Illustrations of the Huttonian Theory of the Earth

Front matter

ILLUSTRATIONS OF THE HUTTONIAN THEORY OF THE EARTH. By JOHN PLAYFAIR, F. R. S. EDIN. AND PROFESSOR OF MATHEMATICS IN THE UNIVERSITY OF EDINBURGH. Nunc naturalem causam quccrimus et assiduam, nan raram it fortuitam. Seneca. EDINBURGH: POINTED FOR CADELL AND DAVIES, LONDON, AND WILLIAM CREECH, EDINBURGH. l8C2. €nfetc& in .Stationer* l^all. Neill & Co. 7 Prioters, Edinburgh. J

ADVERTISEMENT.

. THE Treatise here offered to the Public, was drawn up with a view of explaining Dr Hutton's Theory of the Earth in a manner more popular and perspicuous than is done in his own writings. The obscu rity of these has been often complained of; and thence, no doubt, it has arisen, that so little attention has been paid to the inge nious and original speculations which they contain. The simplest way of accomplishing the object proposed, seemed to be, to present a General Outline of the System, in one con tinued Discourse ; and to introduce after wards, in the form of Notes, what farther Elucidation any particular subject was thought to demand. Through the whole, I have aimed at little more than a clear ex position of facts, and a plain deduction of the conclusions grounded on them ; nor shall I claim any merit to myself, if, in the order which I have found it necessary to ?rdopt, some arguments may have taken a a 2 new

Section I. Phenomena Peculiar To Stratified Bodies

i. Materials ofthe Strata. Page 4 Present strata composed of the remains of more ancient rocks, § 1. Pfbofs from calcareous strata, \ 2. — from siliceous, § 3. — from argillaceous, § 4 — from bituminous, § 5, 6. Absence of organized remains from the strata called primitive, not universally true, § 8, 9. Term Primary substituted for Primitive. Composition from the materials of more ancient rocks, § ic. 2. Consolidation ofthe Strata. p. 15 Consolidation, what, §11. Objections to aqueous consolidation, § 12, 13, 14* Compression affects the action of fire on bodies, § 15, 16, 17. Igneous consolidation of minerals proved from fossil wood, § 19. — from the flints in chalk, § 20.— from sandstone, § 2 1 .-— from CONTENTS. VI from the calcareous strata, § Z3, 24, 25. — from the argillaceous, § 26, 27. — from the bituminous, § 28,29. — from the saline. § 32.

Salt-mines in Chessiire. Trona of Africa, § 34, 35. 3. Position of the Strata. Page 40 Strata formed at the bottom of the sea, § 36. Apparent elevation not produced by the retreat of the sea, § 37. Strata, horizontal, when formed, § 38, 39. Disturbance of the strata proved from their inclined position, § 40, 41, 42 — from shifts, &x. § 42. Shifts of different dates, ib. Disturbance ot" the primitive strata visible at their junction with the secondary, § 43, 44. This disturbance produced by a force directed upward, § 45, 46. This force the effect of subterraneous heat, § 47, 48.

Section II. Phenomena Peculiar To Unstratified Bodies

i. Metallic Veins. P-57 Veins defined. They contain substances that were once infusion, § 49, 50. Metallic veins, native metals, &.c. § 51. Native copper, § 52. Manganese, § 53. Fragments of rocks inc-uded in veins, § $5. Shifting and heaving of veins, § 56, 57 Veins of different dates, § 5S stratification not found in veins. Coating o£ the sides, what, § 59. Metallic veins most common in primitive strata, but not confined to them, § 60. 2. WhinstoiK. CONTENTS. VII 2. Whinstone. Page 66 Enumeration of stones of this genus, § 6t. Whin, whether in veins or in masses, resembles lava, § 62. Is a subterraneous lava, § 63. Columnar structure an argument for fusion, § 64. Not produced by drying* § 65. Whinstone penetrated by pyrites, § 66. Induration of the strata in contact with whin, § 67. Coal charred by whinstone veins, § 68.

Disturbance of the strata by whinstone veins, § 69. Phenomena of whin interposed between strata, § 70, 71. Transition from whin to strata not gradual, § 72. Agates and chalcedonies in whinstone, § 74. This stone melted and reproduced from fusion by Sir James Hall, § 75. Mineral alkali found in it by Dr Kennedy, ib. Whinstones of different formation, § 76. Porphyry a species or variety of whinstone, § 77. 3. Granite. p. 82 Granite defined. Exists in masses and veins, § 77. The basis of other rocks, § 78. Its original fluidity inferred from the crystallization of its parts, § 79. Its fusion, from the structure of the Portsoy granite, § 80, 81. — from granite veins, § 82. General conclusion as to the igneous origin of minerals, § 83, 84, 85. Actual existence of subterraneous heat known from hot springs, volcanoes, earthquakes, § 86.

Volcanic fire seated deep under the surface, § 87. Subterraneous heat not accompanied by burning, § 88, 89 Transmission of subterraneous heat, so as to produce hot springs, &c. § 90, 91. a 4 SECTION CONTENTS.

Section III. Phenomena Common To Stratified And Un- Stratified

bodies. Page 97 Chemical agents which produce the decomposition of mineral substances at the surface, § 92, 93. Mechanical agents, § 93, 96. Proofs of wearing from the sea-shore, § 97, 98. Rivers, $ 99, ico. Defiles among mountains, § ic2. Supply of the foil from the decomposition of rocks, § 103. Gravel in the foil, § 104, 105. Gold found in the foil, § 106. Tin, § 107. Proofs of waste from mountainous countries, § 108, 109. Structure of valleys, § 111. Transportation of stones, § 112. Nearest measure of the waste, § 113. General remarks, § 114, 115. No production of minerals on the surface, § 116. Reproduction at the bottom of the sea, § 117. Continued system of decay and renovation, § xi 8. Defence against the charge of impiety, 119. Antiquity and order of the revolutions of the globe, § 12c, 121, 122, 123, 124.

Consistency with the Sacred Writings, § 123. Scope of this theory of the earth distinguissies it from others ; beauty and extent of its views, § 126. New facts, § 127. Comparison of this theory with that of Buffon, § 129. of Lazzaro Moro, § 130. Plutonic system, § 131. Distinguished by the principle of compression, § 132. Explains the oblate figure of the earth, ib. Prejudices against this system, § 133. What may be expected from the progress of science, § 1 3 | . NOTES CONTENTS. IX NOTES AND ADDITIONS. Note i. — Origin of Calcareous Earth. Page 143 Dr Hutton's opinion on this subject accurately slated, & 134. Misrepresented by Kirwan, § 135. Note ii. — Origin of Coal. p. 147 Vegetable origin of coal. Opinion of Buffon, § 136. — of Arduino, ib — of Lehman, § 137. Distinction attempted between wood-coal and mineral-coal, § 138.

Not of different origin, but gradually pass one into the other, § 1^9. Bovey coal, § 140 Kirwan derives the matter of mineral-coal from the decomposition of hornblende, &c. 142. Absurdity of this supposition, § I43»I44. ■I45>146. Note hi. — Primitive Mountains p. 160 Lehman introduced the term Primitive mountains, J 148. Supposed more ancient than organized bodies, § 149. Stratification of primitive mountains denied by Pini, and maintained by Saussure, § 150. Note iv.— Primary Strata not primitive. p. 163 Shells found in primary strata, § 151. Sandstone in primary mountains, § 152. Quartzy sand in the fchistus of the Grampians, ib. Rocks distinguished by CONTENTS. X by Werner into three orders, § 153. Objections to this arrangement, \ 154. Note v. — Transportation of the materials of the Strata.

Page 171 The transportation of materials, objected to by the Neptunists, is implied in their own system, § 155, 156, 157. Proofs of great transportation from the animal and vegetable remains, found in rocks, § 139. Note vi. — Kirwan's Notion of Precipitation. p. 180 Difficulty of precipitating the materials dissolved in the chaotic fluid, § 16 r. Insufficiency ofthe explanation attempted, ib. Note vii — Compression in the Mineral Regions. p. 181 Effects ascribed to compression by Newton, compared with the effects ascribed to it in this theory, \ 162. Fallacy of Kirwan's argument concerning the fusion of Carrara marble, § 1O4, 165. Heat of the rrtineral regions may be supported without fuel, § 166. Quototation from Newton's Optics, ib. General remarks, § 168. Note viii. — Sparry Structure of Calcareous Petnfactions. p. 140 J Sparry and organic structure co-exist in certain fossils, 173.

Sparry and stratified structure co-exist in gneiss, marble, &.c. § 171. Note CONTENTS. XI Note ix. — Petroleum, &c. Page 194 Petroleum, &c. from the distillation of coal, § 172. Gradation from petroleum to coal often met with, § 173. Connection of amber and coal, § 174. Why mines of blind coal have not always petroleum mines near them, § 175. Note x. — The Height above the Level of the Sea, at which Marks of Aqueous Deposition are found. p. 199 These marks consist either in stratification or in marine objects, § 176. The marks of stratification observed, 14,739 feet above the sea, § 177. Shells in Peru, 14,190, § 178. Kirwan's mistake concerning these sliells, § 179. His error similar to Voltaire's, § 180. Note xi. — Fracture and Dislocation of the Strata. p. 204 Slips, § 181. Rib of limestone in a flip near Huddersfield, § 182, 183.

Singular fracture of pudding-stones at Oban in Argylessiire, § 184. Similar phenomena observed by Saussure between Nice and Genoa, ib. Remarks on it, § 185. Note xii. — Elevation and Inflexion ofthe Strata. v p. 209 Junction of primary and secondary strata, § 186. Breccia incumbent on the primary, § 187. Junction ofthe primary and secondary strata : At Torbay in Devonsnire CONTENTS, XII > shire, § 189, — coast of Berwickssiire, § 190, — Cullen in Banffshire, § 192, — Ardencaple in Dumbartonssiire, Arran, &c. § 193, — Pembrokessiire, § 194, — Jed burgh, § 195, — Ingleburgh in Yorkshire, § 196, — Cumberland, § 197. Inflexion of the strata, § 198. Remarkable instances in the Alps and Pyrenees, § 199, 20c, — on Benlawers in Perthssiire, § 201, — coast of Berwickssiire, ib. — Plymouth, § 202. Stra ta suffering such inflexions have been soft and ductile, § 2 03 j General property of these inflexions, § 204, 205.

Uniform stretch of the primary strata, § 206. Inferences as to the nature ofthe elevating force, § 207. Imperfection of other theories. Cry stallization, ib- Marks of undulæ in the fchistus, § 208. Elevation of the strata a stronghold of the Huttonian theory, § 209. Elevation of the strata enables us to fee far into the interior of the earth, § 210. Note xiii. — Metallic Veins. Page 239 Specimens of native iron, § ail, 212. Margraaf 's specimen, § 213. Kirwan's hypothesis, § 214. Increase of the specific gravity of native gold by fusion, no argument against its igneous origin, § 215. Specimens of gold and silver ssiooting through quartz, an argument in favour of the Huttonian theory, § 217, 218. Proof in favour of the fame from chalcedony including calcareous spar, {219. Matter that fills veins not from above or from either side, § 220.

Opinion of the Neptunists, § 221. Supposed fact that veins are less rich as the depth increases, § 222. No marks of horizontal deposition in veins ; their coating differs CONTENTS. XIII differs from stratification, $ 223. Neptunists appear to be misled by the term Stratification, § 224,225. Veins heave or shift one another, § 226. Vast force employed for that purpose, § 127. Veins of differ ent formation, § 230. Pieces of rock insulated in veins, § 231. Supposition that veins have been filled by infiltrations, absurd, 230. Lenticular veins, and Pipe veins, § 233. Note xiv. — On Whinstone. Page 260 Whinstone, neither of volcanic nor aqueous formation, § 234. Zeolite and carbonat of lime included in whinstone, but not in lava, ib. Not introduced by infiltration, § 2^5. Disposition of whinstone mountains differs from that of streams of lava, § 236.

This argument first employed by Mr Strange, § 237. His general views of this subject, j 238. Explanation of the regular structure of whinstone hills, according to Dr Hutton's theory, § 239. Many hills supposed to be extinguissied volcanoes, are rocks of real whinstone that has flowed deep under the surface. Vein of whinstone mistaken for a stream of lava by Faujas, § 240, 241. Submarine volcanoes of Dolomieu, § 242. Objections to this theory, $ 243, 244. Dolomieu in another place contends for the aqueous formation of basaltes, § 245. His arguments answered; also those of Bergman, § 247, 248. Argument of Werner for the aqueous origin of basaltes, § 249. Remarks on the supposed gradual transition of basaltes to argillaceous fchistus, § 250, 231. Of the ssiells said to be found in basaltes, § 252.

CONTENTS. XIV § 252. Instances from Portrussi in Ireland, and fronj Cerigo on the coast of Greece, ib. and 253, — from the Veronese, § 254. Objections to the Neptunian for mation of whinstone, founded on the difference be tween it and the contiguous stratified rocks, § 355. On the resemblance of the strata below and above certain masses of whinstone, § 2^6. On the irregularity of the thickness of those masses, § 257- Wedge-form masses of whinstone included between strata, § 258. Consequences of this wedge form, § 259. Sandstone fragments included in whin, § 260, 261. Bending of the strata contiguous to whinstone, § 263. In duration, § 264, 263. Charring of coal by whin, § 266. Of the manner in which the bitumen may have been driven off by heat, § 267. Two kinds of fossil coke, § 268. Graduation into plumbago, ib. and 2 6y. Only remaining objection obviated by Sir James Hall's experiments, § 270.

Note xv. — On Granite. Page 307 Grani veinof two kinds. § 273. Veins of which the communication with large masses of the fame stone is not visib : At the isle of Coll, in the Hebrides, § 274, — at Portsoy, § 273, — in Cornwall, § 276, — in Glentilt, § 2 77. Veins visibly connected with larger masses. Argument furnished by them in favour of this theory> § 27$> 279- Impossibility of their being formed by ir.fi ra _ion, § 280. Veins of this kind in Arran, § 281,— Galloway, § 282,— fides of Loch-Chloney, Inverness-ssiire, § 283,— St Michael's Mount, Cornwall, § 284. Fragments of fchistus contained in granite, § 286. a. Granits CONTENTS. XV 2. Granite of Portsoy. Page 320 Description of this granite, § 287. Pierre graphique of M. Patrin not perfectly the fame with that of Portsoy, § 288. Quartz crystallized in the pierre graphique, § 289.

Instances of quartz crystallized in other granites. In that of St Agnes in Cornwall, § 290. Whether this crystallizations only found in secondary granites, § 291. 3. Stratification of Granite. p. 326 Question stated concerning the stratification of granite, § 292. Remarkable examples of stratified granite at Chorley Forest, Leicesterssiire, and at Fassnet Water in Berwickssiire, § 294. Stratification of Mont Blanc, and the Aiguilles of Chamouni maintained by Saussure, § 295, 266. Seems nevertheless doubtful, § 297. In the granite mountains of Arran doubtful, § 299 Explanation of the stratification of granite in this theory, § 300. If granitic veins were found proceeding from real granitic strata, they could not be explained on the principles here laid down, § 301. No such veins have been discovered, § 302.

Answer to an objection made to the igneous origin cf granitic mountains, § 303, 304. Of the proportion of the earth's surface occupied by gi anite rocks, § 303. Not exceeding a ninetieth part, § 306 — 310, Extent of granite in Scotland erroneously estimated by Dr Hutton, § 311. Amounts perhaps to a twenty-fourth of the whole surface, § 312. Observations on Mr Kirwan's opinion, § 313. Note CONTENTS. XVI Note xvi. — Rivers and Lakes. Page 350 The rivers have hollowed out the valleys, § 314. Illustration from the course of the Danube, § $15. Courses of many rivers retain marks of having consisted of a series of lakes, § 316, 317. Filling up and draining of lakes, §319. Instances from the lakes in Cumberland, § 320. Lake of Geneva, § 321. Lakes in North America, ib. Cataracts, §323. Difficulties in explaining the generation and continuance of lakes, exemplified in that of Geneva, § 323.

Attempt to resolve these difficulties, § 324, 323, 326, 327. All lakes not equally subject to them, § 328. Wasting of the land by the rivers, proved from the mouths of rivers on bold coasts, § 329 Examples from Cornwall, § 330, 331. Note xvii. Remains of Decomposed Rocks, p. 371 Plain of Crau, § 333. Its gravel from the decomposition of pudding stone, § 334. Same true os much of the gravel in this island, § 336, 337. Mount Rigi in Switzerland the remains of a body of pudding stone, § ',38. Measure of the destruction in the stratified rocks sometimes afforded by the unstratified, § 339, 340. Rate at which the elevation of mountains has been supposed to decrease, § 341. Note xviii. — Transportation of Stones, &c. p. 381 Gravel smaller and rounder the farther from its native place, § 342. Different sources of cailloux routes, § 343.

CONTENTS. XVII § 343, 344- Stones that have begun their migration before the cutting out ofthe present valleys, § 345. Declivity necessary to enable stones to travel from the top of Mont Blanc to the top of Mont Jura, § .46. Granite from Mont Blanc found eastward in the valley of the Drance, § 347* Machinery em ployed by nature in transporting rocks, § 34S, 349. Instances of transported stones of great size, — from the vicinity of Geneva, § 330, 331, — from the Isle of Arran, § 352. How gravity may contribute to the moving of large stones, even when the declivity is small, § 333. Rocking-stones, § 354. Stone in Bor rowdale, — in the valley of Urseren, § 355. Large stones are sometimes the remains of veins, § 356. Of the hypothesis of a debacle, j 357. Structure of val leys unfavourable to this hypothesis, § 358, 359.

Parti cularly of valleys close at the ends, § 360, 361. Whe ther the supposition of a debacle is necessary to explain the moving of large masses of rock, § 363. Whether the abrupt faces of hills indicate the existence of any sudden torrent, &x. 364. Fact concerning the steep faces of the mountains in the south of Africa, § A fact stated that would lead necessarily to belief in a debacle ; no example of it has yet occurred, § 366. Note xix. — Transportation of Materials by the Sea. Page 413 Ofthe manner in which the detritus of the land is spread out over the bottom of the sea, § 368, 369. Seas rendered ssiallower, § 370. Sand-banks, § 371. Great system of currents traced in the Atlantic, § 372, 373. How far this transportation of materials may affect the b earth's CONTENTS. XVIII earth's diurnal motion, § 375, 376.

Kirwan's misap prehension of Frisi, and of Major Rennel, § 377, 378. His mistake about the tides, § 379, 380, — and about the formation of sand-banks, § 383. Note xx. — Inequalities of the Planetary Motions. Page 437 These inequalities all periodical, § 384. Circumstances on which this depends, § 385. Affinity of this conclusion to that which Dr Hutton has establissied with respect to the changes at the surface ofthe earth, § 386, Note xxi. — Changes in the Apparent Level of the Sea. p. 441 Relative level of the sea and land subject to change, § 387. Proofs that it has funk, on the shores of this island, § 388, — on the coasts of France and Flanders, § 389, 390, — on the ssicres of the Baltic, § 391- This has not arisen from the depression of the sea, but from the elevation of the land, § 392, 393.

The surface of the Hadriatic higher now than formerly, § 394, 393. Also ofthe Mediterranean, § 397. Irregularities in these changes, § 398, 399. Hypothesis of Frisi, that towards tlie equator the sea is every where rising, § 400. Disproved, ib. Conclusion, \ 401. Note xxii. — Fossil Bones. p. 458 Vegetable and animal remains contained in the fossil kingdom, \ 402. Of those that are enveloped or penetrated with calcareous earth, § 404, 403. Of the bones buried in the loose earth, § 406. Bones in Siberia referred to the rhinoceros and the elephant, § 407' CONTENTS. XIX 5 407. Those on the Ohio doubtful, § 407, 408. Opi nion of Camper, § 409, — of Cuvier, § 410. Objec tions to the latter, ib. Enumeration of five species of animals now extinct, § 411. Change in the animal and vegetable kingdom may account for bones found in countries where no analogous species now exists, § 413.

Proofs that the animals whose bones are found in Siberia inhabited that country, § 414 — 416. Note xxxiii. — Geology of Kirwan and DeLuc. Page 477 These authors have improperly drawn religion into their quarrel with Dr Hutton, § 418, De Luc writes a history of what befel the earth before the creation of the fun, § 419. Remarks on Kirwan's geological writings, § 421, 422, 423, 424. Note xxiv.— System of Buffon. p. 483 In what Buffon's theory of the earth and Dr Hutton's agree, and in what they differ, \ 423, 426. Great merit of Buffon, notwithstanding his errors, § 427. Note xxv. — Figure ofthe Ivarth. p. 488 Physical cause of the earth's oblate figure not obvious from its present condition, § 428. How explained by the Neptunists, § 429. Examination of their solution, § 430, 431. Contradiction implied in it, \ 432.

Insufficiency of Buffon's explanation, § 433. Of the principle on which the oblateness of the earth may be accounted for in Dr Hutton's theory, § 434. Of the changes that would happen in> the figure of a terraqueous body like the earth, supposing CONTENTS. XX posing it ever so irregular, § 433, 436", 437. Two different causes of change, ib. Ultimate figure, that by which the causes of change are best resisted, § 438. Spheroidal figure, never perfectly acquired, § 439. Agreement of this theory with observation, § 440. Probable extension of the system of waste and reno vation to the other planets, § 441, 442. Confirmation from the system of Saturn, § 443, 444. Note xxvi. — Prejudices relating to the Theory ofthe Earth. Page 510 Alleged by some that a theory of the earth ought not at present to be attempted, § 445.

The quick succession of geological theories has partly arisen from their object being misunderstood, § 446. A succession of theories is often a continued approximation to the truth, § 447. The more various the phenomena of any class, the greater the chance of discovering their true cause, § 448. Reason to think that the leading facts in geology are now known, § 449, 430. A tendency may be observed in geological systems to approach to one another, and to the Huttonian, § 451. Example from that of Saussure, § 432, — of Dolomieu, § 433, 434. The discoveries of Dr Black were necessary for understanding the true theory of the earth, § 436. Use of theory in matters of observation, § 457, &c IL- ERRATA. Page 44. Hne 4. from the bottom, for th._t read as 1S9. 6. — for appe_ranes. read appearances. 464. 4, /orD'AUB_INIONrf_7_iDAUBENT0V 48 2 . i»*. for adversaries read adversary ILLUSTRATIONS, fefc.

A Very little attention to the phenomena of the mineral kingdom, is sufficient to con vince us, that the condition of the earth's sur face has not been the fame at all times that it is at the present moment. When we observe the impressions of plants in the heart of the hardest rocks ; when we discover trees converted into flint, and entire beds of limestone or of marble composed of shells and corals ; we fee the fame individual in two states, the most widely differ ent from one another ; and, in the latter in stance, have a clear proof, that the present land was once deep immersed under the waters of the ocean. If to this we add, that many masses of rock, the most solid and compact, consist of no other materials but sand and gravel ; that, on the other hand, loose gravel, such as is form ed only in beds of rivers, or on the sea-ssiore, now abounds in places remote from both : if we reflect, at the fame time, on the irregular A and and broken figure of our continents, and the identity of the mineral strata on opposite sides of the fame valley, or the fame inlet of the sea ; we shall see abundant reason to conclude, that the earth has been the theatre of many great revolutions, and that nothing on its surface has been exempted from their effects.

To trace the series of these revolutions, to explain their causes, and thus to connect together all the indications of change that are found in the mineral kingdom, is the proper object of a Theory of the Earth. But, though the attention of men may be turned to the theory of the earth by a very su perficial acquaintance with the phenomena of geology, the formation of such a theory requires an accurate and extensive examination of those phenomena, and is inconsistent with any but a very advanced state of the physical sciences. There is, perhaps, in those sciences, no research more arduous than this ; none certainly where the subject is so complex ; where the appearan ces are so extremely diversified, or so widely scattered, and where the causes that have operated are so remote from the sphere of ordinary observation.

Hence the attempts to form a theory of the earth are of very modern origin, and as, from the simplicity of its subject, astronomy is the eldest, so, on account of the complexness plexness of its subject, geology is the youngest ofthe sciences. It is foreign from the present purpose, to en ter on any history of the systems that, since the rife of this branch of science, have been invent ed to explain the phenomena of the mineral kingdom. It is sufficient to remark, that these systems are usually reduced to two classes, according as they refer the origin of terrestrial bo dies to fire or to water ; and that, conform ably to this division, their followers have of late been distinguissied by the fanciful names of Vul canists and Neptunists. To the former of these Dr Hutton belongs much more than to the lat ter ; though, as he employs the agency both of fire and of water in his system, he cannot, in strict propriety, be arranged with either.

In 'the succinct account which I am now a bout to give of this system, I ssiall consider the mineral kingdom as divided into two parts, namely, stratified and unstratified substances. I ssiall treat, first, of the phenomena peculiar to the stratified ; next, of those peculiar to the un stratified ; and, lastly, of the phenomena com mon to both. Beginning, then, with the first, the subject naturally divides itself into three branches ; viz. the materials, the consolidation, and the position ofthe strata. A2 SECT-

Section I. Of The Phenomena Peculiar To Stratified Bodies

I. Materials of the Strata. I. IT is well known that, on removing the Ja. loose earth which forms the immediate surface of the land, we come to the solid rock, of which a great proportion is found to be regularly disposed in strata, or beds of determi nate thickness, inclined at different angles to the horizon, but separated from one another by equidistant superficies, that often maintain their parallelism to a great extent. These strata bear such evident marks of being deposited by water, that they are universally acknowledged to have had their origin at the bottom of the sea ; and it is also admitted, that the materials which they consist of, were then either soft, or in such a state of comminution and separation, as render ed them capable of arrangement by the action of the water in which they were immersed.

Thus far most of the theories of the earth agree ; but but from this point they begin to diverge, and each to assume a character and direction pecu liar to itself. Dr Hutton's does so, by laying down this fundamental proposition, That in all the strata we discover proofs of the materials having existed as elements of bodies, which must have been destroyed before the formation of those of which these materials now actually make a part *. 2. The calcareous strata are the portion of the mineral kingdom that gives the clearest tes timony to the truth of this assertion. They of ten contain shells, corals, and other exuviæ of marine animals in so great abundance, that they appear to be composed of no other materials. Though these remains of organized bodies are now converted into stone or into spar, their ssiape and interior structure are often so well preserved, that the species of animal or plant of which they once made a part, can still be distin guished and pointed out among the living inha bitants ofthe ocean.

Others of the calcareous strata appear to be composed of fragments of some ancient rocks, which, after having been broken, have been again united into a compact stone. In these we find pieces clearly marked as having been once continuous, but now placed at a distance from A 3 one * Hutton's Theory, vol. i. p. 20. &c. one another, and exhibiting exactly the same appearances as if they floated in a fluid of the fame specific gravity with themselves. From these, therefore, and a variety of similar appearances, Dr Hutton concludes, that the materials of all the calcareous strata have been furnissied, either from the dissolution of former strata, or from the remains of organized bodies. But, though this conclusion is meant to be ex tended to all the calcareous strata, it is not as serted that every cubic inch of marble or of limestone contains in it the characters of its for mer condition, and of the changes through which it has passed.