briefly these : — During the course of some experience as a lecturer on Geology, he has constantly recommended the various works already published on the science, and, as constantly, has been requested to name some treatise more particularly intended for the tyro, and more expressly designed to convey that preliminary information which the mere beginner is so anxious to acquire; some volume, in short, more introductory than the excellent Introduction of Mr. Bakewell — more elementary than the admirable Elements of Mr. Lyell. Not being aware of the existence of such a production, and being naturally desirous to comply with a demand so strongly and so extensively urged, he has undertaken the present publication ; which, in addi tion to its claims on the attention of the novice, its adaptation for the use of schools, and of classes in literary and scientific institutions, will, it is hoped, be X preface. found not wholly devoid of interest for those who have already attained some proficiency in the science.

The writer is not uttering mere words of course in expressing his regret, that the task had not been previously undertaken by some one better qualified to fulfil it ; since, in addition to other deficiencies, he has to regret that the work h. s been composed, not amid the advantages of literary leisure and philosophic ease, but in the brief intervals of duty, and after the daily labour and lassitude of a public and responsible employ. While this circumstance may be farther urged in extenuation of some delay which has occurred in the appearance of the publication, the writer gladly avails himself of recording his obligations to the engraver* — to the artists to whom he is indebted for the drawings f, — and to the printers J ; the whole of these gentlemen having, it will be perceived, fulfilled their respective duties with eminent ability, under circumstances of haste and in terruption, which rendered the task one of no common difficulty and labours.

In submitting the volume to the public, the reader is respectfully reminded, that the work is one of the most elementary character, — that it is designed merely as an * Mr. T. Armstrong, 4, Hartland Terrace, Kentish Town, by whom the whole of the wood-engravings were executed. t Mr. Read, of the British Museum ; Mr. Masters, and Mr. Hine. t Messrs. Schu]_e, 1.3, Poland Street, Oxford Street. . The name of Martin needs no eulogium, and the reader will recognise the genius of this distinguished artist in his splendid and highly-successful delineation of the Age of Reptiles.

PREFACE.

. XI introduction to others of far superior merit, — and that the highest objects of the writer will be attained, if, by means of its pages, the reader should become acquainted with the admirable and judicious reasonings of a Buck-. land, — the philosophic speculations of a Lyell, — the splendid oratory of a Sedgwick, — the fascinating eloquence of a Mantell, — the talented writings of a Phillips, — the able and energetic researches of a Murchison, — the instructive publications of a Fitton, a Dela beche, a Bakewell, and of many, many more, of whom science and literature may be justly proud, and who ma}' be regarded as ornaments to letters and philosophy, and benefactors to the whole family of man. LIST OF PLATES. Frontispiece. Age of Reptiles. Title- Vignette.

Head of Rameses, or Memnon FIG. 1 Page 17 Artesian Well. 2 to 70 ■ 106 to 147 Diagrams relating to Crystallography and Mineralogy. 71 184 Stratified Rock. 72 — — — Horizontal Position. 73 185 Vertical Position. 74 — Inverted Position. 75 — Vertical and Inverted Position. 76 186 Curved arrangement. 77 — Arched arrangement. 78 187 Contorted strata. 79 ■ ■ — Lateral pressure. 80 188 Unstratified Rock. 81 — Granite Veins. 82 189 Overlying granitic masses. 83 — Cleavage resembling stratification. 84 ■ 190 Columnar arrangement. 85 ■ — ■ Prismatic columns. 86 191 Vertical, columnar arrangement. 87 — Horizontal columnar arrangement. 88 ■ — Columnar and massive arrangement. 89 192 General arrangement of deposits. ■ 90 193 Dip. 91 — Dip and Strike, 92 194 The same. 93 195 Anticlinal Line. 94 — Synclinal Line. 95 196 Conformable and Un conformable Position. 96 ■ 197 Deceptive appearances of strata. 97 — The same. 98 198 Thinning out of abed. 99 199 Age of mountain-chain, ino _ The same. 101 — Search for coal, 102 201 An Outlier. 103 -— — Valley of Denudation. 104 202 Valley of Elevation. 105 — Fault. 106 205 Faults in coal-seams.

LIST OF PLATES. XIV FIG 107 Paee 216 Parts of Univalve and Bivalve Shells. IQg 236 Transverse section of dicotyledodonous wood. 109 „ Germ of dicotyledonous plant. , , uq 237 Transverse section of monocotylenous wood. jll Longitudinal section of dicotyledodonous wood. ] 12 Longitudinal section of monocotyledonous wood. H3 — Germ of monocotyledonous plant. 114 238 Leaf of dicotyledonous plant. 115 — Leaf of monocotyledonous plant. 116 239 Longitudinal section of coniferous wood. . 117 . — Transverse section of the same.

US 255 Fucoides Tærgionii. 119 . 257 Recent equisetum. 120 — Equisetum calumnare. 121 — Calamites cannæformis. 122 ■ 269 Pachypteris lanceolata. 123 260 Sphenopteris crenata. 124 261 Cyclopteris Beanii. 125 — Glossopteiis Phillipsii. 126 263 Neuropteris Loshii. 127 263 Odontopteris minor. 128 264 Tæniopteris vittata. 129 265 Pecopteris adiantoides. 130 266 Otopteris acuminata. 131 268 Lycopodites Williamsonis. . 132 269 Lepidostrobus ornatus. . 133 270 Stigmaria ficoides. , 134 271 Pterophyllum comptum. 135 272 Asterophyllites foliosa. 136 277 Sigillaria organum. 137 279 Leaves of Neuropteris, Sphenopteris, Pecopteris, and Odontopteris. 138 281 Cyathea glauca. 139 282 Caulopteris primeva. 140 — Stem of recent tree-fern. . 141 . — Club-Mosses. 142 283 Lycopodium densum. 143 — Branching Trunk of Lepidodendron, 144 — Branching Stem with bark and leaves. 145 285 Crassula tetragona. 146 286 Longitudinal section of Araucaria. 147 287 Pinnate or winged leaf, 148 288 Bipinnate leaf. 149 — Tripinnate leaf. 150 289 Ternate leaf. 151 — Biternate leaf. 152 — Tritemate leaf. 153 290 Pinnatifid leaf. 154 — Bipinnatisid leaf. 155 299 Jaw of Tiger (Carnivora). 156 300 Jaw of Horse (Herbivora). 157 301 Jaw of Squirrel (Rodentia). 158 304 Teeth of African, Asiatic and extinct Elephant. 159 305 Elephant from the Ice. 160 308 Tetracaulodon. 161 309 Mastodon giganteum.

LIST OF PLATES. XV FIG. 162 Page 310 Deinotherium. 163 ■ 311 Megatherium. 164 312 Megaeeros or Irish Elk. 165 313 Tooth of Elephas primigenius. 166 — of Mastodon. 167 314 of Deinotherium. 168 — of Rhinoceros. 169 — of Hippopotamus. 170 — of recent Elk. 171 — of Horse. 172 315 of Crocodile. 173 317 Scale of Placoidians. Fish. 174 ■ — of Ganoidians. 175 318 of Ctenoidians. 176 — of Cycloidians. 177 324 Cyathrocrinites planus. 178 334 Nucula Cobboldiæ. 179 — Tellina obliqua. 180 335 Fusus contrarius. 181 ■ — Murex alveolatus. 189 338 Shells of the London Clay. 190 — Wood perforated by Teredinæ. 191 342 Temple of Serapis. 192 348 Animals discovered by Cuvier. 193 356 Cypris anifasciata. 194 357 Larva of Phryganea rhombica. 195 360 Valley and Castle of Monpezat. 196 363 Gaillonella distans. 197 364 Gaillonella ferruginea. 198 — Semi-opal containing infusoria, &c, 199 to 202 370 Foraminiferous shells in chalk. 203 and 204 374 Sponge in Chalk. 205 — Silicified Ventriculite. 206 375 Echinites. 207 ■ 376 Cidaris margaritifera. 208 — Shells of the Chalk. 209 378 Shells of the Marl, Gault and Greensand. 210 ■ 380 Osmeroides Mantellii. 211 391 Dirt-Bed with its vegetation. 212 ■ — Recent Zamia. 213 392 Mantellia nidiformis.

Br. 214 — Inclined strata, dirt bed, &c, of Lulworth cove. 215 394 Sphenopteris Mantellii. 216 — Clathraria Lyellii. 217 395 Shells of the Weald. 218 397 Sussex Marble. - — . 219 . 399 Tooth of Iguanodon. 220 400 Jaw and teeth of recent Iguana. 221 401 Iguana cornuta. 222 402 Horn of Iguanodon. 223 * 404 Pterodactylus crassirostris. 224 407 SheUs of Oolite. 225 410 Apiocrinites rotundus. 226 412 Tooth of Megalosaurus. 227 — Jaw of Didelphys of Stonesfield. 228 414 Coal-Money. 229 419 Shells of the Lias. 230 — Teeth of Acrodus. 231 420 Teeth and spine of Hybodus. 232 — Head of Chimœra. 233 423 Ichthyosaurus. 234 — Plesiosauras. LIST OF PLATES. FIG. 235 Page 425 Plesiosaurus rugosus. 236 427 Plesiosaurus grandipinnis. 237 428 Fin of Plesiosaurus. 238 436 Impressions of Cheirotberium. 239 438 Tooth of Labyrinthodon. ■ 240 439 Section of the same. 241 440 Restoration of the Labyrinthodon. 242 442 Restored outline of Palæoniscus. 243 — Heterocercal tail. 244 — Homocercal tail. 245 455 Erect Fossil Trees. 246 460 Shells of the Mountain-Limestone. 247 467 Pterichthys. 248 468 Coccosteus. 249 472 Homalonotus delphinocephalus. 250 474 Shells of the Silurian System. 251 493 Models of Hammers. Page 1 51 74 TABLE OF CONTENTS.

Chapter I

Outlines of the Work — Definition of Geology— Vindication of the Science, as a useful and practical, and not a merely speculative and visionary pursuit — Connection of Geology with the following important objects — National and commercial prosperity — Mining — The discovery of coal — Civil engineering — Agriculture — Draining— Artesian wells— Architecture — The Arts- Literature — Mental discipline — Exercises on the above subjects.

Chapter II

Sketch of the History of the Science — Lost work of Theophrastus on fossil shells — System of Pythagoras — Strabo — Livy — Revival of the pursuits of Science with those of Letters — Boccaccio — Leonardo da Vinci — Fracastoro — Hooke — Woodward — Ray — Leibnitz — Lehman — Werner — Dr. Toulmin — Dr. Hutton — William Smith — The Geological Society — The British Association for the promotion of Science 26

Chapter III

First lessons in Geology — Harmony of Science with Revelation — Extreme antiquity of the earth— Proofs of this fact derived from the structure of the earth itself — Similar evidence afforded by astronomy — Origin of our planet — Internal heat of the earth — Crust of the earth — Order and succession of the rocks — Tropical climate of the ancient earth — Efficacy of modern causes

Chapter IV

Qualifications of a Geologist— Instructions for the Beginner— Practical hints for commencing the study of the Science — Scientific institutions—Works on the Science— Collecting, arranging and describing fossils — The microscope — Lectures in general — Lectures at the British Museum TABLE OF CONTENTS. XVIII Page 206

Chapter VIII. Fossil Botany

Brief History of the Science — Classification of vegetables — The natural system — Acotyledons — Monocotyledons — Dicotyledons — Investigation of fossil plants — Arrangement of the vegetation of the ancient earth into four eras by Brongniart, and into three by Count Sternberg— Experiment of Dr. Liudley — Arrangement of the six classes of fossil plants into families, genera and species — Explanation of Botanical terms — Exercises . . . 232

Chapter IX

PALÆONTOLOGY. Cuvier's classification of the animal kingdom— Arrangement of the teeth, in the Carnivora, Herbivora and Rodentia— Extinct fossil animals— The Mammoth — Mastodon — Megatherium and Deinotherium— The Missouriam or Tetracaulodon— The teeth of mammalia and of reptiles— Scales of fish— Trilobites— Corals —Crinoidea — Sponges— Infusoria — Exercises .... TABLE OF CONTENTS. XIX 386 40;

Chapter X. Tkrtiary System

Characteristics of these deposits — Classification of Mr. Lyell into Eocene, Meiocene and Pleiocene — The crag of Norfolk and Suffolk—The London Basin— The Basin of Hampshire and the Isle of Wight — Temple of Jupiter Serapis — Rise of Sweden and of Italy— The Basin of Paris— Discoveries of Cuvier— Tertiary Deposits and organic remains of Aix, of Monte Bolca— Dormant volcanoes of central France, and of the Rhine— Tertiary strata of other regions — Dormant volcanoes of Asia Minor — Fossil infusoria discovered in the tertiary deposits — Conclusion —Exercises 329

Chapter XI. Chalk Formation

Subdivision of the chalk deposits — Their geographical distribution — Organic origin of the chalk and flint — Fossils of the chalk — Sponges, Zoophytes, Echini and shells. — Shells of the Marl — Gait and Green-sand — Fishes of the chalk — The Mososaurus — Denudation of the chalk — Exercises 368

Chapter XII. Wealden Formation

Its peculiar character as a fluviatile deposit — Its true character discovered by Dr. Mantell — Former erroneous opinion of these deposits— Their classification and extent— Their geographical distribution— The isle of Purbeck— The isle of Portland— Wealden strata of the isle of Wight— Organic remains of the Weald— Shells— Sussex Marble— Fossil Fish, Turtles and Colossal Reptiles— The Iguanodon and Hylosaurus— Pterodactyles— Denudation of the strata of the Weald— Exercises .

Chapter XIII. Oolite Formation

Geographical distribution— Shells of the Oolite— Crinoidea- Organic remains of the Stonesfield slate— The Megalosaurus— The Didelphys of Stonesfield— Coal money— Coal of this formation

Chapter XIV. Lias Formation

Derivation of the name — Geographical distribution— Fossils of these deposits— The shells— The fish— The reptiles— The Ichthyosaurus and Plesiosaurus— Origin of the Oolite and Lias — Exercises XX TABLE OF CONTENTS.

Chapter XV. New Red Sandstone

Arrangement of these deposits as they occur in this country — Geographical distribution — Rock-salt and brine-springs — Paucity of fossil remains — Cause of this phenomenon— Fossil footsteps of the Labyrinthodon— Fossil fish — The Homocercal and Heterocercal form of tail — Conclusion — Exercises .... 430

Chapter I. Outline Of The Work

— DEFINITION OF OEOLOOY— VINDICATION OF THE SCIENCE, AS A USEFUL AND PRACTICAL, AND NOT A MERELY SPECULA- TIVE AND VISIONARY PURSUIT — CONNECTION OF OEOLOOY WITH THE FOLLOWING IMPORTANT OBJECTS — NATIONAL AND COMMERCIAL PROSPERITY — MINING — THE DISCOVERY OF COAL — CIVIL ENGINEERING — AGRICULTURE — DRAINING — ARTESIAN WELLS — ARCHITECTURE — THE ARTS — LITERATURE — MENTAL DISCIPLINE.— EXERCISES ON THE ABOVE SUBJECTS. Outline of the work. — It may be desirable to state, at the commencement of this volume, the arrangement proposed by the author in its composition, which is, in substance, the same that he has found most eligible, when deliver ing lectures on the science. Its early pages will comprise a definition of Geology ; an endeavour to rescue the study from certain prejudices, un deservedly attached to its cultivation ; and a vindication of its practical utility and advantage.

The next chapter will afford a brief outline of its history ; and will be followed by miscellaneous information, in the form of first lessons ; together with directions for procuring and describing fossils ; forming a collection, and generally cultivating geological pursuits. The succeeding chapters will contain a brief introduction to the auxiliary studies of Mineralogy ; Physical Geology ; B DEFINITION OF GEOLOGY. Fossil Conchology ; and Fossil Botany, with a few remarks on Palæontology; and the remaining pages will be devoted to a concise account of the various geological formations. Definition of Geology. — Geology may be defined to be, the inquiry into universal Nature, extending throughout all her kingdoms, animal, vegetable, and mineral ; and comprising, in its investigations, all time, past, present, and to come.

The present explains to us the past ; and the past and present reveal to us the future. The examination into existing geological phenomena, causes and effects, enables us to understand those which have occurred in past periods of our earth ; to interpret Nature by herself ; and to appreciate agencies and results which are obscure and remote, by a comparison with such as are familiar and well known ; while the study, both of the past and present, empowers us to deduce presages of the future, and to infer the nature of those changes and vicissitudes, which will, doubtless, occur on the face of our planet, during future æras of its physical history. From the above definition it will be perceived, that Geology is, by no means, to be regarded as a mere single or isolated department of knowledge, but that the pursuits w-hich pass under this general denomination are, in fact, a combination of all the physical sciences, of all those studies which have the harmonies and beauties of Nature as their object, and the perfections of her Divine Author as their ultimate end.

From the magnitude and importance of the objects which it contemplates, Geology may be considered as vying with the most exalted of the natural sciences in grandeur, and extent ; while, in the varied and atmining. 3 tractive character of its investigations, it will be found to surpass them all. So diversified and so universal, indeed, is the sphere of its inquiries as to afford themes for contemplation, fitted for every order of mind, and while it, often, in the same object, calls attention to facts which the infant understanding may comprehend ; it offers problems for solution, which the loftiest intellect is unable to determine. .The shell imbedded in limestone, or the vegetable con verted into coal, the child may perceive to be, the one a marine, the other a terrestial production ; but the process of the conversion of that shell into limestone, while the animal matter is often replaced by flint ; or the agency by which the plant has been transmuted into a mineral substance, while the woody structure is still retained ; each involves questions which the most advanced state of our knowledge is scarcely sufficient to determine.

In addition to other advantages which might be adduced, it must not be forgotten, that Geology, not withstanding the important advances which it has recently made, is still a youthful and a progressive study ; all whose investigations possess the charm of novelty ; all whose discoveries bear the gloss of fresh ness to recommend them. When Columbus revealed a new hemisphere to mankind, the old world was eager and anxious to precipitate itself upon the new ; and, when science discloses a fresh world beneath our feet, we cannot be surprised that all are eager and anxious to explore it. Yet, even the variety, extent, and novelty of geological investigation would never have procured for it so high a degree of popularity and favour as it has b practical utility of the science. now attained ; nor have enrolled among its students men of all ranks, from the peer and the philoso pher to the labourer in the quarry, and the work man in the mine ; were it not recommended by the more valuable advantages of practical utility, and ap plication to many of the most essential wants of man kind.

Before the benefits of philosophic research and discovery were rendered so palpable, as they are now happily become, it was the fate of this, like other scientific studies, to be regarded as a merely speculative and visionary pursuit, which, however well adapted to in terest the philosopher in his closet, was utterly useless and uninteresting to the great mass of mankind. This prejudice though now, in a great measure, dispelled, is still so firmly implanted in the minds of many, who have not paid sufficient attention to the subject, that we shall deem it necessary to devote some of our early pages to a statement of the intimate relation of Geology to some of the most important pursuits of life. To enumerate the whole would far exceed the limits of an elementary treatise, and it will be sufficient to select from the mass, those examples best calculated to remove the erroneous impressions of ignorance or prejudice ; and to substitute those more enlarged and accurate views which will demonstrate the prac tical usefulness of this valuable study, and justify the popularity and favour which it now so pre-eminently enjoys.

Dependence of national prosperity on geological position. — It is a self-evident proposition that the social and commercial condition of whole communities is entirely based on their geological site and condition. its relation to national prosperity. To what, in fact, do we owe our own influential position, and our prosperity, as a nation, but to those advantages which the physical geography of our island so abundantly supplies, which, by yielding us stores of metals, and of ores ; of limestones, and of sandstones; of salts, and minerals, and above all of coal ; and not merely by bestowing these, but by placing most of them in situations, and under circumstances best calculated to render them beneficial, enables us not only to supply our own wants, but to minister to those of others, in dis tant regions, and to convey knowledge and civilization to the very ends of the earth ?

From the remotest periods, when the Carthaginians and Phœnicians traded with our British ancestors for lead and tin, to the present æra, the mineral and geological resources existing in our island, have been eagerly sought by distant nations ; and, at the present moment, countries, the most remote from our own, and from each other, are largely our debtors for many of the advantages which they enjoy. On the sultry plains of India, and of Arabia; and amid the frozen deserts of the North — as far distant as the Antipodes, and at every point between — the natives are clad in garments, and assisted by tools and implements, which the natural resources of our country, aided by our commercial energy and enterprise, enable us abundantly to supply. Had these resources been less amply, less favourably afforded, not only should we have been unable to furnish the wants of others and to promote the cause of knowledge and improvement, but we should have been deficient in the supply of our own necessities, and should, ourselves, have continued in a comparatively degraded and uncivilized condition.

If (it has recently been ITS RELATION TO NATIONAL PROSPERITY. remarked with much force and justice*) the granite of the Scottish mountains had extended as far as the South Downs of Kent and Sussex ; or if the chalk of our southern shores had reached to the Grampian hills, our social and commercial condition would have presented a dreary contrast to the scene of energy, enterprise, and wealth which it now presents. If, on the one hand, the granite had prevailed throughout the entire island, we should have been placed in a country, picturesque, it is true, in its general outline, abounding in the alternations of mountain and of vale ; of hill and of glen; relieved by the torrent, the waterfall, and the lake ; and embellished with a profuse, though monotonous vegetation ; while the rocks beneath would have afforded occasional supplies of precious metals, and yielded veins of tin, copper, silver, and gold : but the climate would have been severe ; its productions limited and few ; its population scanty, scattered, and poor ; and we should have continued a race of miners, and mountaineers : or, on the other hand, had the chalkextended over the whole country, we should have possessed extensive pastures, and sheep-walks, and should have become a community of shepherds, grazing our flocks on the hills, and cultivating a confined and partial vegetation in the valleys and fissures of the chalk.

In neither case could we have attained that prosperity and eminence which we now so happily enjoy ; since we should have been des titute of those natural advantages, which constitute the basis of our national prosperity and power; and ♦ By Leonard Homer, Esq., at the Anniversary of the Geological Society 1341. GEOLOGICAL ADVANTAGES OF GREAT BRITAIN. which, from the chalk of our southern shores, to the granitic formations of the north: from the South Downs of Sussex to the Grampian hills ; and from the clay lands of the east, to the metallic districts of the west ; from the fields of Essex, to the mines of Corn wall, yield a store of benefits calculated not only to enrich ourselves, but to render us the dispensers of the best blessings to regions the most distant and remote. The relation of commercial and social pros perity to geological situation, has been forcibly illus trated, by Dr. Buckland, who, in his Bridgwater Treatise, furnishes an outline of the chief physical features of our native island ; and calls attention to the striking fact, that no less than nineteen of the largest and most important towns in England, from Exeter to Carlisle, are all situated along the line of one geological formation, the new red sandstone, which, in addition to its own mineral treasures of rock-salt, gypsum, and metallic ores, usually covers the invalu able deposit of coal, at once yielding an incentive and supply to the vast and enterprising population of this favoured district.

Dr. Silliman, also, in his excellent introduction to the American edition of Dr. Mantell's Wonders of Geology, adverts to the same point, and, with patriotic zeal, expatiates on the admirable resources of the vast American continent, the variety and riches of its diversified geological deposits, and the favourable prospects of its future inhabitants. / This part of our subject is so varied and important, that to follow it, in all its details, would far exceedthe limits of an elementary treatise, and with one additional ITS APPLICATION TO MINING. remark, illustrative of our obligations, on this account, to an All-wise Providence, we shall pass to other obser vations of like nature. It is found that insular situations are usually favourable to the development of varied, geological formations ; while continents and extensive tracts of country are generally monotonous and unvaried.

Thus, while the Isle of Arran presents a perfect epitome of the lower secondary and primary formations, Mr. Murchison, in his recent visit to Russia, travelled for two thousand miles over old red sand-stone alone. Hence, in addition to the advantages of natural security and defence, our insular position confers those of mineral resources alike diversified and beneficial. The same cause, or train of causes, which rent our island from the adjacent shores of Europe, was, doubtless, associated with intrusions of eruptive rocks, which brought with them to the surface many of those varied and valuable deposits which now so largely enrich, and bless our favoured country. Geology connected with mining. — Among those economical advantages which the science is calculated to confer, its assistance to the miner may be first adduced, since it occurs earliest in the series of geological formations.

It is at once the object and the boast of Geology, to redeem the search after metallic ores, from the mere blind chance, or still more benighted superstition, by which it has frequently been governed ; and by showing that mineral substances have not been distributed at random, but that each is referable to some peculiar geological deposit, to direct the search for them on fixed and enlightened principles, and in conformity with those laws of nature which regulate their occur- ITS APPLICATION TO MINING. 9 rence. In this country the granitic regions are the only districts, in which tin is discovered in sufficient extent and abundance, to justify its being sought for economical purposes. Copper is also found in the greatest abundance in granite, and in the schistose or slaty rocks above it ; and the chief mines of both these metals in this country, are situated in Cornwall ; though this substance also presents itself in the New Red Sandstone, and occurs in Staffordshire.

Lead is chiefly confined to the carboniferous limestone, a de posit which usually underlies the coal, and the most important supplies of this ore exist in Derbyshire and Scotland, amid strata appertaining to this formation. These metals, together with silver and others, occur in veins, which, in some cases, com municate with fissures beneath, and have, probably, been occasioned by deeply-seated subterranean agency ; or they are the result of the chemical segrega tion of metallic particles from the surrounding mass. Gold offers an exception to the general rule of metals occurring in veins ; it is disseminated in minute quantities throughout those rocks (usually of a quartzose character), in which it occurs, and is chiefly ob tained in alluvial gravel, resulting from the decomposi tion of such rocks ; or from the sands of rivers, which flowing over them, have washed out the particles of gold.

Platinum, together with zircon, the diamond, and many other gems, is also found in alluvial deposits, their original source being, probably, the same as that of gold ; while iron, in this country usually occurs, associated with coal and limestone, without both of which sub stances, it would be impossible to reduce this invaluable ore to a metallic and useful state. b DISCOVERY OF COAL. The veins of mineral substances are, by no means, of equal extent or value in all parts of their course, but the ore is distributed in local masses and aggregations along the line of its occurrence ; while it frequently thins into mere filaments, and occasionally dies out altogether ; leaving the miner to infer the path he should pursue, from the occurrence of vein-stones; which, though barren in themselves, are valuable as affording a clue to the occurrence of richer deposits.