cs a, ILLUSTRATIONS OF THE HUTTONIAN THEORY OF THE EARTH. By JOHN PLAYFAIR, F. R. 5. EDIN. AND PROFESSOR OF MATHEMATICS IN THE UNIVERSITY OF EDINBURGH. ii | Nunc naturalem caufam querimus et afiduam, non raram et Sortuitam. SENECA, EDINBURGH: PRINTED FOR CADELL AND DAVIES, LONDON, AND WILLIAM CREECH, EDINBURGH. 1802. Entered in Stationers Balt. Nerit & ĉo. ? Printers, Edinburgh. 5 ADVERTISEMENT. HE Treatife here offered to the Public, was drawn up with a view of explain- ing Dr Hutton’s Theory of the Earth in a manner more popular and perfpicuous than is done in his own writings. The obfcu-. rity of thefe has been often complained of ; and thence, no doubt, it has arifen, that fo little attention has been paid to the inge- nious and original fpeculations which they contain. THE fimpleft way of accomplifhing the object propofed, feemed to be, to prefent a General Outline of the Syftem, in one con- tinued Difcourfe ; and to introduce after- wards, in the form of Notes, what farther Elucidation any particular fubje@ was thought to demand. Through the whole, I have aimed at little more than a clear ex- pofition of fas, and a plain dedudtion of the conclufions grounded on them; nor fhall I claim any merit to myfelf, if, in the - order which I have found it neceflary to adopt, fome arguments may have taken a å 2 new iv ADVERTISEMENT. new form, and fome additions may shave been made to a fyftem naturally rich in the number and variety of its illuftrations. Or the qualifications which this underta- king requires, there is one that I may fafely fuppofe myfelf to poflefs. Having been in- {tructed by Dr Hutton himfelf in his theory of the earth; having lived in intimate friend- {hip with that excellent man for feveral years, and almoft in the daily habit of dif- culling the queftions here treated of; [have — had the beft opportunity of underftanding his views, and becoming acquainted with his peculiarities, whether of expreffion or of thought. Inthe other qualifications necef- fary for the illuftration of a fyftem fo ex- tenfive and various, I am abundantly fen- fible of my deficiency, and fhall therefore, with great deference, and confiderable an- xlety, wait that decifion from which there is no appeal. EDINBURGH COLLEGE, Ift March 1802. t OO EEEO TABLE OF SON 1 EN T S. INTRODUCTION. Objeé of a Theory of the Earth. Divifion of minerals into Stratified and Unflratified. Page 1. SECTION I. PHENOMENA PECULIAR TO STRATIFIED BODIES. 1. Materials of the Strata. Page 4 Prefent ftrata compofed of the remains of more ancient rocks, § 1. Proofs from calcareon ftrata, § 2.—from filiceous, § 3.—from argillaceous, § 4.—from bitumi- nous, § 5,6. Abfence of organized remains from the © ftrata called primitive, not univerfally true, § 8, 9. Term Primary fubftituted for Primitive. Compofition from the materials of more ancient rocks, § ro. T 2. Confolidation of the Strata. p. I5 Confolidation, what, § Ir. Objedions to aqueous con- folidation, § 12, 13, 14. Compreffion affe&ts the ac- tion of fire on bodies, § 15, 16, 17. Igneous confoli- dation of minerals proved from foffil wood, § 19.— from the flints in chalk, § 20.—from fandftone, § 27.— from vi | CONTENTS. from the calcareous ftrata, § 23, 24, 25.—from the ar- gillaceous, § 26, 27.—from the bituminous, { 28, 29. —from the faline, § 32. Salt-mines in Chethire. Trona of Africa, $ 34, 35. 3. Pofition of the Strata. Page 40 Strata formed at the bottom of the fea, § 36. Appa- rent elevation not produced by the retreat of the fea, § 37. Strata, horizontal, when formed, § 38, 39. Dif- turbance of the ftrata proved from their inclined pofi- tion, § 40, 41, 42.—from fhifts, &c. § 42. Shifts of | different dates, 7b. Difturbance of the primitive ftrata vifible at their junétion with the fecondary, § 43, 44. This difturbance produced by a force dire€ted up- ward, § 45,46. This force the effet of fubterra- neous heat, § 47, 48. : ra SECTION II. PHENOMENA PECULIAR TO UNSTRATIFIED BODIES. 1. Metallic Veins. pP. 57 Veins defined. They contain fubftances that were once in fufion, § 49, ṣo. Metallic veins, native metals, &c. § 51. Native copper, § 52. Manganefe, § 53. Frag- ments of rocks included in veins, § 55. Shifting and heaving of veins, § 56, 57. Veins of different dates, § 58. Stratification not found in veins. Coating of the fides, what, § ṣọ., Metallic veins moft common in primitive ftrata, but not confined to them, § 60. 2. Whinftone. ` f f H f f Í 4 terra. DIES. p. 57 > once qé CONTENTS. yä 2. Whinftone: Page 66 © Enumeration of ftones of this genus, § 61. Whin, whe- ther in veins or in mafles, refembles lava, § 62. Is a fubterraneous lava, § 63. Columnar ftructure an argument for fufion, § 64. Not produced by drying, § 65. Whinftone penetrated by pyrites, § 66. In- duration of the ftrata in contaé&t with whin, § 67. Coal charred by whinftone veins, § 68. Difturbance of the ftrata by whinftone veins, § 69. Phenomena of whin interpofed. between ftrata, § 7°, 71- Tranfition from whin to ftrata not gradual, § 72. Agates and chalcedonies in whinftone, § 74. This ftone melted and reproduced from fufion by Sir James Hall, § 75. Mineral alkali found init by Dr Kennedy, 7b. Whin- ftones of different formation, § 76. Porphyry a fpecies or variety of whinftone, § 77: 3. Granite. p. 82 Granite defined. Exifts in maffes and veins, § 77 The bafis of other rocks, § 78. Its original fluidity inferred from the cryftallization of its parts, } 79- Its fufion, from the ftruture of the Portfoy granite, § 80, 81.— from granite veins, § 82. General conclufion as to the igneous origin of minerals, § 83, 84, 85. Adual exiftence of fubterraneous heat known from hot {prings, volcanoes, earthquakes, § 86. Volcanic fire feated deep under the furface, § 87. Subterraneous heat not accompanied by burning, § 88, 89. Tran{miffion of fubterraneous heat, fo as to produce hot f{prings, &c. § 90, 91. a 4 SECTION Vill CONTENTS. SECTION III. PHENOMENA GOMMON TO STRATIFIED AND UN- STRATIFIED BODIES. Page o7 | Chemical agents which produce the decompofition of mi- neral fubftances at the furface, § 92, 93. Mechanical agents, § 95, 96. Proofs of wearing from the fea-fhore, § 97,98. Rivers, § 99, 100. Defiles among mountains, — § 102. Supply of the foil from the decompofition of rocks, § 103. Gravel in the foil, § 104, r05. Gold found in the foil, § 106. Tin, § 107. Proofs of wafte from mountainous countries, § 108, 109. Structure of valleys, § 111. Tranfportation of ftones, § 112. Neareft meafure of the wafte, § 113. General re- marks, § 114, 115. No production of minerals on the furface, § 116. Reproduction at the bottom of 4 the fea, § 117. Continued fyftem of decay and reno- vation, § 118. Defence againft the charge of impie- ty, «19. Antiquity and order of the revolutions of | the globe, § 120, 121, 122, 123, 124. Confiftency | with the Sacred Writings, § 125. Scope of this theory of the earth diftinguifhes it from others; beauty and extent of its views, § 126. New faéts, § 124. | Comparifon of this theory with that of Buffon, § 129. . of Lazzaro Moro, § 130. Plutonic fyftem, § 131. Di- | ftinguihed hy the principle of compreffion, § 132. — | Explains the oblate figure of the earth, 74. Prejudi- | ces againit this fyftem, § 133. What may be expett- ed from the progrefs of fcience, § 134. NOTES. . CONTENTS. ig NOTES AND ADDITIONS. Nore 1.—Origin of Calcareous Earth. Page 143 Dr Hutton’s opinion on this fubject accurately ftated, § 134. Mifreprefented by Kirwan, § 135. Nore 11.—Origin of Coal. P- 147 Vegetable origin of coal. Opinion of Buffon, § 136.— of Arduino, zb.—of Lehman, § 137. Diftindtion at- tempted between wood-coal and mineral-coal, § 138. Not of different origin, but gradually pafs one into * the other, § r39. Bovey coal, § 140. Kirwan derives the matter of mineral-coal from the decompofition of hornblende, &c. 142. Abfurdity of this fuppofition, $ 143,144, 145,146. . Nore 111.—Primitive Mountains. p- 160 Lehman introduced the term Primitive mountains, § 148. Suppofed more ancient than organized bodies, § 149. Stratification of primitive mountains denied by Pini, and maintained by Sauffure, § iso. Nore rv.—Primary Strata not primitive. p- 163 Shells found in primary rata, § 151. Sandftone in primary mountains, § 152. Quartzy fand in the ` {chiftus of the Grampians, 76. Rocks difiinguifhed j by g CONTENTS. \ by Werner into three orders, § 153. Objeĉtions a this arrangement, § 154. Nore v.—Tranfportation of the materials of the Strata. Page 171 The tranfportation of materials, obje&ed to by the Nep- tunifts, is implied in their own fyftem, § 155, 156, 157. Proofs of great tranfportation from the animal and vegetable remains, found in rocks, § 159. Nore vi.—Kirwan’s Notion of Precipitation. p. 180 Difficulty of precipitating the materials diffolved in the chaotic fluid, § 161. Infufficiency of the explanatiog — attempted, 7d. Nore vit.—-Compreffion in the Mineral Regions. p. 181 Effets afcribed to compreflion by Newton, compared with the effects afcribed to it in this theory, § 162. Fallacy of Kirwan’s argument concerning the fufion of Carrara marble, § 164, 165. Heat of the mineral regions may be fupported without fuel, § 166. Quo- totation from Newton’s ort ib; .General re- marks, § 168. Nore vii1.—Sparry Structure of Calcareous Pe- trifactions. p. 140 Sparry and organic ftructure co-exift in certain foils, — § 170. Sparry and ftratified ftru@ture co-exift in gneifs, marble, &c. § 17% Not E a CONTENTS. xi Nore 1x.—Petroleum, &c. Page 194 Petroleurh, &c. from the diftillation of coal, { 172. Gra- dation from petroleum to coal often met with, § 173. Conneétion 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 Depofition are found. p. 199 Thefe marks confift either in ftratification or in marine objects, § 176. The marks of ftratification obferved, 414,939 feet above the fea, § 177. Shells in Peru, 14,190, § 178. Kirwan’s miftake concerning thefe fhells, § 179. His error fimilar to Vonrairsg’s, § 180. Note x1.—Fracture and Diflocation of the Strata. p. 204 Slips, § 181. Rib of limeftone in a flip near Hudders- field, § 182, 183. Singular fraéture of pudding-ftones at Oban in Argylefhire, § 184. Similar phenomena obferved by Sauffure between Nice and Genoa, tå. Remarks on it, § 185. Nore x11.--Eleyation and Inflexion of the Strata. p. 209 Junction of primary and fecondary ftrata, § 186. Brec- cia incumbent on the primary, § 187. Junction of the primary and fecondary ftrata: At Torbay in Devon- fhire zii CONTENTS. fhire, § 189,—coaft of Berwickthire, $ 190,—Cullen in Banffshire, § 192,—Ardencaple in. Dumbartonfhire, Arran, &c, § 193,—Pembrokeshire, $ 194,—Jed- burgh, § 195,—Ingleburgh in Yorkfhire, § 196,- Cumberland, § 197. Inflexion of the ftrata, § 198, Remarkable inftances in the Alps and Pyrenees, § 199, 200,—on Benlawers in Perthhhire, $ 20pm coaft of Berwickfhire, 7.—Plymouth, § 202. Stra- ta fuffering fuch inflexions have been foft and duc- tile, § 203. General property of thefe inflexions, $ 204,205. Uniform ftretch of the primary ftrata, § 206. Inferences as to the nature of the elevating a force, § 207. Imperfeion of other theories. Cry- ftallization, 7b- Marks of undulæ in the fchiftus, § 208. Elevation of the ftrata a ftronghold of the Huttonian theory, § 209. Elevation of the ftrata enables us to fee far into the interior of the earth, § 210. Nore x1i1.—Metallic Veins. Page 239 Specimens of native iron, § 211, 212. Margraaf ’s {pe- cimen, § 213. Kirwan’s hypothefis, § 214. Increafe of the fpecific gravity of native gold by fufion, no argument againft its igneous origin, § 215. Speci- mens of gold and filver fhooting through quartz, an argument in favour of the Huttonian theory, § 217, 218. Proof in favour of the fame from chalce- dony including calcareous fpar, § 219. Matter that fills veins not from above or from either fide, $ 220. Opinion of the Neptunitts, § 221. Suppofed fa& that Veins are lefs rich as the depth increafes, § 222. No marks of horizontal depofition in veins; their coating differs CONTENTS. xili differs from ftratification, § 223. Neptunifts appear to be mifled by the term Stratification, § 224, 225. Veins heave or fhift one another, § 226. Waft force employed for that purpofe, § 227. Veins of differ- ent formation, § 230. Pieces of rock infulated in veins, § 231. Suppofition that veins have been filled by infiltrations, abfurd, 230. Lenticular veins, and Pipe veins, § 233. Nore x1v.—On Whinftone. Page 260 Whinftone, neither of volcanic nor aqueous formation, § 234. Zeolite and carbonat of lime included in whinftone, but not in lava, zb. Not introduced by infiltration, § 235. Difpofition of whinftone moun- tains differs from that of ftreams of lava, § 236. This argument firft employed by Mr Strange, § 237. His general views of this fubje@, § 238. Ex- planation of the regular ftru@ture of whinftone hills, according to Dr Hutton’s ‘theory, § 239. Many hills fuppofed to be extinguifhed volcanoes, are rocks of | real whinftone that has flowed deep under the furface. Vein of whinftone miftaken for a ftream of lava by Faujas, § 240, 241. Submarine volcanoes of Dolo- mieu, § 242, Objections to this theory, § 243, 244. Dolomieu in another place contends for the aqueous formation of bafaltes, $ 245. His arguments an- fwered; alfo thofe of Bergman, § 247, 248. Ar- gument of Werner for the aqueous origin of ba- faltes, § 249. Remarks on the fuppofed gradual tranfition of bafaltes to argillaceous {chiftus, § 250, 251. Of the fhells faid/to be found in bafaltes, A Bees xiv CONTENTS. § 252. Inftances from Portrufh in Ireland, and from Cerigo on the coaft of Greece, 1d. and 253,—from the Veronefe, § 254. Objections to the Neptunian for. mation of whinftone, founded on the difference be. — tween it and the contiguous ftratified rocks, § 2 Te On the refemblance of the ftrata below and above cer- tain mafles of whinftone, § 256, On the irregularity of the thicknefs of thofe mafles, § 257. Wedge-form maffes of whinftone included between ftrata, § 258. Confequences of this wedge-form, § 259. Sandftone fragments included in whin, § 260, 261. Bending of the ftrata contiguous to whinftone, § 263. In. duration, § 264, 265. Charring of coal by whin; § 266. Of the manner in which the bitumen may | have been driven off by heat, § 267. Two kinds of - foflil coke, § 268. Graduation into plumbago, 7. and 269. Only remaining objection obviated by Sir James Hall’s experiments, § 270. . Nore xv.—On Granite. Page 307 TE Granite veins of two kinds. § 273. Veins of which the communication with large mailes of the fame ftone is _ not vifib: At the ifle of Coll, in the Hebrides, § 274, | —at Portfoy, § 275,—in Cornwall, § 276,—in Glen- | tilt, § 277. Veins vifibly conneéted with larger maffes, | Argument furnifhed by them in favour of this theo- ry, § 278, 279. Impoflibility of their being formed by infi raion, § 280. Veins of this kind in Arran, $ 281,—Galloway, § 282,—fides of Loch-Chloney, Invernefs-fhire, § 283,—-St Michael’s Mount, Corn- wall, § 284. Fragments of {chiftus contained in gra- nite, § 286. | = me - 3 o e eT 2, Granite hin may s of CONTENTS. xv 2. Granite of Portfoy. Page 320 Defcription of this granite, § 28%, Pierre graphique. of M. Patrin not perfetly the fame with that of Port- foy, § 288. Quartz cryftallized in the pierre gra- phique, § 289. Inftances of quartz cryftallized in other granites. In that of St Agnes in Cornwall, § 290. Whether this cryftallization is only found in fecondary granites, § 291. 3. Stratification of Granite. p. 326 Queftion ftated concerning the ftratification of granite, § 292. Remarkable examples of ftratifiéd granite at Chorley Foreft, Leicefterfhire, and at Faffnet Water in Berwickfhire, § 294. Stratification of Mont Blanc, and the Aiguilles of Chamouni main- tained by Sauffure, § 295, 266. Seems neverthelefs doubtful, § 297. Inthe granite mountains of Arran doubtful, § 299. Explanation of the ftratification of granite in this theory, § 300. If granitic veins were found proceeding from real granitic ftrata, they could not be explained on the principles here laid down, § 301. No fuch veins have been difcovered, § 302. Anfwer to an objeCtion made to the igneous-origin of granitic mountains, § 303, 304. Of the proportion of the earth’s furface occupied by granite rocks, § 305. Not exceeding a ninetieth part, § 3¢6—310, Extent of granite in Scotland erroneoufly eftimated by Dr Hutton, § 311. Amounts perhaps to a twenty- fourth of the whole furface, § 312. Obfervations on Mr Kirwan’s opinion, § 313. NotE xi CONTENTS. Nore xvi.—Rivers and Lakes. Page 350 The rivers have hollowed out the valleys, § 314. ‘HW luftration from the courfe of the Danube, § 345. Courfes of many rivers retain marks of having confift. ed of a feries of lakes, § 316, 317. Filling up and draining of lakes, § 319. Inftances from the lakes in Cumberland, § 320. Lake of Geneva, § 321. Lakes in North America, 7b. Cataraéts, § 322. Difficul. ties in explaining the generation and continuance of lakes, exemplified in that of Geneva, § 32 3- Attempt to refolve thefe difficulties, § 324, 325, 326, 327% | All lake$ not equally fubjeé to them, § 328. Watt ing of the land by the rivers, proved from the mouths . of rivers on bold coafts, § 329. Examples from Corn- _ wall, § 330, 331. Nore xvi. Remains of Decompofed Rocks. Pp. 371 Plain of Crau, § 333. Its gravel from the decompofition of pudding-ftone, § 334. Same true of much of the gravel in this ifland, § 336, 337. Mount Rigi in Switzerland the remains of a body of pudding ftone, § 38. Meafure of the’ deftru€tion in the ftratified rocks fometimes afforded by the unftratified, § 339, 340. Rate at which the elevation of mountains has ` been fuppofed to decreafe, § 341. Nore xv111.—Tranfportation of Stones, &c. p. 381 Gravel fmaller and rounder the farther from its native place, § 342. Different fources of cailloux roulés, § 343s CONTENTS. xvii § 343, 344° Stones that hayė begun their migration before the cutting out of the prefent valleys, § 345. Declivity neceffary to enable ftones to travel from the top of Mont Blane to the top of Mont Jura, § 346. Granite from Mont Blanc found eaftward in the valley of the Drance, § 347- Machinery em- ployed by nature in tranfporting rocks, § 348, 349. Inftances of tran{ported {tones of great fize,—from the vicinity of Geneva, § 350, 351,—from the Ifle of Arran, § 352. How gravity may contribute to the mowing of large ftones, even when the declivity is f{mall, § 353. Rocking-ftones, § 354. Stone in Bor- rowdale,—in the valley of Urferen, § 355. Large ftones are fomctimes the remains of veins, § 356. Of the hypothefis of a debacle, § 357. Structure of val- leys unfavourable to this hypothefis, § 358,359. Parti- cularly of valleys clofe at the ends, § 360, 361. Whe- ther the fuppofition of a debacle is neceflary to explain the moving of large maffes of rock, § 363. Whether the abrupt faces of bills indicate the exiftence of any fudden torrent, &c. 364. Fact concerning the fteep faces of the mountains in the fouth of Africa, § 365. A fact ftated that would lead neceffarily to belief in g debacle; no example of it has yet occurred, § 366. Nore x1x.—Tranfportation of Materials by the Q ag wea. Page 413. Of the manner in which the detritus of the land is fpread out over the bottom of the fea, § 368, 369. Seas ren- dered fhallower, § 370. Sand-banks, § 371. Great fyftem of currents twaced in-the Atlantic, 4 372, 373- How far this tranfportation of materials may affect the b earth’s xvii CONTENTS. earth's diurnal motion, § 37553 76. Kirwan’s mifap. prehenfion of Friĥ, and of Major Rennel, § 377378. His miftake about the tides, 3 = aii about the formation of fand-banks, § 38 i Nore xx.—Inequalities of the Planetary Mo- tions. Page 437 Thefe inequalities all periodical, § 384: Circumftances on which this depends, § 385. Affinity of this con- clufion to that which Dr Hutton has eftablithed with re{pect to the changes at the furface of the earth, § 386. Nore xxi.—Changes in the Apparent Level of the Sea. P. 441 Relative level of the fea and land fubje@ to change, § 337. Proofs that it has funk, on the fhores of this ifland, § 338,+-on the coafts of F rance and Flanders, § 289, 390,—on the theres of the Baltic, § 391. This has not arifen from the deprefiion of the fea, but from the elevation of the land, § 39°, 393. The furface of the Hadriatic higher now than formerly, § 394, 395- Alfo of the Mediterranean, § 397. Irregulari- ties in thefe changes, § 398, 399- Hypothefis of Frif, that towards the equator the fea is every where rifing, § 490. Difproved, 2d. ' Conclufion, § 401. Nore xx11.—Foflil Bones. p. 458 Ver geta sa animal remains contained in the foffil k ing a om, § 402. Of thofe that are enveloped or pe- riid with ne earth, § 404, 405. Of the bones buried in the loofe earth, { 406. Bones in Si- beria referred to the rhinoceros and the elephant, | § 407. — Rie Phyfical caufe of the earth’s oblate figur CONTENTS. xix § 407. Thofe on the Ohio doubtful, § 407, 408. Opi- nion of CAMPER, § 409,—of Cuvier, § 410. Objec- tions to the latter, 7b. Enumeration of five fpecies of animals now extin@, § 411- Change in the ani- mal and vegetable kingdom may account for bones found in countries where no analogous fpecies now exilts, § 413. Proofs that the animals whofe bones are ry - found in Siberia inhabited that country, § 414—416. Note xxx111.—Geology of Kirwan and De Luc. Page 477 Thefe authors have improperly drawn religion into their quarrel with Dr Hutton, $ 418, De Luc writes a hiftory of what befel the earth before the creation of the fun, § 419. Remarks on Kirwan’s geological writings, § 421, 422, 423, 424. Norse xxiv.—Syftem of Buffon. P- 483 In what Buffon’s theory of the earth and Dr Hutton's agree, and in what they differ, § 425, 426. Great me- rit of Buifon, notwithitanding his errors, § 424, Note xxv.—Figure of the Earth. P. 488 e not obvious from its prefent condition, § 428. How explained by the Neptunitts, $429. Examination of their fo- lution, § 430 431. Contradi@ion implied in iG § 432. Infufficiency of Buffon’s explanation, § 433. Of the principle on -which the oblatenefs of the earth may be accounted for in Dr Hutton’s theo- ry, § 434. Of the changes that would happen in the figure of a terraqueous body like the earth, fup- pofing xk CONTENTS. pofing it ever fo irregular, § 435, 436,437. Two different caufes of change, ib. Ultimate figure, that by which the caufes of change are beft refifted, § 438. Spheroidal figure, never perfectly acquired, § 439. Agreement of this theory with obfervation, § 440, Probable extenfion of the fyftenr of wafte and reno- vation to the other planets, § 441, 442. Confirmation from the fyftem of Saturn, § 443, 444. Nore xxvi.—Prejudices relating to the Theory of the Earth. Page/5ro Alleged by fome that a theory of the earth ought not at prefent to be attempted, § 445. The quick fucceffion of geological theories has partly arifen from their ob- je&t being mifunderftood, § 446. A fucceffion of theo- ries is often a continued approximation to the truth, § 447. The more various the phenomena of any clafs, the greater the chance of difcovering their true caufe, § 448. Reafon to think that the leading faéts in geo- logy are now known, $ 449,450. A tendency may be obferved in geological fyftems to approach to one another, and to the Huttonian, §. 451. Example from that of Sauflure, § 452,—of Dolomieu, § 453, 454 The difcoveries of Dr Black were neceffary for ún- derftanding the true theory of the earth, § 456. Ufe of theory in matters of obfervation, § 457, &c. ERRATA. Page 44. line 4. from the bottom, for that read as 6 s 189. Jor appearanes. read appearances, f — 464. —— Ay Jor D’Avzinton read Dausentow eens 74 82 p ma TZ, aoe. or adverfaries read adverfary IL-f ILLUSTRATIONS, to Very little attention to the phenomena of the mineral kingdom, is fufficient to con- Vince us, that the condition of the earth’s fur- face has not been the fame at all times that it is at the prefent moment. When we obferve the _impreffions of plants in the heart of the hardeft rocks; when we difcover trees converted into flint, and entire beds of limeftone or of marble -compofed of fhells arid corals; we fee the fame l individual in two ftates, the moft widely differ- ent from one another; and, in the latter in- ftance, have a clear proof, that the prefent land was once deep immerfed under the waters of the ocean. If to this we add, that many mafles of rock, the mof folid and compact, confit of no other materials but fand and gravel; that, on the other hand, loofe gravel, fuch as is form- ed only in beds of rivers, or on the fea-fhore, now abounds in places remote from both: if we reflect, at the fame time, on the irregular A. and : ILLUSTRATIONS OF THE and broken figure of our continents, and the identity of the mineral ftrata on oppofite fides of the fame valley, or the fame inlet of the fea ; we fhall fee abundant reafon to conclude, that the earth has been the theatre of many great revolutions, and that nothing on its furface has | been exempted from their effects. To trace the feries: of thefe revolutions, to explain their caufes, and thus to connect toge- ther 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 fu- — perficial acquaintance with the phenomena of | geology, the formation of fuch a theory requires an accurate and extenfive examination of thofe | phenomena, and is inconfiftent with any buta | very advanced ftate of the phyfical fciences. There is, perhaps, in thofe {ciences, no refearch more arduous than this; none certainly where the fubjed& is fo complex ; where the appearan- f ces are fo extremely diverfified, or fo widely {cattered, and where the caufes that have ope- rated are fo remote from the {phere of ordinary obfervation. Hence the attempts to form a` theory of the earth are of very modern origin, and as, from the fimplicity of its fubject, aftro- nomy is the eldeft, fo, on account of the com- i plexnefs — ‘HUTTONIAN THEORY. 3 plexnefs of its fubject, geology is the youngeft of the {ciences. It is foreign from the prefent sts to en- ter on any hiftory of the fyftems that, fince the rife of this branch of fcience, have been invent- , ed to explain the phenomena of the mineral kingdom. It is fufficient to remark, that thefe fyftems are ufually reduced to two claffes, ac- | cording as they refer the origin of terreftrial bo- | dies to FIRE or to WATER; and that, conform- _ ably to this divifion, their followers have of late been diftinguithed by the fanciful names of Vul- į canifts and Neptunifts. To the former of thefe Dr Hurron belongs much more than to the lat- _ ter; though, as he employs the agency both of fire and of water in his fyftem, he cannot, in _ firict propriety, be arranged with either. In the fucciné& account which I am’ nowa- _ bout to give of this fyftem, I fhall confider the _ mineral kingdom as divided into two parts, namely, {tratified and unftratified fubftances. Al fhall treat, firt, of the phenomena peculiar to the ftratified ; next, of thofe peculiar to the un- ftratified ; and, laftly, of the phenomena com- mon to both. Beginning, then, with the firft, the fubje&t naturally divides itfelf into three branches ; viz. the materials, the confolidation, and the po/fition of the ftrata. A2 SECT- 4 ILLUSTRATIONS OF THE SECTION 6 OF THE PHENOMENA PECULIAR TO STRATIFIED BODIES. ; 1. Materials of the Strata. 1. WT is well known that, on removing the | loofe earth which forms the immediate furface of the land, we come to the folid rock, of which a great proportion is found to be re- gularly difpofed in ftrata, or beds of determi- nate thicknefs, inclined at different angles to the — horizon, but feparated from one another by | equidiftant fuperficies, that often maintain their parallelifm to a great extent. Thefe ftrata bear fuch evident marks of being depofited by water, that they are untverfally acknowledged to have | had their origin at the bottom of the fea; and it is alfo admitted, that the materials which they confit of, were then either foft, or in fuch a ftate of comminution and feparation, as render- ed them capable of arrangement by the action of the water in which they were immerfed. Thus far moft of the theories of the earth agree; _ but TFL HUTTONIAN THEORY. 5 but from this point they begin to diverge, and each to affume a character and direction pecu- liar to itfelf. Dr Hutton’s does fo, by laying down this fundamental propofition, That in all the ftrata we difcover proofs of the materials having exifted as elements of bodies, which muft have been deftroyed before the formation of thofe of which thefe materials now actually make a part *. 2. The calcareous ftrata are the portion of the mineral kingdom that gives the cleareft tef- timony to the truth of this affertion. They of- ten contain fhells, corals, and other exuvie of marine animals in fo great abundance, that they appear to be compofed of no other materials. Though thefe remains of organized bodies are now converted into ftone or into fpar, their {hape and interior ftructure are often fo well _ preferved, that the fpecies of animal or plant of © which they once made a part, can ftill be diftin- guifhed and pointed out among the living inha- bitants of the ocean. Others of the calcareous ftrata appear to be compoled of fragments of fome ancient rocks, which, after having been broken, have been again united into a compact ftone. In thefe we find pieces clearly marked as having been once continuous, but now placed at a diftance from , A3 one * Hutton’s Theory, vol.i. p. 20. &c. 6 ILLUSTRATIONS OF THE one another, and exhibiting exactly the fame appearances as if they floated in a fluid of the fame f{pecific gravity with themfelves. From thefe, therefore, and a variety of fimi- lar appearances, Dr Hutton concludes, that the materials of all the calcareous ftrata have been furnifhed, either from the diffolution of former frata, or from the remains of organized bodies, But, though this conclufion is meant to be ex- tended to all the calcareous ftrata, it is not af- ferted that every cubic inch of marble or of limeftone contains in it the characters of its for- mer condition, and of the changes through which it has pafled. It may, however, be fafe- ly affirmed, that there is fcarce any entire ftra- tum where fuch characters are not to be found. Thefe muft be held as decifive with refpect to the whole fyftem of ftrata to which they belong ; they prove the exiftence of calcareous rocks be- — fore the formation of the prefent ; and, as the deftru&tion of thofe is evidently adequate to the fupply of the materials of thefe that we now fee, to look for any other fupply were fuperflu- ous, and could only embarrafs our reafonings by the introduction of unneceflary hypothetes *. 3. The fame conclufions refult from an ex- amination of the filiceous ftrata; under which we may comprehend the common fand-ftone, and * NOTE I. — HUTTONIAN THEORY. x and alfo thofe pudding-ftones or breccias where the gravel confifts of quartz. In all thefe in- ftances, it is plain, that the fand or gravel exift- ed in a ftate quite loofe and unconnected, at the bottom of the fea, previous to its confolidation into ftone. But fuch bodies of gravel or fand could only be formed from the attrition of large = males of quartz, or from the diffolution of fuch _ fand-ftone ftrata as exift at prefent; for it will hardly be alleged, that fand is a cryftallization of quartz, formed from that fubftance, when it paffes from a fluid to a folid ftate. Thofe pudding-ftones in which the gravel is round and polifhed, carry the conclufion ftill farther, as fuch gravel can only be formed in the beds of rivers or on the fhores of the fea; for, in the depths of the ocean, though currents are known to exift, yet there can be no motion of the water fufficiently rapid to produce the at- trition required to give a round figure and = {mooth furface to hard and irregular pieces of ftone. There muft have exifted, therefore, not only a fea, but continents, previoufly to the for- mation of the prefent ftrata. _ The fame thing is clearly fhewn by thofe pe- - trifaGtions of wood, where, though the vegeta- ble firu@ture is perfe&ly preferved, the whole mais is filiceous, and has, perhaps, been found A 4 | in 8 ILLUSTRATIONS OF THE in the heart of fome mountain, deep imbedded in the folid rock. 4. Chara@ers of the fame import are aie _ found among the argillaceous ftrata, though per- haps more rarely than among the calcareous or filiceous. Such are the impreffions of the leaves and {tems of vegetables ; alfo the bodies of fith ‘and amphibious animals, found very often in the different kinds of argillaceous fchiftus, and in moft inftances having the figure accurately preferved, but the fubftance of the animal re- placed by clay or pyrites. Thefe are all re- mains of ancient feas or continents; the latter of which have long fince fipo from the fur- face of the earth, but have ftill their memory preferved in thofe archives, where nature has recorded the revolutions of the globe. 5. Among bituminous bodies, pit-coal is the only one which conftitutes regular and extenfive ftrata; and no foffil has its origin from the wafte of former continents, marked by ttronger and more diftin@ chara@ers. Not to mention that the coal ftrata are alternated with thofe that have been already enumerated, and that they often contain fhells and ‘corals, perfe@ly mineralized, it is fufficient to remark, that there are entire beds of this foffil, which appear to confift wholly of wood, and in which the fibrous ftructure is perfectly preferved. From thefe in- ftances, Spa 7 —] imbedgy bre. alf, ough Der the leave les of fif often i hiftus, ant accurate) animal r are all n he lattero ym the fur ir memo! nature h coal is thi ] extenfi from th Jy ftrong? O mentil vith tho and th perfeôl that the appe!" tb e fibro p thefe ; franc as we may call them; HUTTONIAN THEORY. 9 fiances, the appearances of vegetable ftructure may be traced through all poflible gradations, down to an evanefcent ftate. This laft ftate is undoubtedly the moft common; and though coal does not then, on bare infpection, make known its vegetable origin, yet, if we take it in connection with the other terms of the feries, ` if we confider that the two extremes, viz. coal, with the vegetable ftructure perfe, and coal without any fuch ftructure vifible, are often found in the fame or in contiguous beds; and, if we remark, that through all thefe gradations coal contains near- ly the fame chemical elements, and yields, on _analyfis, bitumen and charcoal, combined with a greater or lefs proportion of earth: if we take all thefe circumftances into account, we cannot doubt that this foffil is every where the fame, and derives its origin from the trees and plants that grew on the furface of the earth before the formation of the prefent land. 6. Dr Hutton has further obferved, that if thofe ancient continents were at all fimilar to the prefent, we can be at no lofs to account for the want of any diftin& mark of vegetable or- ganization in the greater part of the coal ftrata. It is plain, that the daily wafte of animal and vegetable fubftances on the furface of the earth, muft difengage a great quantity of oily as well as I0 ILLUSTRATIONS OF THE as carbonic matter, which, with whatever ‘ele- ment it is at firt combined, is ultimately deli- vered into the ocean. Thus, the oily or fuligi- nous parts of animal and vegetable fubftances, let loofe by burning, firft afcend into the atmo- fphere, but are at length precipitated, and either fall immediately into the fea, or are, in part at leaft, wafhed down into it from the land. From other caufes alfo, much vegetable matter is car- ried down by the rivers; and the whole quan- tity of animal and vegetable fubftances thus de- livered into the fea, muft be very confiderable, amounting annually to the whole refiduum of thofe fubftances, not employed in the mainte- nance or reproduction of animal and vegetable bodies. Whether chemically united to the wa- ters of the ocean, or fimply fufpended in them, this matter is at laft precipitated, and, mingling with earthy fubftances, is formed into ftrata, the place of which will be determined by the cur- rents, the pofition of the prefent continents, and many other circumftances not eafily enumera- ted. | If, then, an order of things fimilar to what we now fee, exifted before the formation of the prefent ftrata, it would neceffarily happen, that the animal and vegetable fubftances, diffufed — through the ocean, being feparated from the water, would be depofited at the bottom of the fea, a ——_ Dianai HUTTONIAN THEORY. II fea, and, in the courfe of ages, would form beds, lefs or more pure, according to the quantity of earth and other fubftances depofited at the fame time. . Thefe beds being confolidated and mi- neralized by operations that are afterwards to _ be confidered, have been converted into pit-coal, the parts of which are impalpable, and retain nothing of their primitive ftructure *. If, then, the formation of coal from animal and vegetable bodies be admitted, the gene- ral pofition which derives the origin of the ftrata from the wafte of former land, as it is applicable to all the kinds already enume- rated, and of courfe to all thofe with which they are alternated, comprehends a very large ‘portion of the earth’s furface. It comprehends, indeed, all the ftrata ufually diftinguithed by the name of Secondary; but there is another great divifion of the mineral kingdom, viz. the rocks, called Primitive, which, as they are ne- ver alternated with the fecondary, but are al- ways inferior to them, muft be further exami- ned, before we can decide whether the fame con- clufion extends to them or not. _7- Here it muft be carefully obferved, that, among the primary rocks, the granite is not meant to be included, except where that ftone is ftratified, and either coincides with veined granite * Nore it. 12 ILLUSTRATIONS OF THE granite or with gneifs. The primitive ftrata, in Dr Hutton’s theory, comprehend, befides gneifs, the micaceous, chlorite, hornblend, and fili- ceous {chiftus, together with flate, and fome other kinds of argillite; to which we muĝ add, ferpentine, micaceous limeftone, and the greater part of marbles. Thefe are moftly diftinguifhed by their laminated ftructure, by having their planes much elevated with re- {pect to the horizon, and by belonging more to the mountainous than the level parts of the earth’s furface. They rarely contain vefti- ges of organized bodies ; fo rarely, indeed, that they were called primitive by the geologifts who firft diftinguifhed them from other rocks, on the fuppofition of their being part of the prime- val nucleus of the globe, which had never un- dergone any change whatfoever; but this, I believe, has now almoft ceafed to be the opi- nion of any geologift*. The Neptunifts hold the rocks, here enumerated, and alfo granite, to be produced by aqueous depofition ; but main- tain them to be in the ftricteft fenfe primeval, and of a formation antecedent to all organized bodies. : 8. In eppofition to this, Dr Hutton maintain- ed, that the primary fchiftus, like all the other ftrata, was formed of materials depofited at the bottom * NofE III. haii —— — 4 HUTTONIAN THEORY. 53 bottom of the fea, and collected from the wafte of rocks ftill more ancient. When, therefore, he conformed to the received language of mine- ralogifts, by calling thefe ftrata primitive, he only meant to defcribe them as more ancient than any other ftrata now exifting, but not as more ancient than any that ever had exifted. They are diftinguifhed, in his fyftem, by the name of Primary, rather than of Primitive ftra- ta. vor That the account now given of their origin is well founded, may be proved by unqueftion- able facts. For, firft, though, agreeably to the obfervation juft made, the ancient ftrata do but rarely contain any remains of organized bodies, they are not entirely deftitute of them. Differ- ent places in this ifland have been pointed out, by Dr Hutton, where marine obje&ts have been difcovered in primary limeftone, either by him- felf or others, and it would not be difficult to add more initances of the fame kind*. In Dauphiny, coal, which is certainly a derivative fubftance, has been found among mountains which have a title to the character of primitive, fuch as no one will difpute. Thefe facts put the compofition of fuch rocks from loofe materials, beyond all doubt, and alfo prove _their formation to be pofterior to the exiftence of * NoTE Iv. i4 ILLUSTRATIONS OF THE of an animal and vegetable fyftem. They do | indeed prove this in the ftricteft fenfe, only of the particular beds in which they are found ; but as thefe beds are in all other refpedts as much to be accounted primary as any part of the mineral kingdom, it is evident that the ne- gative inftances are here of no force, and that nothing can be gained to the adverfaries of this opinion by denying it in general, if they are obliged to admit it in a fingle cafe, 9. Again, itis certain, as Dr Hutton remarks, that there are few confiderable bodies of fchittus, even the mofl decidedly primitive, where fand and gravel may not in fome parts be obferved. Indeed, it is not only true that they are to be found in fome parts of them ; but, in fact, among “ many of the primitive mountains, we find large ‘tracts, compofed entirely of a fchiftofe and much indurated fand-ftone, in beds highly inclined, fometimes alone, fometimes alternated with other fchifti. In many of them, the fand of which they confift appears to be entirely of granite, from the detritus of which rock it fhould feem that they were chiefly formed. ro. Thus we conclude, that the ftrata both primary and fecondary, both thofe of ancient and thofe of more recent origin, have had their materials furnifhed from the ruins of former continents, from the diffolution of rocks, or the deftruction hadi aiai HUTTONIAN THEORY. 15 deftruction of animal or vegetable bodies, fimi- lar, at leat in fome refpedts, to thofe that now occupy the furface of the earth. This conclu- fion is not indeed proved of every individual portion of rock, but it is demonftrated of many and large parts, and thofe fcattered indifferently through all the varieties of the ftrata; and therefore, from the rules of the ftricteft reafon- ing, we muft infer, that the whole is derived from the fame origin *. _ Thus far concerning the materials of the ftra- ta; and, as thefe were originally loofe and un- connected, we muft next confider by what means they were confolidated into ftone. 2. Confolidation of the Strata. 11. Though Dr Hutton has no where defi- ned the meaning of the term confolidation, he has been fcrupuloufly exact in ufing it conftant- ly in the fame fenfe. He underftands by it, not merely that quality in a hard body by which its parts cohere together, but as that ws which it fills up the fpace catiptehe nded within its far- face, being to fenfe withon BASEA and im- pervious to air and moifture, : Now * NOTE ve 76 ILLUSTRATIONS OF THE Now, a porous mafs of unconnected materials, fuch as the ftrata appear originally to have been, can acquire hardnefs and folidity only in two ways, that is, either when it is firft reduced by heat into a ftate of fufion, or at leaft of foftnefs, and afterwards permitted to cool; or when matter that is diffolved in fome fluid menftruum, is in- troduced along with that menftruum into the porous mafs, and, being depofited, forms a ce- ment by which the whole is rendered firm and compact. Fire and water, therefore, are the only two phyfical agents to which we can afcribe the confolidation of the ftrata ; and, in order to determine to which of them that effec is to be attributed, we muft inguire whether there are any certain characters that diftinguifh the ac- tion of the one from that of the other, and which may be compared with the phenomena actually obferved among mineral fubftances. 12. Firft, then, it is evident, that the con- folidation produced by the action of water, or of any other fluid menftruum, in the manner juft referred to, muft neceffarily be imperfect, and can never entirely banifh the porofity of the mafs. For the bulk of the folvent, and of the matter it contained in folution, being great- er than the bulk of either taken fingly, when the latter was depofited, the former would have fufficient room left, and would continue to oc- : cupy HUTTONIAN THEORY. 17 cüpy a certain fpace in the interior of the ftra- ta. A liquid folvent therefore could never fhut up the pores of a body to the entire exclu- fion of itfelf; and, had mineral fubftances been confolidated, as here fuppofed, the folvent ought either to remain within them in a liquid ftate, or, if evaporated, fhould have left the pores empty, and the body pervious to water. Nei- ther of theie, however, is the fact; many ftra- tified bodies are perfectly impervious to water, and few mineral fubftances contain water in a liquid ftate. That they fometimes contain it, chemically united to them, is no proof of their folidity having been brought about by that fluid; for fuch chemical union is as con- fiftent with the fuppofition of igneous as of aqueous confolidation, fince the region in which the fire was applied, on every hypothefis, muft have abounded with humidity. 13. Again, if water was the folvent by which the confolidating matter was introduced into the interftices of the ftrata, that matter céuld confitt only of fuch fubftances as are foluble in water, whereas it confifts of a vait variety of fubftances, altogether infoluble either in it, or in any fingle menftruum whatfoever. The ftrata are confo- lidated, for example, by quartz, by fluor, by feltfpar, and by all the metals, in their endlefs combinations 18 ILLUSTRATIONS OF THE tions with fulphureous bodies. To af. firm that water was ever capable of diffolving thefe fubftances, is to afcribe to it powers which it confefledly has not at prefent ; and, therefore, it is to introduce an hypothefis, not merely gra- tuitous, but one which, phyfically fpeaking, is abfurd and impoffible. This is not all, however; for, éven if this difficulty were to be paffed over, it would fill be required to explain, how the water, which, together with the matter which it held in folu- tion, had infinuated itfelf into the pores of the ftrata, became fuddenly difpofed to depofite that matter, and to allow it, by cryftallization or concretion, to affume a folid form*, The Nep- tunifts muft either affign a fufficient reafon for this great and univerfal change, or muft expect to fee their fyftem treated as an inartificial ac- cumulation of hypothefes which afligns oppofite virtues to the fame fubjed, and is alike at va- riance with nature and with itfelf; in a word, afyftem that might pafs for the invention of an age, when as yet found philofophy had not alighted on the earth, nor taught man that he is but the minifter and interpreter of nature, and can neither extend his power nor his know- ledge * Note VI. HUTTONIAN THEORY. 19 ledge a hair’s-breadth beyond his experience and obfervation of the prefent order of things *. 14. Such are the more obvious, but I think unan{werable objections, that may be urged againft the aqueous confolidation of the ftra- ta. It is true, that ftony concretions, fome of them much indurated, are formed in the humid Way under our eyes. Very particular condi- tions, however, are required for that purpofe, and conditions fuch as can hardly have exifted at the bottom of the fea. Firft, The water muf diffolve the fubftance of which the concretion is to be formed, as it actually does in the cafe of calcareous, and in certain circumftances, in that of filiceous, earth. Secondly, It muft be feparated from that fubftance, as by evaporation, or by a combination of the matter diffolved with fome third fubftance, to which it has a greater aflinity than to water, fo as to form with it an infoluble compound. Laftly, The water that is deprived of its folution muft be carried off, and more of that which contains the folu- ' tion muft be fupplied, as fometimes happens B2 He where * Homo nature minifter, et interpres tantum facit et intelligit, quantùm de naturæ ordine re, vel mente, obfervaverit: nec amplius fcit, aut poteft. ` Nov. Org. lib. i. aph. x. 20 ILLUSTRATIONS OF THE where water runs in a ftream, or drops from the roof of a cavern. The two laft condi. tions are peculiarly inapplicable to the bottom of the fea, where the ftate of the furrounding fluid would neither permit the water that was deprived of its folution from being drawn off, nor that which contained the folution from fue- ceeding it. It is further to be obferved, that the HEEN dation of ftalactitical concretions, that is, the fill- ing up of their pores, is always imperfect, and is brought about by the repeated action of the fluid running through the porous mafs, and continu- ing to depofite there fome of the matter it holds in folution. This, which is properly infiltra- tion, is incompatible with the nature of a fuid, either nearly, or altogether quiefcent. 15. In order to judge whether objections of equal weight can be oppofed to the hypothefis of igneous confolidation, we muft attend toa very important remark, firft made by Dr Hut- ton, and applied with wonderful fuccels to ex- plain the moft myfterious phenomena of the mineral kingdom. It is certain, that the effeéts of fire on bo- dies vary with the circumftances under which it is applied to them, and therefore a confider- able allowance muft be made, if we would com- pare HUTTONIAN THEORY. 2I paré the operation of that element when it con- folidated the ftrata, with the refults of our daily experience. The materials of the ftrata were difpofed, as we have already feen, loofe and unconnected, at the bottom of the fea; that is, even on the moft moderate «ftimation, at the depth of feveral miles under its furface. At this depth, and under the preffure of a column of water of fo great a height, the action of heat would differ much from that which we obferve here upon the furface; and, though our expe- rience does not enable us to compute with ac- curacy the amount of this difference, it never- thelefs points out the direction in which it muft lie, and even marks certain limits to which it would probably extend. The tendency of an increafed preffure on the bodies to which heat is applied, is to re- ftrain the volatility of thofe parts which o- therwife would make their efcape, and to force them to endure a more intenfe ation of heat. At a certain depth under the furface of the fea, the power even of a very in- tenfe heat might therefore be unable to drive off the oily or bituminous parts from the inflam- mable matter there depofited, fo that, when the heat was withdrawn, thefe principles might be found ftill united to the earthy and carbonic parts, forming a fubftance very unlike the re- B 3 fiduum 22 ILLUSTRATIONS OF THE fiduum obtained after combuftion under a pref- fure no greater than the weight of the atmo- fphere. It is in like manner reafonable to be- lieve, that, on the application of heat to calca- reous bodies under great comprefiion, the car- bonic gas would be forced to remain; the ge- neration of quicklime would be prevented, and the whole might be foftened, or even complete- ly melted; which laft effect, though not di- rectly deducible from any experiment yet made, is rendered very probable, from the analogy of certain chemical phenomena. 16. An analogy of this kind, derived from a property of the barytic earth, was fuggefted by that excellent chemift and philofopher, the late Dr Brack. The barytic earth, as is well known, has a ftronger attraction for fixed air than com- -~ mon calcareous earth has, fo that the carbonate of barytes is able to endure a great degree of heat before its fixed air is expelled. Accord- ingly, when expofed to an increafing heat, at a certain temperature, it is brought into fufion, the fixed air ftill remaining united to it: if the heat be further increafed, the air is driven off, the earth lofes its fluidity, and appears in a cauftic ftate. Here, it is plain, that the barytic earth, which is infufible, or very refractory, per fe, as well as the calcareous, owes its fufibility to the prefence of the fixed air; and it is there- fore HUTTONIAN THEORY. 23 fore probable, that the fame thing would hap- pen to the calcareous earth, if by any means the fixed air were prevented from efcaping when great heat is applied to it. This efcape of the fixed air is exactly what the compreflion in ~ the fubterraneous regions is calculated to pre- vent, and therefore we are not to wonder if, among the calcareous ftrata, we find marks of actual fufion having taken place *, 17. Thefe effects of preffure to refift the fle. compofition, and augment the fufibility of bodies, being once fuppofed, we fhall find little difficulty in conceiving the confolidation of the ftrata by heat, fince the intervals between the loofe mate- tials of which they originally confifted may have been clofed, either by the foftening of thofe mate- rials, or by the introduction of foreign matter a- mong them, in the ftate of a fluid, or of an elaftic vapour. No objection to this hypothefis can arife from the confiderations {tated in the preceding cafe; the folvent here employed would want no pores to lodge in after its work was completed, nor would it find any difficulty in making its re- treat through the denfeft and moft folid fubftan- ces in the mineral kingdom, Neither can its incapacity to. diflolve the bodies fubmitted to its action be alleged. Heat is the moft powerful and moft general of all folvents; and, though B4 fome * Note VII. 24 ILLUSTRATIONS OF THE fome bodies, fuch as the calcareous, are able to refift its force on the furface of the earth, yet, as has jut been fhewn, it is perfectly a. greeable to analogy to fuppofe, that, under great preflure, the carbonic ftate of the lime being preferved, the puret limeftone or mar-. ble might be foftened, or even melted. With refpe& to other fubftances, lefs doubt of their fulibility is entertained ; and though, in our experiments, the refraGtory nature of filice- ous earth has not been completely fubdued, a degree of foftnefs and an incipient fufion have neverthelefs been induced. Thus it appears, in general, that the fame dif- ficulties do not prefs againft the two theories of aqueous and of igneous confolidation ; and, that the latter employs an agent incomparably more powerful than the former, of more gene- ral activity, and, what is of infinite importance in a philofophical theory, vaftly more definite in the laws of its operation. 18. A more particular examination of the different kinds of foffils will confirm this con- clufion, and will fhow, that, wherever they bear marks of having been fluid, thefe marks are fuch as characterize the fluidity of fufion, and diftin- guifh it from that which is produced by folu- tion ina menftruum. Dr Hutton has enume- rated many of thefe difcovered in the courfe of : that HUTTONIAN THEORY. 25 that careful and accurate ination of foffils, in which he probably never was excelled by any mineralogift. It will be fufficient here to point out a few of the moft remarkable exam- ples. : 19. Foffil-wood, penetrated by filiceous mat- ter, is a fubftance well known to mineralogifts : it is found in great abundance in various fitua- tions, and frequently in the heart of great bodies of rock. On examination, the filiceous matter is often obferved to have penetrated the wood very unequally, fo that the vegetable firucture re- mains in fome places entire; and in other places is loft in a homogeneous mafs of agate or jafper. Where this happens, it may be remarked, that the line which feparates thefe two parts is quite fharp and diftin@, altogether different from what muft have taken place, had the flinty mat- ter been introduced into the body of the wood, by any fluid in which it was diffolved, as it would then have pervaded the whole, if not uniformly, yet with a regular gradation. In thole fpecimens of foffil-wood that are partly penetrated by agate, and partly not penetrated at all, the fame fharpnefs of termination may be remarked, and is an appearance highly cha- _ racteriftic of the fluidity produced by fufion. 20. The round nodules of flint that are found in chalk, quite infulated and feparate from 26 ILLUSTRATIONS OF THE from one another, afford an argument of the Tame kind ; fince the flinty matter, if it had been carried ae the chalk by any folvent, muft have been depofited with a certain degree of unifor- _ mity, and would not now appear colleéted into feparate mafles, without any trace of its exift- ence in the intermediate parts. On the other hand, if we conceive the melted flint to have been forcibly injected among the chalk, and to have penetrated it, fomewhat as mercury may, by preflure, be made to penetrate through the pores of wood, it might, on cooling, exhibit the fame appearances that the chalk-beds of Eng- land do actually prefent us with. The filiceous pudding-ftone is an inftance clofely connected with the two laft; in it we find both the pebbles, and the cement which unites them, confifting of flint equally hard and confolidated ; and this circumftance, for which it is impoffible to account by infiltration, or the infinuation of an aqueous folvent, is perfedtly confiftent with the fuppofition, that a ftream of melted flint has been forcibly injeted among a mafs of loofe gravel. 21. The common grit, or fandftone, though it certainly gives no indication of having pof- feffed fluidity, is ftrongly expreffive of the ef- fects of heat. It is fo, efpecially in thofe in- — fiances where the particles of quartzy fand, of | 2 which HUTTONIAN THEORY. 27 i which it is compofed, are firmly and clofely united, without the help of any cementing fub- _ ftance whatfoever. This appearance, which is very common, feems to be quite inconfiftent with every idea of confolidation, except an in- ' cipient fufion, which, with the afliftance of a fuitable compreffion, has enabled the particles of quartz to unite into ftone. It has indeed been afferted, that the mere ap- pofition of ftony particles, fo as to permit their ~ corpufcular attrafion to take place, was fufli- cient to form them into ftone. To this Dr Hut- ' ton has very well replied, that, admitting the poflibility of a hard and firm body being pro- duced in this way, of which, however, we have no proof, the clofe and compa& texture, the perfe& confolidation of the ftones we are now {peaking of, would ftill remain to be explained, and of this it is evident that the mere appo- ' fition of particles, and the force of their mu- tual attraction, can afford no folution. 22. Thefe proofs that the ftrata muft have en- dured the action of intenfe heat, though imme- diately deduced from thofe of the filiceous ge- nus only, extend in reality to all the ftrata, of every kind, with which they are found alter- nated. It is impoflible that heat, of the inten- _ fity here -fuppofed, can have acted on a particu- lar 28 ILLUSTRATIONS OF THE lar ftratum, and not on thofe that are contigu- ous to it; and, as there are no {trata of any kind with which the quartzy and filiceous are not intermixed, fo there are none of which the ig. neous confolidation is not thus rendered proba- ble. We need reft nothing, however, on this argument, as the foflils of every genus may be fhewn to {peak diftin@ly for themfelves. 23. Thofe of the calcareous genus do fó perhaps more fparingly than the reft; yet even among them there are many facts, that, though taken unconnected with all others, are fufficient to eftablifh the action of fubterraneous fire. Such, for example, are the calcareous breccias, compofed of fragments of marble or limeftone, and not only adapted to each other’s fhape, but indented into one another, in a man- ner not a little refembling the futures of the hu- man cranium. From fuch inftances, it is im- pofflible not to infer the foftnefs of the calcareous fragments when they were confolidated into one mals. Now, this foftnefs could be induced only by heat; for it muft be acknowledged, that the action of any other folvent is quite in- adequate to the foftening of large fragments of ftone, without diflolving them altogether. 24. In many other inftances it appears cer- tain, that the {tones of the calcareous genus have been reduced by heat into a ftate of flui- dit¥ HUTTONIAN THEORY. 29 in dity much more perfect. Thus, the faline or * finer kinds of marble, and many others that have a ftru@ure highly cryftallized, muft have been foftened to a degree little fhort of fufion, before this cryftallization could take place. _ Even the petrifaGiions which abound fo much in limeftones, tend to eftablith the fame fact ; for they poffefs a fparry ftructure, and muft have acquired that ftructure in their tranfition from a fluid to a folid ftate *. 25. In accounting, by the operation of heat, for thefe appearances of fluidity, Dr Hutton has proceeded on the principle already laid down, as conformable to analogy, that calcareous earth, under great compreflion, may have its fixed air retained in it, notwithftanding the action of in- tenfe heat, and may, by that means, be reduced into fufion, or into a ftate approaching to it. In all this, I do not think that he has departed from the ftricteft rules of philofophical invefti- gation. The facts juft ftated prove, that lime- - ftone was once foft, its fragments retaining at the fame time their peculiar form, an effect to which we know of none fimilar but thofe of fire; and therefore, though we could not con- jecture how heat might be applied to limeftone fo as to melt it, inftead of reducing it to a calx, we fhould, neverthelefs, have been forced to fuppofe * Note VIIL 30 ILLUSTRATIONS OF THE fuppofe, that this had a&tually taken place in the bowels of the earth; and was a fact which, though we were not able to explain it, we were not entitled to deny. The principle juft men. tioned relieves us therefore from a difficulty, that would have embarraffed, but could not have overturned, this theory of the earth. 26. From the arguments which the argilla. ceous ftrata afford for the igneous confolidation of foffils, I fhall fele& one on which Dr Hutton ufed to lay confiderable ftrefs, and which fome of the adverfaries of his fyftem have endeavour- ed to refute. This argument is founded on the ftructure of certain iron-ftones called /eptaria, often met with among the argillaceous {chiftus, particularly in the vicinity of coal. Thefe ftones are ufually of a lenticular or fpheroidal form, and are divided in their interior into diftiné Jepta, by veins of calcareous fpar, of which one fet are circular and concentric, the other ređi- lineal; diverging from the centre of the for- mer, and diminifhing in fize as they recede from it. Now, what is chiefly to be remarked is, that thefe veins terminate before they reach the furface of the ftone ; fo that the matter with which they are filled cannot have been introduced from with- out by infiltration, or in any other way what- foever. The only other fuppofition, therefore, that is left for explaining the fingular ftructure of HUTTONIAN THEORY. 3t Of this foffil, is, that the whole mafs was origin- ally fluid, and that, in cooling, the calcareous part feparated from the reft, and afterwards éryftallized. . 27. It has been urged againft this theory of the feptaria, that thefe ftones are fometimes found with the calcareous veins extending all the way to the circumference, and of courfe communicating with the outfide. But it muft be obferved, that this fa& does not affe& the argument drawn from {pecimens in which no fuch communication takes place. It is at beft only an ambiguous inftance, that may be ex- plained by two oppofite theories, and may be reconciled either to the notion of igneous or of aqueous confolidation: but if there is a fingle clofe feptarium in nature, it can, of courfe, be ij) explained only by one of thefe theories, and the other muft, of néceflity, be rejected. Befides, it is plain, that a clofe feptarium can never have been open, though an open feptarium may very well have been clofe; and indeed, as this ftone is, in certain circumftances, fubject to perpetual exfoliation, it would be wonderful if no one was ever found with the calcareous veins reaching to the furface, With regard to the light, there- fore, that they give into their own hiftory, thefe two kinds of feptaria are by no means on an equal footing; and this may ferve to fhew, how neceflary 32 ILLUSTRATIONS OF THE neceflary it is, in all induGive reafoning, and particularly in a fubject fo complex as geology, to feparate with care fuch phenomena as admit of two folutions, from fuch as admit only of one. 28. The bituminous ftrata come next to be confidered ; and they are of great confequence in the prefent argument, becaufe their diffimi- larity in fo many particulars to all other mine- ral fubftances, renders them what Lord Bacoy calls an infantia fingularis, having the firft rank among facts fubfervient to inductive inveftiga- tion. But though unlike in fubftance to other foffils, and compofed, as has been fhewn, of ma- terials that belonged not originally.to the mine- ral kingdom, they agree in many material cir- cumftances with the ftrata already enumerated. Their beds are difpofed in the fame manner, and are alternated indifcriminately with thofe of all the fecondary rocks, and, being formed in the fame region, muft have been fubjeét to the fame accidents, and have endured the ope- ration of the fame caufes. They are traverfed too like the other ftrata, by veins of all the me- tals, of fpar, of bafaltes, and of other fubftances ; and, whatever argument may hereafter be de- rived from this to prove the action of fire on the ftrata fo traverfed, is as much applicable to coal as to any other mineral. The coal ftra- ta ` 9 Ay ig | Olo ' mI adni aly , to } Mimi Mne ACO ] 193 othe f m min l cir ratei nne thol rme act HUTTONIAN THEORY. 33 ta alfo contain pyrites in great abundance, a fubftance that is perhaps, more than any other, ` the decided progeny of fire. This compound | of metal and fulphur, which is found in mineral bodies of every kind, I believe, without any ex- ception, is deftroyed by the contact of moifture, Ueng ` and refolved into a vitriolic falt. At the fame time it is found in the ftrata, not traverfing them in veins, which may be fuppofed of more recent formation than the ftrata themfelves ; Bie but exifting in the heart of the moft folid rocks, often nicely cryftallized, and completely inclo- fed, on all fides, without the moft minute va- cuity. The pyrites muft have been prefent, therefore, when the ftrata were confolidated, and it is inconceivable, if their confolidation was brought about in the wet way, that a fubftance fhould be fo generally found in them, the very exiftence of which is incompatible with humi- dity. This argument for the igneous origin of the ftrata is applicable to them all, but efpe- cially to thofe of coal, as abounding with pyri- , tes more than any other. 29. The difficulty that here naturally prefents cg _itfelf, viz. how vegetable matter, {uch as coal is fuppofed to have been, could be expofed to the action of intenfe heat, without being deprived | of its inflammable part, is obviated by the prin- ciple formerly explained concerning the effects C of 34 ILLUSTRATIONS OF THE of compreflion. The weight incumbent on the {trata of coal, when they were expofed to the intenfe heat of the mineral regions, may have been fuch as to retain the oily and bituminous, as well as fulphureous parts, though the whole was reduced almoft to fufion; and thus, on cool. ing, the fulphur uniting with iron might cryftal- lize, and aflume the form of pyrites. ' 30.’ The comprefiion, however, has not in every inftance preferved the bituminous, in union with the carbonic part of coal; and hence a mark of the operation of fire quite peculiar to this fof- fil, and found in thofe infufible kinds of it which contain no bitumen, and burn without flame, Thefe refemble, fome of them very precifely, and all of them in a great degree, the products obtain- ed by the diftillation of the common bituminous coal; that is, they confit of charcoal, united to an earthy bafis in different proportions. It is natural therefore to conclude, that this fub- ftance was prepared in the mineral regions by the action of heat, which, in fome inftances, has. driven off the inflammable part of the coal. That the heat fhould,in fome cafes, have done fo, is not inconfiftent with the general effe& attri- buted to compreflion. ‘The conditions neceflary for retaining the more volatile parts, may not have been preient every where in the fame de- é gree 2 HUTTONIAN THEORY. 95 le 3 ~ gree, fo that the latter, though they could not œ efcape, may have been forced from one part of NT Te > t a ftratum, or body of ftrata, to another. 3T. In confirmation of this it muft be obferved, that, as the fixed part of coal is thus found in the bowels of the earth, feparate from the vola- tile or bituminous, fo, in the neighbourhood of coal ftrata, the latter is fometimes found with- _ out any mixture of the former. The fountains of naphtha and petroleum are well known; and Dr Hutton has defcribed a ftratum of limeftone, lying in the centre of a coal country, which is pervaded and tinged by bituminous matter, through its whole mafs, and has, at the fame time, many clofe cavities in the heart of it, lined with calcareous fpar, and containing foffil pitch, fometimes in large pieces, fometimes in hemi- {pherical drops, feattered over the furface of the cavities. This combination could only be ef- fected by a part of the inflammable matter of the beds of coal underneath, being driven off by heat, and made to penetrate the limeftone, while it was yet foft and pervious to heated va- pours *, 32. Hitherto we have enumerated thofe fof- fils that are ‘either not at all, or very {paringly foluble in water. There are, however, faline C2 bodies * Note rx: 36 ILLUSTRATIONS OF THE | bodies among the mineral ftrata, fuch for. in. ftance as rock-falt, which are readily diffolved in water; and it yet remains to examine by what caufe their confolidation has been effec ed. Here the theorifts who confider water as the fole agent in the mineralization of fofiils, are in- deed delivered from one difficulty, but it is on- ly that they may be harder preffed on by ano- ther. It cannot now be faid, that the men- ftruum which they employ is incapable of dif- folving the fubftances expofed to its action, as in the cafe of metallic or ftony bodies; but it may very well be afked, how the water came to depofite the falts which it held in folution, and to depofite them fo copioufly as it has done in many places, without any veftige of fimi- lar depofition in the places immediately conti- guous. If they refufe to call to their affiftance any other than their favourite element, they will not find it eafy to anfwer this queftion, and muft feel the embarraffment of a fyftem, fubje@ to two difficulties, fo nicely, but f unhappily adjufted, that one of them 1s al- ways prepared to act whenever the other is re- moved. If, on the other hand, they will ad- mit the operation of fubterraneous heat, it ap- pears poffible, that the local application of fuch heat { $ i HUTTONIAN THEORY. 37 heat may have driven the water, in vapour, from one place to another, and by fuch action often repeated in the fame fpot, may have produced thofe great accumulations of faline matter, that are actually found in the bowels of the earth. 33. But granting that, either in the way juft pointed out, or in fome other that is unknown, the falt and the water have been feparated, fome further action of heat feems requifite, before a compact, and highly indurated body, like rock- falt, could be produced. ‘The mere precipita- tion of the falt, would, as Dr Hutton has ob- ferved, form only an affemblage of loofe cryftals at the bottom of the fea, without folidity or co- hefion: and to convert fuch a mafs into a firm and folid rock, would require the application of fuch heat as was able to reduce it into fufion. The confolidation of rock-falt, therefore, how- ever its feparation from the water is accounted for, cannot be explained but on the hypothefis of fubterraneous heat. 34. Some other phenomena that have been obferved in falt mines, come in fupport of the fame conclufion. The falt rock of Chefhire, which lies in thick beds, interpofed between {trata of an argillaceous or marly ftone, and is itfelf mixed with a confiderable portion of the fame earth, exhibits a very great peculiarity in its ftrudture. Though it forms a mafs extreme- C 3 ly 38 ILLUSTRATIONS OF THE ly compact, the falt is found to be arranged in round maffes of five or fix feet in diameter, not truly fpherical, but each comprefied by thofe that _furround it, fo as to have the fhape of an irre- gular polyhedron. Thefe are formed of con. centric coats, diftinguifhable from one another by their colour, that is, probably by the greater or lefs quantity of earth which they contain, fo that the roof of the mine, as it exhibits a ho- rizontal feétion of them, is divided into po. lygonal figures, each with a multitude of poly- gons within it, having altogether no inconfider- able refemblance to a mofaic pavement. In the tri- angular {paces without the polygons, the falt is in coats parallel to the fides of the polygons. The circumftances which gave rife to this fingular ftru€ture we fhould in vain endeavour to define; yet fome general conclufions con- cerning them feem to be within our reach. It is clear that the whole mafs of falt was fluid at once, and that the forces, whatever they were, which gave folidity to it, and produced the new arrangement of its particles, were all in action at the fame time. The uniformity of the coat- ed ftructure is a proof of this, and, above all, the comprefiion of the polyhedra, which is always mutual, the flat fide of one being turned to the flat fide of another, and never an 2 angle to an an- gle, nor an angle to a fide, The coats formed as it were HUTTONIAN THEORY. 39 were round fo many different centres of attraction, is alfo an appearance quite inconfiftent with the notion of depofition; both thefe, however, are compatible with the notion of folidity acquired by the refrigeration of a fluid, where the whole mafs is acted on at the fame time, and where no fol- vent remains to be difpofed of after the indura- tion of the reft. 35. Another fpecies of foffil-falt exhibits ap- «= pearances equally favourable to the theory of igneous confolidation. ‘This is the trona of A- frica, which is no other than foda, or mineral al- kali, in a particular ftate. The {pecimen of this foffil in Dr Black’s, now Dr Hope’s, collection, is of a fparry and radiated ftructure, and is evi- dently part of the contents of a vein, having a ftony cruft adhering to it, on one fide, with its own {parry ftructure complete, on the oppofite. It contains but about one-fixth of the water of eryftallization effential to this falt when obtain- | ed inthe humid way; and, what is particularly to be remarked, it does not lofe this water, nor become covered with a powder, like the com- mon alkali, by fimple expofure to the air. It is evident, therefore, that this foffil does not origi- nate from mere precipitation; and when we add, that in its {parry ftruture it contains evi- dent marks of having once been fluid, we have C4 little 4o ILLUSTRATIONS OF THE little reafon to entertain much doubt concern. ing the principle of its confolidation. Thus, then, the teftimony given to the opera. tion of fire, or heat, as the confolidating power of the mineral kingdom, is not confined to a few foffils, but is general over all the ftrata. How far the unftratified foffils agree in fupporting the fame conclufion, will be afterwards examined, 3. Pofition of the Strata *®, 30. We have feen of what materials the {trata are compofed, and by what power they have been confolidated; we are next to in- quire, from what caufe it proceeds, that they are now fo far removed from the region which they originally occupied, and wherefore, from being all covered by the ocean, they are at prefent raifed in many places fifteen thoufand feet above its furface. Whether this great change of relative place can be beft accounted for by the depreffion of the fea, or the elevation of the ftrata themfelves, remains to be confider- ed. Of * Theory of the Earth, vol. i. p. 120. HUTTONIAN THEORY. 41 Of thefe two fuppofitions, the former, at firt fight, feems undoubtedly the moft probable, and we feel lefs reluctance to fuppofe, that a fluid, fo unftable as the ocean, has undergone the great revolution here referred to, than that the folid foundations of the land have moved a fingle fa- thom from their place. This, however is a mere illufion. Such a depreffion of the level of the fea as is here fuppofed, could not happen without a change proportionally great in the fo- lid part of the globe; and, though admitted as true, will be found very inadequate to explain the prefent condition of the ftrata. 37. Suppofing the appearances which clear- ly indicate fubmerfion under water to reach no higher than ten thoufand feet above the pre- fent level of the fea, and of courfe the furface of the fea to have been formerly higher by that quantity than it is now; it neceflarily follows, that a bulk of water has difappeared, equal to more than a feven-hundredth part of the whole magnitude of the globe*. The exiftence of empty caverns, of extent fufficient to contain this vaft body of water, and of fuch a convulfion as to lay them open, and give room to the retreat of the fea, are fuppofitions which a philofopher could only be juftified in admitting, if they pro- mifed to furnifh a very complete explanation of 7 appearances, * Note X. 42 ILLUSTRATIONS OF THE appearances. But this juftification is entirely wanting in the prefent cafe; for the retreat of the ocean to a lower level, furnifhes a very par. tial and imperfect explanation of the phenome. na of geology. It will not explain the num. berlefs remains of ancient continents that are involved, as we have feen, in the prefent, unlefs - it be fuppofed that the ancient ocean, though it rofe to fo great a height, had neverthelefs its fhores, and was the boundary of land ftill high- er than itfelf. And, as to that which is now more immediately the object of inquiry, the pofition of the ftrata, though the above hypothefis would account in fome fort for the change of their place, relatively to the level of the fea ; yet, if it fhall be proved, that the flrata have changed their place relatively to each other, and rela- tively to the plane of the horizon, fo as to have had an angular motion impreffed on them, it is evident that, for thefe facts, the retreat of the fea does not afford even the fhadow of a theo- ry. 38. Now, it is certain, that many of the ftra- ta have been moved angularly, becaule that, in their original pofition they muft have been all nearly horizontal. Loofe materials, fuch as fand and gravel fubfiding at the bottom of the fea, and having their interftices filled with water, poffefs a kind of fluidity: they are difpofed to yield HUTTONIAN THEORY. 43 ti yield on the fide oppofite to that where the ar preflure is greateft, and are therefore, in fome degree, fubject to the laws of hydroftatics. On ne, ; : me this account they will arrange themfelves in ho- ah rizontal layers ; and the vibrations of the incum- ed bent fluid, by imprefling a flight motion back- ward, and forward, on the materials of thefe lay- + a ers, will very much aflift the accuracy of their 1 level. | k It is not, however, meant to deny, that the form ~ ofthe bottom might influence, in a certain de- i gree, the ftratification of the fubftances depofited i onit. The figure of the lower beds depofited on H an uneven furface, would neceffarily be affected by two caufes ; the inclination of that furface, on @ the one hand, and the tendency to horizontality, a on theother; but, as the formercaufe would grow i lefs powerful as the diftance from the bottom i increafed, the latter caufe would finally prevail, it fo that the upper beds would approach to hori- + zontality, and the lower would neither be ex- = adtly parallel to them, nor to one another. u Whenever, therefore, we meet with rocks, dif- f pofed in layers quite parallel to one another, | we may ret affured, that the inequalities of the i bottom have had no effect, and that no caufe , hasinterrupted the ftatical tendency above ex- i plained, Now, A4 ILLUSTRATIONS OF THE Now, rocks having their layers exa@ly paral. lel, are very common, and prove their original horizontality to have been more precife than we could venture to conclude from analogy alone. In beds of fand-ftone, for inftance, no. thing is more frequent than to fee the thin layers of fand, feparated from one another by layers ftill finer of coaly, or micaceous matter, that are almoft exactly parallel, and conti- nue fo to a great extent without any fenfible deviation. Thefe planes can have acquired their parallelifm only in confequence of the property of water juft ftated, by which it ren- ders the furfaces of the layers, which it de polites, parallel to its own furface, and therefore parallel to one another. Though fuch ftrata, ` therefore, may not now be horizontal, they mutt have been fo originally ; otherwife it is impofii- ble to difcover any caufe for their parallelifm, or any rule by which it can have been produ- ced. i 39. This argument for the original horizon- tality of the ftrata, is applicable to thofe that are now fartheft removed from that pofition. A- mong fuch, for inftance, that are highly m- clined, or even quite vertical, and among thofe that are bent and incurvated in the moft fan- taftical manner, as happens more efpecially in the HUTTONIAN THEORY. 45 the primary {chifti, we obferve, through all their finuofities and inflections, an equality of thicknefs and of diftance among their com- ponent lamine. This equality could only be produced by thofe lamine having been ori- ginally fpread out on a flat and level furface, from which fituation, therefore, they muft af- terwards have been lifted up by the action of fome powerful caufe, and muft have fuffered this difturbance while they were yet in a cer- tain degree flexible and ductile. Though the primary direction of the force which thus ele- vated them muft have been from below up- wards, yet it has been fo combined with the gravity and refiftance of the mafs to which it was applied, as to create a lateral and oblique thruft, and to produce thofe contortions of the ftrata, which, when on the great fcale, are among the moft ftriking and infiructive pheno- mena of geology. 40. Great additional force is given to this ar- sument, in many cafes, by the nature of the ma- terials of which the ftratified rocks are compo- fed. ‘The beds of breccia and pudding-ftone, for inftance, are often in planes almoft vertical, and at the fame time contain gravel-ftones, and other fragments of rock, of fuch a fize and weight, that they could not remain in their pre- fent 46 ILLUSTRATIONS OF THE fent pofition an inftant, if the cement which unites them were to become foft; and there. fore they certainly had not that pofition at the time when this cement was aQually foft. This remark has been made by mineralogifts who were not led to it by any fyftem. The judicious and indefatigable obferver of the Alps, deferi- bing the pudding-ftone of Valorfine, near the fources of the Arve, tells us, that he was aftonifhed to find it in beds almoft vertical, a fituation in which it could not poflibly | have been formed. <“ That particles,” he adds, “of extreme tenuity, fufpended in a fluid, might become agglutinated, and form verti- cal beds, is a thing that may be conceived ; but that pieces of ftone, of feveral pounds wéigit fhould have refted on the fide of a perpendicu- lar wall, till they were enveloped in a ftony cement, and united into one mafs, is a fuppofi- tion impoflible and abfurd. It fhould be con- fidered, therefore, as a thing demonftrated, that this pudding-ftone was formed in a horizontal pofition, or one nearly fuch, and elevated after its induration. We know not,” he continues, “the force by which this elevation has been effected ; but it is an important ftep among the prodigious number of vertical beds that are to be met with in the Alps, to have found fome that HUTTONIAN THEORY. 4y that muft certainly have been formed in a ho- rizontal fituation*.”’ 41. Nothing can be more found and conclu- five than this reafoning ; and, had the ingenious author purfued it more fyftematically, it muft have led him to a theory of mountains very lit- tle different from that which we are now en- deavouring to explain. If fome of the vertical ftrata are proved to have been formed horizon- tally, there can be no reafon for not extending the fame conclufion to them all, even if we had not the fupport of the argument from the paral- lelifm of the layers, which has been already fta- ted. 42. The highly inclined pofition, and the manifold inflexions of the ftrata, are not the only proofs of the difturbance that they have fuffered, and of the violence with which they have been forced up from their original place. Thofe interruptions of their continuity which ` are obferved, both at the furface and under it, are evidences of the fame fact. It is plain, that if they remained now in the fituation in which they were at firft depofited, they would never appear to be fuddenly broken off. No ftratum would terminate abruptly ; but, however its na- ; ture * Voyages aux Alpes, tom. ii. § 690. 48 ILLUSTRATIONS OF THE ture and properties might change, it would con- flitute an entire and continued rock, at leafi where the effects of wafte and detritus had not produced a feparation. This, however, is very far from being the actual condition of ftratifie bodies. Thofe that are much inclined, or that make confiderable angles with the horizontal plane, muft terminate abruptly where they come up to the furface. Their doing fo is a ne. ceffary confequence of their pofition, and furnith- es no argument, it may be faid, for their having been difturbed, different from that which has been already deduced from their inclination, There are, however, inftances of a breach of con- tinuity in the ftrata, under the furface, that afford a proof of the violence with which they have been difplaced, different from any hitherto mention- | ed. Of this nature are the /lips or /bifts, that fo often perplex the miner in his fubterraneous journey, and which change at once all thofe lines and bearings that had hitherto dire@ed his courfe. When his mine reaches a certain plane, which is fometimes perpendicular, fometimes oblique to the horizon, he finds the beds of rock broken afunder, thofe on the one fide of the plane having changed their place, by fliding in a particular direction along the face of the others. In this motion they have fometimes preferved their parallelifm, that is, the ftrata on aune HUTTONIAN THEORY. 49 on one fide of the /ip continue parallel to thofe on the other; in other cafes, the ftrata on each fide become inclined to one another, though their identity is ftill to be recognifed by their pollefling the fame thicknefs, and the fame in- ternal characters. Thefe /bifts are often of great extent, and muft be meafured by the quan- tity of the rock moved, taken in conjunétion with the diftance to which it has been carried. In fome inftances, a vein is formed at the plane of the fhift or flip, filled with materials of the kinds which will be hereafter mentioned ; in other ‘inftances, the oppofite fides of the rock remain contiguous, or have the interval between them filled with foft and unconfolidated earth. All thefe are the undeniable effects of fome great convulfion, which has fhaken the very founda- tions of the earth ; but which, far from being a diforder in nature, is part of a regular fyftem, effential to the conftitution and economy of the globe. The produétion of the appearances now de- fcribed, belongs, without doubt, to different pe- riods of time ; and, where flips interfec& one ano- ther, we can often diftinguifh the lefs from the more ancient. They are all, however, of a date pofterior to that at which the waving and -undulated forms of the ftrata were acquired, as they do not carry with them any marks of D the so ILLUSTRATIONS OF THE the foftnefs of the rock, but many of its com. plete induration. The fame phenomenon which is thus exem. l plified on a great fcale in the bowels of the earth, is often moft beautifully exhibited in fin- gle fpecimens of ftone, and is accompanied with this remarkable circumftance, that the inte. grity of the ftone is not deftroyed by the thifts, whatever wounds had been made in it being healed, and the parts firmly re-united to one ano- ther *. 43. Though fuch marks of violence as have been now enumerated are common in fome de- gree to all the ftrata, they abound moft among the primary, and point out thefe as the part of our globe which has been expofed to the greateft viciflitudes. At their junction with the fecondary, or where they emerge, as it were, from under the latter, phenomena occur, which mark fome of thofe viciffitudes with aftonifhing precifion; phenomena of which the nature was firft accurately explored, and the confequences fully deduced, by the geologift whofe fyftem I am endeavouring to explain. He obferved, in feveral inftances, that where the primary {chiftus rifes in beds almoft vertical, it is co- vered by horizontal layers of fecondary fand- ftone, which laft are penetrated by the irre- gular Note XI. DETA — * f HUTTONIAN THEORY. 51 1 gular tops of the fchiftus, and alfo involve x, fragments of that rock; fome angular, others 7 round and {mooth, as if worn by attrition. From fi this he concluded, that the primary ftrata, after ii being formed at the bottom of the fea, in planes i nearly horizontal, were raifed, fo as to become 1i almoft vertical, while they were yet covered by _ the ocean, and before the fecondary ftrata had 7 begun to be depofited onthem. He alfo argued, * that, as the fragments of the primary rock, in- cluded in the fecondary, are many of them rounded and worn, the depofition of the latter " muĝ have been feparated from the elevation of " the former by fuch an interval of time, as gave room for the a@ion of wafte and decay, al- lowing thofe fragments firft to be detached, and afterwards wrought into a round figure *, t 44. Indeed, the interpofition of a breccia be- Í tween the primary and fecondary ftrata, in | which the fragments, whether round or angu- í dar, are always of the primary rock, is a fa@ fo " general, and the quantity of this breccia is often fo great, that it leads to a conclufion more pa- i radoxical than any of the preceding, but from | which, neverthelefs, it feems very difficult to ) | with-hold affent. Round gravel, when in great abundance, agreeably to a remark already made, » muft neceffarily be confidered as a production j D2 peculiar * NOTE XIL ` 52 ILLUSTRATIONS OF THE | peculiar to the beds of rivers, or the fhores of È continents, and as hardly ever formed at great | depths under the furface of the fea. It thould i feem, then, that the primary fchiftus, after at. taining its erect pofition, had been raifed up to the furface, where this gravel was formed; and from thence had been let down again o the depths of the ocean, where the fecondary ; ftrata were depofited on it. Such alternate elevations and depreffions of the bottom of the fea, however extraordinary they may feem, will appear to make a part of the fyftem of the mineral kingdom, from other phenomena here- after to be defcribed. | 45. On the whole, therefore, by comparing the actual pofition of the ftrata, their eretnek, their curvature, the interruptions of their con- tinuity, and the tranfverfe ftratification of the fecondary in refpect of the primary, with the regular and level fituation which the fame ftra- | ta muf have originally poffeffed, we havea f complete demonftration of their having been difturbed, torn afunder, and moved angularly, by a force that has, in general, been directed from below upwards. In eftablifhing this cot clufion, we have reafoned more from the facts which relate to the angular elevation of the fra ta, than from thofe which relate to their ab folute elevation, or their tranflation to a great diftanc? | me o.oo eD E ~ a n a N a a et Se ee enn a ee HUTTONIAN THEORY. 53 diftance from the centre of the earth. This has been done, becaufe the appearances, which trefpect the abfolute lifting up of the ftrata are more ambiguous than thofe, which refpe& the change of their angular pofition. The former might be accounted for, could they be feparated from the latter, in two ways, viz. ei- ther by the retreat of the fea, or the raifing up of the land; but the latter can be explained only in one way, and force us of neceflity to ac- knowledge the exiftence of an expanding power, which has acted on the ftrata with incredible energy, and has been directed from the centre | toward the circumference. 46. When we are affured of the exiftence of fuch a power as this in the mineral regions, we fhould argue with fingular inconfiftency if we did not afcribe to it all the other appearances of motion in thofe regions, which it is adequate to produce. If nature in her fubterraneous a- bodes is provided with a force that could burft afunder the maffy pavement of the globe, and place the fragments upright upon their edges, could fhe not, by the fame effort, raife them from the greateft depths of the fea, to the high- eft elevation of the land? The caufe that is ade- quate to one of thefe effedts, is adequate to them both together; for it is a principle well known in mechanical philofophy, that the force which D3 produces s4 ILLUSTRATIONS OF THE produces a parallel motion, may, according to — the way in which it is applied, produce alfo an angular motion, without any diminution of the former effet. It would, therefore, be extreme. ly unphilofophical to fuppofe, that any other caufe has changed the relative level of the ftra- ta, and the furface of the fea, than that which — has, in fo many cafes, raifed the ftrata from a horizontal to a highly inclined, or even verti- cal fituation: it would be to introduce the ac- tion of more caufes than the phenomena re- quire, and to forget, that nature, whofe opera- tions we are endeavouring to trace, combines the poffeffion of infinite refources with the moft economical application of them. 47. From all, therefore, that relates to the pofition of the ftrata, I think I am juftified in affirming, that their difturbance and removal from the place of their original formation, by a force directed from below upwards, is a fact in the natural hiftory of the earth, as perfedtly afcertained as any thing which is not the fub- ject of immediate obfervation. As to the power by which this great effet has been produced, we cannot expect to decide with equal evidence, but muft be contented to:pals from what is certain to what is probable. We -may, then, remark, that of the forces in nature to which our experience does in any degree a tend, F) ——— k Í HUTTONIAN THEORY. 55 tend, none feems fo capable of the effect we ty would afcribe to it, as the expanfive power of the heat ; a power to which no limits can be fet, and NM, one, which, on grounds quite independent of the her elevation of the ftrata, has been already conclu- m ded to ad with great energy in the fubterra- ij neous regions. We have, indeed, no other al- lj ternative, but either to adopt this explanation, fi or to afcribe the facts in queftion to fome fecret a and unknown caufe, though we are ignorant of its nature, and have no evidence of its exift- m ence. | m Weare therefore to fuppofe, that the power of of the fame fubterraneous heat, which con- = folidated and mineralized the ftrata at the 4, bottom of the fea, has fince raifed them up to the height at which they are now placed, and y, as given them the various inclinations to the horizon which they are found actually to pof- f es t 48. The probability of this hypothefis will be fi greatly increafed, when it is confidered, that, be- of fides thofe now enumerated, there are other indi- j = cations of movement among the bodies of the mi- i = neral kingdom, where effeéts of heat more cha- A racteriftic than fimple expanfion are clearly to i be difcovered. Thus, on examining the marks of ; diforder and movement which are found among the ftrata, it cannot fail to be obferved, that not- i D4 withftanding s6 ILLUSTRATIONS OF THE withftanding the fracture and diflocation, of which they afford fo many examples, there are few empty {paces to be met with among them, as far as our obfervation extends. The breach. es and feparations are numerous, and difting ; but they are, for the moft part, completely fill. ed up with minerals of a kind quite different from the rock on each fide of them, and re- markable for containing no veftiges of ftratifi- cation. We are thus led to confider the unftra- tified foffils, the fecond of the divifions into which the whole mineral kingdom, viewed geological- ly, ought to be diftinguifhed. Thefe foffils are , immediately connected with the difturbance of the ftrata, and appear, in many inftances, tq have been the inftruments of their elevation. SEQ p a S l Ce A EER HUTTONIAN THEORY. 57 SEC TION IL ' QF THE PHENOMENA PECULIAR TO UNSTRATI- FIEÐ BODIES. t. Metallic Veins. 49. HE unftratified minerals exift either in veins, interfecting the ftratified, or in maffes furrounded by them. Veins are of va- rious kinds, and may in general be defined, fe- parations in the continuity of a rock, of a deter- minate width, but extending indefinitely in length and depth, and filled with mineral fub- ftances, different from the rock itfelf. The mi- neral veins, ftrictly fo called, are thofe filled with fparry or cryftallized fubftances, and con- taining the metallic ores. That thefe veins are of a formation fubfe- quent to the hardening and confolidation of the ftrata which they traverfe, is too obvious to re- quire any proof; and it is no lefs clear, from the cryftallized and fparry ftructure of the fyb- ftances contained in them, that thefe fubftances muft have concreted from a fluid ftate. Now, that this fluidity was fimple, like that of fufion by heat, and not compound, like that of folu- tion in a menftruum, is inferred from many phe- nomena. It is inferred from the acknowledged infolubility w 58 ILLUSTRATIONS OF THE infolubility of the fubftances that fill the veins, in any one menftruum whatfoever ; from the total difappearance of the folvent, if there was any ; from the complete filling up of the vein by the fubftances which that folvent had depofited ; from the entire abfence of all the appearances of horizontal or gradual depofition ; and, laftly, from the exiftence of clofe cavities, lined with cryftals, and admitting no egrefs to any thing but heat, 50. Tothe fame effe& may be mentioned thofe groups of cryftals compofed of fubftances the moft different, that are united in the fame fpe- cimen, all interfecting and mutually imprefling one another. Thefe admit of being explained, on the fuppofition that they were originally in fu- fion, and became folid by the lofs of heat; a caufe that acted on them all alike, and alike im- pelled them to cryftallize : But the appearances of fimultaneous -cryftallization feem incompati- ble with the nature of depofition from a folvent, where, with refpect to different fubftances, the effects muft take place flowly, and in fucceflion. 51. The metals contained in the veins which we are now treating of, appear very commonly in the form of an ore, mineralized by fulphur. Their union with this latter fubftance can be produced, as we know, by heat, but hardly by the way of folution in a menftruum, and cer- tainly j ) — r AEREI DIENE, diii HUTTONIAN THEORY. 59 tainly not at all, if that menftruum is nothing elfe than water. The metals, therefore, when mineralized by fulphur, give no countenance to the hypothefis of aqueous folution ; and ftill lefs do they give any when they are found native, as it is called, that is, malleable, pure and uncom- bined with any other fubftance. The great maf- fes of native iron found in Siberia and South America are well known; and nothing certain- ly can lefs refemble the produdts of a chemical precipitation. Gold, however, the moft perfect of the metals, is found native moft frequently ; the others more rarely, in proportion nearly to the fa- cility of their bination with fulphur. Of all fuch {pecimens it may bė fafely affirmed, that if they have ever been fluid, or even foft, they muft have been fo by the action of heat ; for, to fup- pofe that a metal has been precipitated, pure and uncombined from any menftruum, is to trefpafs againft all analogy, and to maintain a phyfical impoflibility. But it is certain, that many of the native metals have once been in a ftate of foftnefs, becaufe they bear on them impreffions which they could not have received but when they were foft. Thus, gold is often imprefled by quartz and other ftones, which ftill adhere to it, or are involved init. Specimens of quartz, containing gold and filver fhooting through them, 60 ILLUSTRATIONS OF THE them, with the moft beautiful and varied ramif. cations, are every where to be met with in the cabinets of the curious ; and contain, in their ftructure, the cleareft proof, that the metal and the quartz have been both foft, and have cry. ftallized together. By the compaétnefs, alfo, of the body which they form, they fhow, that when they acquired folidity, it was by the con- cretion of the whole mafs, and not by fuch par- tial concretion as takes place when a folvent is feparated from fubftances which it held in fo. lution. 52. Native copper is very abundant; and fome {pecimens of it have been found cryftal- lized. Here the cryftallization of the metal is a proof that it has paffed from a fluid to a fo- lid ftate ; and its purity is a proof that it did not make that tranfition by being precipitated from a menftruum,. 53. Again, pieces of native manganefe have been found poileffing fo exaétly the charadters peculiar to that metal when reduced in our fir- naces, that it is impoflible to confider them as deriving their figure and folidity from any caufe but fufion. The ingenious author who de- icribes thefe {pecimens, La Peyroufe, was fo forcibly’ ftruck with this refemblance, that he immediately drew the fame conclufion from it which is drawn here, attributing the only differ- ence, HUTTONIAN THEORY. 6r. ence, which he remarked between the native and the artificial regulus, to the different energy with which the fame agent works when em- ployed by nature and by art *. 54. All thefe appearances confpire to prove, that the materials which fill the mineral veins were melted by heat, and forcibly injected, in that ftate, into the clefts and fiffures of the ftra- ta. Thefe fiflures we muft conceive to have arifen, not merely from the fhrinking of the ftrata while they acquired hardnefs and folidity, but from the violence done to them, when they were heaved up and elevated in the manner which has already been explained +. 53. When thefe fuppofitions are once admit- = ted, the other leading facts in the hiftory of me- tallic veins will be readily accounted for. Thus, for inftance, it is evident to what we muft- afcribe the fragments of the furrounding rock that are often found immerfed in the veins, and encompaffed on all fides by cryftallized fubftan- ces. Thefe fragments being no doubt detached “by the concuffion, which at once tore afunder and elevated the ftrata, were fuftained by the melted matter that flowed at the fame time up- ward * Theory of the Earth, vol. i. p. 68. . Journal de Phyf. Janvier 1786. + NOTE XIII. 62 ILLUSTRATIONS OF THE ward through the vein. Large maffes of rock are often found in this manner completely in. {ulated ; one of thefe, which M. de Luc has deicribed with great accuracy, is no lefs than a vaft fegment of a mountain *. 50. The immenfe violence which has accom: panied the formation of mineral veins, is parti- cularly marked by the flips and fhifts of the ftra- ta on each fide of them, all tending to fhow what mighty changes have taken place in thofe regions, which our imagination erroneoufly paints as the abode of everlafting filence and reft. This fhifting of the ftrata is beft obfer- ved, where the veins make a tranfverfe fe&tion of beds of rock, confiderably inclined to the horizon. There it is common to fee the beds on one fide of the vein flipped along from the correfponding beds on the other fide, and removed fometimes in a horizontal, fometimes in an oblique direGion. In this way, not only the ftrata are fhifted, but veins, which inter- fect one another, are alfo fhitted themfelves, They are heaved, as it is called in the figni- ficant language of the miners, and forced out of their dire&tion. It is impoflible, in fuch a cafe, but to conned in the mind the formation — of * Lettres Payfiques, &c, tom. ili, p. 361. > ee a Re. ee Se yt OS RS ge ga ee een ee ae HUTTONIAN THEORY. 63 of the vein, and the production of the flips which accompany it, and to regard them as parts of the fame phenomenon. 57. Where thefe flips are horizontal, and ex- hibit great bodies of ftrata carried from their place, while the parts of the transferred mafs re- main undifturbed relatively to one another, they ` furnifh a clear proof, that this change of place has not arifen from the falling in of the roofs of ca- verns, as fome geologifts fuppofe. The horizontal direction, and the regularity of the movement, are incompatible with the adtion of fuch a caufe as this; and indeed it is highly interefting to re- mark, in the midft of the figns of difturbance which prevailinthe bowels of the earth, that there reigns a certain fymmetry and order, which in- dicate the action of a force of incredible magni- tude, but flow and gradual in its effets. The parts of the mafs moved are undifturbed rela- tively to one another: what has been broken has been cemented: the breaches of continuity -have been filled up and healed ; and every where we fee the operation of a caufe that could unite as well as feparate. The twofold action of heat to expand and to melt, could fcarce be pointed out more clearly by any fyftem of appearan- 58. As a long period was no doubt required for the elevation of the ftrata, the rents made in 64 ILLUSTRATIONS OF THE in them are not all of the fame date, nor the veins all of the fame formation. This is clear in the cafe of one vein producing a thift or flip in another; for the vein which forces the other out of its place, and preferves its own di. _ rection, is evidently the more recent of the two, and muft have had its materials in a ftate of ac. tivity, when thofe of the other were inert. Some. times, alfo, at the interfection of two veins, we — may trace the current of the materials of the one, acrofs thofe of the other; and here, of confequence, the relative antiquity is determi- ned juft as in the former inftance. 59. The want of any appearance of fteatifica tion in mineral veins has already been taken notice of. There is, however, to be obferved, in many inftances, a tendency to a regular ar- rangement of the fubftances contained in them; thofe of the fame kind forming coats parallel to the fides of the vein, and nearly of an equal thick- nefs. This phenomenon is confidered as one of the itrongeft arguments in favour of the Neptu- nian fyftem, but has nothifig in it, in the leaft in- compatible with that theory which afcribes the formation of veins to. the action of fubterraneous. heat. When melted matter from the mineral re- gions was thrown up into the veins, that which was neareft to the fides would fooneft lofe its heat. The fimilar fubftances, alfo, would unite while this A O HUTTONIAN THEORY. 6s -this procefs was going forward, and would cry- ftallize, as in other cafes of congelation, from the fides toward the interior. Therg is the more rea- fon for fuppofing this to have been the cafe, that the fame fort of coating is often obferved on the infide of clofe cavities, which are, neverthe- lefs, fo conftruéted, as to afford a demonttration that no chemical folvent was ever included in them, (§ 74.). Some veins, it muft alfo be con- fidered, may have been filled by fucceflive in- jeCtions of melted matter, and this would natu- rally give rife to a variety of feparate incrufta- tions *, E 6o. In the view now given of metallic veins, they have been confidered as traverfing only the ftratified parts of the globe. They do, however, occafionally interfe& the unftratified parts, par- ticularly the granite, the fame vein often conti. nuing its courfe acrofs rocks of both kinds, with- out fuffering any material change ; and, if we have hitherto paid no attention to this circum-~ ftance, it is becaufe the order purfued in this effay required, that the relation of the veins to ftratified bodies fhould be firft treated of. Be- fides, the facts in the natural hiftory of veins, whether contained in ftratified or unftratified rocks, * See fome farther remarks on this fubje&t at Noreg XIII. 66 ILLUSTRATIONS OF THE rocks, are fo nearly alike, that in a general view of geology, they do not require to be diftin. guifhed. It is material to remark, that, though metallic veins are found indifcriminately in all the different kinds of rock, whether ftratified or otherwife, they are moft abundant in the clab _ of primary {chifti. All the countries moft re. — markable for their mines, and the mountains diftinguifhed by the name of metalliferous, are — _ primary, and the inftance of Derby thire is per- haps the moft confiderable exception to this rule, that is known. This preference, which the metals appear to give to the primary ftrata, is very confiftent with Dr Hutton’s theory, which — reprefents the rocks of that order as being mok — changed from their original pofition, and thofe | on which the difturbing forces of the fubterra- neous regions have acted moft frequently, and with greateft energy. The primary ftrata are the loweft, alfo, and have the moft dire& com- munication with thofe regions from which the mineral veins derive all their riches. 4, OF. Whin one. 61. Befide the veins filled with fpar, and com | taining the metallic ores, the ftrata are interfed- ed by veins of whinftone, porphyry and granite, the — —— — NSR = Rema ae Pict ae ae = ee -HUTTONIAN THEORY. 6y the characters of which are next to be exami- ned. The term whin, or whinftone, with Dr Hut- ton, like the word trap, with the German mine- ralogifts, denotes a clafs of ftones, comprehend- ing feveral diftiné fpecies, or at leat varieties. The common dba/alz, the wacken, mullen, and crag of Kirwan, the grinftein of Werner, and the amygdaloid, are comprehended under the name of whin. All thefe ftones have a ten- dency to a f{pathofe: ftruture, and difcover at leat The rudiments of eryftallization. They are, at the fame time, without any mark of ftratification in their internal texture, as they are alfo, for the moft part, in their outward cons figuration; ahd, as the different fpecies here enumerated compofe, not unfrequently, parts of the fame continuous rock, the change from one to another being made through a feries of in- fenfible gradations, they may fafely be regard- ed by the geologift as belonging to the fame E genus. 62. Whin, though not ftratified, exifts in two different ways, that is, either in veins, (called in Scotland dykes), traverfing the ftrata like the _ Veins already defcribed, or in irregular maffes, incumbent on the ftrata, and fometimes inter- pofed between them. In both thefe forms, whinftone has nearly the fame charaCers, and E2 bears, 68 ILLUSTRATIONS OF THE bears, in all its varieties, a moft ftriking refem. blance to the lavas which have actually floweg from volcanoes on the furface of the earth, This refemblance is fo great, that the two fub. ftances have been often miftaken for one ano. ther; and many rocks, which have been pro. nounced to be the remains of extinguifhed vol. canoes, by mineralogifts of no inconfiderable — name, have been found, on clofer examination, to be nothing elfe than maffes or veins of whin- ftone. This latter ftone is indeed only to be diftinguifhed from the former, by a careful ex- amination of the internal characters of both; and chiefly from this circumftance, that whin- ftone often contains calcareous {par and zeolite, whereas neither of thefe fubftances is found in fuch lavas, as are certainly known to have been thrown out by volcanic explofions. | Now, from thefe circumftances of affinity be- tween lava and whinftone, on the one hand, and of diverfity on the other, as the formation of the one is known, it fhould feem that fome pro- bable conclufion may be drawn concerning the formation of the other. The affinity in que- ftion is conftant and effential; the difference variable and accidental; and this naturally leads to fufpect, that the two ftones have the fame origin; and that, as lava is certainly a produc- tion of fire, fo probably is whinftone. 63. But — _— on — m m Py e ES ey a eee a Ss HUTTONIAN THEORY. 69 63. But, in order to fee whether this hypo- thefis will explain the diverfity of the two fub- ftances, without which it will not be entitled to much attention, we muft remark, that the prefence of carbonat of lime in a body that has _ been fufed, argues, agreeably to the principles formerly explained, that the fufion was brought about under a great comprefling force, that is to fay, deep in the bowels of the earth, or in the great laboratory of the mineral regions. We- are, therefore, to fuppofe that the fufion of the whin was performed in thofe regions, where the compreffion was fufficient to preferve the car- bonic gas in union with the calcareous earth, fo that thefe two fubftances melted together, and, on cooling, cryftallized into fpar. In the lavas, again, thrown out by volcanic erup- tion, the fufion, as we know, wherever it may begin, continues in the open air, where the pref- fure is only that of the atmofphere: the calca- reous earth, which, therefore, may have been, in the form of a carbonat, among the materials of this lava, muĝ be converted into quicklime, and become infufible ; hence the want of calca- reous {par in lavas that have flowed at the fur- face. Thus, whinftone is to be accounted a fubter- raneous, or wi-erupted lava ; and our theory has the advantage of explaining both the affinity E3 and 40 ILLUSTRATIONS OF THE and the difference between thefe ftony bodies, without the introduction of any new hypothe. fis. In the Neptunian fyftem, the affinity of whinftone and lava is a paradox which admits of no folution. 64. The columnar ftru@ure fometimes found in that fpecies of whinttone called bafaltes, is a fact which has given rife to much difcuffion ; and it muft be confeffed, that though one of the moft ftriking and peculiar charaers of this ; fofiil, it is not that which gives the cleareft and — moft direct information concerning its origin, One circumftance, however, very much in fa- vour of the opinion that bafaltic rocks owe their formation to fire, is, that the columnar form is fometimes affumed by the lava adual- ly erupted from volcanoes. Now, it is cer- tainly of no fmall importance, to have the fynthetic argument on our fide, and to know, that bafaltic columns can be produced by fire; though, no doubt, to give abfolute cer- tainty to our conclufion, it would be necef- fary to fhow, that there are in nature no other means but this by which thefe columns can be formed. This fort of evidence is hard- ly to be looked for; but fince the power of fufion, to produce the phenomena in queftion, is perfectly eftablifhed, and fince the production of the fame phenomena in the humid way is 4 mere p _— ee es — HUTTONIAN THEORY. yr mere hypothefis, if there be the leaft reafon to fufpect the ation of fubterraneous heat as one of the caufes of mineralization, very maxim of found philofophy requires that the bafaltic flruQure, in all cafes, fhould be afcribed to it. 65. The Neptunifts will no doubt allege, with Bercman, that, in the drying of ftarch, clay, and a few other fubftances, fomething analogous tk to bafaltic columns is produced. Here, how- ever, a moft important difference is to be re- marked, correfponding very exactly to one of the characters which we have all along obfer- ved to diftinguifh the products of aqueous, from thofe of igneous confolidation. ‘The columns formed by the fubftances juft mentioned, are di- ftant from one another: they are feparated by -fiffares which widen from the bottom to the top, and which arife from the fhrinking and dry- ing of the mafs. In the bafaltic columns, no fuch openings, nor vacuity of any kind is found ; the pillars are in contact, and, though perfectly diftin@, are fo clofe, that the fharp edge of a wedge can hardly be introduced between them. Chis is a great peculiarity in the bafaltic ftruc- ture, and is ftrongly expreffive of this fac, that the mafs was all fluid together, and that its parts took their new arrangement, not in confequence of the feparation of a fluid from a folid part, by Which great fhrinking and much empty fpace E4 might ° 72 ILLUSTRATIONS OF THE might be produced; but in confequence of a caufe which, like refrigeration, acted equally on all the parts of the mafs, and preferved their abfolute contact after their fluidity had ceafed. 66. A mark of fufion, or at leaft of the ope. ration of heat, which whinftone poffeffes in com. mon with many other minerals, is its being pe- netrated by pyrites, a fubftance, as has been al. ready remarked, that is of all others moft ex. _ clufively the produdtion of fire. Another mark | of fufion, more diftin@tive of whin, is, that both in veins and in maffes it fometimes includes Pieces | of fandftone, or of the other contiguous ftrata, completely infulated, and having the appearance of fragments of rock, floating in a fluid fuffi- ciently denfe and ponderous to fuftain their weight. ‘Though thefe fragments have been — too refractory to be reduced into fufion them- felves, they have not remained entirely un- changed, but are, in general, extremely indu- rated, in comparifon of the rock from which they appear to have been detached. 67. Similar inftances of extraordinary indu- ration are oblerved in the parts of the ftrata in contact with whinftone, whether they form the fides of the veins, or the floors, and roofs of the mafles into which the whinftone i is diftributed. The ftrata whether fandy or argillaceous, in fuch fituations, are ufually extremely hard and confolidated 5 a aes a ee ee ee ee ee ps HUTTONIAN THEORY. 74 eonfolidated ; the former in particular lofe their granulated texture, and are fometimes convert- ed into perfect jafper. This interefting remark was firft made by Dr Hutton, and the truth of it has been verified by a great number of fub- fequent obfervations. 68. To the fame excellent Picci we are indebted for the knowledge of an analogous fac, attendant on the paflage of whinftone veins through coal ftrata. As the beds of ftone where they are in contact with veins of whin, feem to acquire additional induration, fo thofe of coal, in like circumftances, are frequently found to have loft their fufibility, and to be reduced near- ly to the condition of coke, or of charcoal. The exiftence of coal of this kind has been already _ Mentioned, and confidered as a proof of the ope- ration of fubterraneous heat. In the inftances here referred to, that is, where the charring of the coal is limited to thofe parts of the ftrata which are in contac&t with the whin, or in its im- mediate vicinity, the heat is pointed out as re- fiding in the vein; and this is to be accounted for only on the {uppofition of the melted whin, at a period fubfequent to the confolidation of the coal, having flowed through the openings of the ftrata. The heat has been powerful enough, in many cafes, to drive off the bituminous matter of the coal, and to force it into colder and more diftant 74 ILLUSTRATIONS OF THE diftant parts. Few facts, in the hiftory of fofils, are more remarkable than this, and none more dire@ly affimilates the operatioris of the mineral regions, with thofe that take place at the furface of the earth. | 69. Again, the difturbance of the ftrata, wherever veins of whinftone abound, if not a direct proof of the original fluidity of the whin. 1 ftone, is a clear indication of the violence with which it was introduced into its place. This di- fturbance of the pofition of the ftrata, by fhift. ing, unufual elevation, and other irregularities, where they are interfected by whinftone veins, is a fact fo well known to miners, that when they meet with any fudden change in the lying of the metals, they are wont to foretel their ap- proach to maffes, or veins of unftratified matter; and, in their figurative language, point them out as the caufes of the confufion with which they are fo generally accompanied *. The mi- neral veins likewife, as well as the ftrata, are often heaved and fhifted by the veins of whin- ftone. 70. Whinftone of every fpecies is found fre quently interpofed in tabular maffes, between beds of ftratified rocks ; and it then adds to the indications * A Trouble is the name which the colliers in this country give to a vein of whinftone. re i log- ae cic cae SS See SS. Set. Reese z? ci “>: oe HUTTONIAN THEORY. T indications of its igneous origin, already enume- rated, fome others that are peculiar to it when in this fituation. In fuch inftances, it is not un- common to find the ftrata in fome places, conti- guous to the whin, elevated, and bent with their concavity upward, fo that they appear clearly to have been acted on by a force that proceeded from below, at the fame time that they were foftened, and rendered in fome degree flexible: jt is needlefs to remark, that thefe effeGs can be explained by nothing but the fufion of the whin ; ~and that the great force with which it was impelled againft the ftrata, could be produced by no caufe but heat, acting in the manner that is here fuppofed. 71. Again, if it be true that the maffes of whin, thus interpofed among the ftrata, were introduced there, after the formation of the lat- ter, we might expect to find, at leaft in many in- ftances, that the beds on which the whinftone refts, and thofe by which it is covered, are exa@t- ly alike. Ifthete beds were once contiguous, and have been only heaved up and feparated by the irruption of a fluid mafs of fubterraneous lava, - their identity fhould ftill be recognifed. Now, this is precifely what is obférved ; it is known to hold in a vaft number of inftances, and is ftrikingly exemplified in the rock of Salifoury Crag, near Edinburgh. : This: “6 ILLUSTRATIONS OF THE This fimilarity of the ftrata that cover the maffes of whinftone, to thofe that ferve as the bafe on which they reft, and again the diffimilj. tude of both to the interpofed mafs, are fa@s which I think can hardly receive any explana. tion, on the principles of the Neptunian theory, If thefe rocks, both ftratified and unttratified, are to he regarded as productions of the fea, the circumftances would require to be pointed out, which have determined the whinftone, and the ‘beds that are all round it, to be fo extremely unlike in their ftru@ure, though formed at the fame time, and in the immediate vicinity of one another ; as alfo thofe circumftances, on the other hand, which determined the ftratified depofites above and below the whinftone, to be precifely the fame, though the times of their formation muft have been very different. The homo- geneous fubftances, thus, placed at a diftance, and the heteroge brought fo clofely toge- ther, are phenomena equally unaccountable, in a theory that afcribes their origin to the operation of the fame element, and that neceflarily dates their formation according to the order in which they lie, one above another. 72. If, indeed, in thefe inftances, the grada- tion were infenfible, as fome have afferted it to be, between the ftrata and the interpofed mafs, fo that it was impoflible to point out the line where ai r HUTTONIAN THEORY: 77 where the one ended and the other began, what- ever difficulties we might perceive in the Nep- tunian theory, we fhould find it hard to fubfti- tute a better in its room. But the truth feems to be, that, in the cafes we are now treating of, no fuch gradation exifts; and that, though where the two kinds of rock come into contact a change is often obferved, by the ftrata having acquired an additional degree of induration, yet the line of feparation is well defined, and can be precifely afcertained. This at leaft is cer- tain, that innumerable fpecimens, exhibiting © fuch lines of feparation, are to be met with; and wherever care has been taken to obtain a frefh fracture of the ftone, and to remove the effects of accidental caufes, even where the two rocks are moft firmly united, and moft clofely affimilated, I am perfuaded that no uncertainty has ever re- mained as to the line of their feparation. For thefe reafons, it feems probable that the gradual tranfition of bafaltes into the adjoining ftrata, is in all cafes imaginary, and is, in truth, a mere il- lufion, proceeding from hafty and inaccurate obfervation. | 73. Another remarkable fact in the natural hiftory of the whinftone rocks, remains yet to be _ mentioned, and with it I fhall conclude the ar- gument, as far as thefe rocks are concerned. Some 58 ILLUSTRATIONS OF THE Some of the fpecies of whinftone are the common matrices of agates and chalcedonies, which lie inclofed in them in the form of round nodules. The original fluidity of thefe nodules is evinced by their figured, and fome- times cryftallized ftru&ure, and indeed is fo ge- nerally admitted, that the only queftion con- cerning them is, whether this fluidity was the i effect of heat or of folution. To anfwer this queftion, Dr Hutton obferves, that the forma- tion of the concentric coats, of which the agate is ufually compofed, has evidently proceeded from the circumference toward the centre, the exterior coats always imprefling the interior, but never the reverfe. The fame thing alfo fol- lows from this other faét, that when there is _ any vacuity within the agate, it is ufually at the centre, and there too are found the regu- lar cryftals, when any fuch have been forme ed. It therefore appears certain, that the pro- grefs of confolidation has been from the circum: ference inwards, and that the outward coats of the agate were the firt to acquire folidity and hardneis. 74. Now, it muft be confidered that thefe coats are highly confolidated ; that. they are of very pure filiceous matter, and are utterly impervious to every fubitance which we know of, except light and heat. It is plain, therefore, that what- ever P Da e p fomai Bese hd Dag Aid ee. eee ae Na: ee HUTTONIAN THEORY. 79 ever at any time, during the progrefs of confo- lidation, was contained within the coats already formed, muft have remained there as long as the agate was entire, without the leaft poffibility of efcape. But nothing is found within the coats of the agate fave its own fubftance; therefore no extraneous fubftance, that is to fay no fol- vent, was ever included withinthem. The flui- dity of the agate was therefore fimple, and un- aflifted by any menftruum. In this argument, nothing appears to me -~ wanting, that is neceflary to the perfection of a phyfical, I had almoft faid of a mathematical, demonftration. It feems, indeed, to be impof- fible that the igneous origin of foffils could be recorded in plainer language, than by the phe- nomenon which has juft been defcribed. 7g.) Lhe ination of particular {pecimens of agates and chalcedonies, affords many more ar- guments of the fame kind, which Dr Hutton ufed to deduce with an acutenefs and vivacity, which his friends have often liftened to with great admiration and delight *. Thefe, however, muft be pafled over at prefent ; and I have on- ly further to remark, that a feries of the moft interefting experiments, inftituted by Sir Jams Hatt, and publithed in the Tranfactions of the Royal Society of Edinburgh +, has removed the : only * Nove xiv. + Vol. v. p. 43. 86 ILLUSTRATIONS OF THE only remaining objection that could be urged againft the igneous origin of whinftone. This objection is founded on the common obferva- tion, that when a piece of whinftone or bafaltes is actually melted in a crucible, on cooling, it becomes glafs, and lofes its original character en. _ tirely ; and from thence it was concluded, that this character had not been originally produ- ced by fufion. The experiments above men. | tioned, however, have fhewn, in the mof fa- tisfactory manner, that melted whin, by regu- lated or by flow cooling, is prevented from affu- ming the appearance of glais, and becomes a fto- ny fubftance, hardly to be diftinguifhed from whinftone or lava. ` : The experiments of another ingenious che- mit, Dr Kennepy, have fhewn, that whinftone contains mineral alkali, by which, of courfe, its fufion muft have been affifted *. Dr Hutton ufed to afcribe its fufibility, in a great meafure at leaft, to the quantity of iron contained in it: both thefe caufes have no doubt united to ren- der it more eafily melted than the ordinary ma- terials of the ftrata. 76. Ina word, therefore, to conceive aright the origin of that clafs of unftratified rocks, diftin- guifhed by the name of whinftone, we muft fup- pofe, * Tranf. R, S. Edin. vol. v, p: 85. HUTTONIAN THEORY. Sr pofe, that long after the confolidation of the ftrata, and during the time of their elevation, the materials of the former were melted by the force of fubterraneous heat, and injected among the rents and fiffares of the rocks already formed. In this manner were produced the veins or dikes of whinftone ; and, where circumftances allow- ed the ftream of melted matter to diffufe itfelf more widely, tabular maffes were formed, which were afterwards raifed up, together with the furrounding ftrata, above the level of the fea, and have been fince laid open by the operation of thofe caufes that continually change and watte the furface of the land. | Thefe unftratified rocks are not, however, all the work of the fame period 3 they differ evi- dently in the date of their formation, and it is not unufual, to find tabular maffes of one fpe- cies of whin, interfeéted by veins of another fpecies. Indeed, of all the foffil bodies which compofe the prefent land, the veins of whin ap- pear to be the moft recently confolidated *. - Porphyry may fo properly be regarded asa variety of whin, diftinguifhed only by involv- ing cryftallized feltfpar, that, in a geological fketch like the prefent, it is hardly entitled to a feparate article. Like the other kinds of F whin, * NoTE xiv, = 82 ILLUSTRATIONS OF THE whin, it exifts both in veins and in tabular maffes, having, no doubt, an origin fimilar to that which has juft been defcribed. Porphyry, however, has the peculiarity of being rarely found in any but the primary ftrata; it feems to be the whinftone of the old world, or at leat that which is of higheft antiquity in the prefent, It no-where, I believe, aflumes a columnar, or bafaltic appearance, of any regularity ; but this is alfo. true of many other varieties of whin, of all, indeed, except the moft compact and ho- mogeneous. ‘Thefe differences are not fo`con- fiderable as to require our entering into any particular detail concerning the natural hiftory of this foffil. 7 3. Granite. 77. The term Granite is ufed by Dr Hutton to fignify an aggregate ftone, in which quartz, feltfpar and mica are found diftiné from one another, and not difpofed in layers. ‘Fhe addi tion of hornblend, {chorl, or garnet, to the three ingredients juft mentioned, is not underftood to alter the genus of the ftone, but only to confti- ‘tute a fpecific difference, which it is the bufinefs of lithology to mark by fome appropriate cha- racter, annexed to the generic name of granite. The lis eee ee a ae ee TERSA HUTTONIAN THEORY. 83 The foffil now defined exifts, like whinftone and porphyry, both in maffes and in veins, though moft frequently in the former. It 1s like them unftratified in its texture, and is re- garded here, as being alfo unftratified in its out- ward ftructure *. One ingredient which is efen- tial to granite, namely, quartz, is not contained. in whinftone; and this circumftance ferves to ~ diftinguifh thefe genera from one another, though, in other refpects, they feem to be uni- ted by a chain of infenfible gradations, from the , F 2 moft * Thofe rocks that confift of the ingredients here enu- merated, if they have at the fame time a fchiftofe tex- ture, or a difpofition into layers, are properly diftin- guifhed from granite, and called Gneifs, or Granitic Schiftus. But it has been queftioned whether a ftone does not exift compofed of thefe ingredients, and defti- tute of a {chiftofe texture, but yet divided into large beds, vifible in its external form. Dr Hutton fuppofes fuch a ftone not to exift, or at leaft not to conftitute any fuch proportion of the mineral kingdom, as to entitle it _ to particular confideration, in the general {peculations of geology. Whether this fuppofition is perfe&ly corre, may re- quire to be farther confidered: this, however, is certain, that a rock, in ali refpe&s conformable to it, compofes a great proportion of what are ufually called the granite mountains, See NOTE xv. $4 ILLUSTRATIONS OF THE moft homogeneous bafaltes, to granite the mog highly cryftallized. 78. Granite, it has been juft faid, exifts moft commonly in mafles ; and thefe mafles are rare- ly, if ever, incumbent on any other rock : they are the bafis on which others reft, and feem, for the mof part, to rife up from under the ancient, or primary ftrata. The granite, therefore, wherever it is found, is inferior to every other rock ; and as it alfo compofes many of the great- eft mountains, it has the peculiarity of being eles _ vated the higheft into the atmofphere, and funk the deepeft under the furface, of all the mineral fubftances with which we are acquainted. Notwithftanding the circumftance of not be- ing alternated with ftratified bodies, which conftitutes a remarkable difference between gra- nite and whinftone, the affinity of thefe foffils is fuch as to make the fimilarity of their origin by no means improbable. Accordingly, in Dr Hutton’s theory, granite is regarded as a ftone of more recent formation than the ftrata incum- bent on it ; as a fubftance which has been melt- ed by heat, and which, when forced up from — the mineral regions, has elevated the ftrata at. the fame time. 4g. Chat granite has undergone achange from) — a fluid to a folid flate, is evinced from the ery- f ftallized ftructure in which fome of its compo- nent | / | i t HUTTONIAN THEORY. 85 nent parts are ufually found. This cryftalliza- tion is particularly to be remarked of the felt- fpar, and alfo of the fchorl, where there is any admixture of that fubftance, whether in flender fpiculz, or in larger maffes. The quartz itfelf ' isin fome cafes cryftallized, and is fo, perhaps, more frequently than is generally fuppofed. The fluidity of granite, in fome former period of its exiftence, is fo evident from this, as to make it appear fingular that it fhould ever have been confidered as a foflil that had remained al- ways the fame, and one, into the origin of which it was needlefs to inquire. If the regular forms of cryftallization are not to be received as proofs of the fubftance to which they belong having paffed from a fluid to a folid ftate, neither are the figures of fhells and of other fuppofed petri- factions, to be taken as indications of a pailage from the animal to the mineral kingdom; fo that there is an end of all geological theories, and of all reafonings concerning the ancient condition of the globe. To an argument which ftrikes equally at the root of all theories, it be- longs not to this, in particular, to make any re- ply. | 80. We fhall, therefore, confider it as admit- _ ted, that the materials of the granite were ori- ginally fluid; and, in addition to this, we think it can eafily be proved, that this fluidity was F 3 not 86 ILLUSTRATIONS OF THE not that of the elements taken feparately, but of the entire mafs. This lat conclufion follows, from the ftructure of thofe fpecimens, where one of the fubftances is impreffed by the forms which are peculiar to another. Thus, in the Portfoy granite *, which Dr Hutton has fo mi- nutely defcribed, the quartz is impreffed by the rhomboidal cryftals of the feltfpar, and the ftone thus formed is compaé and highly confo- lidated. Hence, this granite is not a congeries of parts, which, after being feparately formed, were fomehow brought together and agglutina- ted; but it is certain that the quartz, at leaf, was fluid when it was moulded on the feltfpar. In other granites, the impreflions of the fubftan- ces on one another are obferved ina different order, and the quartz gives its form to the felt- {par. This, however, is more unufual; the quartz is commonly the fubftance which has received the impreffions of all the reft ; and the fpiculæ of {chorl often fhoot both acrofs it and the felt{par. The ingredients of granite were therefore fluid when mixed, or at leat when in conta@ with one another. Now, this fluidity was not the effect of folution in a menftruum ; for, in that cafe, one kind of cryftal ought not to im- prefs another, but each of them fhould have its own peculiar fhape. 81. The * Theory of the Earth, vol. i. P. 104. HUTTONIAN THEORY. $7 81. The perfe& confolidation of many gra- nites, furnifhes an argument to the fame effect. For, agreeably to what was already obferved, in treating of the ftrata, a fubftance, when cryftal- lizing, or pafling from a fluid to a folid flate, cannot be free from porofity, much lets fill up completely a fpace of a given form, if, at the fame time, any folvent is feparated from it ; be- caufe the folvent fo feparated would ftill occupy a certain fpace, and when removed by evapora- tion or otherwife, would leave that {pace emp- ty. The perfect adjuftment, therefore, of the fhape of one fet of cryfiallizing bodies, to the fhape of another fet, as in the Portfoy granite, and their confolidation into one mais, is as ftrong a proof as could be defired, that they cry- ftallized from a ftate of fimple fluidity, fuch as, of all known caufes, heat alone is able to pro- duce. 82. This conclufion, however, does not reft on a fingle clafs of facts. It has been obferved in many inftances, that where granite and ftra-, tified rocks, fuch as primary {chiftus, are in contact, the latter are penetrated by veins of the former, which traverfe them in various direc- tions. Thefe veins are of different dimenfions, fome being of the breadth of feveral yards, others of a few inches, or even tenths of an inch; they diminifh as they recede from the main bo~ 3 F4 dy $3 ILLUSTRATIONS OF THE dy of the granite, to which they are always firmly united, conftituting, indeed, a part of the fame continued rock. | , Thefe phenomena, which were firt diftinaly obferved by Dr Hutton, are of great importance in geology, and afford a clear folution of the two chief gueftions concerning the relation between granite and fchiftus. As every vein muft be of a date pofterior to the body in which it is contained, it follows, that the {chiftus was not fuper-impofed on the granite, ( after the formation of this laft. If it be argued, that thefe veins, though pofterior to the {chifti, are alfo pofterior to the granite, and were form- ed by the infiltration of water in which the gra- nite was diffolved or fufpended ; it may be re- plied, Imo, That the power of water to dif folve granite, is a poftulatum of the fame kind that we have fo often, and for fuch good reafon, refufed to concede; and, 2do, That in many in- {tances the veins proceed from the main body of the granite upwards into the {chiftus ; fo that they are in planes much elevated in refpect of the horizon, and have a direGion quite oppofite to that which the hypothefis of infiltration re- quires. It remains certain, therefore, that the | whole mafs of granite, and the veins proceeding from it, are coeval, and both of later formation _ than the ftrata, Now, ae HUTTONIAN THEORY. — 89 Now, this being eftablifhed, and the fluidity of the veins, when they penetrated into the fchi- ftus, being obvious, it neceffarily follows, that the whole granite mafs was alfo fluid at the fame time. But this can have been brought about only by fubterraneous heat, which alfo impelled the melted matter againft the fuper- incumbent ftrata, with fuch force as to raife them from their place, and to give them that highly in- _ clined pofition in which they are fill fupported by the granite, after its fluidity has ceafed. Thus a conclufion, rendered probable by the cryftalli- zation of granite, is eftablifhed beyond all contra- diction by the phenomena of granitic veins *. 83. With the granite, we fhall confider the proof of the igneous origin of all mineral fub- {tances as completed. Thefe fubftances, there- fore, whether flratified or unftratified, owe their coniolidation to the fame caufe, though ading with different degrees of energy. The ftrati- fied have been in general only foftened or pene- trated by melted matter, whereas the unftrati- fied have been reduced into perfect fufion. 84. In this general conclufion we may diftin- guifh two parts, which, in their degree of cer- _ tainty, differ perhaps fomewhat from one ano- ther. The firft of thefe, and that which ftands higheft in point of evidence, confifts of two ; propofitions ; * Norte xv. 90 ILLUSTRATIONS OF THE propofitions ; namely, that the fluidity which preceded the confolidation of mineral fubftances Was SIMPLE, that is, it did not arife from the combination of thefe fubftances with any fol- vent; and, next, that after confolidation, thefe bodies have been raifed up by an expanfive force acting from below, and have by that means been brought into their prefent fituation. Thefe two propofitions feem to me to be fup- ported by all the evidence that is neceflary to conititute the moft perfect demonttration. 85. The other part of the general conclufion, that fire, or more properly heat, was the caufe of the fluidity of thefe mineral bodies, and alfo ef their fubfequent elevation, is not perhaps to be confidered as a truth fo fully demonftrated as the two preceding propofitions ; it is, no doubt, a matter of THEORY ; or a portion of one of thofe inyiñble chains by which men feek to connect in the mind the ftate of nature that is prefent, with the flates of it that are paft; and partici- pates of that uncertainty from which our rea- fonings concerning fuch caufes as are not direé objects of perception, are hardly ever exempted. That it participates of this uncertaimty in a ve- ry flight degree, will, however, be admitted, ` when it is confidered that the caufe affigned has been proved fuflicient for the effet; that the fame is not true of any other known caufe ; and that — FE. = i HUTTONIAN THEORY. 9I that this theory accounts, with fingular fimpli- city and precifion, for a fyftem of facts fo va- rious and complex, as that which is prefented by the natural hiftory of the globe. 86. Neither can it be faid that the exiftence of fubterraneous. heat is a principle affumed without any evidence, but that of the geological facts which it is intended to explain: on the contrary, it is proved by phenomena within the circle of ordinary experience, namely, thofe of hot-{prings, volcanoes, and earthquakes. Thefe leave no doubt of the exiftence of heat, and of a moving and expanfive power, in the bowels of the earth; fo that the only queftions are, at what depth is this power lodged? to what ex- tent, and with what intenfity, does it a@? That it is lodged at a very confiderable depth, is ren- „dered probable by the permanency of fome of the preceding phenomena: from the earlieft times many fountains have retained their heat to the prefent day ; and volcanoes, though they be- come extinguifhed at length, have a very long period allotted for their duration. The caufe of earthquakes is certainly a force that refides very deep under the furface, otherwife the extent of the concufflion could not be fuch as has been ob- ferved in many inftances. 87. The intenfity of volcanic fire, is another circumftance that favours the opinion of its be- ing 92 ILLUSTRATIONS OF THE ing feated deep under the furface. That this intenfity is confiderable, is certain from the ex. periments made by Sir James Hall on the fufi. bility of whin-ftone and lava; from which jt appears, that the loweft temperature in which either of thefe ftones melt, is about 30° of Wedgewood’s pyrometer. Some mineralogifts have indeed aflirmed, that lava is melted, not by the intenfity of the heat applied to it, but in confequence of a certain combination formed ‘between it and bituminous fubftances, in a man- ner which they do not attempt to explain, and which has indeed no analogy to any thing that is Known. That a hypothefis, formed in fuch di- rect oppofition to the moft obvious principles of inductive reafoning, fhould have been imagined ‘by a philofopher who had examined the pheno- mena of Ætna and Vefuvius with much atten- tion, and defcribed them with great accuracy and truth, is more wonderful than that it fhould have been adopted by mineralogifts, whofe views of nature may have been confined within a ca- binet or a laboratory. It is, however, a hy- pothefis, which, having never had any fupport but from other hypothefes, hardly merited the dire refutation that it has received from the experiments juft mentioned. | 88. But, if the intenfity of volcanic heat be q fuch as is here ftated, it will be found very — difficult — en, HUTTONIAN THEORY. ~ 93 difficult to account for a fire of fuch activity, and of fuch long continuance in the fame {pot, by any decompofition of mineral fubftances near the furface. In the place where this com- buftion is fuppofed to exift, it muft be remem- bered, that there is no frefh fupply of materials to replace thofe that have been confumed, and that, therefore, the original accumulation of thefe materials in one {pot, muft have been very unlike any thing that has ever been obferved concerning the difpofition of minerals in the bowels of the earth. | 89. If, on the other hand; we afcribe the phenomena of volcanoes to the central heat, the account that may be given of them is fimple, and. confiftent with itfelf. According to all the appearances from which the exiftence of fuch heat has been inferred above, it is of a nature fo far different from ordinary fire, that it may re- quire no circulation of air, and no fupply of combuftible materials to fupport it. It is not accompanied with inflammation or combuttion, the great preflure preventing any feparation of parts in the fubftances on which it adts, and the abfence of that elaftic fluid without which heat feems to have no power to decompofe bodies, even the moft. combuftible, contributing to the unalterable nature of all the fubftances in the mineral regions. There, of confequence, the only 64 ILLUSTRATIONS OF THE only effes of heat are fufion and expanfion ‘ and that which forms the nucleus of the globe may therefore be a fluid mafs, melted, but un. changed by the aétion of heat. go. If, from the confines of this nucleus, we conceive certain fiflures and openings to traverfe the folid cruft, and to iffue at the furface of the earth, the vapours afcending through thefe may in time heat the fides of the tubes through which they pafs to a vat diftance from the lower extremities. It is, indeed, difficult to fix the limit to which this diftance may extend, on account of the great difference between the rate at which heat moves when it has a fluid for its vehicle, and when it is left to make its way alone through a folid body. In the prefent cafe, the fupply of heat is rapid, as being made by a vapour afcending through a tube of folid rock; and the diffipation of it flow, as arifing from its tranfmiffion through the rock. The wafte of heat is therefore f{mall, compared with the fup- ply, and grows fmaller at every given point, the longer the ftream of heated vapour has conti- nued to flow. Such a ftream, therefore, though it may at firt be condenfed within a fmall di- ftance of its fource, will in time reach higher - and higher, and may at laft be able to carry its heat to an immenfe diftance from the place of its original derivation. Thus, it is ealy to con- _ ceive, na e HUTTONIAN THEORY. 95 ceive, that vapours from the mineral regions may convey their heat to refervoirs of water near the furface of the earth, and may in that manner produce hot fprings, and even boiling fountains, like thofe of Rycum and Geyfer. 91. When, inftead of a heated vapour, melt- ed matter is thrown up through the /Aafts or tubes, which thus communicate with the mi- neral regions, veins of whinftone and _ bafal- tes are formed in the interior of the earth. When the melted matter reaches to the fur- face, itis thrown out in the form of lava, and all the other phenomena of volcanoes are produ- ced. | Laftly, Where melted matter of this kind, or vapours without being condenfed, have their progrefs obftruGted, thofe dreadful concuflions are produced, which feem to threaten the exift- ence even of the earth itfelf. ‘Though terrible, therefore, to the prefent inhabitants of the globe, the earthquake has its place in the great fyftem of geological operations, and is part of a feries of events, effential, as will more clearly ap- pear hereafter, to the general order, and to the prefervation of the whole. such, according to this theory, are the chan- . ges which have befallen mineral fubftances in the bowels of the earth; and though different for the ftratified and unftratified parts of thofe fubftances, 96 ILLUSTRATIONS OF THE fubftances, they are conne@ed together by the fame principle, or explained by the fame caufe, It remains to confider that part of the hiftory of both which defcribes their changes after their elevation to the furface; and here we fhall find new caules introduced, which are more dire@ly | the fubjects of obfervation, than thofe hitherto treated of ; caufes, alfo, which aQ@ on all fofiils alike, and alike prepare them for their ultimate deftination. SEG HUTTONIAN THEORY. 97 SECTION IIL OF THE PHENOMENA COMMON TO STRATIFIED AND UNSTRATIFIED BODIES. 92. HE feries of changes which foflil bodies are deftined to undergo, does not ceafe with their elevation above the level of the fea ; it affumes, however, a new direction, and from the moment that they are raifed up to the furface, is conitantly exerted in reducing them again under the dominion of the ocean. The folidity is now deftroyed which was acquired in the bowels of the earth; and as the bottom of the fea is the great laboratory, where loofe mate- rials are mineralized and formed into ftone, the atmofphere is the region where ftones are de- compofed, and again refolved into earth. This decompofition of all mineral fubftances, | expofed to the air, is continual, and is brought about by a multitude of agents, both chemical and mechanical, of which fome are known to us,. and many, no doubt, remain to be difcovered. A- mong the various aériform fluid- which compofe our atmofphere, one is already diftinguifhed as. the grand principle of mineral decompofition ; the others are not inadtive, and to them we muff add: 98 ILLUSTRATIONS OF THE add moifture, heat, and perhaps light; fub- {tances which, from their affinities to the ele- ments of mineral bodies, have a power of enter- ing into combination with them, and of thus di- minifhing the forces by which they are united to one another. By the action of air and moi- fture, the metallic particles, particularly the iron, which enters in fuch abundance into the compofition of almoft all foffils, becomes oxy- dated in fuch a degree as to lofe its tenacity ; fo that the texture of the furface is deftroyed, and a part of the body refolved into earth. 93. Some earths, again, fuch as the calcare- ous, ate immediately diffolved by water; and though the quantity fo diffolved be extremely fmall, the operation, by being continually re- newed, produces a flow but perpetual corrofion, by which the greateft rocks muft in time be fub- dued. The action of water in deftroying hard bodies into which it has obtained entrance, is much affifted by the viciflitudes of heat and cold, efpecially when the latter extends as far as the point of congelation ; for the water, when frozen, occupies a greater {pace than before, and if the body is compact enough to refufe room for this expanfion, its parts are torn afunder by a repulfive force acting in every diredtion. 94. Befides thefe caufes of mineral decompo- fition, the action of which we can in fome mea- furç idiss = HUTTONIAN THEORY. 99 fure trace, there are others known to us only by their effets. We fee, for inftance, the pureft rock cryftal affected by expofure to the weather, its luftre tarnifhed, and the polifh of its furface impaired, but we know nothing of the power by which thefe operations are performed. Thus alfo, in the precautions which the mineralogift takes to preferve the frefh fracture of his fpecimens, we have a proof how indifcriminately all the pro- ductions of the foffil. kingdom are expofed to the attacks of their unknown enemies, and we perceive how difficult it is to delay the begin- nings of a procefs which no power whatever can finally countera&. 95. The mechanical forces employed in the difintegration of mineral fubftances, are more eafily marked than the chemical. Here again water appears as the moft active enemy of hard and folid bodies; and, in every ftate, from tranfparent vapour to folid ice, from the {mallet rill to the greateft river, it attacks whatever has emerged above the level of the fea, and labours inceffantly to reftore it to the deep. , The parts loofened and difengaged by the chemical agents, are carried down by the rains, and, in their de- icent, rub and grind the fuperficies of other bo- dies. Thus water, though incapable of acting on hard fubitances by dire@ attrition, is the G2 caule LOO ILLUSTRATIONS OF THE caufe of their being fo ated on; and, when it defcends in torrents, carrying with it fand, gra- vel, and fragments of rock, it may be truly faid to turn the forces of the mineral kingdom againgt itfelf, Every feparation which it makes is ne- ceflarily permanent, and the parts once detach- ed can never be united, fave at the bottom of the ocean. | ie : 96. But it would far exceed the limits of this fketch, to purfue the caufes of mineral decom- pofition through all their forms. It is fufficient to remark, that the confequence of fo many mi- nute, but indefatigable agents, all working toge- ther, and having gravity in their favour, is a fyf- tem of univerfal decay and degradation, which may be traced over the whole furface of the land, from the mountain top to the fea fhore. That we may perceive the full evidence of this truth, one of the moft important in the natural hiftory of the globe, we will begin our furvey from the latter of thefe ftations, and retire gradually toward the former. | : | 97. If the coat is bold and rocky, it fpeaks a language eafy to be interpreted, Its broken and abrupt contour, the deep gulphs and falient promontories by which it is indented, and the pro- portion which thefe irregularities bear to the force of the waves, combined with the inequality of hardnefs in the rocks, prove, that the prefent - line a a —— ae i x . n aii t p O Cin HUTTONIAN THEORY. IOI line of the fhore has been determined by the action of the fea. The naked and precipitous cliffs which overhang the deep, the rocks hollow- ed, perforated, as they are farther advanced in the fea, and at lat infulated, lead to the fame conclufion, and mark very clearly fo many dif- ferent ftages of decay. It is true, we do not fee the fucceflive fteps of this progrefs exemplified in the ftates of the fame individual rock, but we fee them clearly in different individuals ; and the conviction thus produced, when the pheno- mena are fufficiently multiplied and varied, is as irrefiftible, as if we faw the changes actually effected in the moment of obfervation. On fuch fhores, the fragments of rock once detached, become inftruments of further de- firuction, and make a part of the powerful artillery with which the ocean affails the bul- warks of the land: they are impelled againft the rocks, from which they break off other frag- ments, and the whole are thus ground againft one another ; whatever be their hardnefs, they are reduced to gravel, the fmooth furface and round figure of which, are the moft certain proofs of a detritus which nothing can refift. 98. Again, where the fea-coaft is flat, we have abundant evidence of the degradation of the land in the beaches of fand and fmall gravel; the fand banks and fhoals that are continually . G3 changing 5 102 ILLUSTRATIONS OF THE changing ; the alluvial land at the mouths of the rivers; the bars that feem to oppofe their dif. charge into the fea, and the fhallownefs of the fea itfelf On fuch coafts, the land ufually feems to gain upon the fea, whereas, on fhores of a bolder afpect, it is the fea that generally appears to gain upon the land. What the land acquires in extent, however, it lofes in eleva- tion; and, whether its furface increafe or di- miniifh, the depredations made on it are in both cafes evinced with equal certainty. 99. If we proceed in our furvey from the fhores, inland, we meet at every ftep with the fulleft evidence of the fame truths, and parti- cularly in the nature and economy of rivers. Every river appears to confift of a main trunk, fed from a variety of branches, each running in a valley proportioned to its fize, and all of them together forming a fyftem of vallies, communi- cating with one another, and having fuch a nice adjuftment of their declivities, that none of them join the principal valley, either on too high or too low a level; a circumftance which would be infinitely improbable, if each of thefe vallies were not the work of the ream that flows in it. If indeed a river confifted of a fingle ftream, without branches, running in a ftraight val- ley, it might be fuppofed that fome great con- cuffion, HUTTONIAN THEORY. 103 cuffion, or fome powerful torrent, had open- ed at once the channel by which its waters äre conducted to the ocean; but, when the ufual form of a river is confidered, the trunk divided into many branches, which rife at a great diftance from one another, and thefe again fubdivided into an infinity of fmaller ramifica- tions, it becomes ftrongly imprefled upon the mind, that all thefe channels have been cut by the waters themfelves; that they have been flowly dug out by the wafhing and erofion of the land; and that it is by the repeated touch- es of the fame inftrument, that this curious affemblage of lines has been engraved fo deeply on the furface of the globe. too. The changes which have taken place in the courfes of rivers, are alfo to be traced, in ma- ny inftances, by fucceflive platforms of flat al- _luvial land, rifing one above another, and mark- ing the different levels on which the river has run at different periods of time. Of thefe, the number to be diftinguifhed, in fome inftances, is not lefs than four, or even five; and this ne- eeffarily carries us back, like all the operations we are now treating of, to an antiquity ex- tremely remote: for, if it be confidered, that each change which the river makes in its bed, obliterates at leaft a part of the monuments of former changes, we fhall be convinced, that G4 only 104 ILLUSTRATIONS OF THE only a {mall part of the progreffion can leave any diftinct memorial behind it, and that there is no reafon to think, that, in the part which - we fee, the beginning is included *. 101. In the fame manner, when a river under. mines its banks, it often difcovers depofites of fand and gravel, that have been made when it ran ona higher level than it does at prefent, In other inftances, the fame ftrata are’ feen on both the banks, though the bed of the river is now funk deep between them, and perhaps holds as winding a courfe through the folid rock, as if it flowed along the furface; a proof that it muft have begun to fink its bed, when it ran through fuch loofe materials as oppofed but a very inconfiderable refiftance to its ftream. A river, of which the courfe is both ferpentine and deeply excavated in the rock, is among the phenomena, by which the flow wafte of the land, and alfo the caufe of that wafte, are moft direCtly pointed out. 102. Itis, however, where rivers ifue through narrow defiles among mountains, that the iden- tity of the ftrata on both fides is moft eafily re- cognifed, and remarked at the fame time with the greateft wonder. On obferving the Pa- towmack, where it penetrates the ridge of the Allegany mountains, or the Irtifh, as it iffues from the defiles of Altai, there is no man, how- ever * NOTE xvi, —- HUTTONIAN THEORY. 103 ever little addicted to geological fpeculations, who does not immediately acknowledge, that the mountain was once continued quite acrofs the {pace in which the river now flows ; and, if he ventures to reafon concerning the caufe of fo wonderful a change, ‘he afcribes it to fome great convulfion of nature, which has torn the mountain afunder, and opened a pafiage for the , waters. It is only the philofopher, who has deeply meditated on the effe&s which action long continued is able to produce, and on the fimplicity of the means which nature employs in all her operations, who fees in this nothing but the gradual working of a ftream, that once flowed as high as the top of the ridge which it now fo deeply interfeds, and has cut its courfe through the rock, in the fame way, and almoft with the fame inftrument, by which the lapi- dary divides a block of marble or granite. 103. It is highly interefting to trace up, in _ this manner, the aGion of caufes with which we are familiar, to the produ@ion of effects, which at firft feem to require the introdu@ion of unknown and extraordinary powers; and it is no lefs interefting to obferve, how {fkilfully nature has balanced the a&tion of all the minute caufes of wafte, and rendered them conducive meine general good. Of this we have a moft remarkable inftance, in the provifion made for preferving the foil, or the coat of ve- getable 106 ILLUSTRATIONS OF THE getable mould, fpread out over the furface of the earth. This coat, as it confifts of loofe ma . terials, is eafily wafhed away by the rains, and is continually carried down by the rivers into the fea. This effect is vifible to every one; the earth is removed not only in the form of fand and gravel, but its finer particles fufpend. ed in the waters, tinge thofe of fome rivers con. tinually, and thofe of all occafionally, that is, when they are flooded or fwollen with rains, The quantity of earth thus carried down, varies according to circumftances ; it has been compu- ted, in fome inftances, that the water of a ri- ver in a flood, contains earthy matter fufpended in it, amounting to more than the two hun- dred and fiftieth part of its own bulk *. The foil, therefore, is continually diminithed, its parts being tranfported from higher to lower levels, and finally delivered into the fea. But it is a fact, that the foil, notwithftanding, re- mains the fame in quantity, or at leaft nearly the fame, and muft have done fo, ever fince the earth was the receptacle of animal or vegetable life. The foil, therefore, is augmented from other caufes, juft as much, at an average, as it is diminifhed by that now mentioned ; and this augmentation evidently can proceed from no- thing * See Lehman, Traités de Phyf. &c. tom. ili. p. 35% Note. bal acta q -HUTTONIAN THEORY. 107 ty thing but the conftant and flow difintegration of the rocks. In the permanence, therefore, of a coat of vegetable mould on the furface of the earth, we have a demontftrative proof of the continual deftruction of the rocks; and cannot but ad- mire the fkill, with which the powers of the many chemical and mechanical agents employ- _ ed in this complicated work, are fo adjufted, ty as to make the fupply and the wafte of the foil MN exactly equal to one another. i 104. Before we take leave of the rivers and p = the plains, we muft remark another fact, often 1 obferved in the natural hiftory of the latter, and k clearly evincing the former exiftence of immenfe lt bodies of frata, in fituations from which they Ik have now entirely difappeared. The fa& here i alluded to is, the great quantity of round and hard gravel, often to be met with in the foil, i under fuch circumftances, as prove, that it can t only have come from the decompofition of rocks, | that once occupied the very ground over which i this gravel is now fpread. In the chalk coun- try, for inftance, about London, the quantity of flints in the foil is every where great ; and, in Į particular fituations, nothing but flinty gravel j is found to a confiderable depth. Now, the » {ource from which thefe flints are derived is í quite evident, for they are precifely the fame with thofe contained in the chalk beds, where- 4 | ever = a ae a E o a - ~ x08 ILLUSTRATIONS OF THE ever thefe laft are found undifturbed, and from the deftruction of fuch beds they have no doubt originated. Hence a great thicknefs of chalk muft have been decompofed, to yield the quan. tity of flints now im the foil of thefe countries; for the flints are but thinly fceattered through the native chalk, compared with their abun- dance in the loofe earth. To afford, for ex. ample, fuch a body of flinty gravel as is found about Kenfington, what an enormous quantity of chalk rock muft have been deftroyed? - 105. This argument, which Dr Hutton has applied particularly to the chalk countries, may be extended to many others. The great plain of Crau, near the mouth of the Rhone, is well known, and was regarded with wonder, even in ages when the natural hiftory of the globe was not an object of much attention. The immenfe quantity of large round gravel-ftones, with which this extenfive plain is entirely co- vered, has been fuppofed, by fome mineralo- gifts, to have been brought down by the Du- rance, and other torrents, from the Alps; but, on further examination, has been found to be of the fame kind that is contained in certain hori- zontal layers of pudding-ftone, which are the ba- fis of the whole plain. It cannot be doubted, therefore, that the vaft body of gravel fpread over it, has originated from the deftru@ion of layers HUTTONIAN THEORY. 109 by layers of the fame rock, which may perhaps have My rifen to a great height above what is now the My = furface. Indeed, from knowing the depth of iw the gravel that covers the plain, and the average tig quantity of the like gravel contained in a given wj thicknefs of rock, one might eftimate how much iy of the latter has been a@ually worn away. tq Whether data precife enough could be found, w to give any weight to fuch a computation, muft ny be left for future inquiry to determine *. 106. In thefe inftances, chalk and pudding- ftone, by containing in them parts infinitely lefs deftrudtible than their general mafs, have, after they are worn away, left behind them very une- quivocal marks of their exiftence. The fame has happened in the cafe of mineral veins, where the fubftances leat fubje& to diffolution have - remained, and are fcattered at a great diftance from their native place. Thus gold, the leaft liable to decompofition of all the metals, is very generally diffufed through the earth, and is found, in a greater or lefs abundance, in the fand of almoft all rivers. But the native place of this mineral is the folid rock, or the veins and cavities contained in the rock, and from thence it muft have made its way into the foil. This, therefore, is another proof of the vaft ex- tent to which the degradation of the land, and of the a7. '— aa * Nove xvii. IIO ILLUSTRATIONS OF THE the rock, which is the bafis of it, has been car. ried; and confequently, of the great difference between the elevation and fhape of the earth’, furface in the prefent, and in former ages. 107. The veins of tin furnifh an argument of the fame kind. The ores of this metal are very indeftructible, and little fubje& to decompofi- tion, fo that they remain very long in the ground without change. Where there are tin veins, as in Cornwall, the tin-ftone or tin-ore is found in great abundance in fuch vallies and ftreams as have the fame direction with the veins; and hence the /freaming, as it is called, or wathing of the earth, to obtain the tin-ftone from it. Now, if it be confidered, that none of this ore can have come into the foil but from parts of a vein actually deftroyed, it muf ap- pear evident that a great wafte of thefe veins has taken place, and confequently of the {chiftus or granite in which they are contained. 108. Thefe leffons, which the geologift is taught in flat and open countries, become more ftriking, by the fludy of thofe Alpine trads, where the furface of the earth attains its great- eft elevation. If we fuppofe him placed for the firt time in the midft of fach a fcene, as foon as he has recovered from the impreffion made by the novelty and magnificence of the {pectacle before him, he begins to difcover the footfteps = pe ee ee eee ee ee | HUTTONIAN THEORY. I footiteps of time, and to perceive, that the works y of nature, ufually deemed the moft permanent, are thofe on which the characters of viciffitude are moft deeply imprinted. He fees himfelf in the midft of a vaft ruin, where the precipices ME which rife on all fides with fach boldnefs and af- I perity, the fharp peaks of the granite mountains, ot and the huge fragments Da furround their ME bafes, do but mark fo many epochs in the pro- wf grefsof decay, and point out the energy of thofe Cay deitructive caufes, which even the magnitude wy and folidity of fuch great bodies have been un- Je able to refift. fe 109. The refult of a more minute invettiga- tj tion, is in perfect unifon with this general im- i preflion. Whence is it, that the elevation of 4 mountains is fo obvioufly conne@ed with the si hardnefs and indeftru@ibility of the rocks which pi compofe them? Why is it, that a lofty moun- tain of foft and fecondary rock is no where to _ be found; and that fuch chains, as the Pyrenees or the Alps, never confift of any but the hardeft fione, of granite for inftance, or of thofe prima- rary ftrata, which, if we are to credit the pre- ceding theory, have been twice heated in the fires, and twice tempered in the waters, of the mineral regions? Is it not plain that this arifes, not from any direct connection between the hardnefs of Hones, and their height in the at- mofphere, ziz ILLUSTRATIONS OF THE mofphere, but from this, that the wafte and da tritus to which all things are fubje@, will not allow foft and weak fubftances to remain long in an expofed and elevated fituation? Were it not for this, the fecondary rocks, being in pofi. tion fuperincumbent on the primary, ought to be the higheft of the two, and fhould cover the primary, (as they no doubt have at one time done), in the higheft as well as the loweft fitua- tions, or among the mountains as well as in the plains. 110. Again, wherefore is it, that among all mountains, remarkable for their ruggednefs and afperity, the rock, on examination, is always found of very unequal deftructibility, fome parts yielding to the weather, and to the other caules of difintegration, much more flowly than the reft, and having ftrength fufficient to iupport themfelves, when left alone, in flender pyramids, bold projeCtions, and overhanging cliffs ? Where, on the other hand, the rock waftes uniformly, the mountains are fimilar to one another; their {wells and flopes are gentle, and they are bound- ed by a waving and continuous furface. The intermediate degrees of refiftance which the rocks oppofe to the caufes of deftruction, produce intermediate forms. It is this which gives to the mountains, of every different fpecies of rock, a reeni HUTTONIAN THEORY. 113 a different habit and expreflion, and which, in particular, has imparted to thofe of granite that venerable and majeftic character, by which they rarely fail to be diftinguifhed. 111. The ftructure of the vallies among mountains, (hews clearly to what caufe their exiftence is to be afcribed. Here we have firt a large valley, communicating dire@ly with the plain, and winding between high ridges of mountains, while the river in the bottom of it defcends over a furface, remarkable, in fuch a {cene, for its uniform declivity. Into this, open a multitude of tranfverfe or fecondary vallies, interfecting the ridges on either fide of the for- mer, each bringing a contribution to the main 3 ftream, proportioned to its magnitude; and, ex- cept where a catara now and then intervenes, all having that nice adjuftment in their levels, (99.) which is the more wonderful, the greater the irregularity of the furface. Thefe fecon- dary vallies have others of a fmaller fize open- ing into them; and, among mountains of the firft order, where all is laid out on the greatett fcale, thefe ramifications are continued to a fourth, and even a fifth, each diminifhing in fize as it increafes in elevation, and as its fup- ply of water is lefs. T hrough them all, this law is in general obferved, that where a higher val- ley joins a lower one, of the two angles which it II4 ILLUSTRATIONS OF THE it makes with the latter, that which is obtufe | is always on the defcending fide ; a law that is the fame with that which regulates the con- fluence of ftreams running on a furface nearly of uniform inclination. This alone is a proof that the vallies are the work of the ftreams; and indeed what elfe but the water itfelf, work- ing its way through obftacles of unequal refift. . ance, could have opened or kept up a commu- nication between the inequalities of an irregular and alpine furface. 112. Many more arguments, all leading to the fame conclufion, may be deduced from the general facts, known in the natural hiftory of mountains ; and, if the Oreologift would trace back the progrefs of wafe, till he come in fight of that original firuCture, of which the remains are ftill fo vaft, he perceives an immenfe mafs of folid rock, naked and unfhapely, as it firt emerged from the deep, and incomparably greater than all that is now before him. The operation of tains and torrents, modified by the hardnefs and tenacity of the rock, has worked the whole into - its prefent form; has hollowed out the vallies, and gradually detached the mountains from the | general mais, cutting down their fides into fteep precipices at one place, and {moothing them in- to gentle declivities at another. From this has refulted a tranfportation of materials, which, both for —_—, e o> 3s t HUTTONIAN THEORY. ZIG at, for the quantity of the whole, and the magni- % tude of the individual fragments, muft feem in- tj credible to every one, who has not learned to Dy calculate the effects of continued action, and to wq refle&, that length of time can convert acciden- ij talinto fteady caufes. Hence fragments of rock, eil from the central chain, are found to have tra- m ç Velled into diftant vallies, even where many in- ~ ferior ridges intervene: hence the granite of Mount Blanc is feen in the plains of Lombardy, or on the fides of Jura; and the ruins of the Carpathian mountains lie fcattered over the fhores of the Baltie *. 113. Thus, with Dr Hutton, we mhall be dif. - pofed to confider thofe great chains of moun- tains, which traverfe the furface of the globe, as cut out of maffes vaftly greater, and more lofty than any thing that now remains. The prefent appearances afford no data for calcula- ting the original magnitude of thefe maffes, or the height to which they may have been ele- vated. The neareft eftimate we can form is, where a chain or group of mountains, like thofe of Rofa in the Alps, is horizontally ftratified, and where, of confequence, the undifturbed po- fition of the mineral beds enables us to refer _ the whole of the prefent inequalities of the fur- face to the operation of wafte or decay. Thefe H2 mountains, z Nove xvin. i16 ILLUSTRATIONS OF THE mountains, as they now ftand, may not inapt. ly be compared to the pillars of earth which workmen leave behind them, to afford a mea- fure of the whole quantity of earth which they have removed. As the pillars, (confidering the mountains as fuch), are in this cafe of lefs height than they originally were, fo the meafure fur- nifhed by them is but a limit, which the quan- tity fought muft neceflarily exceed. 114. Such, according to Dr Hutton’s theory, are the changes which the daily operations of wafte have produced on the furface of the globe. Thefe operations, inconfiderable if taken fepa- rately, become great, by confpiring all to the fame end, never counteracting one another, but proceeding, through a period of indefinite ex- tent, continually in the fame direction. Thus every thing defcends, nothing returns upward ; the hard and folid bodies every where diffolve, and the loofe and foft no where confolidate. The powers which tend to preferve, and thofe which tend to change the condition of the earth’s furface, are never im equilibrio ; the latter are, in all cafes, the moft powerful, and, in refpect of the former, are like living in comparifon of dead forces. Hence the law of decay is one which fuffers no exception: The elements of all bodies were once loofe and unconnected, and to the Lm, HUTTONIAN THEORY. 117 by the fame ftate nature has appointed that they ly = fhould all return. the. 115. It affords no prefumption againft the th reality of this progrefs, that, in refpe@ of man, gh it is too flow to be immediately perceived: The fy utmoft portion of it to which our experience can extend, is evanefcent, in comparifon with the whole, and muft be regarded as the momentary increment of a vaft progreffion, circum{cribed by no other limits than the duration of the world. Tıme performs the office of integrating the infinitefimal parts of which this progreffion is made up; it collects them into one fum, and produces from them an amount greater than any that can be afiigned. 116. While on the furface of the earth fo much is every where going to decay, no new production of mineral fubftances is found in any region acceflible to man. ‘The inftances of what are called petrifactions, or the formation of fto- ny fubftances by means of water, which we. fometimes obferve, whether they be ferruginous concretions, or calcareous, or, as happens in fome rare cafes, filiceous ftalatites, are too few in number, and too inconfiderable in extent, to be. deemed material exceptions to this general rule. The bodies thus generated, alfo, are no fooner formed, than they become fubject to wafte and. diffolution, like all the other hard fubftances in H 3 nature 3. r15 ILLUSTRATIONS OF THE nature; fo that they but retard for a while the progrefs by which they are all refolved into duft, and fooner or later committed to the bofom of the deep. ; 117. We are not, however, to imagine, that there is no where any means of repairing this walte; for, on comparing the conclufion at which we are now arrived, viz. that the prefent continents are all going to decay, and their ma- terials defcending into the ocean, with the pro- pofition firt laid down, that thefe fame conti- nents are compofed of materials which muft have been collected from the decay of former rocks, it is impoflible not to recognife two corre- {ponding fteps of the fame progrefs; of a pro- grefs, by which mineral fubftances are fubje&ed to the fame feries of changes, and alternately wafted away and renovated. In the fame man- ner, as the prefent mineral fubftances derive their origin from fubftances fimilar to them- felves; fo, from the land now going to decay, the fand and gravel forming on the fea-fhore, or in the beds of rivers; from the {hells and corals which in fuch enormous quantities are every day accumulated in the bofom of the fea; from the drift wood, and the multitude of vegetable and animal remains continually depofited in the ocean: from all thefe we cannot doubt, that firata are now forming in thofe regions, to | which ee | HUTTONIAN THEORY. 119 which nature feems to have confined the powers of mineral reproduction; from which, after being confolidated, they are again deftined to emerge, and to exhibit a feries of changes fimi- lar to the paf *. 118. How often thefe viciflitudes of decay and renovation have been repeated, is not for us to determine: they conftitute a feries, of which, as the author of this theory has remark- ed, we neither fee the beginning nor the end ; a circumftance that accords well with what is known concerning other parts of the economy of the world. In the continuation of the dif- ferent fpecies of animals and vegetables that in- habit the earth, we difcern neither a beginning nor an end; and, in the planetary motions, where geometry has carried the eye fo far both into the future and the paft, we difcover no mark, either of the commencement or the ter- mination of the prefent order}. It is unreafon- able, indeed, to fuppofe, that fuch marks fhould any where exift. The Author of nature has not given laws to the univerfe, which, like the infti- tutions of men, carry in themfelves the elements of their own deftruction. He has not permit- ted, in his works, any fymptom of infancy or of old age, or any fign by which we may eftimate either their future or their paft duration. He may put anend, as he no doubt gave a begin- Hg ning, * NOTE xIx. + NOTE xx. 3 120 ILLUSTRATIONS OF THE ning, to the prefent fyftem, at fome determinate period; but we may fafely conclude, that this great caiaftrophe will not be brought about by any of the laws now exifting, and that it is not indicated by any thing which we perceive. 119. To affert, therefore, that, in the econo- my of the world, we fee no mark, either of 4 beginning or an end, is very different from af. firming, that the world had no beginning, and will have no end. The firft is a conclufion jut. tified by common fenfe, as well as found phi- lofophy ; while the fecond is a prefumptuous and unwarrantable affertion, for which no reafon from experience or analogy can ever be afligned, Dr Hutton might, therefore, juftly complain of the uncandid criticifm, which, by fubftitu- ting the one of thefe affertions for the other, en- deavoured to load his theory with the reproach of atheifm and impiety. Mr Kirwan, in bring- ing forward this harth and ill-founded cen{ure, was neither animated by the {pirit, nor guided _ by the maxims of true philofophy. By the fpi- rit of philofophy, he muft have been induced to refle&, that fuch poifoned weapons as he was preparing to ufe, are hardly ever allowable in {cientific conteft, as having a lefs dire& ten- dency to overthrow the fyftem, than to hurt the perfon of an adverfary, and to wound, perhaps incurably, his mind, his reputation, or his peace. By ie a E o ey eel a peT r dba a ae eer HUTTONIAN THEORY. IZI By the maxims of philofophy, he muft have 3 been reminded, that, in no part of the hiftory = of nature, has any mark been difcovered, either of the beginning or the end of the prefent or- der ; and that the geologift fadly miftakes, both the object of his fcience and the limits of his un- derftanding, who thinks it his bufinefs to explain the means employed by INFINITE WISDOM for eftablifhing the laws, which now govern the i world. ti By attending to thefe obvious confiderations, al Mr Kirwan would have avoided a very illiberal a and ungenerous proceeding ; and, however he might have differed from Dr Hutton as to the truth of his opinions, he would not have cen- fured their tendency with fuch rath and unjufti- fiable feverity. But, if this author may be blamed for want- ing the temper, or neglecting the rules, of phi- lofophic inveftigation, he is hardly lefs culpa- ble, for having fo flightly confidered the fcope and fpirit of a work which he condemned fo freely, In that work, inftead of finding the world reprefented as the refult of neceffity or chance, which might be looked for, if the accufations of atheifm or impiety were well founded, we fee every where the utmoft atten- tion to difcover, and the utmoft difpofition to admire, the inftances of wife and beneficent de- fign, 122 ILLUSTRATIONS OF THE fign manifefted in the ftruture, or economy of the world. ‘The enlarged views of thefe, which his geological fyftem afforded, appeared to Dr Hutton himfelf as its moft valuable refult. They were the parts of it which he contemplated with greateft delight; and he would have been lefs flattered, by being told of the ingenuity and originality of his theory, than of the addition which it had made to our knowledge of final caufes. It was natural, therefore, that he fhould be hurt by an attempt to accufe him of apinions, fo different from thofe which he had always taught; and if he anfwered Mr Kirwan’s attack with warmth or afperity, we mutt afcribe it to the indignation excited by unmerited reproach. _ 120. But to return to the natural hiftory of the earth : Though there be in it no data, from which the commencement of the prefent order can be a{certained, there are many by which the exift- ence of that order may be traced back to an anti- quity extremely remote... The beds of primitive ‘{chiftus, for inftance, contain fand, gravel, and other materials, collected, as already fhewn, from the diffolution of mineral bodies; which bodies, / therefore, muft have exifted long before the oldeft part of the prefent land was formed. Again, in — this gravel we fometimes find pieces of fandftone, and cf other compound rocks, by which we are of courfe carried back a ftep farther, fo as to reach a z r m A: HUTTONIAN THEORY. 123 i, = 3 fyftem of things, from which the prefent is to) the third in fucceffion ; and this may be confi- Th dered as the moft ancient epocha, of which any memorial exifts in the records of the foflil hy kingdom. ke 121. Next in the order of time to the confo- lidation of the primary ftrata, we muft place their elevation, when, from being horizontal, h and at the bottom of the fea, they were broken, fet on edge, and raifed to the furface. Itis even probable, as formerly obferved, that to this fuc- ceeded a depreflion of the fame ftrata, and a fe- lit cond elevation, fo that they have twice vifited ii the fuperior, and twice the inferior regions. During the fecond immerfion, were formed, firk, i the great bodies of pudding-ftone, that in fo ls many inftances lie immediately above them; i and next were depofited the ftrata that arẹ I` ftri&ly denominated fecondary. w. 122. The third great event, was the raifing up of this compound body of old and new ftra- ta from the bottom of the fea, and forming it into the dry land, or the continents, as they now exift*. Contemporary with this, we muft fup- pofe the injeCtion of melted matter among the frata, and the confequent formation of the cry- ftallized and unftratified rocks, namely, the gra- nite, metallic veins, and veins of porphyry and whinftone. y Note XXI, rd 124 ILLUSTRATIONS OF THE whinftone. This, however, is to be confidered as embracing a period of great duration; and it muft always be recollected, that veins are found of very different formation ; fo that when we {peak generally, it is perhaps impoffible to ftate any thing more precife concerning their an- tiquity, than that they are pofterior to the ftrata, and that the veins of whinftone feem to be the moft recent of all, as they traverfe every other, 123. In the fourth place, with refpe& to time, we mutt clafs the facts that regard the de- tritus and wafte of the land, and muft carefully diftinguifh them from the more ancient pheno- mena of the mineral kingdom. Here we are to reckon the fhaping of all the prefent inequa- lities of the furface; the formation of hills of gravel, and of what have been called tertiary ftra- ta, confifting of loofe and unconfolidated mate- rials ; alfo collections of fhells not mineralized, like thofe in Turaine; fuch petrifactions as thofe contained in the rock of Gibraltar, on the coaft of Dalmatia, and in the caves of Bayreuth. The bones of land animals found in the foil, fuch as thofe of Siberia, or North America, are 3 probably more recent than any of the former *. 124. Thefe phenomena, then, are all fo many marks of the lapfe of time, among which the principles of geology enable us to diftinguith a certain * NOTE xxiL Fa all HUTTONIAN THEORY. 12 ty certain order, fo that we know fome of them to A be more, and others to be lefs diftant, but with- h, out being able to afcertain, with any exactnefs, th the proportion of the immenfe intervals which bh feparate them. Thefe intervals admit of no it, comparifon with the aftronomical meafures of ly time; they cannot be expreffed by the revolu- yj tions of the fun or of the moon; nor is there fy any fynchronifm between the mof recent epo- a, chas of the mineral kingdom, and the moft an- nj cient of our ordinary chronology. i 125. On what is now faid is grounded ano- ther objection to Dr Hutton’s theory, namely, that the high antiquity afcribed by it to the earth, is inconfiftent with that fyftem of chro- ui nology which refts on the authority of the Sacred. Writings. This objection would no doubt be of weight, if the high antiquity in queftion were not reftricted merely to the globe of the earth, but were alfo extended to the human race. That the origin of mankind does not go back beyond fix or feven thoufand years, is a pofition fo involved in the narrative of the Mo- faic books, that any thing inconfiftent with it, would no doubt fland in oppofition to the teftimony of thofe ancient records. On this fubject, however, geology is filent; and the high as any authentic monuments extend, refers j i hitory of arts and fciences, when traced as f j the ate 126 ILLUSTRATIONS OF THE the beginnings of civilization to a date not very different from that which has juft been men- tioned, and infinitely within the limits of the moft recent of the epochas, marked by the phy- fical revolutions of the globe. On the other hand, the authority of the Sa. cred Books feems to be but little interefted in what regards the mere antiquity of the earth it-° felf; nor does it appear that their language is to be underftood literally concerning the age of that body, any more than concerning its figure or its motion. The theory of Dr Hutton ftands here precifely on the fame footing with the fyf- tem of Copernicus; for there is no reafon to fuppofe, that it was the purpofe of revelation to furnifh a ftandard of geological, any more than of aftronomical {cience. It is admitted, on all hands, that the Scriptures are not intended to refolve phyfical queftions, or to explain matters in no way related to the morality of human actions ; and if, in confequence of this princi- ple, a confiderable latitude of interpretation were not allowed, we fhould continue at this moment to believe, that the earth is flat ; that the fun moves round the earth; and that the circum- ference of a circle is no more than three times | its diameter. - It is but reafonable, therefore, that we fhould extend to the geologift the fame liberty of fpe- culation, HUTTONIAN THEORY. 127 culation, which the aftronomer and mathema- tician are already in poffeffion of; and this may be done, by fappofing that the chronology of Moszs relates only to the human race. This liberty is not more neceflary to Dr Hutton than to other theorifts. No ingenuity has been able to reconcile the natural hiftory of the globe with the opinion of its recent origin; and ac- cordingly the cofmologies of Kirwan and De Luc, though contrived with more mineralogical {kill, are not lefs forced and unfatisfactory than thofe of Burnet and Whitton. 126. It is impoffible to look back on the fyf- tem which we have thus endeavoured to illuf- trate, without being flruck with the novelty and beauty of the views which it fets before us. The very plan and fcope of it diftinguifh it from all other theories of the earth, and point it out as a work of great and original invention. ‘The fole object of fuch theories has hitherto been, to explain the manner in which the pre- fent laws of the mineral kingdom were firft eftablifhed, or began.to exift, without treating of the manner in which they now proceed, and T _ by which their continuance is provided for. The authors of thefe theories have accordingly gone back to a ftate of things altogether unlike the prefent, and have confined their reafonings, or their i28 ILLUSTRATIONS OF THE their fictions, to a crifis which never has exifted but once, and which never can return, Dr Hutton, on the other hand, has guided his in- veitigation by the philofophical maxim, Caufam naturalem et afiduam querimus, non raram et fortuitam. His theory, accordingly, prefents us with a fyftem of wife and provident economy, where the fame inftruments are continually em- ployed, and where the decay and renovation of foflils being carried on at the fame time in the different regions allotted to them, preferve in the earth the conditions effential for the fupport of animal and vegetable life. We have been long accuftomed to admire that beautiful ton- trivance in nature, by which the water of the ocean, drawn up in vapour by the atmofphere, im- parts, in its defcent, fertility to the earth, and be- comes the great caufe of vegetation and of life ; but now we find, that this vapour not only ferti- lizes, but creates the foil; prepares it from the fo- lid rock, and, after employing it in the great ope- rations of the furface, carries it back into the re- gions where all its mineral charaGers are renew- ed. Thus, the circulation of moifture through the air, is a prime mover, not only in,the annual fucceffion of the feafons, but in the great geolo- gical cycle, by which the wafte and reproduc- tion of entire continents is circumfcribed. Per- haps a more ftriking view than this, of the wil- dom ani HUTTONIAN THEORY. 128 dom that prefides over nature, was never pre- fented by any philofophical fyftem, nor a great- er addition ever made to our knowledge of final caufes. It is an addition which gives confiftency to the reft, by proving, that equal forefight is ex- erted in providing for the whole and for the parts, and that no lels care is taken to maintain the conftitution of the earth, than to preferve the tribes of animals and vegetables which dwell on its furface. In a word, it is the peculiar ex- cellence of this theory, that it afcribes to the phenomena of geology an order fimilar to that which exifts in the provinces of nature with which we are beft acquainted ; that it produ: ces feas and continents, not by accident, but by the operation of regular and uniform caufes ; that it makes the decay of one part fubfervient to the reftoration of another, and gives ftability to the whole, not by perpetuating individuals, but by reproducing them in fucceffion. 127. Again, in the detail of this theory, and the ample induGion on which it is founded, we meet with many facts ‘and obfervations, either entirely new, or hitherto very imperfectly un- derftood. Thus, the veins which proceed from _ Imafles of granite, and penetrate the incumbent {chiflus, had either efcaped the obfervation of former mineralogifts, or the importance of the phenomenon had been entirely overlooked. Dr Hutton 130 ILLUSTRATIONS OF THE Hutton has defcribed the appearances with great accuracy, and drawn from them the moft inte. refting conclufions. At the jun@tion of the pri- mary and fecondary ftrata, the faéts which he has noted had been obferved by others; but no. one | think had fo fully underflood the language which they fpeak, or had fo clearly perceived the confequences that neceffarily follow from them. He is the firt who diftin@ly pointed out the characters which diftinguith whinftone from lava, and who explained the true relation that fubfifts between thefe fubftances. He alfo difcovered the induration of the ftrata, in con- tact with veins of whin, and the charring of the coal in their vicinity. His theory alfo enabled him to determine the affinity of whinftone and granite to one another, and their relation to the other great bodies of the mineral kingdom. To the obfervations of the fame excellent geologift, we are indebted for the knowledge of the general and important ta@, that all the hard fubtiances of the mineral kingdom, when ele- vated into the atmofphere, have a tendency to decay, and are fubje& to a difintegration and wafte, to which no limit can be fet but that of their entire deftru@iion; that no provifion 18 — made on the turface for repairing this watte, and that there, no new foffil is produced ; that the formation of all the varied {cenery which the furtace VS ee ee eS E R HUTTONIAN THEORY. 131. furface of the earth exhibits; depends on the operation of caufes, the momentary exertions of which are familiar to us, though we knew not before the effects which their accumulated ac- tion was able to produce. Thefe are faéts in the natural hiftory of the earth, the difcovery of which is due to Dr Hutton; and, fhould we lay all further fpeculation afide, and confider the theory of the earth as.a work too great to be attempted by man, we muft ftill regard the phe- nomena and laws juft mentioned, as forming a folid and valuable addition to our knowledge. 128. If we would compare this theory with others, as to the invifible agents which it €m- ploys, we muft confider, that fire and water are the two powers which all of them muft make ufe of, fo that they can differ from one another only by the way in which they combine thefe powers. In Dr Hutton’s fyftem, water is firt employed | to depofite and arrange, and then fire to confo- lidate, mineralize, and laftly, to elevate the ftra- ta; but, with refpeé ta the unftratified or cry- ftallized fubfiances, the ation of fire only is recognifed. The fyftem having leaft affinity to this is the Neptunian, which afcribes the for- i mation of all minerals to the action of water alone, and extends this hypothefis even to the unftratified rocks. Here, therefore, the a¢tion of fire is entirely excluded ; and the Neptunifts ; I2 have 132. ILLUSTRATIONS OF THE have certainly made a great facrifice to the love of truth, or of paradox, in rejecting the affift. ance of fo powerful an auxiliary *. i 129. In the fyftems which employ the ssd of the latter element, we are to look for a great- er refemblance to that of Dr Hutton, though many and great marks of diftinction are eafily perceived. In the cofmologies, for example, of Leisnirz and Burron, fire and water are both employed, as well as in this; but they are em- ployed in a reverfe order.” Thefe philofophers introduce the action of fire firt, and then. the action of water, which is to invert the order of nature altogether, as the confolidation of the rocks muft be pofterior to their ftratification. Indeed, the theory of Buffon is fingularly de- fective : befides inverting the order of the two great operations of ftratification and confolida- tion, and of courfe giving no real explanation of the latter, it gives no account of the elevation, or highly inclined pofition of the ftrata ; it makes no diftin@ion between ftratified and unftratified bodies, nor does it offer any but the moft unfa- tisfactory explanation of the inequalities of the earth’s furface. This fyftem, therefore, has but a very diant refemblance to the Huttonian theory +. 130. The fyftem of Lazzaro Moro has been remarked as approae hing nearer to this theo- ry * NOTE xxiii. t Nove xxiv. HUTTONIAN THEORY. 133 it ty than any other; and it is certain, that one } very important principle is common to them Ney both. The theory of the Italian geologift was ca. chiefly directed to the explanation of the re- tet ‘ mains of marine animals, which are found in fh mountains far from the fea; and it appears to, Y | have been fuggefted to him by the phenomenia nh of the Campi Phlegrai, and by the produdtio:n 7 = of the new ifland of Santorini in the Archipt2- et j lago. He accordingly fuppofes, that the iflancls t and continents have been all raifed up, like the ni above-mentioned ifland, from the bottom of tlhe tht fea, by the force of volcanic fire: that thefe a fires began to burn under the bottom of the bk ocean, foon after the creation of the world, when as yet the ocean covered the whole earth: that they at firft elevated a portion of the land; and in this primitive land no fhells are found, as the original ocean was deftitute of fifh. The vol- canoes continuing to burn; under the fea, after the creation of animated nature, the firata that were then raifed up by their action were full of fhells and other marine objects; and, from the violence with which they were elevated, arofe the contortions and inclined pofition which they _. frequently poffefs * Se. 13 This * Dé Croftacei, et degli altri Marini Corpi, che fi trovano fu’ Monti: di Ant. Lazzaro Moro, Vinezia. 1740. 134 ILLUSTRATIONS OF THE This fyftem is imperfe&, as it makes no pe- culiar provifion for the confolidation of the ftra. ta, which, according to it, as well as the Nep- tunian fyftem, muft be afcribed to the action, not of fire, but of water. No account is given «of the mineralization of the fhells found in the Í trata, or of the difference between them. and tlie fhells found loofe at the bottom of the fea; aiid no diftinction is made between ftratified and unftratified fubftances. But, with all this, Lazzaro Moro has certainly the merit of having perceived, that fome other power than that which depofited the ftrata, muft have been em- ployed for their elevation, and that they have endured the action of a difturbing force. 131. From this comparifon it appears, that Dr Hutton’s theory is fufliciently diftin&, even from the theories which approach to. it mof nearly, to merit, inthe ftrictett fenfe, the appel- lation of new and original. There are indeed few inventions or difcoveries, recorded in thë hiftory of fcience, to which nearer approaches were not made before they were fully unfolded. It therefore very well deferves to be diftinguith- ed by a particular name; and, if it behoves us to follow the analogy obferved in the names of the two great fyftems, which at prefent divide the opinions of geologifts, we may join Mr Kir- wan in calling this the PLuronic System. For my HUTTONIAN THEORY. 135 my own part, I would rather have it characteriz- ed by a lefs fplendid, but jufter name, that of the Hurronrtan THEORY. 132, The circumftance, however, which gives to this theory its peculiar character, and exalts it infinitely above all others, is the introduétion of the principle of preffure, to modify the effects of heat when applied at the bottom of the fea. This is in fact the key to the grand enigma of the mineral kingdom, where, while one fet of > phenomena indicates the action of fire, another fet, equally remarkable, feems to exclude the poflibility of that action, by prefenting us with mineral fubftances, in fuch a ftate as they could never have been brought into by the operation of the fires we fee at the furface of the earth. Thefe two claffes of phenomena are reconciled together, by admitting the power of compreflion to confine the volatile parts of bodies ‘when heat is applied to them, and to force them, in many inflances, to undergo fufion, inftead of being calcined or diffipated by burning or inflamma- tion. In this hypothefis, which fome affe& to confider as a principle gratuitoufly aflumed, there appears to me nothing but a very fair and legi- » timate generalization of the properties of heat. Combuttion and inflammation are chemical pro- ceffes, to which other conditions are required, befides the prefence of a high temperature. The I 4 flate 136 ILLUSTRATIONS OF THRE ftate of the mineral regions makes it reafonable to prefume, that thefe conditions are wanting in the bowels of the earth, where, of confe: quence, we have a right to look for nothing but expanfion and fufion, the only ‘operations which feem effential to heat, and infeparable from the application of it, in certain degrees, to certain fubitances. Though this principle, therefore, had no countenance from analogy, the admirable fimplicity, and the unity, which it introduces into the phenomena of geology, would fufficient- ly juftify the application of it to the theory of the earth, As another excellence of this theory, I may, perhaps, .be allowed to remark, that it extends its confequences beyond thofe to which the au- thor of it bas himfelf adverted, and that it ailords, which no geological theory has yet done, a fatisfaCtory ‘explanation of the {pheroidal fi- gure of the earth *, 133. Yet, with all thefe cir jinality, grandeur, and fimplicity in its favour, with the addition of evidence as demonftrative as the nature of the fubje@ will admit, this theory has probably many obftacles to overcome, before it meet the general approbation. The ( greatnefs of the objects which it fets before us, alarms the imagination; the powers which it fuppoies to be lodged in the fubterraneous re- gions, n ces of ori- * NOTE xxv. HUTTONIAN THEORY. 137 gions; a heat which has fubdued the moft re- ‘frattory rocks, and has melted beds of marble and quartz; an expanfive force, which has fold- ed up; or broken the ftrata, and raifed whole continents from the bottom of the fea; thefe are things with which, however certainly they = may be proved, the mind cannot foon be fami- zf Jiarifed. ‘The change and movement alfo, which this theory afcribes to all that the fenfes declare “~~ to be moft unalterable, raife up againft it the ti {ame prejudices which formerly oppofed the be- “lief in the true fyftem of the world ; and it af- E fords a curious proof, how little fuch preja- ) dices are fubje@ to vary, that as ARISTAR- i cHus, an ancient follower of that fyftém, was t charged with impiety formoving the everlafting i} Vasra from her place, Dr Hutton, nearly on i the fame ground, has been fubjected to the very I} fame accufation. Even the length of time il which this theory regards as neceflary to the re- 3 } volutions of the globe, is looked on as belong- | ing to the marvellous; and man, who finds himfelf conftrained by the want of time, or of {pace in almoft all his undertakings, forgets, that in thefe, if in any thing, the riches of na- ture rejects all limitation *. ? The evidence which muft be oppoled to all | thefe caufes of incredulity, cannot be fully un- deritood without much ftudy and attention. | ae It * NOTE xxvi. 138 ILLUSTRATIONS OF THE It requires not only a careful examination of particular inftances, but comprehenfive views of the whole phenomena of geology ; the com. parifon of things very remote with one ano- ther; the interpretation of the obfcure by the luminous, and of the doubtful by the decifive ap. pearances. The geologift muft not content him: felf with examining the infulated {pecimens of his cabinet, or with purfuing the nice fubtleties of mineralogical arrangement; he muft ftudy the relations of foffils, as they actually exift; he mutt follow nature into her wildeft and mof inacceflible abodes; and mutt fele&, for the places of his obfervations, thofe points, from which the variety and gradation of her works can be moft extenfively and accurately explored. Without fuch an exag and comprehenfive fur- vey, his mind will hardly be prepared to relifh the true theory of the earth. “ Narure-enim vis atque majeftas omnibus momentis fide caret, Ji quis modo partes atque non totam complectatur animo *,”’ 134. If indeed this theory of the earth is as well founded as we fuppofe it to be, the lapfe of time muft neceflarily remove all obje&tions to it, and the progrefs of {cience will only develope — its evidence more fully. As it ftlands at pre- fent; > * Prin. Hitt, Nat. lib. vii. cap. i. HUTTONIAN THEORY. 136 fent, though true, it muft be ftill imperfed ; and it cannot be doubted, that the great prin- ciples of it, though eftablifhed on an immove- i able bafis, muft yet undergo many modifica- ‘ tions, requiring to be limited, in one place, or to be extended, in another. A work of fuch varie- | ty and extent cannot be carried to perfection ag by the efforts of an individual. Ages may be te required to fill up the bold outline which Dr h : Hutton has traced with fo mafterly a hand ;. to et = detach the parts more completely from the. ge- ln — neral mafs; to adjuit the fize and pofition of Il the fubordinate members; and to give to the ft whole piece the exa@ proportion and true co- Wi louring of nature. lone This, however, in length of time, may be €X- eh pe&ed from the advancement of fcience, and ri from the mutual affiftance which parts of know- i ledge, feemingly the moft remote, often afford oi toone.another. Not only may the obfervations Į of the mineralogift, in tras yet unexplored, complete the enumeration of geological facts; «, and the experiments of the chemift, on fubftan- je ces not yet fubjeĝëd to his analyfis, afford | amore intimate acquaintance with the nature of foffils, and a meafure of the power of thofe = chemical agents to which this theory afcribes fuch vaft effects: but alfo, from other {ciences, lefs dire@tly connected with the natural hiftory of ‘Nt vimi ï40 ILLUSTRATIONS, &¢. of the earth, much information may be received, | The accurate geographical maps and furveyg which are now making ; the foundings; the oh. fervations of currents ; the baromettical meafure. — ments, may all combine to afcertain the reality, and to fix the quantity of thofe changes which terreftrial bodies continually undergo. Every new improvement in fcience affords the means of delineating more accurately the face of na. _ ture as it now exifts, and of tran{mitting, to future ages, an account, which may be com: pared with the face of nature as it fhall then exift. If, therefore, the fcience of the prefent times is deftined to furvive the phyfical revo- lutions of the globe, the Hurronian THEORY may be confirmed by hiftorical record ; and the author of it will be remembered among the il- luftrious few, whofe fyftems have been verified by the obfervations of fucceeding ages, fupport- ed by facts unknown to themfelves, and efta- blifhed by the decifions of a tribunal, flow, but _ infallible, in diftinguifhing between truth and falfehood. 3 NOTES — i o = al NOTES ann ADDITIONS. j l | [ 143 ] NOTES anp ADDITIONS. Note tr. § 2. Origin of calcareous rocks. 134. WL has been aflerted, that Dr Hutton went further than is ftated at § 2., and maintained all calcareous matter to be originally of animal formation. This pofition, however, is ` fo far from being laid down by Dr Hutton, that it belongs to an inquiry which he carefully avoid- ed to enter on, as being altogether beyond the limits of philofophical inveftigation. He has indeed no where treated of the firi origin of any of the earths, or of any fubftance whatfoever, but only of the transformations which bodies have undergone fince the prefent laws of nature were eftablifhed. He confidered this lat as all that a fcience, built on experi- ment and obfervation, can poflibly extend to; and willingly left, to more prefumptuous in- quirers, the tafk of carrying their reafonings beyond the boundaries of nature, and of unfold- ing the properties of the chaotic fluid, with as much minutenefs of detail, as if they were de- feribing M 144 ILLUSTRATIONS OF THE {cribing the circumftances of a chemical procef which they had a&tually witneffed. | The idea of calcareous matter which really be. longs to the Huttonian Theory, is, that in all the changes which the terraqueous globe has undergone in paft ages, this matter exifted, as it does now, either in the form of limeftone and marble, or in the compofition of other ftones, or in the ftate of corals, hells, and bones of animals. It may be true, that there jis no particle of calcareous matter, at prefent exift- ing on the furface of the earth, that has not, at fome time, made a part of an animal bo- dy ;-but of this we can have no certainty, nor is it of any importance that we fhould. It is enough to know, that the rocks of marble and limeftone contain in general marks of having been formed from. materials collected at the bottom of the fea; and of this a fingle cockle- fhell, or piece of coral, found included in a rock, is a fufficient proof with refpe@ to the whole mafs of which it makes a part.. The principal obje& which Dr Hutton had in view when he fpoke of the maffes of mar- ble and limeftone, as compofed of the calca- 7 reous matter of marine bodies *, was to prove, | that they had been all formed-at the bottom of | the - eames 4 —_ * Theory of the Earth, vol. i, p. 23, 246 af ae E —— ae x — > HUTTONIAN THEORY. _ 145 the fea, and from materials there depofited. His general conclufion is, “ that all the ftrata of the earth, not only thofe confifting of fuch calca- reous maffes, but others fuperincumbent upon thefe, have had their origin at the bottom of the fea, by the collection of fand and gravel, of fhells, of coralline and cruftaceous bodies, and of earths and clays varioufly mixed, or feparated and accumulated. This is a general conclufion, well authenticated by the appearances of nature, and highly important in the natural hiftory of | the earth *.’’ _ 135. In his Geological Efays, Mr Kirwan fays, that “ fome geologifts, as Buffon, and of late Dr Hutton, have excluded calcareous earth from the number of the primeval, afferting the maffes of it we at prefent behold to proceed from fhell- fih. But, in addition to the unfounded fuppo- fition, that fhell-fith, or any animals, poffefs the power of producing any fimple earth, thefe phi- lofophers fhould have confidered, that, before the exiftence of any fifh, the ftony maffes that inclofe the bafon of the fea, muft have exifted ; and, among thefe, there is none in which calca- reous earth is not found. Dr Hutton endea- \ Yours to evade this argument, by fuppoling the. world we now inhabit to have arifen from the ruins x Theory of the Earth, vol. i. p. 26. 146 ILLUSTRATIONS OF THE ruins and fragments of an anterior, without pointing at any original. If we are thus to proceed zn infinitum, I fhall not pretend to fol- low him; but, if he ftops any where, he will find the fame argument equally to occur *,” The argument here employed would certain. ly be conclufive againft any one, who, in dif. puting about the jfirff origin of things, fhould deny that the calcareous is as ancient as any other of the fimple earths. But this has nothing to do with Dr Hutton’s {peculations, which, as has been juft faid, never extended to the firft origin of tubftances, but were confined entirely to their changes ; fo that what he afferts concern- ing the calcareous rocks, is no more than that _ thofe which we now fee have been formed from loofe materials, depofited at the bottom of the fea. It was not therefore in order to evade Mr Kir- wan’s argument, as the preceding paffage would lead us to believe, that he fuppofed the world which we now inhabit to have arifen from the ruin and wafte of an anterior world ; but it was becaufe this feemed to him a conclufion which neceffarily followed from the phenomena of geology, and it wasaconclufion that he had deduced long before he heard of Mr Kirwan’s objections to his fyftem. Inftead of an evafion, ` therefore, ——) x Geal. Efays, pe I3. EP OS E E PA A HUTTONIAN THEORY: 144 ei i PF at therefore, any one who confiders the fubjeét dng fairly, will fee, in Dr Hutton’s reafoning, no- he À | thing but the caution of a philofopher, wlio ré) | wifely confines his theory within the fame limits by which nature has confined his ‘experience ET and obfervation. d It is neverthelefs true, that Dr Hutton has ' R fometimes expreffed himfelf as if he thought a that the poen eae argons — are all compo- hick, fed of animal remains *, ‘This conclufion, how- the ever, is more general than the facts warrant > M and, from fome incorrectnefs or ambiguity of enag language, is certainly more general than he in- onen tended. The idea of calcareous rocks, on which ian tt} he argues throughout his whole theory, is precife- ed int ly that which is ftated in the preceding article: Mr Kr > woul Note Ii. § 6. e wif Origin of coal. om t t it i 136. The vegetable origin of coal feems to be hid fufficiently proved by the reafoning in § 5. and 6.; and that reafoning will appear ftill more ia- © tisfađorý, from what is faid at § 25. and 29. | A concerning the confolidation of this fol. Dr fi ~ Hutton has treated both cf the matter of coal oa K 2 and ot Theory of the Earth, vol. 1. p. 23: 148 ILLUSTRATIONS OF THE and of its confolidation, Part. I. Chap. 8. of his Theory of the Earth *. | The notion, however, that coal is of vegeta. ble origip, is not peculiar to this theory, but has been for fome time the prevailing opinion, Buffon fuppofes this mineral to be formed from vegetable and animal fubftances, the oil and fat of which have been converted into bitumen by the action of acids}. A fundamental miftake, however, is committed by this author, and by M. Gensanne, (author of the natural hiftory of Languedoc), on whofe obfervations he greatly re- lies, in confidering coal as confifting of bitumen united to earth, thus omitting the only ingre- dient effential to coal, namely the carbon or charcoal. This may truly be confidered as the eflential part, becaufe coal may exift without — bitumen, as in the inftance of blind-coal, but not without charcoal. Another theory of coal, very analogous to Dr Hutton’s, is that of Arpurno, profefior of mi- neralogy at Venice, in which he fuppofes it formed from vegetable and animal remains from the land and fea, but chiefly from the latter $. * Vol. i. p: 558, &c. + Hift. Nat. des Mineraux, tom. i. p. 429. 4to edit. ł Saggio Fifico-mineralogico del Sig. Giovy, Arduinoy Atti di Siena, tom. v, P. 228, 281, &e, This — een t | l. 1 | HUTTONIAN THEORY. 149 This theory of coal is contained in Dr Hutton’s, W in which the animal and vegetable remains muft = be fuppoied to come both from the earth and It the fea. It feems to be without any good rea- lfy fon that Arduino confiders the fea as the chief iy fource of thefe materials. His remarks, how- mj) ever, are very ingenious, and deferving of atten- iy tion. | Thefe accounts of the origin of coal are all nearly the fame ; it is in what relates to the di- , . tinction between the common coal, in which | there is no ligneous ftru@ure, and thofe varieties of it in which that ftructure is apparent, and again in explaining the confolidation of both, _ that the theory, laid down here, is peculiar. 137. Some other mineralogifts refer one of the ingredients of coal to the vegetable king- dom, but not the other. Unable to refift the conviction which arifes from the fibrous ftruc- ture of parts of ftrata, and even entire ftrata of coal, they have fuppofed, that wood, which had been fomehow buried in the earth, or perhaps depofited at the bottom of the fea, had become impregnated with bitumen, which laft, however, _. they confider as of mineral origin. This appears -to be the opinion of Lehman, and alfo of fome very late writers. There feems, however, to be hardly lefs reafon for referring the origin of one part of coal to the vegetable or animal kingdom K 3 than aoe Pa = 730 ILLUSTRATIONS OF THE | than another. The two laft are certainly capable of furnifhing both the carbonic and bituminous parts; and therefore, to derive thefe from dif. ferent fources, is at leaft a very unneceflary com. © plication of hypothefes. 138. Another explanation of coal, very dif ferent from any of the preceding, has lately been advanced and fet up in oppolition to the Hut. — tonian Theory. Mr Kirwan *, the only minera- ` ee logift, I believe, who has attempted to derive both the carbonic and bituminous matter of coal from the mineral kingdom, diftinguifhes between wood-coal and mineral-coal, and gives a theory entirely new of the formation of the latter. Wood-coal is that in which the ligneous ftruc- ture is fo apparent, as to leave no doubt of its - vegetable origin; mineral coal is that in which no luch ftructure can be difcovered, and is the fame which Dr Hutton derives from the vegeta- ble juices, and other remains, comminuted, dif- perfed, carried into the fea, and there precipi- tared, fo as to unite with different proportions of earth, and to become afterwards mineralized. Thefe two fpecies of coal, which the Hutto- | nian theory confiders as gradations of the fame, — z, fubitance, Mr Kirwan regards as perfectly di- fing, conftituting two minerals, of an origin an Se o # Geol. Effays, eflay vil. p. 290. HUTTONIAN THEORY. 151 and formation entirely different. He therefore endeavours to afcertain the diftinguifhing: cha- racters of each, confidered geologically. 139. But here the leading diftinction, implied in all the reft, that the two kinds of coal are ne- ver found in the fame bed, but always in differ- ent fituations, and with different laws of ftrati- fication, is exprefsly contradicted by matter of fact. Coal, as is faid above, with its ligneous texture quite apparent, and coal with no fuch firucture vifible, are often found in the fame feam, are brought up from the fame mine, and united in the fame fpecimen. I have a fpeci- men from a bed of coal, in the Ifle of Sky, found under a bafaltic rock, confifting of a ligneous part, which graduates into one in which there is no veftige of a fibrous texture, and in which the furface is fmooth and gloffy, with a fracture al- moft vitreous. The upper part of the fpecimen is therefore perfe& wood-coal, and the under part perfect mineral-coal, in the language of Mr Kirwan; at the fame time that the tranfition from the one to the other is made by infenfible degrees. This fpecimen, were it perfectly fo- litary, is fuflicient to prove the identity of the two. fpecies of coal we are now {peaking of, and to fhew, that the difference between them is ac- _cidental, not effential, The fpecimen, however, is far from being folitary ; the number of fimi- K 4 lar 152 ILLUSTRATIONS OF THE lar appearances is fo great, as hardly to have ef. caped the obfervation of any mineralogift. Mr Kirwan admits, that wood-coal is often found un- der bafaltes*; but what is effential to be remark. ed is, that, in this inftance, we have both the wood-coal, and the common mineral-coal, lying under that rock, and the one paffing gradually into the other. It appears, indeed, that many of the facts which Mr Kirwan produces, in treating of what he calls carboniferous foils, are quite in- confiftent with the diftin&ion he would make between wood-coal and mineral-coal +, 140. It is, however, true, that there are in- ftances in which the wood-coal, or foflil- wood, as it is ufually called, forms entire beds, quite unconnected with the ordinary coal, and ftrati- fied in fome refpects differently. Such is the Bovey coal in Devonfhire, the wood-coal in the north of Ireland, and perhaps the Surturbrandt of Iceland. With refpe& to the Bovey coal, it does by no means anfwer to one of Mr Kirwan’s re- marks, viz. that late obfervations have afcertained, that no fuch parallelifm of the beds, as in mine- ral-coal, nor even any diftiné& number of ftrata, is found. In the Bovey coal, the number of ftrata is very well defined, by beds of clay re- gularly interpofed ; but as to the extent of thefe beds, * Geol. Effays, p. 310. t ibid. p. 311. a in R ERE re ij b- HUTTONIAN THEORY. 153 beds, the coal having been worked only at one place, and by an open pit, without any extenfive fubterraneous excavation, nothing is known with certainty. In the Bovey coal too, I muft obferye, shotigh its beds have the ligneous ftructure very difting, the clay interpofed between thefe beds, which is but little indurated, contains a great deal of coaly matter, in the form of thin flakes, inter- {perfed through it. So far as I know, there are no mineral veins nor fhifts, nor any bed of in- durated ftone, that accompany this coal; fo that, though one cannot doubt of its vegetable origin, fome doubt may be entertained concerning the. nature of the mineralizing operations, to which it has been fubje@ed. Theconfideration of thefe, however, does not belong to the prefent argument ; and the peculiarities of this femi- mineralized coal, as it may be called, have nothing to do with the general queftion, whe- | ther wood-coal and mineral-coal are the fame fubftance ; about which quettion, if the grada- T tions are properly confidered, I think, no rea- fonable doubt can remain. 141. One of Mr Kirwan’s objections to the vegetable origin of coal, is founded on this fact, = that there is, in the mufeum at Florence, a cel- lular fandftone, the cells of which are filled with genuine mineral coal, « Could this, (adds he) have 154 ILLUSTRATIONS OF THE have been originally wood *?”” The anfwer to the interrogatory propofed here as a reduétio aq abfurdum, is, that moft undoubtedly it may have been wood. Sandftone with charred wood, that is, with wood-coal in it, is not an uncommon phenomenon in coal countries. I have feena fpecimen of this kind from the Hales Quarry, near Edinburgh, confifting of a piece of charred wood, imbedded in fandftone; the wood was much altered, but the remains of its fibrous ftructure were diftin€ly vifible. This affordsa perfect commentary on the fpecimen in the Flo. rence cabinet. 142. If then it be granted, as I think it mutt, that the two kinds of coal we have been fpeak- ing of are of the fame origin, it is not very ne- ceflary to enter on a refutation of Mr Kirwan’s theory with refpect to either of them. His ac- count of the formation of mineral-coal, however, is fo fingular, that it cannot be a over with- out remark. Mr Kirwan fuppofes, rmo, That natural carbon was originally contained in many mountains of the granite and porphyritic order, and alfo in filiceous f{chiftus ; and might, by difintegration and decompofition, be feparated from the ftony particles. 2do, That both petrol and carbon are often contained in trap, fince hornblend, which —— aeaa N * Geol. Effays, p. 324. n ai HUTTONIAN THEORY. 158 which has lately been found to contain carbon, very frequently enters into its compofition. “ My opinion : adds he) is, that coal mines, or ftrata of coal, as well as the mountains in which they are found, owe their origin to the difinte- gration of primeval mountains, either now to- tally deftroyed, or whofe height and bulk, in confequence of fuch difintegration, are confider- ably leffened ; and that thefe rocks, anciently deftroyed, contained moft probably a far larger proportion of carbon and petrol than thofe of the fame denomination now contain, fince their difintegration took place at fo early a period *. “ By the decompofition of thefe mountains, the felt{par and hornblend were converted into clay ; the bituminous particles, thus fet free; reunited, and were abforbed, partly by the argil, but chiefly by the carbonaceous matter, with which they have the greateft affinity. The carbo- nic and bituminous particles, thus united, being difficultly mifcible with water, and fpecifically heavier, funk through the moift, pulpy, incohe- rent argillaceous mafles, and formed the loweft ftratum,’’ &c. Such is Mr Kirwan’s theory of the formation of coal, and nobody I think will difpute the originality of it. 143. To * Geol. Effays. p 328, &c. 156 ILLUSTRATIONS OF THE 143. To enter on a formal refutation of ap opinion fo loaded with objeCtions, would be a tafk as irkfome as unneceflary. A few obferya- tions will fuffice. The notion of the great degradation of moun- tains, involved in this hypothefis, is the part of it to which I am leaft difpofed to obje&. But I cannot help reminding Mr Kirwan, that the effects of wafte are not fuppofed lefs in this, than in Dr Hutton’s theory ; and that he has affumed the very principle,.of which that theo- ry makes fo much ufe, though he has referved to himfelf, as it fhould feem, the right of denying it, when it does not accord with his fyftem. . It is indeed worth while to compare what is faid concerning the degradation of mountains, in the above quotations, and {till more fully in the book itfelf, with what is advanced concerning their indeftruciibility, in another paflage of the fame volume *: “ All mountains are not fubje& to decay; for inftance, fcarce any of thofe that confift of red granite. The ftone of which the Runic rocks 1 have withftood decompofition for two as ire formed, thoufand years, as their characters evince,” &c. tic pillars, in general, bid defiance to decay,” &c. He goes on to deny every ftep of the degradation of land, by which it is watted, carried ET, ` ée Badal Balali -e : Page 436. — Pi # HUTTONIAN THEORY. = 57 carried into the fea, and {pread out over its bot- tom, though all thefe are neceflary po/fulata in his theory of the formation of coal. One can be at no lofs about eftimating the value of a fyftem, in which fuch grofs inconfiftencies make a neceflary part. 144. The quantity of hornblend and filiceous fchiftus, neceflary to be decompofed, in order to produce the coal ftrata prefently exifting, is enormous, and would lead to an eftimate of what is worn away from the primeval mountains, far exceeding any thing that Dr Hutton has {uppo- fed. It is true, that Mr Kirwan, never at all embarraifed about preferving a fimilitude be- tween nature as fhe is now, and as fhe was here- tofore, lays it down, that the part of the prime- val mountains which is worn away, contained much more carbon than the part which is left behind. This, however, is an arbitrary fuppo- fition ; and fince, in this fyftem, fuch fuppofi- tions are fo eafily admitted, why may we not conceive, in the primeval mountains, a more copious fource of carbonic matter than horn- blend or filiceous {chiftus? We have but to imagine, that the diamond exifted among thefe mountains in fuch abundance, as to conftitute large rocks. This ftone being made up of pure, or highly concentrated carbon, the ada- mantine fummits of a fingle ridge, by their - decompofition, 158 ILLUSTRATIONS OF THE decompofition, might afford a carbonic bafis; fufficient for the coal beds of all the furround. ing plains. 145. We may alfo obje& to Mr Kirwan, that the filiceous part of the mountains has not been che. mically diffolved ; it has been only abraded and wornaway. Mechanical action has reduced the quartz to gravel and fand, but has not produced on it any chemical change. ‘The carbon, there. fore, could not be let loofe. Experiment, in- deed, might be employed, to determine whether the filiceous matter of the fecondary, and of. the primary ftrata contains this fubftance in the fame proportion. Again, a more fatal fymptom can hardly be ‘imagined in any theory, than that, when the cir- -cumftances of the phenomena to be explained are a little changed, the theory is under the necefli- a ty of changing a great deal. Now, this is what happens to Mr Kirwan’s theory, in the attempt made to explain by it the ftratum of coal de- fecribed in the Annales de Chimie *, as cutting a mountain of argillaceous ftrata in two, at about three-fourths of its height. This ftratum, Mr Kirwan fays, muft have been formed by ¢tranjfu- dation from the fuperior part of the mountain f. Befides that this is a gratuitous fuppofition of a thing, * Tom. xi. p. 272. + Geol. Effays, p. 335: : HUTTONIAN THEORY. 159 thing, without example, it involves in it an ab- "oy furdity, which becomes evident the moment the bai} _ queftion is afked, What occupied the place of 1 _ the coal-bed before the tranfudation from the ej, UPPer part of the mountain? Has the liquid í coal, as it percolated through the upper ftrata, ed expelled any fubttance from the place it now duj occupies? or has it been powerful enough to PE nit up, or to float, as it were, the upper part Dg of the mountain ? I The fituation of this bed of coal is not fingu- nd g lar, and its formation is eafily explained on Dr int _ Hutton’stheory. It is part of a ftratum of coal, _ which has been depofited, like all others, at the yt bottom of the fea ; from whence certain caufes, ied’ of very general operation, have raifed it up, to- ela gether with the attending ftrata: thefe ftra- ei ta have fince been all cut down, and worn away by the operations of the furface; and the moun- tj tain, with the coal ftratum in the middle of it, is Jj a part of them which has been left behind. There in is no-wonder, that a coal ftratum fhould be abe i found alternating with others, in a mountain, { any more than in the bowels of the earth, and no more need of a feparate explanation *. ih 146. After di ; ee oe - n * This ftratum of coal, which is defcribed by Has. _ S8ENFRATZ, is remarkable for being in a mountain which a rels immediately on primary {chiftus and granite. 160 ILLUSTRATIONS OF THE 146. After all, it may be afked, for what purpofe is it that fo many incongruous and ill-fupported hypothefes are thus piled on one another? is it only to avoid afcribing the carbonic and bituminous matter of coal to a fubftance in which we know with certainty that fuch matter refides in great abundance, in order to derive it from other fubftances, in which a fubtle analyfis has fhewn, that it exifts ina very {mall proportion? Such reafoning is fo great a trefpafs on every principle of common fenfe, not to fay of found. philofophy, that, to beftow any time on the refutation of it, is, in fome degree, to fall under the fame cenfure. Nore 111. § 7. Primitive mountains. 147. The enumeration of the different kinds of primary {chiftus, at § 7., is not propofed as at all complete. It will be lefs defective, how- ever, if we add to it talcofe fchiftus, and lapis- ollaris or potftone*. 148. The rocks called here by the name of primary, were firft diftinguifhed, as forming the = bafis —— al * Kirwan’s Mineralogy, vol, i. p. 155. n P” HUTTONIAN THEORY. I6r þafis of all the great chains of mountains, and as conftituting a feparate divifion of the mineral kingdom, by J. G. Lenman, director of the Pruffian mines. See his work, intituled, Efai dune Hiftoire Naturelle de Couches de la Terre *. Thefe rocks were regarded by Lehman as parts of the original nucleus of the globe, which had undergone no alteration, but remained now fuch as they were at firft created; and, agreeably to this f{uppofition, he beftowed on them, and on the mountains compofed of them, the name of pri- mitive. He remarks, neverthelefs, their diftri- bution into beds, either perpendicular to the ho- tizon, or highly inclined, and the fuper-pofi- tion of the fecondary, and horizontal ftrata. However mineralogifts may now differ in their theories from Lehman, they muft confider this diftinction as a great ftep in the {cience of gEO- logy, and very material to the right arrange- ment of the natural hiftory of the earth. 149. Several mineralogifts have agreed with him in the fuppofition, that thefe rocks area part of the original ftru@ture of the globe, and prior to all organized matter. Of this number is PAL- Las}; and alfo De Luc, who applies the term L primordial * Tom. iii. p. 239, &c. The French tranflation is in 2759, but the original preface is dated at Berlin 1956. t Obfervations fur la Formation des Montagnes. 162 ILLUSTRATIONS OF THE primordial to the rocks in queftion, and confi- ders them as neither ftratified nor formed by water *. In his fubfequent writings, however, he admits their formation from aqueous depofi- tion, as the Neptunifts do in general, but holds them to be more ancient than organized bodies, 150. Pini, profeffor of natural hiftory at Mi- lan, has denied the ftratification of primitive mountains, ina memoir on the mineralogy of St Gothard, and in another on the revolutions of the globe}. His reafonings are oppofed by SAUSSURE f, and are certainly, in many refpeds, very open to attack. ‘They proceed on a com- parifon between the divifion of rocks, by what is called the planes of their ftratification, and their divifion by tranfverfe fiffures ; two things, which he thinks fo much alike, that they ought not to be referred to different caufes; and, as the one cannot be regarded as the effect of aque- ous depofition, fo neither fhould the other. This is a very fallacious argument, becaufe it con- founds two things that are effentially different; and, * Lettres Phyf. fur l'Hiftoire de la Terre, tom. ii. p.206. t Memoria fulle Rivoluzione del Globo Terreitre ; Memorie della Societa Italiana, tom. v. p. 222, &c. t Voyages aux Alpes, tom. Iv. § 1881, ee ee ee ` 1 HUTTONIAN THEORY. 163 and, inftead of inquiring about a matter of fact, inquires about its caufe. The truth is, that the eng. difpute has arifen from not diftinguifhing the w granite from the fchiftus mountains, and from iy involving both under the name of primitive. T M. Pini feems to be in the right, when he holds _ the granite of St Gothard to be unftratified ; but O .... | i it is without any good reafon, that he would ex- oy ye tend the fame conclufion to the {chiftus of that uttog mountain. CHARPENTIER, and Sauflure, in his laft two volumes, contend even for the ftratifica- ME tion of granite *, tt As the confent, if not univerfal, is very gene- ral for the ftratification of the primary fchiftus, U and the fa@ itfelf abundantly obvious, in almoft lif all the inftances I have ever met with, I have ge not confidered it as neceffary to enter here into d! any argument on this fubject. Th coh x m NOTE Iv. § 8. a Primary ftrata not primitive. A j $ I5I. An account of the fads referred to § 8., may be found in Hutton’s Theory, vol. i. gi L 2 p- 332; * See Note xv. on Granite. 164 ILLUSTRATIONS OF THE p- 332, &c. To what is there faid, of the fhells contained in the primary limeftone of Cumberland, I muft add, that I have fince had an opportunity of verifying the conjecture, that the limeftone rock, in which the fhells were found, near the head of Coni/ton Lake, is part of the fame body of ftrata, where fhells were found, in a quarry between Amblefide and Low-wood, The limeftone of that quarry contains feveral ma- rine objects; it is in ftrata declining about 10° from the perpendicular, toward the S. E., and forms a belt, ftretching acrofs the country from N. E. ta 5. W. In a quarry where the vabim fchiftus, on the fouth fide of this limeftone belt, is worked for pavement, are impreflions of what I think may fafely be accounted marine objeés; they have the form of fhells, are much indurated, and full of pyrites. They feem to be of the fame kind with the impreffions faid to be found ina flate quarry, near the villaga of Mat in Swit- zerland *. Another fpot, affording inftances of fhells in primary limeftone, is in Devonfhire. On the fea-fhore on the eaft fide of Plymouth Dock, oppofite to Stonehoufe, I found a fpecimen of {chiftofe micaceous limeitone, containing a fhell o ell a * Hutton’s Theory, vol.i. p. :327. HUTTONIAN THEORY. 165 of the bivalve kind: it was truck off from the folid rock, and cannot poffibly be confidered as an adventitious foffil. Now, no rocks can be more decidedly prima- ry than thofe about Plymouth. They confit of calcareous ftrata, in the form either of marble or micaceous limeftone, alternating with varie- ties of the fame fchiftus, which prevails through Cornwall to the weft, and extends eaftward into Dartmoor, and on the fea-coaft, as far as the Berry-head. Thefe all interfe@ the horizontal plane, in a line from eaft to weft nearly ; they are very erect, thofe at Plymouth being elevated tothe north. ` Though, therefore, the remains of marine animals are not frequent among the primary rocks, they are not excluded from them; and hence the exiftence of thell-fifh and zoophytes, is clearly proved to be anterior to the formation even of thofe parts of the prefent land which are juftly accounted the moft ancient. 152. The rocks which contain fand or gravel, or which are of a granulated texture, muft alfo be confidered as carrying in themfelves a teftimony of the moft unequivocal kind, of their being derived from the detritus and wafte of former tocks. Now, the fa@ ftated in the text, con- cerning fand found in fehiftus, moft juftly ac- counted primary, might be exemplified by actual L 3 reference 166 ILLUSTRATIONS OF THE reference to many fpots on the earth’s {urface, A few fuch will be fufficient in this place. St Gothard is a central point, in one of the greateft tracts of primary mountains on the face of the earth, yet arenaceous ftrata are found in its vicinity. Between Ayrolo and the Hofpice of St Gothard, Sauffure found a rock, compofed of an arenaceous or granular pafte, including in it hornblend and garnets. He is fomewhat un. willing to give the name gres to this {tone, which M. Beffon had done; but he neverthe- lefs defcribes it as having a granulated ftruc- ture *, ; Among the moft indurated rocks that com- pofe the mountains of this ifland, many are ares naceous. Thus, on the weftern coaft of Scot- land, the great body of high and rugged moun- tains on the fhores of Arafaig, &c. from Ardna- murchan to Glenelg, confifts, in a great mea- fure, of a granitic fand{tone, in vertical beds. This ftone fometimes occupies great tracts ; at other times it is alternated with the micaceous, or other varieties of primary {chiftus; it occurs, likewife, in feveral of the iflands, and is a fof- fil which we hardly find defcribed or named by the writers on mineralogy. Much, alfo, of * Voyages aux Alpes, tom. iv. § 1822, HUTTONIAN THEORY. 167 4 highly indurated, but granulated quartz, is found in feveral places in Scotland, in beds or ftrata, alternated with the common {chiftus of the mountains. Remarkable inftances of this may be feen on the north fide of the ferry of Bala- chulifh, and again on the fea-fhore at Cullen. At the latter, the ftrata are remarkably regular, alternating with different fpecies of {chiftus. At the former, the quartz is fo pure, that the ftone has been miftaken for marble. Thefe examples are perhaps fufficient; but I muĝ add, that in the micaceous and talcofe {chifti themfelves, thin layers of fand are often found, interpofed between the layers of mica or talc. I have a f{pecimen, from the fummit of one of the higheft of the Grampian mountains, where the thin plates, of a talcky or afbeftine fubftance, are feparated by layers of a very fine quartzy fand, not much confolidated. The mountain from which it was brought, confifts of vertical ftrata, much interfected by quartz veins. It is impoffible to doubt, in this inftance, that the thin plates of the one fubftance, and the {mall grains of the other, were depofited together at the bottom of the fea, and that they were alike produced from the degradation of rocks, more ancient than any which now exif. L4 153. In T j N 168 ILLUSTRATIONS OF THE 153. In the Neptunian fyftem, as improved by Werner, an attempt is made to take off the force of fuch inftances as are produced in § $, 9, and 151, &c. by diftinguithing rocks, as to their formation, into three different orders, the primitive, the intermediate, and the fecon- dary, or, to {peak more properly, into primary, fecondary, and tertiary. The fame mineralo- gift diftinguifhes, among the materials of thefe rocks, between what he terms chemical and me- chanical depofites. By mechanical depofites, are underftood fand, gravel, and whatever bears the mark of fracture and attrition ; by chemical depofites, thofe which are regularly cryftallized, or which have a tendency to cryftallization, and in which the action of mechanical caufes cannot be traced. This diftinGion is founded in na- ture, and proceeds on real and palpable differen- ces; but the application made of it to the three kinds of ftrata juft enumerated, feems by no means entitled to the fame praife. The primitive rocks contain, it is faid, none but chemical depofites, and are entirely com- pofed of them: the intermediate contain a mix- ture of both, and alfo fome veftiges of organized bodies: the fecondary confit almoft entirely of the mechanical, or of the remains of fuch bo- dies, with little of the chemical. The firft of thefe, then, are held to contain no mark or vel- tige HUTTONIAN THEORY. 169 : l my = tige whatfoever of any thing more ancient than 1 themfelves, and are, in the ftricteft fenfe, prime- i wal, or formed of the firt materials, depofited by the immenfe ocean which originally encom- paffed the globe. wf After them were formed the intermediate, w moftly confifting of chemical depofites, but con- th taining alfo fome animal remains, and fome fpoils th from the land, fubjected to the various kinds lt, of deftruction, which even then made a part of ft the order of nature. Thefe rocks, it is alleged, are chiefly argillaceous, are lefs indurated than w the primary, and not interfeGed by veins of i quartz. al The fecondary were formed from the re- Mm mains of the other two, and contain more me- œ chanical depofites than any other. m This {ketch of what I underftand to be Wer- hte ner’s opinion concerning the different formation w Of the ftrata, is chiefly taken from a view of his fyftem, in the Journal de Phyfique for 1800. 154. The main objeGion to the diftinGion here made between the primary and the intermediate ftrata, is founded on the fas that have been jut ftated. The fandftone of St Gothard is from a country having every character of a pri- mary one in the higheft perfection. The in- ftances I have mentioned from the Highlands of Scotland, are from mountains, lefs elevated indeed EE, aiii ie = & S&S 2 er 170 ILLUSTRATIONS OF THE indeed than the Alps, but where the rock tg micaceous, talcofe, or filiceous, in planes ereĝ to the horizon, and interfected by veins of quartz. ‘The fhells from Plymouth are from a rock, that Werner would, I think, admit to be truly primitive. Thofe from the lakes, alfo, are from the centre of a country, occu- pied by porphyry, fchorl, hornftone-fchiftus, „and many others, about the order of which there can be no difpute. It is true, that in this tract there are argillaceous ftrata, of the kind that might be accounted intermediate, were they not interpofed among thofe that are cer. tainly primary ; and this very intermixture fhews, how little foundation there is for the di- ftinGion attempted to be made between the for- mation of the one and of the other. If there is any principle in mineralogy, which may be con- fidered as perfectly afcertained, it is, that rocks fimilarly ftratified, and alternated with one ano- ther, are of the fame formation. Hence we conclude, that there is zo order of Strata yet known, that does not contain proofs of the exiftence of more ancient ftrata. We fee nothing, in the ftrict fenfe, primitive. It muft be underftood, that what is here faid has no reference to granite, which Ido not confi- der as a ftratified rock, and in which neither the remains of organized bodies, nor fand, have I believe a po | 3 HUTTONIAN THEORY. 141 believe been ever found ; though fome inftances will be hereafter mentioned, where granite con- | tains fragments of other ftones, viz. of different A kinds of primary fchiftus. A To the inftances of fand involved in primary A {chiftus, I might have added many from the WE rocks of that order on the coaft of Berwickthire, ity of which mention is fo often made in thefe Th Illuftrations ; but I wifhed to draw the evi- Mi dence from thofe rocks that are moft unequivo- ‘li cally primary, and to which the Wernerian di- m tinction of intermediate could not poflibly be TE applied. inte If any one affert, as M. de Luc has done, Mi that fand is a chemical depofite, a certain mode eh of cryftallization which quartz fometimes af- fumes, let him draw the line which {eparates fand .@ from gravel ; and let him explain why quartz, in ol the form of fand, is not found in mineral veins, w in granite, nor in bafaltes, that is, in none of the fituations where the appearances of cryftalliza- i tion are moft general and beft afcertained. w f ! | Nore v. § 10. T Tranfportation of the materials of the firata. ‘= y Pe. 1 She—Lhe great tranf{portation or travelling of the materials of the ftrata, fuppofed by Dr Hut- ton, i72 ILLUSTRATIONS OF THE ton, has been treated as abfurd by fome of hig opponents, particularly De Luc and Kirwan, Thefe philofophers feem not to have obferved, that their own fyftem, and indeed every fyheni which derives the fecondary ftrata from the primary, involves a tranfportation of materials, hardly lefs than is fuppofed in the Huttonian theory, and a degradation of the primeval mountains, in many inftances much greater, To form fome notion of this degradation, it muft be recollected, that the primeval mountains, which furnifhed the materials of the fecondary {trata in the plains, cannot have ftood in the place now occupied by thefe plains. This is obvious ; and therefore we muft neceflarily res gard the fecondary ftrata as derived from the primitive mountains which are the heareft to them, and of which a part ftill remains. This part is fufficient to define the bafe of the original mountains; and the quantity of the fecondary ftrata which furround them may help us to make fome eftimate of their height. Let us take, for inftance, the extenfive tract of fecondary country about Newcaftle, where coal mines have been funk through a fucceflion of fecondary ftrata, to the depth of more than a thoufand feet. This fecondary country may be confidered as com- prehending almoft the whole of the counties of Northumberland and Durham, and probably as extending j HUTTONIAN THEORY. 173 extending very far under the part of the Ger- man Ocean which wathes their coafts; and the whole ftrata compofing it muft be derived, on the hypothefis we are now confidering, from the Cheviot Hills, on one fide, and from thofe in the high parts of Weftmoreland and Cum- berland on the other, comprehending the Alfton- Moor Hills, and the large group of primary mountains, fo well known from the fublime and romantic fcenery of the Lakes. Now, the moun- tains which ftood on this bafe, had not only to fupply the materials for the tract already men- tioned, on the eaft, but had alfo their contingent to furnifh to the plains on the weft and north ; the Cheviots to Roxburghfhire and Berwick- fhire; the Northumberland mountains to the coal ftrata about Whitehaven, and along the fea-coaft to Lancafhire. On the whole, we fhall not exceed the truth, if we fuppofe, that the fe- condary ftrata, at the feet of the above moun- tains, are fix or feven times more extenfive than the bafe of the mountainous tract. If then we take the medium depth of thefe fecondary ftra- ta to be one thoufand feet, it is evident, that the mafs of {tone which compofes them, if it were placed on the fame bafe with the primitive mountains, would reach to the height of fix thoufand feet. This is fuppofing the mafs to preferve the breadth of its bafe uniformly to : the 174 ILLUSTRATIONS OF THE the fummit; but if it be {uppofed to taper, aş mountains ufually do, we muft multiply this fix thoufand by three, in order to have the height of thefe primeval mountains, which, therefore, were originally elevated not lefs than eighteen thou- fand feet: in height, therefore, they once rivalled the Cordelieras, and are now but poorly reprefent. ed by the hills of Skidaw and Helvellyn. It were ealy to fhew, that this eftimate is ftill below the refult that ftri€tly follows from the Neptunian hypothefis ; but it is unneceflary to proceed fur- ther, than to prove, that the principle of the de- gradation of mountains, is involved in that hypo- thefis to an exceffive and improbable degree; and that the fupporters of it, have either been guilty of the inconfiftency of refufing to Dr Hutton the moderate ufe of a principle, which they them- felves employ in its utmoft extent, or of not having fufficiently adverted to the confequences of their own fyftem. ; 156. The formation of fecondary ftrata from the degradation of the contiguous mountains, on clofe examination, is fubje@ to many other dif- ficulties of the fame kind. Mountains of fecon- dary ftrata, and nearly horizontal, are found in this ifland of the height of three thoufand feet. Such are Ingleborough, Wharnfide, and perhaps fome others on the weft of Yorkthire. The wholg m me n a HUTTONIAN THEORY. 175 whole chain, indeed, for fecondary mountains, js of great elevation. The ftrata are of lime- ftone, and of a very coarfe-grained fandftone, alternating with it. No mountains can more clearly point out, that the ftrata of which they » confit were once continued quite acrofs the val- lies which now feparate them; and hence, if the materials of thofe ftrata were indeed fur- nifhed from any contiguous primitive moun- tains, the latter muft have been, out of all pro- portion, higher than any mountains now in | Britain. | ae 157. Thus, a great degradation of the primi- tive mountains, and of courfe a great travelling of their materials, is proved to make a neceflary part of the Neptunian theory. The extent of this travelling or tranfportation may be render- ed more evident, if we apply a fimilar mode of reafoning to larger portions of the globe. The north-weft of Europe furnifhes us an in- ftance of a very extenfive trat of fecondary country, comprehending the greater part of Bri- tain, the whole of Flanders and Holland, part of Germany, the northern provinces of France, and probably the bed of the German Ocean, at leaft for a great extent. Within this circle al- moft all is fecondary, and on the fides of it all round are placed ridges or groups of primitive mountains, namely, the mountains of Auvergne, at 276 ILLUSTRATIONS OF THE at leaft in part, and going round by the eaft, the Alps, the Vofges, the Hartz, the Highlands and Weftern Iflands of Scotland, the hilly coup. tries of Cumberland, Wales and Cornwall, Thi, zone of primitive mountains, on the fuppo. fition of the Neptunifts, muft have rifen up ip the form of iflands in the great ocean, that orj- ginally covered the earth, forming a kind of circular Archipelago, including in its bofom a fea, which was from feven to five hundred miles in diameter. Over the whole of this extent, the detritus of the above mountains mut have been carried, in order to form the flat in. terjacent countries which are now expofed to our view. Such then, even on their own fuppofi- tion, is the extent to which the Neptunifts muft admit that the materials of the primeval moun- tains were tranfported by the ocean. 158. This tranfportation of materials, may not be fo great as that which is involved in Dr Hutton’s theory, but is fuch as fhould make the enemies of his fyftem confider, how nearly the principles they muff introduce, agree with thofe that they would rejeQ. This is one fact out of many, which fhews, that there is at prefent a much nearer agreement between, the fyftems of geology, than between their au- thors. = 159. To ay —— HUTTONIAN THEORY. 1% é 159. To thefe fats, demonftrating the great tran{portation of foffils in fome former condi- tions of the globe, we may add another, re- cognifed by all mineralogifts. The animal ex- uvie contained in limeftone and marble, are often known to belong to feas, extremely re- mote from the countries where they are now found. In the chalk-beds of England, in the limeftones of France, a great proportion of the petrifactions belong to the tropical feas, and ap- pear to have been brought from the vicinity of the equator. Buffon obferves, that of the fotlil Shells found in France, it has been difputed, whether the foreign are not more numerous than the native; and, though he is himfelf of opinion that they are not, it is evident that they muft bear a confiderable proportion to the whole *. In the petrifa@iions of Monte Bolca, near Ve- rona, where the impreflions of fifh are preferved between the laminz of a calcareous ichiftus, one hundred and five different fpecies have been enu- merated, of whichthirty-nine are from the Afiatic feas, three from the African, eighteen from thofe of South, and eleven from thofe of North Ame- rica +. Similar obfervations have been made on the marine plants, and the impreffions of ve- - getables, found in rocks, in different parts of M Europe. * Buffon, Théorie de la Terre, art. 8. t Sautlure, Voyages aux Alpes, tom, ili. § 1535. 178 ILLUSTRATIONS OF THE Europe. At St Chaumont, near Lyons, is found an argillaceous fchiftus, covering a bed of coal, every lamina of which is marked with the im- preffions of the ftem, leaf, or other part of fome plant; and it happens, fays M. FONTENELLE, by an unaccountable deftination of nature, that not one of thefe plants is a native of France, . They are all ferns of different fpecies, peculiar to the Eaft Indies, or the warmer climates of America. Here alfo was found the fruit of a tree, which grows only on the coafts of Malabar and Coromandel *. The fame holds of the bodies of amphibious animals which now make a part of the foffil kingdom. The head and the bones of croco- diles have been found in the ifland of Shepey, at the mouth of the Thames; and the remains of an animal of the fame fpecies, but of a va- - riety now peculiar to the Ganges, have been difcovered in the alum rocks on the coaft of York- fhire +. Thefe proofs of the tranfportation of materials * Mém. de l’Acad. des Sciences, 1718, p. 3. and 2873 and 1721, p. 89, &c. t Phil. Tranf. vol.1, p.688. Camper denies that the remains here mentioned belong to the crocodile, or any amphibious animal, and refers them to the balena. He paffes the fame judgment on thofe foflil bones from St Pe- ter’s Mount, near Maeftrich, which have been fuppofed to belong EE ne ee ETT ¥ —— rl i | HUTTONIAN THEORY. 179 ? N materials by the fea, have the advantage of in- 5 = yolving nothing hypothetical, and of being equal- \ lyaddreffed to the geologifts of every perfuafion. h On this fubje& I cannot help obferving, that W the accurate comparifon of the animal exuviæ Hk of the mineral kingdom, with their living arche- a types, is not merely a curious inquiry, but is et one that may lead to important confequences, ti = concerning the nature and diredtion of the for- ti = œe which have changed, and are continually alh changing, the furface of the earth. | 160. Thefe remarks I have thought it proper im toadd to the proofs of the compofition of the ` fii prefent from former ftrata, in order to fhew, that w the great tranfportation of materials involved in ep ‘that fuppofition, is not only conformable to the mi hypothefis of the Neptunifts concerning the fe- aw condary firata, but is alfo proved by the moft w dire& evidence, independently of all hypothefis. a All this reafoning regards the ancient flate of on M2 the’ wi — belong to the crocodile ; he looks on them as belonging to it whales, though of an unknown fpecies. In this Mount, fo famous for its petrifactions, he finds many fpecimens of J bones, which he thinks belong to the turtle. Phil. Tranf. wi vol, Ixxvi. p.443. The opinion of an author, fo well oth {killed in comparative anatomy, muft be regarded as of J great weight : if it takes from our argument in one part, gf i it adds to it in another, and the acquifition of the turtle ji makes up abundantly -for-the lofs-of the crocodile. A 180 ILLUSTRATIONS OF THE the globe. Whether fuch a travelling of ftony bodies makes a part of the fyftem now actually carrying on, will be confidered in another place *, Note vi. § 13. Mr Kirwan’s notion of precipitation. 161. The Neptunift who has provided the means of diffolving the materials of the ftrata, has only performed half his work, and muft find it a tafk of equal difficulty to force this power- ful menftruum to part with its folution. Mr Kirwan, aware in fome degree of this diffi- culty, has attempted to obviate it in a very fin- gular way. Firft, he afcribes the folution of all fubftances in water, or, in what he calls the chaotic fluid, to their being finely pulverifed, or created in a ftate of the moft minute divifion. ‘Next, as to the depofition, the folvent being, as he acknowledges, very infuflicient in quantity, the precipitation took place, (he fays), on that account the more rapidly. If he means by this to fay, that a precipitation without folution would take place the fooner the more inadequate the menftruum was to dif- folve the whole, the propofition may be true; but * See Nore XIX. HUTTONIAN THEORY. 181 but will be of no ufe to explain the cryftalliza- tion of minerals, (the very object he has in view), becaufe to cryftallization, it is not a bare fubfi- dence of particles fufpended in a fluid, but it is a paflage from chemical folution to non-folu- tion, or infolubility, that is required. If, on the other hand, he means to fay, that the folution actually took place more quickly, and was more immediately followed by precipitation, becaufe the quantity of the menftruum was in- fufficient, this is to affert, that the weaker the caufe, the more inftantaneous will be its effe@. Of two propofitions, the one of which is nu- gatory, and the other abfurd, it is not material to anquire which the author had in view. Nore vil. § 16. Compreffion in the mineral regions. 462. It is worthy of remark, that the effects afcribed to compreffion in the Huttonian Theo- ry, very much refemble thofe which Sir Isaac Newton fuppofes to be produced in the fun and the fixed flars by that fame caufe. “ Are not,” fays he, “ the fun and fixed ftars great earths, vehemently hot, whofe heat is conferved by the greatnefs of the bodies, and the mutual action M 3 7 and 182 ILLUSTRATIONS OF THE and reaction between them, and the light Which they emit; and whofe parts are kept from fu- ming away, not only by their fixity, buit alfo by the vaft weight and denfity of the atmofpberes incim bent upon them, and very firongly compreffing them*,”” 163. The fatt, of water boiling at a lower temperature under a lefs compreffion, is fafi- cient to juftify the fuppofition, that bodiés may be made by preffure to endure extreme heat, without the diffipation of their parts, that is, without evaporation or combuftion. A further poftulatum is introduced in Dr Hutton’s theoty, namely, that compound bodies, fuch as carbo- nat of lime, when the compreffion prévents their feparation, may admit of fufion, notwith- ftanding that the fixed part may be infufible when feparated from the volatile. This affump- tion is fupported by the analogical fact of the fufion of the carbonat of barytes, as mentioned in the text. 164. In a region where the action of heat was accompanied with fach compreffion as is here fuppofed, there could be no fire, properly fo called, and no combuiftion: this is admitted by Dr Hutton, and it is therefore a fallacious ar- gument which is brought againft his theory, from the impoffibility of fire being maintained in amaA 167. Some a —— * Newton's Optics, ubi /upra. 1358 ILLUSTRATIONS OF THE 167. Some recent experiments, feem to make the fuggeftions in this query applicable to an opaque body like the earth, as well as to lumi- nous bodies, fuch as the fun and fixed ftars, The radiation of heat, where there is no light, was firft rendered probable by the experiments — of M. Picter of Geneva * ; and the only ob- jeCtions to which the conclufions from thofe ex- periments feemed liable, are removed by the late very important difcoveries of Dr Her. SCHEL}. From thefe it appears, that heat is capable of refraction and refleGion, as well as light, fo that it is not abfurd to fuppofe, that the heat of great, denfe, and fixed bodies, may be conferved by the greaine/s of the bodies, and the mutual action and reaction between them and the beat which they emit. The exiftence of fubterraneous heat is ftill further rendered probable from the refearches of Marran, which tend to fhew, that there is another fource of terreftrial heat befides the in- fluence of the folar rays f. Whatever be the truth with regard to thefe conjectures, it is certain, that the firt and ori- ginal fource of heat is independent of burning. Burning 1s an effect of the concentration of heat; and * Effai fur le Feu. + Phil. Tranf. 1800. p. .84. į Mém. de Acad, des Sciences, 1765, p. 143- HUTTONIAN THEORY. 189 by and though, by a certain reaction, it has the “hy power of continuing and augmenting that heat, Uy it never can be regarded as its primary and ma- dj, terial caufe. When, therefore, we fuppofe a Ol, fource of heat, independent of fire and of burn- tity - ing, we fuppofe what certainly exifts in nature, tl; though we are not informed of the manner of ley its exiftence, nor of its place, otherwife than by from confidering the phenomena of the mineral Th kingdom. 168. Laftly, we are not entitled, according ’ _ to any rules of philofophical inveftigation, to re- ei jet a principle, to which we are fairly led by i i an induGion from fas, merely becaufe we can- if not give a fatisfactory explanation of it. It | would be a very unfound view of phyfical fcience, which would induce one to deny the principle of gravitation, though he cannot ex- plain it, or even though the admiffion of it reduces him to great metaphyfical difficulties. If indeed a downright abfurdity, or inconfiften- cy with known and eftablifhed facts, be invol- ved in any principle, it ought not to be ad- _ mitted, however it may feem calculated to ex- plain other appearanes. If, for inftance, Dr Hutton held, that combuftion was carried on in a region where there was no vital air, we fhould have faid, that he admitted an abfurdity, and that a theory founded on fuch poffulata, was worfe than chimerical, But, if the only thing imputable 190 ILLUSTRATIONS OF THE imputable to him is, that, being led by induc. tion to admit the fufion of mineral fubftances in the bowels of the earth, he has affumed the ex. iftence of fuch heat as was fufficient for this fy. fion, though he is unable to affign the caufe of it, I believe it will be found, that his fyitem only fhares in an imperfection, which is com. mon to all phyfical theories, and which the ut. moft improvement of fcience will never com. pletely remove. 169. Thus, then, we are led, it mutt be allow. ed, into the region of hypothefis and conjecture, but by no means into that of chimeras. Indeed, the reproach of flying into the latter region, may be faid to come but ill from one, who has trode fo often the crude conjiftence of the chaos, and who delights to dwell beyond the bounda- ries of nature. By fojourning there long, it is not impoffible that the eye may become fo ac- cuftomed to fantaftic forms, that the figures and proportions of nature fhall appear to it deform- ed and monftrous. Norte VIIL § 24. Sparry firucture of calcareous petrifactions. 170. When the fhells and corals in limeftone are quoted by mineralogifts, it is not always confidered HUTTONIAN THEORY. igi confidered in what ftate they are found. In general, they have a {parry ftructure, very dif- ferent from that of the original fhell or coral, of which, however, they retain the figure with wonderful exactnefs, though probably fome- times altered in fize. Though fparry, they are often foliated, and preferve their animal, in con- junction with their mineral, texture. Now, this cryftallization is a mark of fome operation, quite different from any that can be afcribed to the water in which thefe bodies had their origin, and by which they were brought into their place. They were impervious to wa- ter; and it cannot be faid that their fparry ftruture has been derived from the percolation of that fluid, carrying new calcareous matter into their pores. We can account for the change produced in them, I think, only by fuppofing them to have been foftened by heat, fo as to permit their parts to arrange them- felves anew, and to aflume the characteriltic organization of mineral fubftances. All fhells have not the change effected on them that is here referred to; thofe in chalk, for inftance, retain very much their original form in all refpe&s. This is what we might expect from the very different degree of inten- fity, with which the mineralizing caufe has acted on chalk, and on limeftone or marble. In general, it is in the hardeft and moft confolida- ted 192 ILLUSTRATIONS OF THË ted limeftone, that the marine objects are mof completely changed into fpar. It would be exceedingly interefting to ex. amine, whether any of the phofphoric acid re. mains united to fhells of either of thefe kinds, We might moft readily expeé it to be united, in a certain degree, to the fhells that are leat mineralized. This experiment would enable us alfo to ap- preciate the force of Mr Kirwan’s argument againft the finer marbles, fuch as the Carrara, containing fhells*. This argument proceeds on _ an experiment, mentioned in the Turin Memoirs for 1789, from which it appears, that no phof- phoric acid is found in pure limeftone; and its abfence, Mr Kirwan fays, cannot be attribu- ted to fufion, as phofphoric acid is indeftrudible by heat. 2 7 He calls this a demonftration ; but, in order to entitle it to that name, it will be neceflary, firft, to prove, that phofphoric acid exifts in thofe limeftones which evidently coniift of fhells in a mineralized ftate. If thefe are found with- out phofphoric acid, it is evident that the pre- ceding argument fails entirely. If they are found to contain that acid, it will then no doubt afford a probability, though not a demonftration, that Carrara * Geol, Effays, p. 458, co a l HUTTONIAN THEORY. r93 l Carrara marble does not directly originate from hy —thellls. | tidy, That nature has fome procefs, by which the _ above acid is feparated from the earth of bones, iy and probably alfo from the earth of fhells, is _ evident from the ftate in which the bones are found in the caves of Bayreuth. Thofe that are the moft recent, and leaft petrified, contain moft of the phofphoric acid. Where the petrifaction has proceeded far, that acid is not found. 171. Among many of the ftrata, fuch a fluidi- ty has prevailed, as to enable fome of thé fub- ftances included in them to cryftallize. Calca- reous fpar and filiceous cryftals are often found in ftratified rocks, forming veins of fecretion, or lining clofe cavities, included on all fides by the uncryftallized rock. In the inftances of gneifs, 7 and many fpecies of marble, almoft the whole a matter of the ftratum is cryftallized. This iy union of a ftratified and cryftallized ftru€ture in _ the fame fubftance, has a great affinity to that it! §—_ union of the cryftallized with the organic ftruc- il turcof hells and corals which has juft been pi mentioned; and both are doubtlefs to be refer- 0 _ red to the fame caufe. a ae N Nore 194 ILLUSTRATIONS OF THE | Nove 1x. § 31. Petroleum, Se. 172. According to the theory of coal laid down above, its two chief materials, charcoal and bitumen, being furnifhed by the vegetable and animal kingdoms, both of the land and of the fea, have formed with one another a new bination, by the action of fubterraneous heat; but have alfo, in fome cafes, been fepa- rated by that fame action, where the degree of compreflion neceflary for their union, happened to be wanting. The carbonic part, when thus feparated from the bituminous, forms an infufi- ble coal, which burns without flame: the bitu- minous part, when feparated from the carbonic, is found in the various ftates of naphtha, petro- leum, afphaltes, and jet. | The great refemblance of infufible or blind coal, to the refiduum obtained by the diftilla- tion of bituminous coal; and again, the coin- cidence of the bitumens juft named, with the volatile part, or the matter brought over by fuch diftillation, are ftrong arguments in fa- vour of this theory. The other fads in the na- tural hiftory of coal, ferve to confirm the fame conclufion; but it muĝ be confefled, that what we — t HUTTONIAN THEORY. 1905 -we know of the pure bitumens, except the cir- cumftance juft mentioned, is of a more ambigu- ous nature, and may be reconciled with different theories. The drops of petroleum contained within the cavities of the limeftone, mentioned at § 31., are however ftrong facts in confirmation of Dr Hutton’s opinions, and they are furnifhed by the fubftances purely bituminous.. A careful examination would probably make us acquainted _ with others of the fame kind, for limeftone is very often the matrix in which petroleum and afphal- tes are contained. The greateft mine of afphal- tes in Europe, that in the Val de Travers, in the territory of Neufchâtel, is in limeftone, from which, though it in fome places exudes, it is in general extracted by the application of heat. The ftrata for feveral leagues are impregnated with bitumen; and, if examined with atten- tion, would probably afford fpecimens fimilar to thofe which have juft been mentioned. 173. It is a general remark, that, where pe- troleum is found, on digging deeper, they come to afphaltes; and, at a depth ftill greater, they difcover coal. This probably does not hold in- variably ; but it is certain, that moft of the fountains of petroleum are in the neighbourhood of coal ftrata. Petroleum and afphaltes are found in great abundance in Alface, in a bed of fand, between two beds of clay or argillaceous N 2, {chiftus, 196 ILLUSTRATIONS OF THE {chiftus, and the fame country alfo affords coal ¥, This is true likewife of the foflil-pitch of .Coal- Brookdale ; and of the petroleum found in St $ Katharine’s well, near Edinburgh. Auvergne + contains abundance of foflil-pitch, which exudes, in the warm feafon, from a rock impregnated with it through its whole mafs. There are -alfo coal ftrata in the fame country, not far diftant. A very fatisfactory obfervation relating to this fubject, has lately been communicated from a country, with whofe natural hiftory we were till of late entirely unacquainted. In the Bur- mha empire, petroleum is dug up in an argilla- ceous earth, from the depth of feventy cubits. ‘This argillaceous earth, or fchiftus, lies under a bed of freeftone ; and under all, about one hun- dred and thirty cubits from the furface, is a bed of coal f. l 174. In the petroleum lake of the Ifland of Trinidad, defcribed Phil. Tranf. 1789, the pe- troleum evidently exudes from the rock, and is collected in a variety of fprings in the bottom, after which it hardens, and acquires the confift- ency * Encyclopédie, mot, d/pdalte. ¥ + Voyage en Auvergne, par Legrand, tom. i. p, 351+ t Afiatic Refearches, vol. vi. art. 6. p. 130. HUTTONIAN THEORY. 197 q encyof pitch. The manner, therefore, in which a eT ~~ 4 ue it a SE ee Se Se petroleum exifts in the ftrata, is very confiftent ‘with the idea of its having been introduced in the form of a hot vapour. Even amber appears to have fome relation to coal. It is found in the unconfolidated earth in Pruffia and Pomerania; but I am not fure whe- ther this earth is travelled or not. In the fame earth where the amber is found, there is often a mixture of coaly matter, which burns in the fire; it is apparently fibrous, and has been con- fidered as a kind of foffil-wood *. Thefe citcumftances make out a connection between the purer bitumens and ordinary coal ; but do not, it muft be acknowledged, eftablith any thing with refpect to the more immediate relation, f{uppofed in this theory to exift between ‘them and blind-coal. It is probable, indeed, that, to difcover any facts of that kind, the na- tural hiftory of both fubftances muft be more carefully examined ; the natural hiftory of blind- coal, in particular, has hitherto been but little attended to. 175. A fad is mentioned by Mr Kirwan, which muft not be regarded as lefs valuable for being adverfe to this theory. It is, that neither pe- troleum, nor any foffil bitumen, is found in the _ Vicinity of the Kilkenny coal, as might be ex- N 3 pected, * Buffon, Hitt, Nat. des Mineraux, tom. ii. p. 5. 198 ILLUSTRATIONS OF THE pected, if that coal was deprived of its bitumi- nous part by fubterraneous diftillation *. This, however, admits of explanation. ‘Though a ge. | neral connection, on the above hypothefis, might be expected between bitumens and infufible coal, we cannot look for it in every inftance, The heat which drove off the bitumen from one part of a ftratum of coal, may only have forced it to a colder part of the fame ftratum; and thus, in feparating it from one portion of carbonic matter, may have united it to another, Blind-coal may therefore be found where no bitumen has been actually extricated. In like manner, bitumen may have been feparated, where the coal was not reduced to the ftate of coak, as | a part of the bitumen only may have been driven off, and enough left to prevent the coal from becoming abfolutely infufible. It fhould be confidered too, if the bitumen was really feparated, and forced, in the ftate of vapour, into fome argillaceous or limeftone ftras tum, that this ftratum may have been wafted and worn away long ago, fo that the bitumen it con- tained may have entirely difappeared. It does not therefore neceffarily follow, that, wherever we find blind-coal, there alfo we fhould difcover fome of the purer bitumens. | Note *. Geol, Effays, pP. 473> HUTTONIAN THEORY. 199 hi K tn) : 3S tih Nore x. § 37. B. | a am The height above the level of the fea at which the fy marks of aqueous depofition are now found, Da i 176. We have two methods of determining the the minimum of the change which has happen- a ed to the relative level of the fea and -land ; T or for fixing a limit, which the true quantity i of that change muft neceflarily exceed. The me one is, by obferving to what height the regular i ftratification of mountains reaches above the i prefent level of the fea; the other is, by deter- i mining the greateft height above that level, at which the remains of marine animals are now found. Of thefe two criterions, the firft feems preferable, as the fa& on which it proceeds is moft general, and leaft fubject to be affected by “i accidental caufes, or fuch as have operated fince coh the formation of the rocks.. The refults of both, however, if we are careful to felect the extreme cafes, agree more nearly than could have been expected. : 177. The mountain Rofa, in the Alps, is en- WW —_‘tirely of ftratified rocks, very regularly difpofed, A N4 and too ILLUSTRATIONS OF THE and nearly horizontal *. The higheft fummit of this mountain is, by Sauffure’s meafurement, 2430 toifes, or. 14739 Englifh feet, above the level of the fea, or lower than the top of Mont Blanc only by 20 toifes, or 128 feet +. This is, I believe, the higheft point on the earth’s fur- face, at which the marks of regular ftratifica- tion are certainly known to exift; for though, by the account of the fame excellent mineralo- gift, Mont Blanc itfelf is ftratified, yet, as the ` rock is granite, the ftratification vertical, and fomewhat ambiguous, it is much lefs proper than Mont Rofa for afcertaining the limit in queftion. 178. Again, in the new continent, we have an inftance of fhells contained in a rock, not much lower than the fummit of Mont Rofa. This is one defcribed by Don Uxtoa; near the quickfilver mine of Guanca-Velica, in Peru. The height at which a fpecimen of thefe fhells, given by Ulloa to M. le Gentii, was found, Was 22224 toifes, or 14190 feet Englifh, above the level of the fea f. This height agrees with the preceding, within 549 feet, a quantity com- paratively fmall. 179. The * Voyages aux Alpes, tom. iv. § 2138. t lbid. § 2135. t See Hit. Acad. des Sciences, 1770. Phyf, Géne- rale, No. 7. HUTTONIAN THEORY. 205” 179. The laft of the facts juft mentioned is curioufly commented on by Mr Kirwan. As he has proved, he fays, that the mountains higher than 8500 feet. were-all formed before the crea- tion of fifth, it follows, that the fhells found at Guanca-Velica, muft have been carried there by the deluge*. Now, without objecting to the proof here referred to, (though it feems very open to objection), it is fufficient to remark, that, if the ~ fhells at Guanca-Velica were carried there by the deluge, or any other caufe that operated after the formation of the rock of which the mountain confifts, they can make no part of that rock, but muft lie, like other adventitious foffils, loofe and _ detached on the furface, or at moft externally agglutinated to the flone. This, however, is certainly not the fa&t ; for, in the account juft quoted, we read, that Don Ulloa told M. le Gen- til, © qu’il avoit détaché ces coquilles d’un banc fort épais.” This feems plainly to indicate, that the fhells were included in a bed of rock. But, granting that the expreffion is a little ambiguous, on turning to the Mémoires Phi- lofophiques of the fame author, the difficulty is completely removed, and it is made evident, that thefe fhells are in fa@ integrant parts of the rock, ‘* On voit dans ces montagnes-la, (about Guanca- “4 Geol. Elay: P- 54, 202 ILLUSTRATIONS OF THE Guanca-Velica, and particularly at that in which is the quickfilver mine), des coquilles entières, petrifiées et enfermées au milieu de la roche, que les eaux de pluie mettent à decouvert. Ces coquilles font corps avec la pierre ; mais malgré cela, on remarque que la partie qui fut coquille, fe diftingue par la couleur, la ftru@ure, la qua- lité de la matière de tout autre corps pierreux qui l’enferme, et du maffif qui s’eft fixé entre les deux ecailles *,” &c. He goes on to fay, that one can diftinguifh marks of thefe fhells having been worn, before they were included in — the ftone. | 180. Thus it appears, that whatever proof any foflil-fhell affords, that the rock in which it is found was formed under the fea, the fame is afforded by the foffil-thells of Guan- ca-Velica ; and we are, therefore, perfectly en- titled to conclude, that the relative level of the fea and land has changed, fince the forma- tion of the latter, by more than 14000 feet, The height affumed in § 37. is therefore much under the truth; and the water, for which the Neptunifts muft provide room in fubterraneous caverns, might very well have been ftated at more duane * Mém, Philofophiques de Don Ulloa, Difcours xvi» voli. p. 364. as | HUTTONIAN THEORY. 203 ti, more than a five-hundredth part of the whole mats of the earth. Thus alfo the argument by which the Nep- y tunifts would connect the creation of fifh with the beginning of the fecondary mountains, falls SF Pade a =e a i = entirely to the ground. Indeed, it is ftrange w that Mr Kirwan fhould have fuppofed it- poffi-, ble, that the fhells in queftion were loofe and 7 unconnected with the rock, and had continued ji fo, ever fince the deluge, in fuch elevated ground, i | where the torrents wear and cut down the moun- eii tains with unexampled violence, and have hol- lowed out Quebradas fo much deeper and more ni abrupt than the glens or vallies among other hi mountains. He had not, I believe, feen the paf- il fage I have quoted from Ulloa; but the circum- W ftances did not warrant the fhells in queftion to be yai regarded as extraneous and adventitious foffils. | A geologift fhould have known better than to m fuppofe this poffible. When we fee VOLTAIRE, fi afcribing to accidental caufes the tranfportation nu _ of thofe thells which he had been told were often i found among the Alps, we can excufe in a Poet @ anda Wit, that ignorance of the facts in mine- ji ralogy, which concealed from him the ex- we treme abfurdity of his affertion; but when a Chemift or Mineralogift talks and reafons in the fame manner, we cannot confider him as enti- ff tled to the fame indulgence. = cS — Note 204 ILLUSTRATIONS OF THE Nore x1. § 42. Fracture and diflocation of the ftrata. 181. The greateft part of the fa&s relative to the fracture and diflocation of the {trata, belongs to the hiftory of veins. The inftances of flips, where no new mineral fubftance is introduced between the feparated rocks, are what properly belong to this place. The frequency of thefe, and their great extent, are well known where- ever mines have been wrought. In fome of them no opening is left, but the flipped ftrata remain contiguous ; in other cafes, there is in- troduced an-unconfolidated earth, often a clay, which may be fuppofed to have come from above, and very probably to have been car- ried down by the water. In fome fuch cafes, however, there are not wanting appearances, which fhow the matter in the flip to have been forced up from below, as we find it to contain fubftances which could not have come from the furface *. = 189% * Unconfolidated earth contained between the fides of a rock that has flipped, is frequent in Cornwall, and is called a Hleukan- HUTTONIAN THEORY. 208 182. A very remarkable fact of this kind oc- a curred not long ago, in digging the Huddersfield | canal in Yorkfhire ; and a very diftin@ account of it is given in the Philofophical Tranfactions, by the engineer who directed the work. In carrying a tunnel into the heart of a hill, the tit) miners came to what is called in the defcription : a fault, throw, or break, or what we have here EA called a hift, which was filled with /Bale fet on Oli; edge, mixed with fofter earth, and in fome pla- lope ces With {mall lumps of coal. The fault or ‘thi = {pace filled with thefe materials, was in general whe about four yards broad, and lay nearly in the me; direction of the tunnel, fo that a confiderable ify extent of it was vifible. Befide the fhale, it contained a rib of limeftone, about four feet 1 thick, which run parallel to the fides of the fault, fy and about four feet from the fouthern margin = ofit. On each fide of this rib were found balls ak -«f limeftone, promifcuoufly fcattered, and of va- = rious fizes, from an ounce to one hundred pounds a fy A f- ts ati = = ail ie We weight. ‘The balls, when broken, were found 2 ti _ to contain fome pyrites near their edges; they és y were not perfeCtly globular, but flattened on the i : j oppofite fides, and fimilar to one another *. d At the time when the account was written, about " _ feventy yards of the rib had been difcovered. is @ 183. Now, w E E * Phil, Tranf. 1796. p. 350. 206 ILLUSTRATIONS OF THE 183. Now, it is certain, that neither this rib of limeftone, nor the balls that accompanied it, can have come from above, as there is no lime. ftone within twenty miles of the place where they were found. They muft, therefore, haye been forced up from below, and no doubt be. long to fome limeftone ftrata, which lie there at a great depth under the furface. The length of this fragment of rock, which, from the ac. count, one muft fuppofe to have been entire, conveys no mean idea, either of the intenfity or regularity of the force by which it was brought into its prefent fituation. In veins, it is not un- common to meet with ftones that appear to have come from a greater depth: but this is probably the moft remarkable inftance of the fame phe- nomenon, which has appeared in a mere flip, and none, I think, can {peak a language lefs liable to be mifunderftood. — 184. I {hall here mention another mark of violent fracture, that has been obferved in rocks of breccia or pudding-ftone, which, though not of the fame kind with the preceding, and of a nature quite peculiar, belongs rather to this place than any other. In rocks of the kind, juft mentioned, it fometimes happens, that con- fiderable portions are feparated from one ano- ther, as if by a mathematical plane, which had eut right acrofs all the quartzy pebbles in its way. a —_—- . HUTTONIAN THEORY. 204 a way. None of the pebbles is drawn out of its focket, that is, out of the cement that furrounds = it, but is divided in two with a very fmooth and . even fracture. The pebbles, in the inftances ny which I have feen, were of quartz, and other | fpecies of primary and much indurated rock. x Lord Wess Seymour and I obferved pud- i ding-ftone rocks, exhibiting inftances of this _ fingular kind of fracture, near Oban, in Argyle- ‘i fhire, about three years ago. The phenomenon ty = was then entirely new to us both; but I have 0} fince met with an inftance of the fame kind in ott Sauffure’s laft work. As the fact is of fo par- okl ticular,a kind, I fhall ftate it in his own words: oii The place was on the fea-thore, near the little town of Alaffio, between Nice and Genoa. pi “En paffant entre ces blocs de breche, j’ad- bk’ mirai quelques-uns d’entr’eux, d’une grandeur | confidérable, et taillés en cubes, avec la plus atk parfaite régularité. Il y avoit ceci de remar- i quable, c’eft que l’action de la pefanteur, qui avoit hi taillé ces cubes en rompant leurs couches, avoit ji coupé tous les cailloux des breches à fleur de la »# furfage de la pierre, aufi nettement que fi c’etit yw. été une maffe molle qu’on efit tranchée verti- of calement avec un rafoir, Cependant parmi ces g cailloux, la plupart calcaires, il s’en trouvoit de très durs, de petrofilex, par exemple, même de . jade, a SS aia —s iiad #08 ILLUSTRATIONS OF THE jade, qui étoient tranchées tout t aufi nettement que les autres *,”’ 185. This defcription is no doubt accurate, though it involves in it fomething of theory, viz, that the fra@ure was made by the weight of the ftone. This may indeed be true ; the ope. ration probably belongs altogether to the fur. face, and is one with which the powers of the mineral regions are not dire@tly concerned. The phenomenon, however, appears to me, on every fuppofition, very difficult to explain. In the fpe- cimen which I brought from Oban, the fmalleft pieces of ftone are cut in two, as well as the lar- geft. The confolidation and hardnefs of the mafs are very great, and the connection of the differ: ent fragments fo perfed, that it is no wonder the whole fhould break as one ftone. But fill, that the fracture fhould be fo exactly in one plane, and without any fhattering, is not a little enig- matical ; if it is indeed a fracture, it muft be the confequence of an immenfe impulfe, very fud- denly communicated. Note * Voyages aux Alpes, tom. ili, § 1371. — e SN R DEAS HUTTONIAN THEORY. > o9 Nore xi. § 43. Elevation and inflexion of the ftrata. 186. The evidence of the different formation of the primary and fecondary ftrata, and of the changes which the former have undergone, is beft feen at the points where thofe ftrata come into contact with one another. Dr Hutton was | not the firt who obferved thefe junctions, though the firft who rightly interpreted the appearances which they exhibit. He has men- tioned obfervations of this fort by De Luc on the confines of the Hartz ; by the author of the Tableau de la Suiffe, at the pafs of Yetz; by - Voight, in Thuringia; and Schreiber, at the = mountain of Gardette *. The leading facts to be remarked, are, _ 1, The vertical or very upright polition of = the primary. or lower ftrata. 1. The fuperftratification of the fecondary, in a pofition nearly horizontal, fo as to be at _ tight angles to thofe on which they reft. ui. The interpofition of a breccia between mA 3 them ; or, as happens in many cafes, the tranfi- | tion of the loweft of the fecondary beds into a O breccia, ‘Steen cneeene: * Theory of the Earth, vol. i, from p. 410, to 453- gro ILLUSTRATIONS OF THE breccia, containing fragments fometimes worn, fometimes angular, of the primary rock. This laft is a phenomenon extremely general, and all our fubfequent information confirms Dr Hutton’s anticipations concerning it. ‘ It wil} be very remarkable,” he fays, “ if fimilar ap- pearances, (fuch as thofe of the breccia defcri- bed by Voight), are always found upon the junc- tion of the Alpine with the level countries #,” Sauffure, ina part of his work, not publithed when Dr Hutton wrote this paflage, has attefted the ge. nerality of the fact with refpe@ to the whole Alps, from the Tyrol to the Mediterranean: “ Un fait que Pon obferve fans aucune excep- tion, ce font les amas de débris, fous la forme de blocs, de breches, de poudingues, de grés, de fable, ou amoncelés, et formant des montagnes, ou des collines, difperfée fur le bord exterieur, ou méme dans les plains qui bordent la chaine des Alpes +.” | This paflage is perfectly decifive as to the ge- nerality of the fact, that the Alps, from the Ty- rol to the Mediterranean, are bordered all round by pudding-ftones or breccias. At the fame time, it is neceflary to remark, that M. Sauffure, by enumerating loofe blocks and fand, along with pudding-ftones, breccias and grit, confounds to- gether things which are extremely different, and which erage * Theory of the Earth, vol. i. p. 448. + Voyages aux Alpes, tom. iv. § 2330. = grounded the hypothefis of the double raifing of HUTTONIAN THEORY. 21% which have had their origin at periods extremely remote from one another. The confolidated rocks of breccia, pudding-ftone and grit, though they are indications of wafte, have received their prefent charaCter at the bottom of the fea: the loofe blocks of ftone, the fand and gravel, on the other hand, are the effets of the wafte now going forward on the furface of the land, and ‘are the materials out of which rocks of the three kinds juft mentioned may hereafter be compofed. If fo fkilfal a mineralogift as Sauffure is guilty of fuch inaccuracy, it muft be afcribed to the confufion neceflarily arifing from the fyftem which he followed, and not to his own want of difcrimination. 3 187. The fame phenomenon, of a breccia cir- cumicribing the primary mountains, is met with in Scotland ; and the Grampians, wherever they Ü are bounded by fecondary ftrata, whether on the fouth or north, afford examples of it. The breccia generally confilts of the fragments of the primary rock, moft commonly rounded, but fometimes alfo angular, united by a cement of fecondary formation, and the whole difpofed in horizontal beds. It was on the conftancy of this accompaniment of the primary ftrata, and on the great quantity of highly polifhed gravel of- ten included in thefe breccias, that Dr Hutton up 212 ILLUSTRATIONS OF THE | up and letting down of the. ancient flrata. See § 43. : 188. As the {pots where the primary and fe. condary rocks may be feen in contact with one another are of great importance in geology, and prefent to the fenfes the moft ftriking monu- ments of the high antiquity and great revolu- tions of the globe, it may be ufeful to point out {fuch of them as have been obferved in this ifland, To thofe which Dr Hutton has defcribed, I have a few more to add, the refult of fome geological excurfions, which I made in company with the Right Honourable Lord Wess Seymour, to whofe affiftance I have been much indebted i in the profecution of thefe inquiries. 189. The moft fouthern junction which we obferved is at ‘Torbay, where the ancient fchil- tus which prevails along the coaft, from the Land’s End to that point, receives a covering of red horizontal ftandftone, the fame which com- pofes the greater part of Devonfhire. The fpot where the immediate contact is vifible, is on the fhore, a little to the fouth of Paynton; and one circumftance, which among many others ferves to diftinguith the different formation of the two kinds of rock, is, that the fchiftus, which is elevated here at an angle of about 45°, is full of quartz veins, which veins are entirely con- fined -HUTTONIAN THEORY. 213 fined to it, and do not, in as far as we could ob- ferve, penetrate into the fandftone, in a fingle inftance. It is probable, that on the north fhore of the bay, the fame line of junétion is vifible: we faw it at Babicomb Bay, fill more to the northward. 190. From this place, the fecondary ftrata of different kinds prevail without interruption, along the coaft of the Britifh Channel, and of _ the German Ocean, as far ‘as Berwick upon ' Tweed, and for fome miles beyond it. The fea-coaft then interfects a primary ridge, the Lammermuir Hills, which traverfes Scotland from eaft to weit, uniting, near the centre of the country, with the metalliferous range of Lead- hills, and afterwards with the mountains of Gal- loway. ‘The fe@ion which the fea-coaft makes of the eaftern extremity of this ridge, is highly inftructive, from the great difturbance of the _ primary ftrata, and the variety of their inflex- ions. The junction of thefe ftrata with the fecondary, on the fouth fide, is near the little fea-port of Eyemouth, but the immediate con- tact is not vifible. On the north fide of the ridge, the jun&tion is at a point called the Siccar, not far from Dun- glais, the feat of Sir James Hall, Baronet. By being well laid open, and diffe@ed by the work- ing of the fea, the rock here difplays the rela- tion between the two orders of ftrata to great | O 3 advantage. 214 ILLUSTRATIONS OF THE advantage. Dr Hutton himfelf has deferibed this junction; Zbeory of the Earth, vol. i, P. 464. 19t. From the point juft mentioned, the fe- condary ftrata continue as far as Stonehaven, where the fouthern chain of the Grampian mountains is interfected by the fea-coaft. Here a great mafs of pudding-ftone appears to lie on the primary ftrata, but their immediate conta@ has not been obferved. 192. Going along the coaft toward the north, the next junctions which we faw were on the fhore, one near Gardenfton, and another near Cullen, in Banff-fhire. The latter is very di- ftin&; it is about a mile to the weftward of the rocks called The Three Kings, where a red fand- ftone, the lower beds of which involve much quartzy gravel, lies horizontally upon very re- gular, upright, and highly indurated ftrata. Some of thele ftrata are micaceous, and others of the granulated quartz, mentioned in § 152. 193. This laft is, I believe, the moft northern junction which has been obferved in our ifland. ‘The weitern coait furnifhes feveral more, which however are not all vifible. The line of fepa- ration, between the primary fchiftus of the Grampians and the fanditone which covers it, is interfected at its weftern extremity by the Frith of Clyde, not far from Ardencaple in Dun- bartonthire. The two kinds of ftone ean be traced 1 [ d | 4 i ; HUTTONIAN THEORY. ois hy traced within a few yards of each other, but Mi not to the actual contact: the beds of fandftone | neareft the fchiftus form as ufual a breccia, load- My ed with fragments of the primary rock. The it, fecondary rock, which begins here, continues i for about fifty miles fouth, to Girvan in Ayr- i) fhire, where the primary fchiftus again rifes up, lt) but is not feen in contad with the fecondary. on = It extends to the Mull of Galloway and the | fhores of the Solway Frith. wi The Hle of Arran, however, not far diftant nth _ from this part of the coaft, contains a junction rw at its northern extremity, where fecondary ftra- yi ta of limeftone lie immediately on a primary ff micaceous {chiftus. This is defcribed by Dr _ Hutton, and was the firt phenomenon of the kind which he had an opportunity of examin- ing *. The jundion is vifible but at one fpot, and is not feen fo diftin&ly as in fome of the inftances | jut mentioned ; but the great quantity of pud- , ding-ftone near it, renders it more interefting "than it would be otherwife. As the greater part of this little ifland is furrounded by fecon- dary ftrata, other junctions might be expected _ to be vifible. = 194. On the coaft of England and Wales, from the Solway Frith to the Land’s End, though there are feveral alternations from fecondary to pri- O4 mary J * Theory of the Earth, vol, i, p. 429. 216 ILLUSTRATIONS OF THE mary ftrata, I know not that any of them have been obferved. At St Bride’s Bay, in Pem- brokefhire, the primary and fecondary ftrata are’ feen very near their junction; but the precife line I believe is not vifible. The coal-pits in the fecondary ftrata, approach here within a few hundred yards of the primary. The fecondary itrata which commence at this place, occupy both fides of the Briftol Channel, and meet the Cor- nifh {chiftus, which extends acrofs the north of Devonthire to the Quantock Hills, in a line that may be looked for on the fea-coaft, fomewhere between Watchett and Minehead. 195. Befides the fea-coaft, the beds of rivers may be expected to afford information on this fubje&t. To the inftances I have mentioned, I have accordingly two others from the inland country to be added. One of them is from the river Jed, a little way above Jedburgh, where the fecondary ftrata are feen lying horizontally on the primary, a fection of both being made by the bed of the river. The phenomena here are very diftind, and ftrongly marked: Dr Hutton has defcribed and reprefented them in a plate *. He has mentioned another junction, not far from this, which he faw in the Tiviot. Both thefe belong to the fame primary ridge with the Siccar Point. 196. I * Theory of the Earth, vol.i, p. 430.3 alfo plate 3 HUTTONIAN THEORY. ary 196. I fhall mention only one other, which was difcovered by Lord Webb Seymour and myfelf, at the foot of the high mountain of E Ingleborough, in Yorkfhire. As we went along the Afkrig road from Ingleton, about a mile and a half from the latter, an opening appeared in the fide of the hill, on the right, about one hun- dred yards from the road, formed by a ‘large ftone, which lay horizontally, and was {upported by two others, ftanding upright, On going up to the fpot, we found it was the mouth of a {mall cave, the ftone lying horizontally, being part of a limeftone bed, and the two upright ftones, vertical plates of a primary argillaceous fchiftus. The limeftone bed, which formed the | roof of the cave, was nearly horizontal, decli- ning to the fouth-eaft ; the {chiftus nearly verti- cal, ftretching from north-weft by weft, to fouth- - eaft by eaft. The {chiftus, though clofe in con- tact with the limeftone, feemed to contain no- thing calcareous, and did not effervefce with acids in the flighteft degree. As this cave is at the foot of Ingleborough, a cold wind, 24° below the temperature of the ; external air, which iffued from the mouth of it, 4 might very well be fuppofed to come from the inmoft receffes of that mountain. Ingleborough, Which confifts entirely of ftrata of limeftone and {| 8stit, nearly horizontal, and alternating with one another, rifes to the height of 1800 or 2000 feet above 218 ILLUSTRATIONS OF THE above the fpot where we now ftood. This, I be. lieve, is the greateft thicknefs of fecondary ftrata that has ever been obferved incumbent on the primary, and it is therefore a geological faq highly deferving of attention. The country all round, toa very great extent, is compofed of limeftone, with a few beds of grit interpofed, and forming, befide Ingleborough, fome other high mountains, fuch as Wharnfide and Penni- gant, all refting, it is probable, on the fame foundation, At the fpot juft defcribed, no breccia appear- ed to be interpofed between the primitive and fecondary rock ; but we found a breccia at ano- ther point of the fame junction, not far di- fant. This was at a cafcade, in the river Greata, called Thornton Force, about two miles — and a half from the place juft mentioned, The Greata here precipitates itfelf from a horizon- tal rock of limeftone; and, after a fall of a- bout eighteen or twenty feet, is received into a bafon which it has worked out in the pri- mary {chiftus. This {chiftus is in beds al- moft perpendicular ; it exadly refembles that which has juft been defcribed, and ftretches nearly in the fame direCtion. On the fouth fide of the river a breccia was feen, lying upon the {chiftus, or rather, it might be faid, that the loweft beds of limeftone contained in them ma- ny rounded fragments of ftone, which, on com- parifon, E fi a Se HUTTONIAN THEORY. 219 parifon, refembled exactly the {chiftus under- neath. The primary rock itfelf is here feven or eight hundred feet above the level of the fea. The fame {chiftus, fomewhat lower down the valley, and nearer to Ingleton, appears in large quantities, and is quarried for flate. Here, how- ever, the immediate junction of the limeftone and ichiftus does not appear. , I have dwelt longer on the defcription of thefe appearances than on any others of the fame kind, becaufe, from the great mafs of fecondary ftrata which here covers the primary, the circumftan- ces are fuch as we cannot expect to fee very often exemplified. © 197. The Lakes of Cumberland are muchvifited by travellers; and it may be worth remarking, on that account, that, as the fite of thefe lakes is a patch of primary country, bounded on all fides by fecondary, fo, in the rivers that run from the lakes, fuch jun@ions as we are now treating of may be expected to be found. Un- der Dun-Mallet, on the fide toward Ulles Wa- ter, we obferved a breccia, which was in horizon- tal layers, and feemed to lie on the primary ichiftus, fo that the whole hill is perhaps a piece of more indurated breccia, or fecondary rock, which has refifted the wearing and wafhing down of the rivers better than the reft. 198. After afcertaining the fact of the diftur- bance of the ftrata, and their removal from their original 220 ILLUSTRATIONS OF THE original pofition, it is of confequence to inquire into the direGtion of the force by which thefe changes have been produced. Now, if the dj. fturbed or elevated ftrata, were every where in planes, without bending or finuofity, it might perhaps be hard to determine, whether that force had acted in the dire&ion of gravity, or in the oppofite. Either fuppofition would account for the appearances ; and, as gravity is a known force, providing we can find fome place fit to receive the matter impelled down- ward by it, its action would furnith the mot probable folution of the difficulty. It is on this principle that the Neptunian fyf- tem proceeds, imagining, that certain great ca- verns or vacuities having been opened in the in- terior of the globe, a great part of the waters which formerly covered its furface, retired into them, and much of the folid rock alfo funk down at the fame time. In this way, one extremity of a ftratum has been elevated, while the other has been depreffed, and a certain inclination to the horizon has been given to the whole of it. Thus one caufe ferves two purpofes; the va- cuities in the interior of the earth account, both for the depreflion of the fea, and the elevation of the land; and the Neptunifts, if the pheno- mena were all fuch as have been now ftated, might boaft of a felicity of explanation, not very nfual in their fyftem. 7 3 But T -N HUTTONIAN THEORY. 22I s But this appearance of fuccels vanifhes, when % f the elevation and difturbance of the trata are at more minutely examined, and are found to in- a clude waving and inflexion, in a great variety W of forms. It then becomes evident, that the il beds of rock, at the time when they were di- My = fturbed from their horizontal pofition, had Ni’ not, their prefent hardnefs and rigidity, but vy were, in a certain degree at leaft, foft and flexi- iw ble. Without thefe qualities, they could not i have received, as they have often done, the wl curvature of a circle, not many feet, nay, not | many inches, in diameter ; nor could they have a) been bent into fuperficies, with their curvature ti} in oppofite directions, fo that the fame furface is wi in one part convex, and in another concave, on i) the fame fide, with a line of contrary flexure in- jmt terpofed. Thefe are appearances, not reconci- jn) lable with the mere falling in, and breaking ji down of indurated rocks. _ ii 199. The inflexions and wavings that we are wt = here fpeaking of, though not peculiar to the fi Primary ftrata, are found moft frequently among 4 them, and are perfeétly familiar to every one | who has travelled among mountains with any ‘view to the ftudy of geology. The following are a few inftances of this phenomena, out of a f great number which might be produced. Sauffure, 222 ILLUSTRATIONS OF THE Sauffure, in defcribing the rout from Geneyg to Chamouny, mentions many remarkable jn. {tances of the bending of the ftrata, and parti- cularly where the {mall ftream of Nant d’Ay. penaz forms a cafcade, by falling over the face of a perpendicular limeftone rock. The ftrata of this rock are bent into circular arches, ex- tremely regular, and with their concavity turned to the left. What deferves particularly to be remarked, is, that a mountain behind the caf. cade has its ftrata bent in a direction oppofite to the former, or with their concavity to the right, There is no doubt that the ftrata of both rocks are the fame, fo that a vertical feCtion of them would give a curve, in the figure of an S*, Thefe circumftances are mentioned by Sauflure, and from them we may infer this other proper- ty of thefe ftrata, that their fection by a hori- zontal plane, muft exhibit a fyftem of ftraight lines, probably all parallel to one another. The fame mineralogift defcribes the calcareous ftrata which compofe the mountain Axenberg, on - the fide of the Lake of Lucerne, as having from top to bottom of the mountain the form of the letter S comprefled (écra/ce), with their curva- ture in fome places very great. Thefe inflex- ions * Voyages aux Alpes, vol. i. § 472.; alfo, Theoty of the Earth, vol. ii. p. 30. HUTTONIAN THEORY. 223 ions are repeated feveral times, and often in con- trary directions ; the layers are fometimes bro- ken, where their curvature is greateft *. On the fide of the fame lake, is another in- - ftance of bent ftrata, in a mountain, of which the beds are horizontal in the lower part, but are bent at one end upwards, in the form of the letter C. The horizontal part is of great extent, and the rock is alfo calcareous ie The Montagne de la Tuile, near Montmelian, receives its name from the beds of rock being incurvated in form of a tyle f. Among fecon- dary mountains, the fame kind of phenomena are obferved, though lefs frequently, and with lefs variety of inflexion. The chain of Jura is fe- condary, and the beds which compofe it are of limeftone, or of grit: they are bent in fuch a manner, that in a tranf{verfe fection of the moun- tain, each layer would have the figure of a pa- Tabola §. 200. The Pyrenees furnifh abundance of phe- nomena of the fame kind, as we learn from the Efai fur la Mineralogie des Pyrénées. The i calcareous * Voyages aux Alpes, tom. iv. § 1935. + Ibid. $ 1937- f Ibid, vol. iii. § 1182, and plate i, § Ibid, tom. 1. § 334. 224 ILLUSTRATIONS OF THE calcareous {trata of the valley of Afpe, repre. | fented plate v. of that work, deferve particu. larly to be remarked. 201. Our own ifland abounds with examples - of the bending and inflexion of the ftrata, efpe. cially the primary, and many of them very much refembling thofe in the Alpes and Pyrenees, On the top of the mountain of Ben-Lawers, in Perthfhire, there isla rock, the face of which exhibits a fection of a great number of thin equidiftant layers, bent backwards and fòr- wards, like thofe defcribed by Sauffure; and this unequivocal proof of the rock having once exifted in the ftate of a flexible and tenacious pafte, is rendered more ftriking, by the great elevation of the fpot, and the rug- gednefs and induration, both of the ftone it- felf, and of every thing that furrounds it. Ma- ny other mountains in this trac confift of a {chiftus, which is talcofe rather than mica- ceous, and fubjeét, in a remarkable degree, to the fort of finuofity and inflexion here treated of, The appearances of the primary ftrata on the coaft of Berwickfhire, have been already men- tioned, as affording much valuable infiruction in geology. They alfo exemplify the waving and inflexion of the ftrata ona large {cale, and with great variety. A fection of fome of them ee is it ee alias HOTTONIAN THEORY. 225 js given by Dr Hutton, in his Theory of the Earth, vol. i., from a drawing made by Sir James | Hall. The nature of the curve fuperficies into which the ichiftus is bent, is the better under- ftood from this, that, befides tran{verfe fe@ions from north to fouth, the deep indentures which the fea has made, and the projeGing points of rock, exhibit many longitudinal feétions, in a direction from eaft to weit. 202. The dock-yards at Plymouth are in fe- veral places cut out of a folid rock of primary {chiftus, fingularly incurvated. The inflexions are feen there to great advantage, being exhibi- ted in three fections, at right angles to one ano- ther, tranfverfe, longitudinal and horizontal. 203. From thefe inftances, to which it were eafy to add many more, two conclufions may be drawn. The firt of thefe is very obvious, viz. that the ftrata muft have been pliant and foft when they acquired their prefent form. The bending of an indurated bed of ftone into an arch of great curvaturéyand without fracture, as in the preceding examples, is a phyfical im- = pollibility. Sauffure has indeed obferved a frac- ture to accompany the bending, in one or two cafes; but it is an uncommon phenomenon, and, where it happens, muft no doubt be under- ~ flood to indicate an imperfe@ flexibility. Now, if it be granted that the firata were at any time foft 226 ILLUSTRATIONS OF THE foft and flexible, fince their complete formation, | it will be found impoffible to deny their having been foftened by the application of heat. - 204. ‘Phe fecond conclufion, alluded to above, refults from a property, which belongs very ge- nerally, if not univerfally, to the inflexions of the ftrata. This confifts in their curvature being fimple, or in one dimenfion only, likea _ cylindric fuperficies, not double, or in two di- menfions, like the fuperficies of a {phere or {pheroid. This may be otherwife expreffed, by faying, that the fections of the bent ftrata, by a horizontal plane, are ftraight lines, pa- : rallel to one another. On this account, every fuch ftratum feems as if it were bent over an axis, and the axes of all thefe different bendings, for a great extent of country, are nearly paral- lel. : The truth of this is evident, where the ftrata are feen both tranfverfely and longitudinally. It holds remarkably of the primary fchiftus on the coaft of Berwickfhire; where the beds of rock, if cut tranfverfely, by a vertical plane, exhibit the figures of very complicated curves, with various maxima and minima, and points of contrary flexure; but, if they are cut by a ho- rizontal plane, the fection will produce nothing but ftraight lines, nearly parallel. 205. The = =e HUTTONIAN THEORY. 229 205. The conftancy of the direGtion of the primary ftrata, when eftimated by their inter- fection with the horizontal plane, is often very remarkable. Their clevation and flexure are fubject to great and fudden changes, fo as to pafs not only from greater to lefs, but from one fide to the oppofite, within a {mall diftance ; but the horizontal line in which they /retch, ufually preferves the fame bearing to a great extent. The general direction of the primary ftrata, in the fouth part of Scotland, is from E. N. E. to W. S. W.; and the fame is nearly true of thofe which compofe the ridge of the Grampians on the north, and the hills of Cum- berland and Weftmoreland toward the fouth, though between the fchiftus of thefe three tracts, theré is no communication at the furface, each being entirely feparated from the one next it, by the interpofition of fecondary ftrata. I have already mentioned the obfervations of Lord Webb Seymour and myfelf, at the foot of Ingle- borough ; and it appears from them, that the vertical fchiftus on which that mountain refts, though it fill preferves an eaftern and weftern dire@tion, varies feveral points from that of the More northern ftrata. ‘The ftrata of Wales re- turn more to the firft-mentioned direction, and thofe of Devonthire and Cornwall agree with it very nearly. In all this, it will be eafily con- P 2 ceived, 228 ILLUSTRATIONS OF THE ceived, that I do not mean to fpeak with abfo- ute precifion, or to deny the exiftence of great local irregularities. The refult given is only a kind of average, deduced from obfervations hardly fufceptible of great exactnefs, and not yet fufficiently multiplied to give to the con- clufion all the accuracy it may attain. 206. This tendency of the primary ftratato ° take a uniform dire&tion, has alfo been obferved in other countries. Sauffure remarked in the Alps, that the beds of fchiftus are generally pa- rallel to the chains of mountains compofed of them *; and this remark is probably applica- ble to all mountains confifting of primary ftrata. The general direction, therefore, of the {chiftus of the Alps, muft be confined between W. 10° S. and W. 40° S. In the Pyrenees, the direction of the ftrata is about W. N. W +. If Sanflure’s. rule may be depended on, the {chiftus of the Altaic, and moft of the other great chains in the old continent, are in directions that run con- fiderably to the fouth of weft. The Ourals, and perhaps fome other of the northern chains, are however entirely different- In the Ourals, | as we learn not only from the general direction of the chain, but from a feCtion of it in the roth vo- lume * Voyages aux Alpes, tom. i. § 577° + Efai fur le Mineralogie des Pyrenées. HUTTONIAN THEORY. 229 lume of the Nova Ata of Peterfburgh, (tab. 12.), the direCtion of the ftrata is nearly from N. to S: This laft is probably the direction in the great chains of South America; fo that the uniformity of direction in the primary ftrata, which fome mineralogifts would extend to thofe of the whole earth, is certainly imaginary, though there can be no doubt that it extends over "a large por- tions of the earth’s furface ¥. 207. The * It is perhaps unneceflary to obferve, that the two propofitions, that the interfedctions of the ftrata with the horizon are parallel lines; and that they are lines which preferve the fame bearing with refpeé to the points of the compafs; are nearly the fame thing for tra@ts of thoderate exterit, but for large portions of the earth’s furface are extremely different. If, for inftance, the belt of primary vertical {chiltus, which traverfes the fouth of Scotland, were to be produced eaftward in thé fame plane, from its northern extremity, where its di- tection is E.N. E. and its latitude 559.54’, it would cut the meridian always lefs obliquely as it advanced, till, having increafed its longitude about 260.28’, it would be at right angles to the meridian, and its direc- tion of confequence due eat and weft. This would happen in the parallel of 589.51’, (on the fhore of the Gulf of Finland, near Revel), the ftrata being now ex- tended about 880 G. miles from the Siccar Point. Con- verfely, vertical ftrata, having the fame bearing with Je refpe& 230 ILLUSTRATIONS OF THE 207. The tendency of the primary ftrata to remain {traight in the horizontal direGtion, and to be bent in the vertical, is a phenomenon which points very directly to the caufes from whence it has arifen. A furface of fimple cur- vature, or a furface ftraight in one diredtion, is what wefpect to. the meridian, may be im planes very much. inclined to.one another. A ftratum which bears eaft and weft in Cornwall, and one that does the fame at the eaft end of the Altaic chain, will be in planes, which, if produced, would cut one another at right angles. All this is fufficiently plain from the doétrine of the fphere,, and is mentioned here, merely as a caution to prevent too hafty conclufions from being drawn:from any corre- fpondence of bearing among the ftrata of remote coun- tries. For the fake of thofe who would. deduce the medium bearing of any body of ftrata from a number of obfer- vations, it may be proper to take notice, that the true average is not to be found by fimply taking an arith. metical mean among all the obfervations. A more ex- act way is to work by the traverfe table, as in keep- ing a fhip’s reckoning, (fuppofing the diftance run to be always unity), and to compute from the obferved bearings’ the amount of all the fouthing or northing, and alfo of all. the eafting or wefting. The fum of all he latter, di- vided by the fum of all the former, is the tangent of the angle which the general dire¢tion of the ftrata makes: with the. meridian. HUTTONIAN THEORY. 232 uy what the application of forces to different points | ofa plane, which is flexible, though with a cer- U | tain degree of rigidity, will naturally produce. by The fuppofition, therefore, that thele ftrata were wl once flat and horizontal, and were impelled up- Mi ward from that fituation before they had be- My come rigid or hard, will explain their having >| the kind of curvature which removes them as my little as poffible from their original condition. as But no other hypothefis affords any reafon why ty they fhould have that curvature more than any hi | other. From the falling in of roofs of caverns, : A ] we mightexpec fracture and diflocation, without ne any order or regularity ; but certainly no bend- om ing or finuofity, nor any fymmetrical arrange- om ment. If, as fome mineralogilts allege, the curva- _ | ture, as well as inclination of the ftrata, arofe from fim! the irregularities of the bottom on which they nt were depofited, why is the former in one dimen- tt fion only, and why is it not in every direction, itl like that of hills and valleys, or the actual furface i of the earth? Or, laftly, if the whole ftrudure @ of the primitive mountains is an effed of cryftal- oF lization, and if thefe mountains are now fuch as i they have ever been from the time of their con- i _ folidation, whence is it, that, in their bendings _ the law juft mentioned is fo conftantly obfer- ` ved? Indeed, the idea of afcribing the inflex- ions of the ftrata to cryftallization, though fug- gefted 432 ILLUSTRATIONS OF THE gefted by Sauffure *, and fince become a favonrs ite fyftem with feveral mineralogifts, appears to me in the higheft degree unfatisfaGtory and il- lufive. The purpofe for which cryftallization is here introduced, is not to give a fpecific figure to a particular fubftance, but to arrange the fubftances which it has formed and figu- red, according to certain rules; a work which we know not how it is to perform, and in which we have no experience of its power, Accordingly, this principle does not account, in any way whatever, for the circumftances which attend the inflexion of the ftrata, for the fimple curvature which they affect, nor for that parallelifm of their layers, which, in all their bendings, is fo accurately preferved. It does, indeed, fo little ferve to explain thefe facts, that, were the appearances completely reverfed ; did the ftrata afflume the moft com- plex, inftead of the moft fimple curvature; inftead of equidiftant, were they converging, or alternately receding and approaching to one another; the theory of cryftallization might be equally applied to them. The ftate of the phenomena is a matter of perfect indifference to fuch a theory as this: all things are explain- ed by it with the fame facility ; the ftraight and ; the % Voyages aux Alpes, tom. 1, § 475. HUTTONIAN THEORY. 233 > the crooked, the {quare and the round, the move- IE able and the immoveable. Is it not evident ti = that fuch an explanation is a mere word; or, if ay) any thing more than a word, an expreffion of tt | our ignorance, fo awkward and indirect, as to ly) deprive us of whatever credit might have been by gained by a plain and candid avowal of it ? hig It fhould never be forgotten, that a theory di = Which accounts for any thing, and a theory which Mi accounts for nothing, tand precifely on the fame Wf footing, and ought to be banifhed from all parts mt of philofophy, as they have been from thofe tt} fciences which are juftly honoured with the name tii} ofaccurate. The animated orbs of Ariftotle, and nil the vortices of Des Cartes, have long ceafed to be jl) mentioned in phyfical aftronomy ; the firft, be-. hel | caufe they accounted for every thing alike ; the tj fecond, becaufe, when they accounted for one t thing, they never could be made to account for ma another. Both theories, therefore, have very ih properly been rejected; and, when geology ot fhall undergo a fimilar purification, the princi- if ple we have been contfidering will not be the b only facrifice required of the Neptunian fyftem. P| 208. An appearance obferved in fome kinds ih of primary {chiftus, which clearly indicates their i | depofition by water, and in planes very different i E from thofe in which we now fee them, though it might have been introduced before, is alfo much 234 ILLUSTRATIONS OF THE much conneéted with the prefent argument, This appearance confifts of {mall wavings or un. dulz on the furface of the plates of {chiftus, precifely fimilar to thofe marks which are left by the fea on a gently inclining beach of fand, at the ebbing of the tide. All the fpecies of {chiftus do not feem to afford inftances of thefe wavings. The rocks which do fo, are, I think, chiefly of the argillaceous kind, but often highly indurated; fo that the lamine containing the firini are not to be torn afunder but with great difficulty. Inftances of it abound in the {chiftus of Berwickfhire, and are alfo not unfre- quent in that of Galloway. All muf agree about the agent which produced thefe marks ; it could be no other than the fea; but it mutt have been the fea acting on loofe, fmall and round particles, lying on a furface which was nearly horizontal. 209. Dr Hutton’s theory is no where ftronger, than in what relates to the elevation and inflex- ion of the ftrata ; points in which all others are fo egregioufly defeQive. The phenomena to be connected are here extremely various, and even in appearance contradictory : the horizontality of one part of the ftrata; the inclined or verti- cal pofition of another; the perfect planes in which one fet are extended; the breaking and diflocation HUTTONIAN THEORY. 235 in| diflocation found in a fecond ; the inflexion and ty finuofity of a third ; and almoft every where the “ wtmoft rigidity and induration, combined with appearances of the greateft foftnefs and flexibi- lity; the prefervation of a parallelifm of fu- perficies in the midft of fo much irregularity, and the affumption of a determinate fpecies of curvature, under circumflances the moft diflimi- lar ; all thefe appearances were to be connected ~ with one another, and with the confolidation of the ftrata, and this is done by the twofold hypo- thefis, of aqueous depofition, and the aion of fub- terraneous heat. When thefe circum{tances are fairly confidered, and when the fhifts which other fyftems are put to on this occafion are remem- bered, I think it will be granted, that few attempts at generalization have been more fuc- _eefsful, than that which is here made by the _ Huttonian Theory. 210. To the fa@ of the elevation of the ftra- ta, the ftudy of geology is much indebted. The ftratified form of a. great proportion of the earth’s furface, gives to minerals that organiza- tion and regularity, which makes their difpofi- tion an object of fcience, and their inclined po- fition ferves to bring that organization into view, from far greater depths than we can ever reach by artificial excavations. If, for inftance, the ter- mination of frata, that make with the horizon an 236 ILLUSTRATIONS OF THE an angle of. 30°, lying one over another, is feex for a horizontal diftance of two miles ; then it is certain, that if thefe ftrata have that extent under ground, which may be reafonably fup: poled, the thicknefs of the whole mafs, mea. fured by a line perpendicular to its {tratifica. tion, is half the horizontal diftance, or amounts to one mile. It would alfo require a pit to be funk from the uppermoft of thefe ftrata, to the depth of (2 miles x tan 30°, =) 6093 feet, be. fore it could interfe@ the undermoft; and therefore, if we fuppofe the fame ftratum to pre- ferve the fame character for the extent of fome miles, we obtain the fame information from in- {pecting the edge-feams, and fee in reality as far into the bowels of the earth, as if we had funk a perpendicular fhaft to the depth of 6000 feet. = In general, the length of the horizontal line drawn acrofs the ftrata, from the loweft in po- - fition to the higheft,, multiplied into the fine of the inclination of the ftrata to the horizon, gives the thicknefs of the whole, meafured perpendi- cularly to the plane of the ftratification: and the fame horizontal diftance, multiplied into the tangent of the inclination, gives the actual depth at which the loweft ftratum would meet a per- pendicularto the horizon, drawn from the high- eft extremity of the upper ftratum. In ee nes ee HUTTONIAN THEORY. 237 In many cafes, the extent of ftratified mate- rials admitting of fuch an examination as this, js much greater than has now been fuppofed. M. Pallas defcribes a range of hills on the fouth-eaft fide of the peninfula of the Tauride, which is cut down perpendicularly toward the fea, and offers a complete fection of the parallel beds of a primary, or, as he calls it, an ancient limeftone, inclined at an angle of 45° to the hori- zon ; and this fection continues for the length of 130 verfis, or about 86 Englifh miles. The beds are fo regular, that M. Pallas compares / them to the leaves of a book*. The height of thefe hills does not exceed 1200 feet, but the real height of the uppermoft ftratum above the undermoft, is 86x \/; = 86 x $ = 61 miles nearly. 4 If therefore we conceive that there is no fhift Ji in all this great fyftem of ftrata, we in reality ind are enabled, by means of it, to fee no lefs than igi 61 miles into the interior of the earth, nearly _ a65th part of the radius of the globe. It is # true, that we can hardly fuppofe fo great a body gf ftrata to have been raifed without fhifting, oe fo that we muft diminifh this depth confider- A ably ; but were it reduced even to one-half, it $ T Se if ji * See Nova Aĝa Acad. Petropol, tom, x. (1792,) P: 257. 238 ILLUSTRATIONS OF THE will appear, that men fee much farther into the interior of the globe than they are aware of, and that geologifts are reproached without reafon for forming theories of the earth, when all that they can do is but to make a few feratches on its furface. Art indeed can do little more; but nature {upplies the deficiency, and makes difco. veries to the attentive obferver, on the fame great fcale with her other operations. The fimpleft account that can be given of the vaft body of parallel and highly inclined ftrata juft mentioned, is, that it confifts of the ends of horizontal ftrata,.or of ftrata not greatly inclined, that have been forced up when they were all foft and flexible. This is a much more con- ceivable fuppofition than Pallas’s, viz. that the greater part of this mafs has funk down into fome vaft cavern in the interior of the earth. Nore HUTTONIAN THEORY. 239 N , tj Nore XII. § 53. li l : Metallic Veins. hs 21r. The large fpecimens of native iron found iy ‘jn Siberia and Peru, mentioned above, § 51r., ty are among the moft curious facts in the natural hiftory of metals. It has been doubted, how- ft ever, by fome, whether they really belong to it, natural hiftory, or are not rather to be account- ii ed artificial produ&ions. If they had been im’ found in the heart of rocks, or in the midft of ti metallic veins, no doubt of this fort could pofi- (m bly have been entertained; but, as they he tty quite on the furface, in the middle of flat coun- it) tries, and at a diftance from any known vein of , metal, the conjecture that they may be artificial, | and the remains of the iron founderies of an- | cient and unknown nations, is at firft fight not | entirely deftitute of probability. This proba- ith bility, however, will appear to be the lefs, the | More carefully the fpecimens are examined, | The metal is too perfe@t, and the mafies too | large, to have been melted in the furnaces, or to have been tranfported by the machinery, of a rude people. The fpecimen in South Amefica Weighs 300 quintals, or about 15 tons, and is foft 240 ILLUSTRATIONS OF THE foft and malleable *. The Siberian {pecimen, defcribed by Pallas, is alfo very large; it is toft and malleable, and full of round cavities, con- taining a fubftance, which, on examination, has been found to be chryfolite +. Now, it is cer. tainly quite impoffible, that, in an artificial fu- fion, fo much chryfolite could have come by any means to be involved in the iron ; but, if the fufion was natural, and happened ina mi- neral vein, the iron and the chryfolite were both in their native place, and their mecting toge- ther has nothing in it that is inexplicable. 212. Some circumftances in the. defcription of the fpecimen in South America, fuch as the impreflions of the feet of men and of birds on its furface, are not to be accounted for on any hypothefis, and certainly require more care- ful inveftigation. It is faid, that this iron is very little fubje& to ruft, and the analyfis of a piece of it by Prousr makes it probable, that it owes this quality to its union with nickel f. It appears, alfo, that the country of Chaco, where this fpecimen was found, affords many others of the fame kind, one of which is men- tioned in the defcription above referred to. That country * Phil. Tranf. 1788. p. 37. alfo p. 183, &e. + Kirwan’s Mineralogy, vol.ii. art. Native Iron. + Annales de Chimie, tom. xxxv. Mefiidor, p. 47e HUTTONIAN THEORY. 241 country lies on the eaf fide of the Plata, and is afplain, extremely level, and of vaft extent; without any appearance of mineral veins; but fuch veins may neverthelefs exit undilcovered, in a tract fubje@ to periodical inundations, and where the native rock is covered with alluvial earth and gravel to a great depth. The veins may be wafhed away, and the more durable fubftan- ces, fuch as thofe pieces of native iron, may be left behind; and, though they muft be of a for- mation extremely ancient, according to this hy- JE pothefis, they may not have been very long on the furface. 213. Specimens of native iron have been found, lefs remarkable than the preceding for their fize, but in circumftances that excluded all idea of artificial fufion. Of this fort was Marcraar’s {pecimen of native iron, the firt of the kind that was known; it confifted of {mall bits of foft and malleable iron, found in the heart of a brown iron-ftone*. This makes it certain, that native iron is a natural production, and the mere circumftance of great magnitude, in the {pecimens ‘before mentioned, does not en- title us to doubt of their having that fame ori- gin, It is a circumftance, befides, not in the dleat material to this argument; the finalleft J- piece * Kirwan’s Mineralogy, vol, ii. p. 156. 242 ILLUSTRATIONS OF THE piece of native iron being as much a proof of fufion as the greateft; and the fpecimen of Margraaf being juft as conclufive in favour of the Huttonian Theory, as thofe of Pallas or De Celis, fuppofing their reality as mineral produc- tions to be completely eftablifhed. A metal malleable and duétile, in ever fo fmall a quan- tity, cannot be the refult of precipitation from a menftruum, without a very particular combi- nation of circumftances. Such a metal, on the other hand, can be readily produced by igneous fufion ; fo that here the negative and affirmative parts of the inductive argument may both be regarded as complete. 214. Mr Kirwan, in order to account for the magnitude of the two large {fpecimens mentioned above, fuppofes, that {mall pieces of native iron (about the formation of which he appears to have no difficulty), have been originally agglu- tinated by petroleum, and left bare, when the furrounding ftony or earthy maffes either wi- thered or were walhed off *. This is no doubt the mof fingular of all the opinions which have been advanced on the fubje@ ; and, as it bor- rows nothing from analogy, it admits of no proof, and requires no refutation. None buta chemift of eminence could have ventured with impunity ete * Geol. Effays, p. 405, eer HUTTONIAN THEORY. 243 impunity on an affertion fo inconfiftent with all the phenomena and principles of his {cience. 215. Aremark of the fame author, on the fubject of the native gold found in the county of Wicklow in Ireland, is entitled to more atten- tion. “ That thefe lumps of native gold,” he fays, “ were never in fufion, is evident from their low fpecific gravity, and the grains of fand — found in the midft of them. I found the {pe- cific gravity of a lump of the fize of a nutmeg | tobe only 12800, whereas, after fufion, it be- E came 18700 *.”’ This argument is plaufible; but, I think, neverthelefs inconclufive. The fand found in the gold, accounts, at leaft in part, for its lightnefs. It is only by repeated fufions that any of the metals is brought to its utmoft pu- rity and higheft fpecific gravity; and on no fuppofition can the melting of gold in the mineral regions, be very likely to feparate it. | I from heterogeneous fubftances. That quartzy fand fhould be found in it, after fuch a procefs, is _ haturally to be expected. The impreflions which | | the quartz cryftals have left on the Wicklow gold, would be received as a full proof of the fufion of that metal, if geologifts always regu- Q2 lated * Geol. Effays, p. 402. 244 ILLUSTRATIONS OF THE lated their theories by the principles which de- termine the belief of ordinary men. 216. Don Rubin de Celis, in the paper re- ferred to above, mentions fome mafies of filver found at Quantajaia, and alfo fome duft of pla- tina, in terms that excite a ftrong defire to have more information concerning them. They are confidered by him as effects of volcanic fire; fo we may conclude, that they contain evident marks of fufion, and would in this fyftem be aferibed to that heat, from which volcanic fire is but a partial and accidental derivation. — 217. The ftate alfo in which gold and filver are often found pervading mafles of quartz, and fhooting acrofs them in every direction, furnithes a firong argument for the igneous origin, both of the metal and the ftone. From fach fpeci- mens, it is evident, that the quartz and the me- te, at the fame time; and it is hardly lefs clear, that this fluidity did not proceed from fo- lution in any menftruum: For the menftruun, whether water or the chaotic fluid, to enable it to diffolve the quartz, muft have had an alka- line impregnation; and, to enable it to diffolve the metal, it muft have had, at the fame time, an acid impregnation. But thefe two oppofite qualities could not refide in the fame fubjeđ; the acid and alkali would unite together, 5 i HUTTONIAN THEORY. 245 if equally powerful, form a neutral falt, (like fea-falt), incapable of acting either on the me- tallic or the filiceous body. If the acid was moft powerful, the compound falt might act on the metal, but not at all upon the quartz ; and if the alkali was moft powerful, the compound might a& on the quartz, but not at all on the metal. In no cafe, therefore, could it a@& on both at the fame time. Fire or heat, if fuffi- ciently intenfe, is not fubjec to this difficulty, as it could exercife its force with equal+¢effec& on both bodies. _ 218. The fimultaneous confolidation of the _ quartz and the metal is indeed fo highly impro- bable, that the Neptunifts rather fuppofe, that the ramifications in fuch fpecimens as are here allu- ded to, have been produced by the metal diifufing itfelf through rifts already formed in the ftone *. = But it may be anfwered, that between the chan- ` nels in which the metal pervades the quartz, and the ordinary cracks or fiffures in ftones, there is no refemblance whatever: That a fyf- tem of hollow tubes, winding through a ftone, ~ {as the tubes in queftion, muft have been, ac- cording to this hypothefis, before they were filled by the metal), is itfelf far more inconceivable _ than the thing which it is intended to explain ; Q 3 | and * Geol. Effays, p. gor. 246 ILLUSTRATIONS OF THE and laftly, that if the ftone was perforated by fuch tubes, it would ftill be infinite to one that they did not all exaétly join, or inofculate With one another. 219. The compenetration, as it may be call. ed, of two heterogeneous fubftances, has here furnifhed a proof of their having been melted by fire. The inclufion of one heterogeneous fubftance within another, as happens among the {pars and drufens, found fo commonly in mine- ral veins, often leads to a fimilar conclufion, Thus, from a fpecimen of chalcedony, including in it a piece of calcareous fpar, Dr Hutton has derived a very ingenious and fatisfaétory proof, that thefe two fubftances were perfe@ly foft at the fame time, and mutually affeted each other at the moment of their concretion *. i Each of thefe fubftances has its peculiar form, which, when left to itfelf, it naturally affumes ; the fpar taking the form of rhombic crytftals, and the chalcedony affe&ting a mammalated ftruc- ture, or a fuperficies compofed of fpherical feg- ments, contiguous to one another. Now, in the fpecimen under confideration, the {par is inclu- ded in the chalcedony, and the peculiar figure of each is impreffed on the other; the angles and planes of the fpar are indented into the chalce- dony, — * Theory of the Earth, vol.i. p. 93. HUTTONIAN THEORY. 247 dony, and the fpherical fegments of the chalce- dony are imprinted on the planes of the fpar. Thefe appearances are confiftent with no notion of confolidation that does not involve in it the fimultaneous concretion of the whole mafs; and fuch concretion cannot arife from precipitation from a folvent, but only from the congelation of a melted body. This-argument, it muft be remarked, is not grounded on a folitary {peci- men, (though if it were it might fill be perfect- ly conclufive), but on a phenomenon of which there are innumerable inftances. 220. According to this theory, veins were filled by the injection of fluid matter from be- low; and this account of them, which agrees fo well with the phenomena already defcribed, is confirmed by this, that nothing of the fubftances which fill the veins is to be found any where at the furface. It is not with the veins as with the ftrata, where, in the loofe fand on the fhore, and in the fhells and corals accumulated at the bottom of the fea, we perceive the fame mate- tials of- which thefe ftrata are compofed. The fame does not equally hold of metallic veins: “ Look, fays Dr Hutton, into the fources of our mineral treafures? Afk the miner from whence has come the metal in his veins? Not from the earth or air above, nor from the ftrata which the vein traverfes: thefe do not contain an atom Q4 of 248 ILLUSTRATIONS OF THE of the minerals now confidered. There is but one place from whence thefe minerals may have come ; this is the bowels of the earth ; the place of power and expanfion ; the place forti whence has proceeded that intenfe heat, by which loofe materials have been confolidated into rocks, as well as that enormous force, by which the re- gular ftrata have been broken and difplaced *,” 221. The above is a very juft and natural re- fletion; but if, inftead of interrogating the miner, we confult the Neptunift, we will receive a very different reply. As this philofopher never embarrafles himfelf about preferving a uniformity in the courfe of nature, he will tell us, that though it may be true, that neither the air, the upper part of the earth’s furface, nor even the fea, contain at prefent any thing like the materials of the veins, yet the time was when thefe materials were all mingled together in the chaotic maf, and con- ftituted one vaft fluid, encompaffing the earth ; from which fluid it was, that the minerals were precipitated and depofited in the clefts and fif- {ures of the ftrata. 222. It is alleged, in proof of this hypothefis, that mineral veins are found to be lefs rich as. they go farther down, whereas they ought to be richer, if they were filled by the projection of melted — a * Theory ofthe Earth, vol.i. p. 130. a ee ee ee ` ee a HUTTONIAN THEORY. 249 melted matter from below. But the fad, that mines are lefs rich as they defcend farther, though it may hold in fome inftances, is not ge- neral, and may therefore be fuppofed to arife from local caufes, fuch as are, in refpeé of us, accidental, and beyond the limits to which our theories can be expected to reach. Thus the mines of Mexico and Peru are faid to be fub- jet to the preceding rule; but in the mines of Derbyfhire and Cornwall, the very contrary is underftood to take place. Befides, what we ' are pleafed to call the riches of a mine, are _ riches relatively to us, and relatively to a diftinc- tion which nature does not recognife. The fpars and veinitones which are thrown out in the rub- bifh of our mines, may be as precious in the eyes of nature, as conducive to the great objects of her economy, and are certainly as chara¢teriftic of mineral veins, as the ores of filver or gold, to which we attach fo great a value. Unlefs the former are in fmaller quantity, or lefs highly. cryftallized at great than at fmall depths, which _ Ibelieve is not alleged, no conclufion can be _ drawn from fubftances, which occupy in gene- ral but a {mall proportion of any vein, and, in their diffemination through it, do not feem to be always guided by the fame law. 223. Again, if the veins were filled by depo- fition from above, we ought to difcover in them . fee 3 fuch 250 ILLUSTRATIONS OF THE fuch horizontal ftratification as is the effe@ of depofition from water, and we ‘thould perceive no marks of the materials having been introdu- ced with violence into their place. The Neps | tunifts cannot object to the trial of their theory by thefe two fads. As to the firft, it is acknowledged, that there is a certain regular difpofition of the fubftances in mineral veins, as ftated § 59, but it is one which has hardly any thing in common with the real phenomena of ftratification. It con- fifts in the diftribution of the principal fubftan- ces in coats parallel to the fides of the vein, each fubftance forming a feparate coat. Ina vein, for inftance, containing quartz, fluor, calcareous {par, lead, &c. we might expe to find a lining of quartz cryftals, applied immediately to the walls of the mine, and following exadly the irregularities of their furface; next, perhaps, a coat of fluor, then of calcareous fpar, and laft of Jead-ore in the centre of the vein, the fame or- der being obferved on the oppofite fide. Thefe fucceflive coats, it is material to remark, are not in planes, but in uneven furfaces, of which the inequalities are evidently determined by thole of the walls, that is, of the rock which forms the fides of the vein; neither are they horizon- tal, but are parallel to the walls, whether thele be perpendicular or inclined. Here, therefore, . there HUTTONIAN THEORY. ~ 254 there is no appearance of the action of that fta- tical law which has directed the arrangement of the other ftrata, and which tends to make the | plane of every ftratum depofited by water per- pendicular to the direction of gravity. The coating of the veins has therefore been perform- ed under the conduct of fome other power than that which prefides over aqueous depofition. If, as the Neptunifts maintain, the materials in the veins were depofited by water, in the moft perfect tranquillity, it is wonderful that we do = not find thofe materials difpofed in horizontal _ layers, acrofs the vein, inftead of being parallel to its fides; and it feems very unaccountable, that the common ftrata, depofited as we are told while the water was in a ftate of great agita- tion, have fo rigoroufly obeyed the laws of hy- droftatics, (§ 38.), and acquired a parallelifm in the planes of their ftratification, which ap- proaches fo often to geometrical precifion ; while the materials of the veins, in circumftances fo much more favourable for doing the fame, have _ done nearly the reverfe, and taken a pofition, _ often at right angles to that which hydroftatical = Principles require. This is a paradox which the Neptunian fyftem has created, and which __ therefore it is not very likely to refolve. 224. Mere words fhould have little power to miflead, in a {cience which treats of fenfible ob- jecis, 252 ILLUSTRATIONS OF THE jects, fuch as are always eafily fubjeCted to the examination of fight or of touch; yet there jg fome appearance as if the Neptunifts were mifled in this, and other inftances, by the term firatification. Though an incruftation on the perpendicular face of a rock has very little affinity to a ftratum, fuch as we are accuftomed to fee depofited by water, yet the fame name being once impofed on both, mineralogifts have proceeded to reafon concer ning them, as if they were precifely the fame thing, and were both to be afcribed to the fame caufe. Indeed, every perpendicular or highly-inclined bed of ftone, is inexplicable as an effect of aqueous depofition, in a fyftem, unprovided, as the Neptunian is *, with the means of raifing up fuch beds froma horizontal into a vertical pofition. This obfer- vation may alfo be extended to all cafes of vertical ftratification. Water cannot direAly { arrange its depofites in planes highly inclined, and therefore I have often wondered to fee the Neptunifts contending fo eagerly for the ftrati- fication of certain rocks, fuch as granite, which, being vertical, or highly inclined, was much lefs friendly to their fyftem than the entire ab- fence of all ftratification would have been. I was difpofed to admire their candour, when the 2 ufe a ol * See preceding note. — p HUTTONIAN THEORY. 453 ufe which they made of the fact convinced me, that I ought only to wonder at their inconfequen- tial reafoning. The Huttonian Theory is, in- deed, the only one which poffefles the means of reconciling the elevation of the ftrata with their horizontal depofition, and which is entitled to confider ftratification, in whatever. plane it may be, as originally the work of the ocean. The geologifts who attach themfelves exclufively to the action of water, will never be able to ex- = tend the dominion of that element fo far as Dr Hutton has done, by combining it with fire. 225. But, though the Neptunian fyftem were provided with engines, powerful enough to raife up ftrata from a level to a vertical plane, this would avail nothing in the prefent inftance ; fince, on no fuppofition, can the incruftations on the perpendicular fides of a vein have ever been horizontal. On no fuppofition, therefore, can thefe incruftations be received as a proof of aqueous depofition: it may indeed be certainly inferred from them, that the matter which they = confit of was fluid at the time of their forma- tion; but the abfence of all appearance of a | horizontal difpofition, in any part of the vein, amounts nearly to a demonftration, that this fluidity did not proceed from folution in a men- ftruum. We muft therefore conceive the coats to have been formed during the refrigeration of the melted 454. ILLUSTRATIONS OF THE melted matter inje@ed from the mineral regions into the clefts and fiffures of the ftrata (} 59.) 226. Mineral veins, particularly at their jp. terfeCtions with one another, contain abundant marks of the moft violent and repeated diftur. bance, ({ 56). Not to mention that they owe their firt formation to the fra@ure and dif- placing of rocks already confolidated, it ap- pears, that they have originated at very differ- ent periods, and that the birth of each has been accompanied with convulfions, which fhook the foundations of the earth. In Cornwall, for in- ftance, the principal veins, and thofe which they diftinguifh particularly by the name of Lodes, have nearly the fame direGion with the itrata or vertical {chiftus, extending from about E. N. E. to W.S. W. Thefe, however, are of- ten interfe&ted nearly at right angles by other mineral veins, called Crofs Courfes, and this hardly ever happens without the latter moving, or, as it is called, heaving the former out of their direGion. This plainly indicates, that the cro courles are of later origin than the others, and that their formation was accompanied with fuch a force, as muft, in many inftances, have moved the whole body of rock which conftitutes the promontory of Cornwall, and probably much more, for feveral yards, in a horizontal direc- tion. Sometimes, alfo, both the longitudinal and Ne HUTTONIAN THEORY. 453 and the crofs vein are forced out of their place by a third. Thefe difturbances arife not only from mineral veins, but from veins of porphyry and granite, the production of which has been attended with no lefs violence than of the others. 227. What is here faid of Cornwall, is the hiftory, in fome degree, of all mineral countries whatever. The great horizontal tranflation which has thus accompanied the formation of 4 veins; the movement impreffed on fuch vaft d bodies of rock, and the frequent renewal of thefe - immenfe convulfions ; are not to be explained by the mild and daui dominion of the watery element. They require the utmoft power that is | known any where to exift, and were it not for the admonitions of the volcano and the earthquake, = we might doubt if even fubterraneous heat itfelf poilefied an enegy adequate to thefe aftonith- | ing effects. 228. From the heaving of one vein by ano- ther, it is evident, that there was a force of pro- trufion in the direction of one of them, that adted at the time of its formation. This force = cannot be accounted for on the fuppofition that = veins were produced by the mere fhrinking of the ftrata ; for the rocks could not, in that cafe, have been rent afunder, and impelled forward at the fame time. It appears mof likely, that fif- fures / 256 ILLUSTRATIONS OF THE fures in the ftrata were made, at leaft in many inflances, and the matter poured into them, nearly at the fame time, both being effedts of the fame caufe, the expanfive force of fubterra.. neous heat. . 229. It is remarked, at § 56., that the fhifting of the ftrata is beft obferved where the veins make a tran{verfe feCtion of beds of rock, con- fiderably inclined to the horizon. It is alfo true, that in fome cafes the near approach of — the ftrata to the level, may make the fhifts pro. | duced by the veins very eafy to be difcovered. — Thus in Derbyfhire, where the mineral veins — are in fecondary ftrata, nearly horizontal, there is almoft no inftance in which the correfpond- ing ftrata are not obferved to be on different le- vels, on the oppofite fides of the fame vein. 230. The fad defcribed by De Luc, and re- ferred to at § 55., may, for what we know of it, admit of being explained in two ways. The great wedge of rock which appears to be infu- lated between two branches of the fame vem, may either be a mafs that has been broken off, and fuftained by the melted matter that flowed all around it; or, it may be a mafs of rock con- tained between two veins that are in reality ditin, and of different formation. Whether this laft fuppofition is the truth, would probably be evident from a careful examination of both parts HUTTONIAN THEORY. 285 parts of the vein; as fome difference of charac- ter cannot fail to be the confequence of differ- ent formation. If no fuch difference is obfer- = ved, the two branches muft be fuppofed to be- _ long to the fame vein, and the only probable explanation of the infulation of fo large a mafs of rock will be by the firft-mentioned fuppofi- . i | tion. This fact, therefore, notwithftanding the q great attention M. De Luc has beftowed on it, _ ftill requires further examination, before it can - be decided whether it inclines to the Huttonian ; Theory, as on the firft fuppofition, or is, as on the latter hypothefis, equally balanced between it and the Wernerian. : 231. Whatever be the cafe with this fact, the _ general one of pieces of rock being found infu- i lated in veins, is certainly favourable to the no- tion of an injeĝed and ponderous fiuid having q originally fuftained them. Where, as happens _ in fome inftances, the ftones contained in the _ veins have no affinity to any of the rocks above, _ they cannot be fuppofed to have come any how _ but from below, and to have been carried up by _ the matter of the vein. ‘The inftance from the 4 flip at the Muodonfieid Canal has been already -= mentioned. 232. The preceding obfervations have been 4 d principally directed againft that theory of veins PE os pome them to have been filled by de- ; A pofition 258 ILLUSTRATIONS OF THE pofition from water. There is another theory maintained by fome of the Neptunifts, that the metals in veins were introduced there by infil. tration *. ‘This opinion is fufficiently refuted by the fad, that rarely any metallic ore is found out of the vein, or in the rock on either fide of it, and leaft of all where the vein is richeft, This is inconfiftent with the notion of the ore being carried into the vein by water percolating through the adjacent rocks, unlefs fome fatisfac- tory reafon is afligned, which determined the water to leave the ore in the vein and no where elfe. Befides, this hypothefis does not account ‘or the formation of the fpars and veinftones which fill the vein, and which appear clearly to have been brought there at the fame time with the ore, and no doubt by the fame caufe. 233. The veins, properly fo called, are inde- finitely extended ; but there are alfo thin plates of fpar, and of cryftals of different kinds, often found included in rocks, and fhut in on all fides, to which the name of veins is commonly ap- plied. Thefe laft ought certainly to be diftin- guifhed from the former, and may not impro- perly be called Plate Veins or Lenticular Veins, the plate or cake of {par of which they confift having very often the form of a lens, though, as * Geol. Effays, p. 401. HUTTONIAN THEORY. 259° as may be fuppofed, confiderably irregular. Ei- ther of thefe terms being derived entirely from external characters, has the advantage of in- volving nothing theoretical. herp The lenticular veins are certainly not formed is like the ufual mineral veins, by inje@ion, fince fy) they are fhut in, on all fides, by the folid rock. When they are found, therefore, in ftratified _ rocks, fuch as have not themfelves been melted, we muft conceive them to be compofed of ma- terials more fufible than the furrounding rock, | fo that they have been brought into fufion by a _ |.) degree of heat which the reft of the rock was a able to refift, and, on cooling, have affumed a : {parry ftruGure. When they are found in À rocks, of which the whole has been fluid, they ~ Ò muft be confidered as component parts of that = maf, which, by an eleđtive attraction, have united with one another, and feparated them- {elves from the fubftances to which they had Eee anity. = —— E The veins of this kind feem to be connected _ With thofe called in Derbythire Pipe Veins, in | Which the ores of metals are fometimes found. i The pipe veins, indeed, are not in all cafes com- 7 pletely infulated, but fometimes communicate with the veins properly called mineral. I am 4 too little acquainted, however, with their natu- Tal hiftory, to ‘be able to fay with certainty to R2 which TTEA 260 ILLUSTRATIONS OF THE which of the two fpecies they ought to be re. ferred. Note xiv. § 75. On W. hinftone. 234. To the facts and reafonings given above, I fhall, in this note, add a few remarks, tending to fhew, that whinftone is not of volcanic, nor of aqueous, but certainly of igneous origin. It is afferted (§ 62.), that carbonat of time and zeolite aré often contained in whinftone, but ne- ver in lava, and that this circumftance may fome- times ferve to diftinguifh thefe ftones from one another. With refpect to carbonat of lime, in par- ticular, it feems evident, that this fubftance can- not enter into the original compofition of any la- va, becaufe the fame heat which melted the lava, - would, where there was no greater preffure than the weight of the atmofphere, expel the carbo- nic acid and produce quicklime. Notwithftand- ing this, rocks, containing carbonat of lime, have often been confidered as lavas, into the pores and cavities of which, calcareous matter having been carried by the infiltration of water, had cryftallized into fpar. Thus SPALLANZANI, in. HUTTONIAN THEORY. 261 in his account of the Euganean Hills, in Lom- bardy, defcribes fome of the rocks as abound- ing at their furface, and even in th-ir interior, with air-bubbles of various fizes, from uch as are hardly perceptible, to fome that are half an inch in diameter ; and which, he fays, are all of et the fame direCtion. This he confiders as a proof | that the rock is a genuine lava; for the air- _, bubbles prove the ftone to have had its fluidity _ from fire; and by their elongation in the fame - direction they prove, that the mafs when fluid a = was alfo in motion. Spallanzani adds, that ma- “= ny of thefe cavities are filled with cryftals of the yl carbonat of lime, an effect of the infiltration of "quater *, : : 235. Though the argument here advanced e for the igneous origin of the rock may be admit- me ted as conclufive, the introdu&tion of calcareous a {par into it by infiltration muft ftill be que- ‘ftioned. Lava, except in a ftate of decay or de- compofition, is not readily penetrated by water ; and, if it were, the filling of cavities with fpar, A By means of the water percolating through them, i’ Would fill be fubject to many difficulties, (§ 12.). a Befides, whinftone rocks are frequently found R 3 fo * Voyages dans les deux Siciles, tom. iii. p. 157. 3 f Edit. de Faujas de St Fond. an oval figure, with their longeft diameters in -` F 262 ILLUSTRATIONS OF THE fo full of calcareous fpar, or of zeolite, that they would become porous to fuch a degree, if the cavities filled with thefe latter fubftances were all empty, that they could hardly fuftain their own weight, and much lefs that of the great maffes of rock incumbent on them. In fuch cafes, it jg certain, that the cryftallized fubftances were part of the original compofition of the rock. The truth is, that the infiltration of the water is a mere gratuitous aflumption, introduced for the pur- pole of explaining the exiftence of carbonated lime in a tone which had endured the ation of intenfe heat; and this aflumption ought of courfe to be rejected, if the phenomenon can be explained by a theory, that is in other refpeds conformable to nature. The fpar, then, may be confidered as a proof, that the rocks in que- fion are to be numbered with thofe unerupted lavas which have flowed deep in the bowels of the earth, and under a great comprefling force, This is the more probable, that the Euganean . Hills, like fome whinftone hills in our own coun-. try, have, in certain places, a covering of flaty and calcareous firata incumbent on them, even at their fummits *, fo that the torrent of melted Rone, of which they are admitted to confiff, can- not have flowed from the mouth of avolcano. Ido | not * Phil, Tranf. 1775, p. 34; HUTTONIAN THEORY. 263 not mean to fay, that there are among thefe hills no veftiges of volcanic explofion. I am f yery far from having data fufficient for drawing this conclufion ; but I believe it may be fafely affirmed, that the bulk of them is no more com- pofed of volcanic lava, than the bafaltes of Staffa, or of the Giant’s Caufeway. 236. But, befides the evidence deduced from = calcareous {par and zeolite, againft the rocks containing them being real lava, there are other - marks, even lefs equivocal perhaps, that diftin- guifh the lavas which we fuppofe to have flow- 4 ed in the mineral regions, from thofe which have actually flowed on the furface. Thefe are what we colle from the difpofition, the orga- nization, or, as we may fay, the phyfical geogra- phy of whinftone countries, unlike, in fo many re- {pects, to that of volcanic countries. The fhape of whinftone hills ; their large flat terraces, rifing one above another ; their perpendicular faces, and the correfpondence of their heights even at confiderable diftances ; have nothing fimilar to them in the irregular torrents of volcanic lavas. _ «The phenomena of the former are alfo on a fcale _ of magnitude very far exceeding the latter, and _ Clearly indicate, that though both have been _ produced by fire, it has been by fire in very dif- ferent circumftances, and regulated by very dit- ferent laws. The ftructure of the two kinds of E. R4 rock 264 ILLUSTRATIONS OF THE. rock agrees, in many refpects, and fo does their chemical analyfis ; but their difpofition and ar. rangement are fo diffimilar, that they cannot be fuppofed to be of the fame formation. 237. This argument, I believe, was firft fta. ted by Mr Srranes, in a letter to Sir Joun PRINGLE, publifhed in the 65th volume of the Philofophical Tranfactions *, That intelli- gent obferver, after vifiting the countries in Eu rope moft remarkable either for burning, or for what are accounted, extinguifhed volcanoes, and examining them with a very difcriminating eye, remained convinced, that there are two difting fpecies of rock, which both owe their origin to fire; but to fire aGing in circumftances and feats extremely different. The firft is the common volcanic lava; the other, to which he gives the name of a bafaltine rock, comprehends fuch rocks as the Giant’s Caufeway, the bafaltes of the Vivarais, of the Euganean Hills, &c. and © differs in nothing from that which is called here by the name of whinftone. Mr Strange con- ceived, that the one of thefe kinds of ftone could, no more than the other, be accounted the work of aqueous depofition, but was led to the diftinc- tion juft mentioned, by obfer ving the organization and * Account of Two Giants Caufeways in the Vene- tian State, &c. by John Strange, "Efq; Phil. Tranf, vol. lev: (1775.) p. 5, &e, a] HUTTONIAN THEORY. 265 and arrangement in the rocks of the latter kind, _ and comparing them with the diforder and ruin ` that every where mark the footfteps of volcanic fire. He does not pretend to determine the nature of the fire to which the bafaltine rocks owe their formation, nor the circumftances in which it has acted: he is fatisfied with the negative conclu- fion, that it is not volcanic ; and his paper affords a fpecimen of what is perhaps rare in any of the A fciences, and certainly moft rare of all in geolo- — gy, viz. a philofophic induction carried juft as far as the facts will bear it out, and not a fingle ftep beyond that point. 238. Several other hints contained in this pa- per are highly deferving of notice; for we not = only find in it the nétion of a formation of ba- = faltic rocks, igneous though not volcanic, but alfo that of their fimultaneous cryftallization *, together with the fuggeftion, that granite and = bafalt are of the fame origin +. Thefe opi- = nions had not, I believe, occurred at that time to any mineralogift except Dr Hutton, nor _ had they been communicated by him to any but a few of his moft intimate friends; fo that Mr Strange has without doubt all the merit of a firit difcoverer. Indeed, without the knowledge of the # Phil, Tranf. abi fupra, p. 17. + Ibid. p. 36. and 37. 266 ILLUSTRATIONS OF THE the principle of compreffion, fuch as it is laid down by Dr Hutton, it was hardly poflible for him to proceed further than he has done. He remarked the usburnt limeftone that lies on the tops of fome of the Euganean bafaltes, and feems to have been aware of the great difficulty, which it was referved for the Huttonian Theory to over. come. His letter contains alfo fome excellent general remarks on the rocks of the Vivarais and Velay, which he had vifited, before Fauyas pE ST Fonn had publithed his curious and ela. borate defcription of thefe countries. 239. The caufe of the peculiar ftru@ure which has juft been obferved to diftinguith whinftone from volcanic countries, is ealily afligned in the Huttonian Theory. According to that theory, the whinftone rocks were formed, in the bowels of the earth, of melted matter poured into the rents and openings of the ftrata. They were caf, therefore, in thofe openings, as in a mould; and seceived the impreffion and charaéer of the rocks by which they were furrounded. Hence the tabular maffes of whinftone, which when foft have been interpofed between ftrata, and comprefled by their weight, fo as almoft to have themfelves acquired the appearance of ftratifica- tion. Hence the perpendicular faces of the fame rocks, produced by their being abutted when yet ————— E E E HUTTONIAN THEORY. 267 ` yet foft, againft the abrupt fides of the ftrata. The rocks which formed thofe moulds have, in many cafes, entirely difappeared ; in others, a part ftill remains, furrounding, or even covering, the bafaltes, as in the Euganean Hills, in thofe of the Val di Noto in Sicily, the rocks near Lifbon *, and in different parts of Great Britain. - Above all, the veins of whinftone which in- terfect the ftrata, are the completeft proofs of M the theory here given of thefe rocks, and the | moft inconfiftent, in all refpects, with the hypo- ~ thefis of their volcanic origin. | 240. If thefe criteria are applied to what are - called extinguifhed volcanoes, I have no doubt that many which have been reckoned of that number, will be found to derive their origin more directly from the fire of the mineral re- gions. The bafaltic rocks of the Vivarais, I am well perfuaded, belong to this clafs ; and I con- clude that they do fo, not only from the account of them given by Mr Strange, but from the de- {cription of Faujas himfelf, who, though under g the influence of the oppofite theory, feems very fair and accurate in his defcription of pheno- mena. The moft unequivocal mark of real whinftone rock, and of a formation in the ftrict- eft i A Te far les Volcains Eteints du Vivarais; Lettre de ao P> 443. 268 ILLUSTRATIONS OF THE eft fenfe mineral, is where veins of that kind of rock interfect the ftrata. Now, ina letter tg Buffon, on the ftreams of lava found in the ip. terior of certain calcareous rocks in the lower Vivarais, Faujas defcribes what can be account. ed nothing elfe but a vein or dike of whinftone, accompanied with feveral of its moft remarkable and characteriftic appearances: ‘ Figurez-vous un courant de lave, de la nature du bafalte noir, dur et compacte, qui a percé a travers les maffes calcaires, et s’eft fait jour dans quelques parties, paroiffant et difparoiflant alternativement : Cette coulée de matiére volcanique s’enfonce fous une partie de la ville, bâtie fur le rocher ; elle re- paroit dans la cave d’un maréchal, fe cache et fe montre encore de temps en temps en defcen- dant dans le vallon, &c. Ce qu’il y a d’admi- rable, c’eft que la lave forme deux branches bien extraordinaires, dont l’une s’éleve fur la crête du rocher, tandis que lautre coupe hori- zontalement de grands bancs calcaires efcarpés, qui font à découvert, et bordent le chemin, o Quels efforts n’-a-t-il pas falla pour forcer cette lave fe prendre une telle dire&tion, et fe percer cette fuite de rochers calcaires? Si cette longue coulée de lave avoit eu 200 ou 300 toifes de largeur, je ne ferois pas furpris qu’un tor- rent de matière en fufion de ce volume eut pu produire des effets extraordinaires et violens ; mais y M | wonder that he confidered as marvellous what is HUTTONIAN THEORY. 26g mais figurez-vous, Monfieur, que dans les en- droits les plus larges, elle wa tout-au-plus qu en- viron 12 ou 15 pieds ; elle wen aque 3 ou 4 dans certaines parties *.”’ 3 This narrow ftream is to:be traced acrofs the ftrata for more than a league and a half; and ‘ the whole appeared to Faujas fo marvellous, that he fays he almoft doubted the teftimony of his q fenfes. He would have done much better, how- ® ever, to have doubted the conclufions of his theory ; for it was by them that the phenomena before him were rendered fo mytfterious and in- credible. While he continued to regard what is defcribed above as a ftream of melted lava, which had defcended from the top of one moun- tain, and climbed up the fides of the oppofite, like water in a conduit pipe, piercing occafion- ally through vaft bodies of folid rock, it is no indeed phyfically impoffible. Had his belief in the volcanic theory permitted him to fee in all this, not a fuperficial current, but one of inde- finite depth, he would have beheld the object divefted, not of what was curious and interett- ing, but of what was incredible or abfurd, and reduced to the fame clafs of things With mineral veins. That it belongs really to this clafs, and is no more than a vein or dike of * Volcains Eteints du Vivarais, p. 328, &c. 270 ILLUSTRATIONS OF THE of whinftone, interfeting the ftrata to an un. Known depth, and moft probably, like other veins, com icating with the mineral regions, cannot be doubted by any one who has ftudied the fubject of bafaltine rocks, through any other medium than the volcanic theory. The rami- fications which run from it into the calcareous rock, contrived, Faujas fays, juft as if on purpofe to perplex mineralogifts, is one of the well Known and charaéteriftic appearances of bafal- tic veins. | 241. It can hardly be doubted, that the lava defcribed by the fame author as heaving up’ a mals of granite¥, and including pieces of it, is a rock of real whinftone. The fame may be faid of many others; and, though I pretend not to affirm that there is nothing vol- canic in the Vivarais, I muft fay, that nothing decidedly volcanic appears in the defcription of that country, but many things that are certainly of a very different origin. In the prefent ftate of geological fcience, a fkilful mineralogift could hardly employ him- {elf better, than in traverfing thofe ambiguous countries, where fo much has been afcribed to the ancient operation of volcanic fire, and mark- ing out what belongs either clearly to the erupt- ed sname * Volcains Eteints du Vivarais, fol. p. 365, &c. HUTTONIAN THEORY.’ 291 ed or unerupted lavas, and what parts are of doubtful formation, containing no mark by which they may be referred to the one of thefe any more than to the other. Such a work would contribute very materially to illuftrate the natu- ral hiftory of the earth. . 242. One of the moft ingenious attempts to “fapport the volcanic theory, is the fyftem of | MN fubmarine volcanoes, imagined by the celebrated pi - mineralogit Doromrru. The phenomenon that . | Ted to this hypothefis, was what he had obferved „in the hills near Lifbon, and ftill more remark- _ ably in thofe of the Val di Noto in Sicily, where the bafaltine rocks had regular ftrata incumbent on them, and in fome cafes interpofed or alter- nated with them *. It feemed from this evi- dent, that the ftrata were of later formation than the ftone on which they refted; and as they muft, on every fuppofition, be held to be depo- fited by water, it was~concluded, that the lava which they covered had been thrown out by volcanoes at the bottom of the fea; that the ftrata had afterwards been depofited on this la- va; and that, in fome cafes, there had been fre- quent * Mémoire de Deodate de Dolomieu, fur les Vol- cains Eteints du Val di Noto, en Sicile. Journal de, Phyf. tom. xxv. (1784. Septembre.) p. 191. 232. ILLUSTRATIONS OF THE ‘quent alternations of thefe eruptions and depo. fitions *, 243. Though this hypothefis does certainly deliver the fyftem of the Volcanifts from one great difficulty, it is itfelf liable to infurmount. able objections. I fhall juft mention fome of the principal. x. The regular and equidiftant ftrata that we often fee covering the tops of whinftone or bafaltic rocks, could not have been depofited in the oblique and very much inclined pofition which they now occupy. į This is remarkable in the ftrata which cover the bafaltic rock of Salifbury Craig, near Edin- burgh, at its northern extremity. The ftrata are very regular, and muft have been depofited in a plane nearly horizontal; yet the furface of the bafaltes on which they now reft is very much inclined, dipping rapidly to the north-eaft. The neceflity of a horizontal depofition in ftrata, which, though not now horizontal, have their planes — * Near Vizini, in the Val di Noto, Dolomieu tells us, that he counted eleven beds, alternately calcareous and volcanic, in the perpendicular face of a hill, which at a diftance appeared like a piece of cloth, ftriped black and white; uz fupra. In another inftance he faw more than twenty of thefe alternations. He has fince made fimilar obfervations in the Wincentine and in Tirol. Journal de Phyf. tom, xxxvii. (1790), partie 2. p. 200. HUTTONIAN THEORY. 2493 S planes nearly parallel to one another, has been’ proved at § 38. 2, If there is any truth in’ the principles I eftablifhed above, even the ftrata themfelves have not been confolidated without the action of fire. By Dolomieu’s fyftem, therefore, the confolidation of the ftrata which cover the ba- faltes is not accounted for. 3. There are no means furnifhed by the " hypothefis of fubmarine volcanoes for bringing the bafalt, and the ftrata which cover it, above ee | _ the level of the fea. If it is faid that the waters of the fea have been drained off, the objections are all incurred that have been ftated at § 37 *. If it is faid, that the rocks themfelves have been elevated by a force, impelling them upwards, we _ fay, that the exiftence of fuch a force, when = admitted, furnifhes another means of explain- ing the whole phenomenon, namely, that of the injection of melted matter among the ftrata, the # fame that is ufed in the Huttonian Theory. 4. The phenomena of balfaltic veins are not | inthe leaft explained by the hypothefis of fub- marine volcanoes. That hypothefis, then, even if the foregoing objections were removed, does 3 not * Dolomieu adopts this fuppofition ; he thinks, that the furface of the fea muft have been formerly 509 Of 600 toifes above its prefent level. Thid. p: 196. 274 ILLUSTRATIONS OF THE not ferve to explain all the facts refpecting the rocks of this genus, and wants, of confequence, one of the moft important characters of a true theory. It muft be allowed, however, that it m#kes a confiderable approach to fuch a theory, and that the fubmarine voleanoes of Dolomieu, | have an affinity to the unerupted lavas of Dr Hutton. 244. Though in thefe remarks I have endea- voured to expoie the errors of the volcanic fyftem, I cannot but confider that fyftem as coming infinitely nearer to the truth than the Neptu. nian. It has the merit of diftinguifhing an or- der of rocks, which bears no mark of aqueous formation, and in which the cryftallized, fparry, or lava-like ftructure, befpeaks their primeval fluidity, and refers their origin to fire. The Neptunian fyitem, on the other hand, ftrives to confound the moft marked diftin@tion in the mineral kingdom, and to explain the formation, both of the ftratified and unftratified rocks, by the operation of the fame element. Though — chargeable with this inconfiftency, it has be- c me the prevailing fyftem of geology ; and the arguments which fupport it are therefore enti- tled to attention. 245. It will no doubt be thought fingular, that the fame mineralogift, whom we have jut feen exerting his ingenuity in defence of the volcani¢ I Egyptian bafaltes. But there is no reafon why, ` HUTTONIAN THEORY. 275 volcanic fyitem, fhould now appear equally ftre- nuous in defence of the Neptunian. Though Dolomieu contends for the volcanic origin of fome bafaltic rocks, he does not admit that all bafaltes is volcanic, nor even all of igneous for- mation. Thus he ftates, that he had examined at Rome fome of the moft ancient monuments of art, executed in baialtes, brought from Upper T Egypt, and that he could difcover n mark of Mm the action of fire in any of them *. On the contrary, he found that fome of them confift- ed of green bafaltes, which changes its colour to a bronze, when expofed even to a mo- derate heat, and which therefore, he argues, can never have endured any ffrong ation of fire, } The anfwer to this argument is very plain, if we admit the effects afcribed by Dr Hutton to the compreffion which neceflarily takes place in the mineral regions. If indeed the heat in thofe regions refemhled exa&ly that of our fires at the furface, it would not be eafy to deny the above conclufion, which therefore certainly holds good againft the volcanic origin of the under {trong compreffion, the colouring matter 5 2 j of m ih * Journal de Phyfique, tome XXXVilg ioo .) partie 2. #193. $ ie ‘ 276 ILLUSTRATIONS OF THE of thefe ftones might not be fixed, and inde ftrudible by heat, though it can be eafily vola. tilized or confumed when fuch comprefiion is removed. This argument then is againft the volcanic ; but not againft what has been called the Plutonic formation of bafaltes. 246. As to the other marks of fire which Do- lomieu fought for and did not find in the above- mentioned ftones, we are not exa@ly informed in what they confifted. If the cryftallized or {pathofe texture that belongs to this defcription of ftones was wanting, the {pecimens were not to be confidered as of the real bafaltie or whin- itone genus, whatever their name or hiftory may feem to indicate. If they did poffefs that tex- ture, they had the only mark of an igneous ori- gin that could be expected, fuppofing that ori- gin to have been in the bowels of the earth. No part, therefore, of the obfervations of this ingenious mineralogift, can be confidered as in- confiftent with the theory of bafaltic rocks which has been laid down above. 247. Bergman had before reafoned on this fubject precifely in the fame manner, but from better data, as the ftones from which he deri- ved his argument were in their native place: “ Trap,” fays that ingenious author, (that is, whinftone), “ is found in the ftratified moun- tains of Weft Gothland, in a way that deferves to. +HUTTONIAN THEORY. 207 to be defcribed. The lower flratum, which is -feveral Swedifh miles in circuit, (10% of thefe miles make a degree), is an arenaceous ftone, horizontal, refting on granite, and having its particles agglutinated by clay. The ftratum above this is calcareous, full of the petrifaGtions of marine animals, and above this is the trap. Thefe three kinds of rock compofe the greater part of the mountains juft mentioned, though there are fome other beds, particularly very thin beds of marl and of clay, which feparate the middle ftratum, both from that which is under it and over it, and are frequently fo penetrated with bitumen that they burn in the fire. This {chiftus is black ; when burnt it becomes red, and afterwards, when wafhed with water, af- fordsalum. How can it be fuppofed,”’’ he adds, “that the trap has ever been violently heated, while the {chiftus on which it is incumbent re- tains its blacknefs, which however it lofes by the action even of a very weak fire *.”’ The anfwer to this argument is already given. The reafoning, as in the former inftance, is con- clufive only againft the action of volcanic fire, or fire at the furface ; but not againft the action of heat deep in the bowels of the earth, and un- 9 3 der * Bergman de Produétis Volcaniis Opufcula, tom. ili. Pp 214, &c, 278 ILLUSTRATIONS OF THE der the preffure of the fuperincumbent ocean, In fuch a fituation, the bituminous {chiftus might be in contact with the melted bafalt, and yet there might be no evaporation of the vola- tile, nor combuftion of the inflammable parts, It does not, however, always happen, that the bituminous fubftances, or fubftances alterable by fire, which are found in contaét with bafaltes, are without any mark of having endured the operation of fire. Inftances in which fuch operation is apparent are given above, § 30. ; and more will be added in the conclufion of this note. — 248. The fame mineralogift founds another argument for the aqueous formation of whin or trap, on the exiftence of that ftone in the form of veins, included in primeval rocks: “ Inveni- tur hoc faxum (trap) in Suecia pluribus locis, feepeque in montibus primevis, anguftas implens venas, adeo fubtilis ftruGture, ut particule fint impalpabiles, et, dum niger eft, genuinum efficit lapidem Lydium. In hifce montibus, nulla ad- funt ignis fubterranei veftigia *.” The phenomenon here defcribed, namely, a vein of compa@ whinftone traverfing a primary rock, is, without doubt, as incapable of being explained by the operation of a volcano, as it is By * Opufcula, ubi fupra, < HUTTONIAN THEORY. 279 by that of aqueous depofition. It is, however, a moft complete proof of the original foftnefs of © the fubftance of which the veins confit, and af- fords one of the ftrongeft poflible arguments for fuch an operation of fire as is fuppofed in the prefent theory. The main arguments, there- fore, which have been propofed as fubvertive of the igneous origin of bafaltes, are only fubver- | = five of their formation by one’ modification of fire, viz. of fire acting near the furface; and thus the weapons which directly pierce the ar- mour of the Volcanift, and infli@ a mortal wound, are eafily turned afide by the fuperior temper of the Plutonic mail. 249. An argument founded on facts very fi- milar to fome of the preceding, and leading to the fame conclufion, is employed by the mine- ralogift to whom the Neptunian fy{tem owes its chief fupport. Werner, in his obfervations on volcanic rocks and on bafaltes, has refted his proof of the aqueous formation of the latter, on their interpofition between beds of ftone in mountains regularly ftratified, and obvioutly formed by water. He defcribes an inftance of this in the bafaltic hill of Scheibenberg ; and the- facts, though moft of them are not uncommon, are highly deferving of attention. Near the top of this hill, and above the bafaltic rock _ which compofes the body of it, he tells us, that wae there 280 ILLUSTRATIONS OF THE there was a fand-pit; a cir {tance which he © appears to confider as not a little fingular. It was, however, at the bottom of the hill, that he met with the appearances which chiefly attra@. ed his notice: “ Firft,” fays he, “or loweft, was a thick bank of quartzy fand, above thata. bed of clay, then a bed of the argillaceous ftone called wacken, and upon this laft refted the ba- faltes.” “ When I faw,” adds he,“ the three firk beds running almoft horizontally under the ba- faltes, and forming its bafe; the fand becoming finer above, then argillaceous, and at laft chang- ing into real clay, as the argil was converted in- to wacken in the fuperior part; and, laftly, the wacken into bafaltes: ina word, when I found a perfect tranfition from pure fand to argilla. ceous fand, from the latter to a fandy clay, and from this fandy clay, through many gradations, toa fat clay, to wacke, and at laf bafaltes, I was irrefiftibly led to conclude, that the bafaltes, the wacke, the clay, and the fand, are all of one and the fame formation; and that they are all the effect of a chemical precipitation during one and the fame fubmerfion of this country *.” i Firft, * «Combien je fus furpris de voir en arrivant au fond, un épais banc de fable guartzeux, puis an-deflus une couche d’argile, enfin une couche de la pierre argileufe nommée Wacke, et fur celle-ci repofer le bafalte, Quand | je HUTTONIAN THEORY. (285 tic hill, it is moft probably the remains of cer- tain fandftone ftrata that originally covered the bafaltic part, but are now worn away. We are _ therefore to confider this as an inftance of a ba- faltic rock, interpofed between {trata that are undoubtedly of marine origin. In this, how- l. fuer, there is nothing inconfiftent with Dr Hut- Taa theory of bafaltes; on the contrary, it is one fe je vis les trois premières couches s'enfoncer prefqw bori- gontalement fous le bafalte, et former ainfi fa bafe; le fable devenir plus fin au-deffus, puis argileux, et fe changer enfin en vraie argile, comme Vargile fe convertiffoit en wacke dans fa partie fup¢rieure ; et finalement la wacke en bafalte: en un mot, de trouver ici une tranfition par- Sabloneuje, et de L'argile fabloneuf', par plufieurs grada- tions, à Purgil gri fe, Ala wacke, et enfin au ba/alte. A cette vue, je fus fur-le- champ et irréfiftiblement entrainé à penfer, (comme lauroit été -fans doute tout ` connoiffeur impartial frappé des conféquences de ce ~ ph nomène); je fus, dis-je, irréfiftiblement entrainé aux “Ades fuivantes: Ce bafatte, cette wacke, cette argele, et ce fable. font d'une feule et méme formation ; ils font tous Veflet dune precipitation par voie bumide dans une feule et même fubmerfion de cette contrée; les eaux qui la _ Couvroient alors tranfportoient d’abord le Jable, puis de- Pofoient l'argile, et changoient peu-d-peu leur précipita- tion en wacke, et enfin en vraie bafalte.” — Journal de Phyfique, tome xxxviii. (1791), partie 1. p. 415. Firft, as to the fand on the top of this bafal- fat du fable pur au fable argileux, de celui-ci a /’argile 282 ILLUSTRATIONS OF THE one of the principal facts on which that theory is founded. It has indeed been argued by fome mineralogifts, that bodies thus contiguous muĝ owe their origin to the fame element, and that a mineral fubftance cannot be of more recent formation than that which lies above it. But the maxim, that a foffil muft have the fame origin with thofe that furround it, does not hold, unlefs they have a certain fimilarity of ftructure. It is, for inftance, the want of this fimilarity, that authorifes us to affign different periods of formation to mineral veins, and to the rocks in which they are included. In a fucceflion of ftrata, no one can doubt, that the loweft were the firft formed, and the others in the order in which they lie; but, when between two ftrata of fanditone or of limeftone we find an intermediate rock, fo different as to refemble lava, and to have nothing f{chiftofe or {tratified in its compofition, the fame inftrument cannot be fuppofed to have been employed in the formation of both; nor is there any reafon why we may not fuppofe, that the intermediate body was interpofed between the other two, by fome aétion fubfequent to their formation. It was thus that Dolomieu concluded, when he faw a lava-like ftone interpofed between calca- reous firata in the Val di Noto, that, though contiguous, HUTTONIAN THEORY. 283 contiguotis, thefe two rocks could not poffibly . be of the fame formation ; and thus far it is cer- tain, that every unprejudiced obferver muft agree m | With him. | 250. But the circumftance on which Mr Wer- ‘ner feems to lay the greateft ftrefs, is the gra- © dual tranfition from the fand to the bafalt, “| through the intermediate fteps of clay and at i wacken ; this gradual tranfition he confiders th r asa direct proof, that they are all of the fame _ formation. _ A gradual tranfition of one body into another, can only be faid to take place, when itis im- } poflible to define their common boundary, or to aj determine the line where the one begins and the i other ends. Now, if this be the proper notion ine of gradual tranfition, I mutt fay, that after much tf careful examination, I have never feen an j inftance, in which fach a tranfition takes i place between whinftone and the contiguous E frata. The fine of feparation, though in fome ' places lefs évident than in others, has, on the i whole, been marked out with great precifion ; and, though the ftones have been firmly united, OT, as one may fay, welded’ one upon another, | yet, when a freh fratture was obtained, the sh - ftratified and unttratified parts have rarely failed jf to be diftinguithed. The freth fracture is in- | deed often neceflary, for many fpecies of whin- {tone 284 ILLUSTRATIONS OF THE ftone get by decompofition a granulated texture at the furface, fo as hardly to be diftinguithed from real fandftone. Some of the kinds of primary fchiftus alfo, par- ticularly the argillaceous, when much indurated, have in their ftructure a confiderable refemaieal to whinftone ; they are flightly granular, or la. minated, and A ave a tendency toa fparry texture, Where it happens that this fort of {chiftus and whinftone are contiguous, it is natural to expect, that their common boundary will be traced with difficulty, and in many parts will be quite un- certain. Still, however, if a careful examination is made; if the effects of accidental caufes are removed ; and, above all, if the more ambiguous inftances are compared with the more decifiye, and interpreted by them, though fingle fpeci- mens may be doubtful, we will hardly ever find that any uncertainty remains with re{pect to en- tire rocks. 251. This general fact, which I ftate on much better authority than that of my own obferva- tions, viz. on thofe of Dr Hutton, is not given as abfolutely without exception. The theory of whinftone which has been laid down here, leads us indeed to look for fome fuch exceptions. It is certain, that the bafis of whinftone, or the material out of which it is prepared by the ac- tion es HUTTONIAN THEORY. 285 : tion of fubterraneous heat, is clay in fome ftate or other, and probably in that of argillaceous iy ; fchiftus. It follows, of confequence, that ar- in gillaceous {chiftus may by heat be converted in- to whinftone. When, therefore, melted whin- ~ fone has been poured over a rock of fuch fchif- i q tus, it may, by its Heat, have converted a part of A that rock into a ftone fimilar to itfelf; and thus may now feem tobe united, by an infenfible grada- tion, with the ftratum on which it is incumbent ; and phenomena of this kind may be epee to have really happened, though but rarely, as a particular combination of circumftances feems _neceffary to produce them. Hence it is evident, _ that ftones may graduate into one another, with- out being of the fame formation ; and that it is fallacious to conclude, from the infenfible tran- fition of one kind of rock into another, without 4 any other circumftance of affinity, that they have both the fame origin. I am difpofed, therefore, to make fome limi- tation to what is faid in § 72, where I have ex- preffed an abfolute incredulity as to fuch tranfi- tions as are here referred to. The great fkill Eee, and experience of the mineralogift'who has de- {eribed the ftrata at Scheibenberg, do not al- low us to doubt of his exactnefs, though fome of the appearances are fuch as decompofition and wearing might well enough be fuppoted to produce. 206 ILLUSTRATIONS OF THE produce. The faireft way is to take Mr Wer. ner’s obfervations juft as they are given us, and to try whether they cannot be explained with. out the afliftance of his theory. In effe@, the wacken which he defcribes, refts, it would feem, on an unconfolidated bed of clay ; and it may be fuppofed, that a part of this bed has been converted into wacken by the heat of the incumbent mats, and has thus produced the apparent gradation from the one fubitance to the other. As the appearances of the rocks of — Scheibenberg feem to be confidered by Werner as furnifhing a very ftrong, and even an unex- pected confirmation of his fyftem, I cannot help thinking, that an explanation of them, on the principles of Dr Hutton, without any ftraining or forcing of thofe principles, contributes not a i little toward extending the empire of the latter over all the phenomena of geology. 252. Another fact, which has been much infift- ed on of late, in proof of the aqueous formation of bafaltic rocks, is that fhells are found in them. Of the reality of this faé&, -however, or at leaft of the inftances hitherto produced, great doubts I think may be reafonably enter- tained. The fpecimens of the fuppofed bafaltes, with fhells included in them, that are chiefly relied on, are found at Portrufh in Ireland, a rocky promontory to the weftward of the Giant’s Caufeway, ang feparated from it by 4 confiderable HUTTONIAN THEORY. 287 confiderable body of calcareous ftrata. Some of thefe fpecimens were brought to Edinburgh = about a year ago, and. were fuppofed, I believe, - to contain an irrefragable proof of the Neptu- I pian origin of the bafaltic promontory where they were found. 1 went to fee thefe fpecimens | in company with Lord Webb Seymour and Sir _ James Hall; and, on examining them carefully, A we were all of opinion, that the ftones which ul contained the fhells, or the impreffions of the ii) fhells, were no part of the real bafaltes. They | were all very compa, and had all more or lefs of a filiceous appearance, fuch as that of chert; Í they had nothing of a {parry or cryftallized ftruc- i ture; their frature was conchoidal, and but i flightly uneven. In twoof them, one of which wer! Dore the impreffion of a cornu ammonizs, the {chif- tofe texture might bediftin@ly perceived. A fpe- | cimen which accompanied th>, but in which pi there was no fhell, ferved very exacily to explain 4 the relation between thefe ftones and the true bafaltes. Part of this {pecimen was a true ba- q falt, and the reft a fort of hornftone, exadtly the fame with that in which the fhells were, and Not unlike t:e jafper that is under the whinftone of Salifbury Crag, and in conta& with it; fo i that on the whole it was evident, that the rock containing the thells is the fchiftus or ftrati- fied ftone, which ierves as the bafe of the ba- faltes, 288 ILLUSTRATIONS OF THE faltes, and which has acquired a high degree of induration, by the vicinity of the great ignited mafs of whinftone. This folution of the difficulty has fince been confirmed by obfervations made on the {pot by Dr Hope, who difcovered two or three alterna. tions of the bataltic rock, with the beds of the {chiftus in which the fhells are contained. 233. This alfo explains fome obfervations-of Spallanzani, made in the ifland of Cerigo, on the — coaft of Greece, the Cythera of the ancients*, The bafe of that ifland is limeftone; but it abounds alfo in unftratified rocks, which the Italian naturalift fuppofes to be of volcanic oris - gin; but which, if I miftake not, we would re- gard as whinftone, or perhaps porphyry; and they are faid to contain oyfter-fhells and pec- tenites of a large fize, perfe@ly mineralized. Thefe petrifaGtions, however, Spallanzani fays, — are not contained in the lava that has ae- tually flowed, but in ftones which have only endured a flighter action of fire. Without the commentary afforded by the Portruth fpecimens, it would be difficult to make out any thing very precife from this defcription. By help of the information derived from thofe {pecimens, we may conclude, that the condition of the fhells in al * Journal de Phyfique, tom. xlviii, (1798), p- 278: HUTTONIAN THEORY. 280 in them, and in the rocks of Cerigo, is perfet- ly alike; and that, in both cafes, the fhells are involved in parts of the rock which are truly © ftratified, but which have been, in fome degree, | aflimilated to the bafaltes by the heat which ’ they have endured. Spallanzani would proba- bly have ufed exaétly the fame terms which he _| employs in {peaking of Cerigo, if he had been » | _ required to defcribe the petrified fhells at Port- W tuh. U 254. In the inftances juft mentioned, the petri- fied marine objeéts are not found in the real whinftone ; but if they were found in it, when it wilt’ borders on ftratified rocks containing fuch ob- mll jeéts, the thing would not be at all furprifing, i nor furnifh any argument againft the igneous uai confolidation of the ftone. If a torrent of | melted matter was poured in among the ftrata, by a force which at the fame time broke up and § difordered thofe ftrata, nothing could be more wi natural, than that this matter fhould contain | fragments of them, and of the objects peculiar „y to them. = @ In one inftance, mentioned by Mr Strange, al _ this feems a&ually to have taken place. Inthe * | Veronefe, a country remarkable for a mixture of limeftone ftrata, containing marine objeds, with volcanic or bafaltine hills, he affures us, that he had feen a mafs of ftone, which had T evidently. 290 ILLUSTRATIONS OF THE evidently concreted from fufion, in which the marine foffil bodies, originally, as he fuppo- fes, contained in the ‘ftrata, were perfectly di- ftinguifhable, though varioufly disfigured *, Jt may be, that in this, as in the foregoing exam. ples, it was not real. bafaltes, or real lava, ‘which contained the fhells, but- the conterminal rock; but, fuppofing it to be as Mr Strange reprefents it, there appears to be no inconfiftency between the phenomenon, and the igneous origin of the rock in which the fhells were included. Here, however, it fhould be remarked, that the pre- fence of great preffure, to prevent the conver- fion of the fhells into quicklime, feems abfolute- ly necefiary ; and that the phenomenon of thefe bafaltic petrifaCtions, requires the application of heat to have been deep under the furface of the earth. 255. The phenomena we have been confider- ing, have been felected as the moft unfavourable to the igneous origin of bafaltic rocks; and we have feen, that when duly examined, they are not at all inconfiftent with it. We are now to take a view of fome appearances, that feem quite irreconcilable with the aqueous formation of thefe rocks. | Where a eel * Phil. Tranf, 1775, P: 25- wl HUTTONIAN THEORY. 291 Where whinftone rocks are found in mafies, pounded by the ftrata, and infulated among them, they fubje& the Neptunian fyftem to great difficulties. For, fuppofing it true that this - ftone may be produced by the precipitation and ayh lization. of mineral fubftances diffolved in water, yet it feems unaccountable, that this e£- 2 fe& has been fo local and limited in extent, ten to be confined to an irregular figure a few acres, while, all round, the fubftan- ces depofited have had no tendency to cry- Aallzaton, and have been formed into the mmon fecondary ftrata. The rock of Sa- E; Craig, for inftance, is a mafs of whin- Rone, having a perpendicular face eighty or ninety feet high toward the weft, and ex- tending from north to fouth with a circular tweep about goo yards. The whole of this rock re pelts on regular beds of fecondary fandftone, not rizontal, but confiderably depreffed toward e north-eaft : the rock is loftieft in the mid- ! Bend decreafes in thicknefs toward each end, terminating at its northern extremity in a kind fwedge. It is covered at top, toward that ex- femity, with regular beds of fandftone, per- fimilar to thofe on which it is incumbent ; and it is not improbable, that this covering os erly extended over the whale. E +2 Now, 292 ILLUSTRATIONS OF THE Now, what caufe can have determined the co- lumn of water, which refted on the bafe at prefent occupied by this rock, to depofite nothing but the materials of whinftone, while the water on the fouth, weft, and north, was depofiting the materials of arenaceous and marly ftrata ? Wherefore, within this {mall fpace, was the pre- cipitate every where chemical, to ufe the lan- guage of Werner, while clofe to it, on either i fide, it was entirely mechanical? Why is there, in this cafe, no gradation? and why is a mere mathematical line the boundary between re- gions where fuch different laws have prevailed? Whence alfo, we may afk, has the bafaltic de- pofite been abruptly terminated toward the weft, fo as to produce the fteep face which has juft been mentioned ? The operation of currents, or of any motion that can take place in a fluid, will furnifh no explanation whatever of thefe phenomena; yet they are phenomena far from being peculiar to a fingle hill; they are among the moft general and characteriftic appearances in the natural hiftory of whinftone mountains; and a geological theory which does not account for them, is hardly entitled to any confidera- tion. 256. The bafaltic rock, juft defcribed, is alfo covered, at leaft partly, with ftrata perfectly fimi- lar Po A a E, : pears altogether unaccountable, that after the = water had done depofiting the materials of the Mi l whin on the fpot in queftion, the former order y 1 was fo quickly refumed, and a depofition of My fand, and of the other materials of the ftrata, DNI took place juft as before. All this is quite un- f intelligible ; : and the principles of the Neptu- ‘nian fyftem feem here to ftand as much in need of explanation, as any of the appearances which ‘they are intended to acccunt for. _ 257. The unequal thicknefs, and great irre- -gularity i in the furface of the whinftone mafs, here treated of, and of many rocks of the fame kind, is alfo a great objection to the notion of their aqueous formation. This feems to have been perceived by Werner, in the inftance of the rocks formerly mentioned ; and he endea- yours to explain it, by fuppofing, that much of thefe rocks has been deftroyed by wafte and de- -compofition, fo that an irregularity of their fur- face, and want of correfpondence has been given “to them, which they did not originally poffefs. In the inftance of Salifbury Craig, however, we have a proof, that the great irregularity of fur- face, and the inequality of thicknefs, do not al- _ Ways arife from thefe caufes. The thinneft part E” that rock, toward its northern extremity, is - T3 -knl HUTTONIAN THEORY. 293 jar to thofe that lie under it. Now, it ap- 294 ILLUSTRATIONS OF THE ftill covered by the ftrata in their natural place, and has been perfectly defended by them from every fort of wearing and decay. The cunei form fhape, therefore, which this rock takes at its extremities, and the great difference of its thicknefs at them and in the middle, is a part of its original conftitution, and can be attributed to nothing cafual, or fubfequent to its confolida- tion, rocks, where an inequality of thicknefs, moft unlike to what belongs to aqueous depofites, is known to exift in beds of whinftone that are till deep under the furface. Thus the toadftone of Derbytfhire, even where it has a thick cover- ing of ftrata over it, has been found, by the fink- ing of perpendicular fhafts, to vary from the thicknefs of eighteen yards to more than fixty, within the horizontal diftance of lefs than a fur- jong.. Nothing of this kind is ever found to take place in thofe beds of rock which are cer- tainly known to originate from aqueous depofi- tion, and no character can more ftrongly mark an effential difference of formation. 258. We have had frequent occafion to con- fider the characters of thofe mafles of whinftone which are fo often found interpofed between ftratified rocks. Thefe have been found in ge- neral very adverfe to the Neptunian fyftem ; and two ‘4 The fame may be faid of many other bafaltic = HUTTONIAN THEORY. = 205 4 twoof them which yet remain to be mention- : ed, are even more fo than any of the reft. _ Where a bed or tabular mafs of whinftone is _ Biterpotea between ftrata, and wherever an op- hia offers of feeing its termination, if the _ ftrata under it are not broken, it may be re- | = marked, that they do not abut themfelves bluff nd abrupt againft the whin. “On the con- ry, if we mark the courfe of the ftratum which covers the whinftone, and of that which is the bafe of it, we fhall find they converge toward one another, the interpofed _ mafs growing thinner and thinner, like a wedge. _ When the latter terminates, the two former : ‘come in contact, and have no ftratum interpo- fed between them. Thus the roof and bafe of the whinftone rock are contiguous. beds, that _ appear as if they had been lifted up and bent, and _ feparated by an interpofed mafs. Had the whole : been an effect of fimultaneous depofition, the re- gular ftrata muft have been abruptly terminated. by the whin, like two courfes of different forts f of mafonry where they meet with one another. - 259. From this wedge-form of the whinftone _maffes, and in general from the irregularity of “their furfaces, another conclufion follows, fimilar l to the preceding, and one which has been already © mentioned. Where the furface of the interpo- wa K at «fed 296 ILLUSTRATIONS OF THE fed mafs is greatly inclined to the horizon, the ftrata which reft on this inclined plane, are ne. verthelefs as exadtly parallel to that plane, and to one another, as if they were really horizon- tal. It is certain, therefore, that they were not depofited on the fame inclined plane on which they now reft; for, if fo, they would have been ftill nearly horizontal, and by no means parallel to the inclined fide of the whinftone. This fol- i lows from the nature of aqueous depofition, as already explained. We have a remarkable inftance of the pheno- menon here referred to, in the rock of Salifbury Graig, of which mention has been fo often made, and in which almoft every circumftance is uni- ted, that can ferve to elucidate the natural hifto- ry of bafaltte rocks. The north end of that rock is in the figure of a wedge, with its in- clined fide confiderably fteep, and covered by ftrata of grit, perfectly regular, and parallel to the furface on which they lie. The in- fpection of them will convince any one, that they were not depofited by the water, on a bottom fo highly inclined as that on which they now reft. They are of a ftructure very {chiftofe; their layers very thin; fo that any inaccuracy of their parallelifm would be readily obferved. The appearances of the horizontal depofition of thefe ftrata, are indeed fo clear, and fo impofli- : ble HUTTONIAN THEORY. 297 ple to be mifunderftood, that the followers of LF. the Huttonian fyftem would not rifk much, if they were to leave the whole theory of whin- — - ftone to the decifion of this fingle fa@, and fhould agree to abandon that theory altogether, if the Neptunifts can fhew any phyfical or ftatical principle, on which thé depofition now defcribed can poflibly bave been made ; ; or will point out he rule, by which nature has given a ftruGure fe fo nicely ftratified to arenaceous beds depofit- ed on a furface fo highly inclined. If no a principle can be pointed out, though we cannot conclude that the Huttonian Theory is q tue, we certainly may conclude that the Nep- -tunian is falfe. 260. Proofs of the igneous formation of whin- Boss, ftill more direct, are derived from the induration of the contiguous ftrata; from their difturbance when interfeGted by veins of whin- ` ftone ; and from the charring of the coal which happens to be in conta@ with thefe veins. Thefe f confidered above at § 66, 67, &c.; and it s particularly taken notice of at § 66, that pie- “ces of fandftone are fometimes found as if floating _in the whinftone, and, at the fame time, greatly altered in their texture. One of the beft and - moft unequivocal inftances of this fort which I have feen, is to be found on the fouth fide of ; Arthurs Seat, near Edinburgh. The rock E which 298 ILLUSTRATIONS OF THE which compofes the upper part of the hill, op that fide, is a whinftone breccia, fuch as we have many examples of, and, I believe, very much refembling what is called a lava brecciaty by the volcanic geologifts. The ftony frag. ments included in this compound mafs, are for the greater part rounded; and fome of them are of whinftone, others ‘of porphyry, ftrongly — characterized by retangular maculz of feltfpar, _ and many feem to be of fandftone, but fo coñ- fiderably altered, as to leave it at leaft difputa: ble whether they really are fo or not. In one part, however, where the face of the rock is nearly perpendicular, a narrow ridge is feen ftanding out from the reft, and of a different co- lour, being more entirely covered with mofs than the rock round about it, and, as may be prefumed from that circumftance, lefs liable to decompofition. On examination I found, that this ridge does not confift of whinftone, but of a very hard and highly confolidated fand- fione. It appears to be the edge of a ftratum, of the thicknefs of about nine or ten inches, and of the height of fifteen or fixteen feet. It is not perfectly ftraight, but flightly waved, its general direction being nearly vertical; and it is on both fides firmly embraced by the whinftone. When broken, it appears that this fand- ftone refembles in colour, and in every thing but put its greater confolidation, and more vitreous ‘ftru@ure, the common grit found at the bottom of the hill, and over all the adjacent plain. | è 261. If all thefe circumftances are put toge- her, there appears but one conclufion that can be drawn from them. We have here the ma- nifeft marks of fome power which could lift up is fragment of rock from its native place, di- t at leaft feveral hundred yards from its pre- fituation, place it upright on its edge, en- compafs it with a folid rock, of a nature quite heterogeneous to itfelf, and beftow on it, at the fame time, a great addition of folidity and in- a uration. If the mafs in which this ftone is now imbedded, be fuppofed to have been once ‘in i fion, and forcibly thrown up from below, it wading the ftrata, and carrying the fragments ng with it, the whole phenomena now de- ibed admit of an explanation, and all the cir- mftances accord perfe&tly with one another ; but, without this fuppofition, they are fo many Aeparate prodigies, which have no connection 4 with one another, nor with any thing that is i known. It is indeed impoflible, that the effects of motion and heat can be more clearly expref- fed than they are here, or the fubject in which thefe powers refided more diftinétly pointed HUTTONIAN THEORY. 299 300 ILLUSTRATIONS OF THE 262. The preceding fa&s being fufceptible but of one interpretation, are on that account extremely valuable. The phenomena of Salif. bury Craig, near the fame place, are almot equally free from ambiguity. The bafaltic rock which forms that precipice, refts on are. naceous or marly ftrata; and thefe, in their immediate contact with the former, afford an inftance of what is mentioned § 67, namely, the converfion of the ftrata in fuch fitua- tions into a kind of petrofilex, or even jafper, ‘The line which feparates the one rock from the other, is, at the fame time, fo well defined, as, in the eyes even of the moft determined Neptu- nift, to exclude all idea of infenfible gradi tion. 263. The fame rock affords fome remarkable inftances of the difturbance of the ftrata conti- guous to the whinftone. The beds of the for- mer are bent upwards in feveral places; and, at one in particular, form an arch, with its con- vexity downward, fo as to make it evident, that the force which produced this bending was di- rected from below upwards. 264. It is, however, where whinftone takes the form of veins, interfecting the ftrata, that the induration of the latter is moft confpicuous. The coaft of Ayrfhire, and the oppofite coaft of Arran, eS ee ae ” and abundance. The ftrata are, in ma- ny inftances, fo reticulated by the veins, and E eriad at fuch fmall diftances, that it pe neceflary to fuppofe, that the fiffures up. This at leaft is true, if the veins are to ‘be accounted all of the fame formation; and, in the greateft number of inftances by far, ere is no mark of the one being pofterior to. ‘the other. k 265. The induration of the fides of thefe veins, in fome cafes, has been fuch, that the fides have become more durable than the vein itfelf ; Bie the whinftone has been worn away by the wafhing of the waves, and has left the fides ftanding up, with an empty fpace, like a ditch, between them. One of thefe I remarked on the fouth fide of Brodick Bay, in Arran, which, where it met the face of an abrupt cliff, was not kef than forty or fifty feet in depth. 266. I fhall pafs over whatever argument fonia: be drawn in favour of our fyftem, from the flender ramifications of the veins, and the Varieties of their fizes, from a few inches to ma- ny fathoms in diameter, and alfo from the con- neđion which they often appear to have with the p E tabular maffes of bafaltes; god fhall only e add HUTTONIAN:THEORT. goz Biin, exhibit thefe veins in an varie- in them were hardly fooner made than filled 302 . ILLUSTRATIONS OF THE add a few remarks on the charring of coal ip the vicinity of veins or maffes of whinftone, The connection between the charring of coal and the prefence ‘° whinftone, was firit obferved by Dr Hutton; and, as far: as opportunities of verifying the obfervation have yet occurred, ap- pears to be a fa&@ no lefs general than it is cu- rious and interefting. In the coal-mines of Scot- land, it certainly holds remarkably, particularly in thofe about Saltcoats in Ayrfhire, where a whinftone dike is known to ftretch acrofs the whole of the coal country, and to be every where accompanied with blind or uninflammable coal. At Newcaftle, dikes of the fame kind are met with, and one, in particular, in: what is called the Walker Colliery, has proved the action of fubterraneous fire, to the fatisfa€tion of minera- logifts nowife prejudiced in favour of the Hut- tonian fyfiem, : The coal found under bafaltes, in the Ifland of Skye, has been already mentioned, § 139. To what was faid concerning the fibrous ftruc- ture of the parts of that foffil in immediate con- taét with the whin, it may be added; that it is alfo charred in thofe parts, fo as to have hardly any flame when it is burnt, though further down it is of the nature of ordinary coal. Indeed, if there be any truth in Mr Kirwan’s general re- mark, — E HUTTONIAN THEORY. — 303 SENS 4 ee it muft be underftood to arife from this, quently charred, and its fibrous ftructure, by ‘that means, rendered. more ‘vifible. 3 267. It has been objected to the e ‘of coal having its bituminous part driven off ‘by the heat of the whinftone, that this ought F; ot, on Dr Hutton’s principles, to happen in he mineral regions. But it may be replied, ihas been -done above, that the local ap- ication of heat might certainly produce this from a hotter to a colder. part of the fame í ratum. The bitumen has not been fo vola- tilized and expanded as entirely to efcape fi rom the mineral regions; but it has been ex- pelled from fome parts of a mafs, only to be condenfed and concentrated in others. This fp iron coincides exactly with the appear- inces. 1 to two varieties. The firft is the moft common, ‘in which, though the coal is perfectly charred, itis folid, and breaks with a fmooth and fhining Tarface. The fecond is alfo perfect charcoal, but very porousand fpungy.. This {ubftance is much Tarer than the other: Dr Hutton mentions an inftance mark, that it is common to find wood:coal under hat the coal in contact with the bafaltes is fre- effet, and might drive off the volatile parts 268, The native or foffil-coke which accom- ` panies whinftone, has been diftinguifhed in- 304 ILLUSTRATIONS OF THE inftance of it at the mouth of the river Ayr, where there is a whinftone dike *. I had the fatisfaction of vifiting it along with him. It was in the bed of the river, below the high-wa. ter mark ; the fpecimens had the exac& appear. ance of a ‘Gina. In the banks of the fame river, fome miles higher up, he found a piece of coal, belonging to a regular ftratum, involved in whinftone, and extremely incombuftible. It confumed v flowly in the fire, and deflagrated with nitre like plumbago. This he confidered as the fame foffil which has been defcribed under the name of plombagine. Near it, and conne&ed with the fame vein of whinftone, was a real and un- doubted plumbago. From thefe circumftances he alfo conclu- ded, that plumbago is the extreme of a gra- dation, of which foffil-coal is the beginning, and is nothing elfe than this laft reduced to per- fect charcoal. This agrees with the chemical — analyfis, which fhows plumbago to be compofed of carbon; combined with iron. In confirmation of this theory, he men- tions a fpecimen, in his poffeflion, of fteati- tical whinftone, from Cumberland, containing nodules of a very perfe&t and beautiful plum- bago; and he alfo takes notice of a mine of this pee til * Theory of the Earth, vol.i. p. 611. HUTTONIAN THEORY. 305 Dr Kennedy, who has examined it with great are, I can ftate as being contained, or enve- bpi: in whinftone ; and I hope the public will foon be favoured with a particular defcription of this very interefting {pot, by the fame inge- nious and accurate obferver. 4 269. Thus the mineralogical and chemical di: overies agree in reprefenting coal, blind-coal, plombagine, plumbago, as all modifications of he fame fubftance, and as exhibiting the fame p Ecin, carbon, in a ftate of greater or lefs this feries fhould be placed the diamond ; but we are yet unacquainted with the matrix of this curious foffil, and its geological relation to other m inerals. When known, they will probably gi give t to this fubftance the fame place in the geo- logical, as in the chemical arrangement : in the mean time, it is hardly neceflary to remark, how well all the preceding facts agree with the hypothefis of the igneous formation of whin- fone, and how anomalous and unconneéted they a ae according to every other theory. _ 270. Notwithftanding all this accumulated and unanfwerable evidence for the i igneous for- tion of bafaltes, a great objection would {till s courate and eonelufive experiments toncern- 3 U ing combination. As the laft and higheft term of- Jatt, in Ayrfhire, which, on the authority of `, re main to our theory, were it not for the very 306 ILLUSTRATIONS OF THE ing the fufion of this foffil, referred to above, $75. A ftrong prejudice againft the produc. tion of any thing like a real ftone by means of - fufion, had arifen, even among thofe mineralo- gifts, who were every day witneffes of the ftony appearance aflumed by volcanic lava. They ftill maintained, on the authority of their own imperfect experiments, that nothing but glafs ean ever be obtained by the melting of earths or of ftones, in whatever manner they are combi. — ned. block of bafaltes, in which he difcovered fuch appearences, as inclined him to admit its igne- ous confolidation, reje&s that hypothefis, mere- ly from the imaginary inability of fire to give i to any fubftance a ftony character: “ Quelque — mélange,” fays he, “ de terres que Pon fuppofe, quelque foit le degré de feu que Pon imagine, quelque foit le tems que Pon emploie, il eft très ` certain que l’on n’obtiendra pas, par le feul fluide igné, ni bafakte, ni rien qui lui reffemble *.” Sir James Hall’s experiments have complete- ly demonftrated the contrary of what is here atferted ; they have added much to the evidence of the Huttonian fyftem ; and, independently of = Journal de Phyf, tom. xlix, (1799.) p. 36- An ingenious naturalift, after defcribing a all a ee hee — a AAS HUTTONIAN THEORY... 3 Í theory, have narrowed the circle of prejudice 4 pend error. Note xv. § 83. On Granite. i Granite Veins. | a It is faid above, § 77+, that gratiite ig >f in unftratified maffes, and in veins. In the rmer of thefe conditions, it conftitutes entire mountains, and forms the central ridge of many of the greateft chains that traverfe the furface E the earth. It is the granite of this kind that | has been moft generally defcribed by travellers — and mineralogifts. The veins have not been fo much attended to, though they are of pecu- r importance for afcertaining the relation be- n granite and other foflils. 292. Though Dr Hutton was the firft geologitt who explained the nature of granite veins, and who obferved with attention the phenomena which accompany them, he is not the firft who mentioned them. M. Beflon found veins this kind in the Limoges, in an argillaceous © iftus, and unconnected, as far as appa, with any aa mafs of granite *. | 2 Sauflure 4 * Journal de Phyf. tom, xxix. p. 89. 308 ILLUSTRATIONS OF THE Sauffure met with granite veins in the Valor- fine, but did not fee them diftinaly. ‘He afcrib. ed them to infiltration *. The date of this ob- fervation is in 1776: He afterwards difcovered fimilar appearances at Lyons +. Werner alfo, in enumerating the fubftances of which veins are formed, reckons granite as one of them. | 273. Veins of granite may be confidered as of two ine: according as they are conneéted, or not connected apparently with any large mafs of granite. It is probable, that thefe two kinds of veins only differ in appearance, and that both are connected with maffes of the fame rock, though that connection is vifible in fome inftan- ces, and invifible in others. The diftinétion, - however, whatever it be with refpec& to the thing obferved, is real with refpect to the ob- ferver ; and, as it is right, in a defcription of facts, to avoid every thing hypothetical, I thall {peak of thefe veins feparately. 274. Veins of granite, having no communica- tion, fo far as can be difcovered, with any mals of the fame rock, are found in the Weftern If- lands of Scotland, particularly in that of Coll, where * Voyages aux Alpes, tom. i, § 598, 599. t+ Lbid. § 601, HUTTONIAN — | 309 4 plend fchiftus, which compofe the main body of the ifland. They are fometimes feveral q fathoms n thicknefs, obliquely interfecting the _ planes of the ftrata juft mentioned, which are pearly vertical. In thefe veins the feltfpar is _ predominant ; it is very highly cryftallized, and of a beautiful flefh colour. Many {maller veins y e alfo to be met with in the fame place; but no large mafs of granite is found, either in this or the adjacent ifland of Tiree. = 275. The Portfoy granite, of which mention 4 has been already made, § 80, alfo conftitutes a vein or dike, traverfing a highly indurated mica- ; ceous fchiftus, about a mile to the eaftward of _ the little town of Portfoy, and not vifibly con- nected with any large mafs of the fame kind. - More dikes than one of this granite have been - obferved ear the fame fpot. — A fimilar granite is likewife found inland, in the neighbourhood of Huntly, about eigh- | teen miles fouth of Portfoy ; but whether in the | ee of a vein or a mafs, I have not been able to learn. 276. Veins of granite are alfo frequent in q Reornivall, where they are known by the name _ of lodes, the fame name which is applied in that a country to metallic veins. The granite veins fre- E U3 quently 310 ILLUSTRATIONS OF THE quently interfe& the metallic, and are remarkable for producing fhifts in them, or for throwing them out of their natural direGion. The mineral Veins, particularly thofe that yield copper and tin, run nearly from eaft to weft, having the rote di- rection with the beds of the rock itfel f, which isa very hard {chiftus. The granite lodes, as alfo thofe of porphyry, called elvan in Cornwall, are at right angles nearly to the former ; and it is remarked, that they generally heave the mineral veins, but that the mineral veins fel. dom or never heave the crofs- -yeins, In this country, therefore, the veins of granite and pors phyry are pofterior in formation to the metallic _ veins. ‘Thefe veins of granite may perhaps be connected with the great granitic mafs that rung longitudinally through Cornwall, from Dart- moor tothe Land’s End. This much is certain, that their dire@tions in general are fuch, that, if produced, they would interfe@ that mals, nearly at right angles. 277. The granite veins in Glentilt, where Dr Hutton made his firft obfervations on this fub- ject, are not, I believe, vifibly conne@ed with any large mafs of the fame rock *. The bed of the ri- ver Tilt, in the diftance of little more than a mile, is deem * Trant. Royal Society Edin. vol, iii. p. 77, KC. ae ee Se a ws HUTTONIAN THEORY. 31I y 4 js interfected by no lefs than fix very powerful i, _ veins of granite, all of them accompanied with | 7 fuch marks of diforder and confufion in the ftra- | ta, as indicate very ftrongly the violence with _ which the granite was here introduced into its _ place. Thefe veins very probably belong to the great mafs of granite which is known to form the central ridge of the Grampians further tothe north; but they are feveral miles diftant - from it, and the connedtion is perhaps invifible " in the prefent ftate of the earth’s furface. _ 278. The fecond kind of granite vein, is one d which proceeds vifibly from a mafs of that rock, _ and penetrates into the contiguous ftrata. The _ importance of this clafs of veins, for afcertain- "T ing the relation between granite and other mi- IU neral bodies, has been pointed out, § 82.; and i by means of them it has been fhewn, that the i) granite, though inferior in pofition, is of more ‘ recent formation than the fchiftus incumbent on | it; and that the latter, inftead of having been i} quietly depofited on the former, has been, long after its depofition and confolidation, heaved up j from its horizontal pofition, by the liquid body -of granite forcibly impelled againft it from be- low. | la It has been alleged, in order to take off the l force of the argument derived from granite By D4 veins, 312 ILLUSTRATIONS OF THE veins, that thefe veins are formed by infiltra- tion, though, to give any probability to this fuppofition, it would be neceflary to fhew, that water is able to diffolve the ingredients of gra. nite; and even if this could be done, the di- rection which the veins have, in many inftances, rifing up from the granite, is a proof, as remark- ed § 82., that they cannot be the effed of in- filtration. aa ` Another objedion has been thrown out, | namely, that the veins here referred to are not of true granite, according to the definition which mineralogifts have given of that fubftance, The force of a faa, however, is not to be leffen- ed by a change of names, or the ufe of arbitrary definitions. The general fad is, that the gra- nitic mafs, and the vein proceeding from it, con- ftitute one continuous, and uninterrupted body, without any line of feparation between them, The geological argument turns on this circum- ftance alone; and it is no matter whether the rock be a fyenite, a granitelle, or a real granite. The phenomenon fpeaks the fame language, and leads to the fame conclufion, whatever be the technical terms the mineralogift employs in de- {cribing it. i | 279. it muft, however, be admitted, that a difference of character is often to be obferved between the granite mafs and the veins proceed- Ing HUTTONIAN THEORY. 313 ing from it; fometimes the fubftances in thè latter are more highly cryftallized than in the F former; fometimes, but more rarely, they are r ' lefs cryftallized, and, in fome inftances, an in- 7 gredient that enters into the mafs feems entirely l wanting in the vein. Thefe varieties, for what _ we yet know, are not fubje&t to any general rule ; | but they have been held out as a proof, that the q mafles and the veins are not of the fame forma- tion, It may be anfwered, that a perfe& fimi- larity between fubftances that, on every hypo- - thelis, muft have cryftallized in very different circumftances, is not always to be looked for; "but the moft dire anfwer is, that this jaka : -fimilarity does fometimes occur, infomuch that, Mm in certain inftances, no difference whatfoever ie ‘can be difcovered between the mafs and the i, vein, but they confift of the fame ingredients, | i] ‘and have the fame degree of cryftallization. a _ Some inftances of this are juft about to be re- i marked. 280. A ftrong objection to the fuppofed c ori- gin of granitic veins from infiltration, and in- - deed to their formation in any way but by ig- if © neous fufion, arifes from the number of frag- ments of fchiftus, often contained, and complete- y infulated in thofe veins. How thefe frag- “ments were introduced into the fiffures of the " fehittus, and fuftained till they were furrounded © Eo q . 7 ; -py d La et 314 ILLUSTRATIONS OF THE _ by the matter depofited by water, is very hard to be conceived ; but if they were carried in by the melted granite, nothing is more eafily underftood. The following are fome of the places where the toads of granite veins may be difting. ly feen. = RN The ifland OE Arran, remarkable for col- leCting into a very {mall compafs a great number of the moft interefting facis of geology, exhibits many inftances of the penetration of {chiftus by E a EEEE E TENE x ett TAA m veins of granite. A group of granite moun- — tains occupies the northern extremity of the ifland, the higheft of which, Goatfield, rifes nearly to the height of 3000 feet, and on the fouth fide is covered with {ehiftus to the height of 1100. From thence, the line of junc- tion, or that at which the granite emerges from — under the fchiftus, winds, fo far as I was able | to obferve, round the whole group of monntains, with many wavings and irregularities, rifing fometimes to a greater, and defcending fome- — times to a much lower level, than that jut mentioned. Along this line, particularly on the fouth, wherever the rock is laid bare, and cut into by the torrents, innumerable veins of granite are to be feen entering into- the sho growing narrower as they advance into — ; and being directed, in roy many cafes, from below B |_‘-HUTTONIAN THEORY. 315 T a | below upwards, they are precifely of the kind 7 which the infiltration of water could not pro- l 3 duce, even were that fluid capable of diffolving T the fubftances which the vein confifts of. From _ this fouth face of the mountain, and from the = bed of a torrent that interfeds it very deeply, Dr Hutton brought a block of {chiftus, of feve- | yal hundredweight, curioufly penetrated by gra- ' nite veins, including in them many infulated — agments of the ichiftus. _ the granite and {chiftus defcends towards the welt fide of the mountain, and is vifible at the - bottom of a deep glen, (Glen- -Rofa), which de- _ taches Goatfield from the hills farther to the — d wef, The jundtion is laid bare at feveral pla- ces in the bed of the river which runs in the es; of this glen ; and in all of them exhi- p bits in a greater or lefs degree, the appearan- ces of difturbance and violence which have ac- E vanied the injection of the granite veins. a ial circumftances render this {pot interefting toa geologift, and, among others, an interfec- tion of the granite, a little above its jun@ion "with the {chiftus, by a dike or vein of very com- ad whinftone. _ The fame line of jun@ion is found on the _ Oppofite, or north-eaft, fide of the mountain, an a where 4 From this, point, the common fe@ion ofo 316 ILLUSTRATIONS OF THE | where it is interfe@ed by another little rive, the Sannax, which on this fide determines the ` bafe of the mountain. This jun@tion i is no lef remarkable than the other two. The ifland of Arran contains, I have no doubt, many other {pots where thefe phenome. na are to be feen; but I have had no opportu- nity of benii them, nor do I find that Dr _ Hutton met with any others in’ his vifit to o this ifland. ug = 282. Another feries of granite veins is faoal i in Galloway, which was firt difcovered by Dr Hutton and his friend Mr Clerk, and afterwards more fully explored by Sir James Hall and Mr Douglas, the`prefent Earl of Selkirk. The two laft traced the line of feparation between a mafs of granite and the fchiftus incumbent upon it, all round a tra@ of country, about eleven miles by feven, extending from the banks of Loch Ken weftward ; and in all this tract they found, “ that wherever the junction of the granite with the fchiftus was vifible, veins of the former, from fifty yards, to the tenth of an inch in width, were to be feen running into the latter, and pervading it in all direCtions, fo as to put it beyond all doubt, that the granite of thefe veins, and confequently of the HUTTONIAN THEORY. 31) Ni the great body itfelf, which was obferved to form with the veins one uninterrupted mafs, muft have flowed ina See or liquid ftate into E its prefent pofition*.”’ I have only further to : 1 add, that forne of thefe veins are remarkable for containing granite, not fenfibly different, in any refpect, from the mafs from which they _ proceed. 283. In Invernefsfhire, between Bernera and i Fort Auguftus, the fame phenomena occur a ‘on the north fide of Loch Chloney, where fomeé i granite mountains rife from under the fchiftus. In travelling near this place, Lord Webb Sey- mour and myfelf were advertifed of our ap- proach to a jundtion of granite and {chiftus, le q by finding among the loofe ftones on the road _ many pieces of {chiftus, interfeCted with veins ji of feltfpar and granite. We walked along this i _ junction for more than a mile; and toward i the eat end, where the road leaves it, we faw, p in the bed of a ftream that runs into Loch S many beautiful fpecimens of granitic J Veins pervading the fchiftus, and EA out into very minute ramifications. | 284. The laft inftance I have to men- f tion from my own obfervation, is at St Mi- f chael’s i, ae . Tranf, Royal Society Edin, vol, iu. p. 8. 318. ILLUSTRATIONS OF THE chael’s Mount in Cornwall. That mount js _ entirely of granite, thruft up from under ag _ very hard micaceous fchiftus, which furrounds it on all fides. At the bafe of it, on the weft fide, a great number of veins run off from the granite, and fpread tħemfelves like fo many roots fixed in the fchiftus : they are feen at low water. In the fmaller veins, the granite is of very minute, though diftin& parts; in the lars ‘ger, it is more highly cryftallized, and is undis ai ftinguifhable from the mafs of the hill. S Befides the above, Cornwall probably affords. many other inftances of the fame kind, which I have not had an opportunity to examine. Such inflances may in particular be looked for at the Land’s End, where a promontory, confifting of _ a central part of granite, and covered by mica- ceous fchiftus on both fides of it, is cut trank- | verfely by the fea-coaft, and the conta@ of the granite and {chiftus of courfe twice expofed to view. i i 285- Scotland alfo affords other examples of granite veins, and fome of them have been actually defcribed. ` Mr Jamiefon has taken notice of fome which he faw in the bottom of the river Spey, at Glen Drummond, in Badenach, and has reprefented them in an en- graving. HUTTONIAN THEORY. 319 Ering *. They traverfe the ftrata in va- rious directions, and inclofe pieces of the mi- caceous {chiftus; and, from the great number of loofe blocks which he found, exhibiting por- | tions of fuch veins, it is probable,. that they are very numerous in this quarter. The fame mineralogift mentions fome inftances of fimilar veins in the Shetland Ifles $. " n Rofs-fhire, Sir George Mackenzie has wee fe ved a great variety of granite veins, fome of them of large fize. One of them, in particular, ; not far from Coul, when firft difcovered, was 4 fuppofed to be a fingle mafs, rifing from under ‘the {chiftus ; but, on a more careful examina- tion, has been found to be a part of a great fyftem of veins, which interfects the micaceous. {ehiftus of this tract in various directions. _ 286. The granite veins are not the only proof | ‘that this ftone is more recent than fome other productions of the mineral kingdom. : Speci- “mens of granite are often found, containing — ‘round nodules of other ftones, as, for example, of gneifs ot micaceous f{chiftus. Such is the {pe- cimen of granite containing gneifs, which Wer- f ner himfelf is faid to be in poffeffion of, and a s . -to ! ® * Mineralogy of the Scottith Hes, vol. ii, p. 173. Lt Ibid. p. 216. 320 ILLUSTRATIONS OF THE to confider as a proof, that the fchiftus is of greater antiquity than the granite. Such alfo feemed to me fome pieces of granite, which I met with in Cornwall, near the Land’s End; and others which I faw in Ayrfhire, in loofe blocks, on the fea-coaft between Ayr and Gir- van. It is impoflible to deny that the contain- ing ftone is more modern than the contained, The Neptunifts indeed admit this to be true, but allege, that all granite is not of the ame ] formation ; and that, though fome granite is re- q cent, the greater part boafts of the higheft an: tiquity which belongs to any thing in the fof- — fil kingdom. This diftin@ion, however, is pure- ly hypothetical; it is a fiction contrived on purpofe to reconcile the fact here mentioned with the general fyftem of aqueous depofition, © and has no fupport from any other phenome- non. 2. Granite of Portfoy. i 287. The granite of Portfoy is one of the moft fingular varieties of this ftone, and is re- markable for this circumftance, that the felt- fpar is the fubftance which has affumed the fi- gure of its proper cryftal, and has given its form to “@ HUTTONIAN THEORY. 32 y to the quartz, fo that the latter is imprefled both “with the acute and obtufe angles belonging to ‘the rhombic figure of the former. The angu- ‘Jar pieces of quartz thus moulded on the felt- “far, and ranged by means of it in rows, give tothis ftone the appearance of rude Bees “writing. - Now, Dr Hutton argued, that fubftances pre- J cipitated from a folution, and cryftallizing at a cannot be fuppofed to imprefs one ano- ther in the manner here exemplified; and that they could do fo only when the whole mafs ac- quired folidity at the fame time, or at the fame time nearly *. Such fimultaneous confolidation can be produced in no way that we know of, but by the cooling of a mafs that has been in | fufion. | T 288. A granite, brought from Daouria by ) M. Patrin, and defcribed by him in the Journal de Phyfique for 1791, p. 295, under the name of pierre graphique, feemed to Dr Hutton to have 0 great a refemblance to the granite of Portfoy, | iat he ventured to confider them both as the | fame ftone, and as both containing quartz T moulded on feltfpar t. It fhould feem, how- T ever, 1 ; | o Theory of the Earth, vol.i. p. 104. t Tranf, Royal Society Edin, vol, iii. p. 83. 322 ILLUSTRATIONS OF THE ever, from further explanations, which M. Pa. trin has fince given, that Dr Hutton was mif taken in his conjecture, and that, in the pierre graphique of the former mineralogift, the quartz gives its form to the feltfpar, preferving in its cryftals their natural angle of 120 degrees *, Jt is impoflible, I think, to doubt of the accuracy of this ftatement; and the graphical ftone of ` Portfoy muft therefore be admitted to differ materially from that of Daouria. They are not, however, without fome confiderable affinity, be. fides that of their outward appearance; for, though the quartz in the former is generally moulded on the felt{par, the feltfpar is alfo oc- cafionally impreffed .by the quartz, and fome- times even included in it. They may be con- — fidered as varieties of the fame fpecies of gra- ” nite; and the pierre graphique of Corfica is probably a third variety, different from them both. 289. It would feem, however, that all thefe ftones lead exactly to the fame conclufion. M. Pa- trin deferibes his fpecimen as containing quarts cryftals, that are for the moft part only ca/es, hâ- ving their interior filled with feltfpar. “ Le felt- ? fpath * Journal Britannique (of Geneva), 1798, vol. vu. Sciences et Arts, p. 78. HUTTONIAN THEORY. 323 fpath en maffe contient des cryfteaux quartzeux, = qui n’ont le plus fouvent que le carcafle, et dont € Yinterieur eft rempli de feltfpath; fouvent il manque à ces carcaffes quelques unes de leurs d faces, et fouvent la fection de cette pierre dans un fens tranfverfal aux cryftaux, prefente une d fuite de figures qui font ‘des portions d’hexagones, T et qui ne refemblent pas mal à des carađtères 4 Hebraiques en A Thefe imperfect hexagonal cafes of quartz, l filled with feltfpar, certainly indicate the cry- ™ ftallization of fubftances, which all affumed My _ their folidity at the fame time, and, in doing fo, á 3 conftrained the figures of one another. To y 7 ufe the words of Dr Hutton, “ whether cry- La - flallizing quartz inclofe a body of feltfpar, or " concreting feltfpar determine the fhape of fluid II quartz, particularly if we have, as is here the E cife, two folid bodies including and included, it | amounts to a demonftration, that thofe bodies i have concreted from a fluid ftate of fufion, and A q have not cryftallized, in the manner of falts, from gi 2 folution +.” 290. The quartz in granite fo generally re- | tives the impreflions of all the other fubftances, X 2 particularly * Journal Britannique, :dd. + Tranf, Royal Society Edin. ubi /upra, p.84. 324 ILLUSTRATIONS OF THE particulary of the felt{par and fchorl, and appears to be fo paflive a body, that it has been doubted by fome mineralogifts, whether in this ftone it ever aflumes its own figure, except where cavities afford room for its cryftallization. But it is certain that, befide the Daourian granite juft mentioned, there are others, in which the quartz is completely cryftallized. Of this fort are fome {pecimens, found in a granite vein on the weft fide of the hill of St Agnes, in Corn- wall. The vein traverfes the primitive fchif- tus, of which that hill confifts, from fouth to north nearly: the ftone is much decompofed, and the feltfpar in general is almoft reduced to the ftate of clay. In this decompofed mafs, quartz cryftals are found, having the fhape of double hexagonal pyramids, perfeCtly regular and complete. The fide of the hexagon, which is the bafe of the two oppofite pyra- mids, varies from half a tenth to a tenth of an inch in length, and is the fame with the altitude of each of the pyramids. In fome few fpeci- mens, the two pyramids do not reft on the fame bafe, but are feparated by a very fhort, though regular, hexagonal prifm. The furfaces of thefe eryftals are rough, and fomewhat opaque, with flender fpiculæ of fhorl frequently traverfing them. This roughnefs is occafioned by flight furrows HUTTONIAN THEORY. 325 a furrows on the furface of the cryftal, very re- | gularly difpofed, and parallel to one another, being without doubt impreffions from the thin | plates of the feltfpar, which furrounded the | cryftal, and flightly indented it. They very ’ much refemble fome impreflions, remarked by il Dr Hutton in the granite of Portfoy, and afcri- W bed by him alfo to a fimilar caufe. He has re- prefented thefe in his Theory of the Earth, i) yol. i. plate 2. fig. 4. The aéion and reaction tik)! of two cryftallizing bodies, hardly admits of a ftronger and more unequivocal expreffion, than » in thefe two inftances. Where the granite was little decompofed, the quartz was not eafily difengaged from the sj) mafs it was imbedded in, and often broke in pie- q ces before it could be extricated. The cryftalli- a zation of the quartz, therefore, would not have T been difcovered, but for the decompofition of | the feltfpar; and it is probable, that fimilar » cryftallizations exift in many granites where | they are not perceived. 291. Some mineralogifts : are inclined to think, * thatthe regular cryftallization of quartz is to be found only in what they call fecondary granites, or in thofe that are of a formation fubfequent to _ the great maffes which conftitute the granite © mountains. It is indeed true, that in the in- A 3 {tances 326 ILLUSTRATIONS OF THE ftances given here, both from Cornwall and Daouria, the granites containing quartz-cryftals are from veins that interfe& the primary {chif. tus, and are therefore, on every hypothefis, of a formation fubfequent to that fchiftus. But it does not follow from thence, that they are lef ancient than the great mafles of unftratified gra- nite; with thefe laft they are moft probably coëval, nor can there be any reafon for thinking the cryftallization of quartz a mark of more recent formation than that of feltfpar. 3. Stratification of Granite. 292. What are the various modes in which granite exifts, is a queftion not abfolutely de- cided among mineralogifts. r. That it exifts as a {chiftofe ftone of a fiffile texture, in gneifs and veined granite, is on all hands admitted, though in this ftate the name of granite is generally withheld from it. 2. That it exifts often with- out any indication of a fiffile texture, and alto- gether unftratified, is likewife acknowledged. 3. That it is found in veins, interfecting the firata, has been fhown above. The only mode of its exiftence fubject to difpute, is that in which it is faid to be ftratified in its out- = ward oe HUTTONIAN THEORY. 327 ‘ward configuration, but not {chiftofe’ in its texture. On this point mineralogifts do not _ perfectly agree: Dr Hutton did not think that this was a ftate in which granite ever appears, When not fchiftofe in its ftructure, he fuppofed “it to be unftratified altogether; and he con- {dered it as a body which, like whinftone, "was originally in a ftate of igneous fufion, and, in that condition, injected among the ftra- ta The fchool of Werner, on the other hand, F maintain, that granite, if not always, is general- ly firatified, and difpofed in beds, fometimes ho- yizontal, though more frequently vertical, or highly inclined. In forming an opinion where there are great ' authorities on oppofite fides, a man muft truft F chiefly to his own obfervations, and ought to T efteem himfelf fortunate if thefe lead to any certain conclufion. Mine incline me to differ from Dr Hutton, on the one hand, and from the Neptunifis on the other, as they convince me, that granite does form ftrata where it has no character of gneifs; and, at the fame time, induce me to fufpect, that the ftratification afcribed by the Neptunifts to the granite moun- tains, is, in many inftances, either an illufion, or at leaft fomething very different from what, in other ftones, is accounted ftratification. X 4 293. The 328 ILLUSTRATIONS OF THE 293. The firftexampleI ever faw of granite that was ftratified, and yet had no character of gneifs, was at Chorley Foreft, in Leicefterfhire. The greater part of that foreft has for its bafe a horn- ftone fchiftus, primary and vertical; and, on its eaftern border, particularly near Mount Sorrel, are beds-of granite, holding the fame diređtion with thofe of the fchiftus. The ftone isa real.gra- nite; it has nothing in its internal ftru@ture ofa fchiftofe or fiffile appearance; and its beds, which it is material to remark, are no thicker than thofe of the hornftone ftrata in the neighbourhood, This granite is remarkable too, for being clofe to the fecondary fandftone {trata ; I did not fee their contaé, but traced them within a {mall diftance of one another ; fo that I think it is not likely that any body of rock intervenes. At the fame time that I flate my belief of this rock of granite being in regular ftrata, I muft acknow- ledge, that a very intelligent mineralogift, who viewed thefe rocks at the fame time, and whofe eye was well practifed in geological obfervation, remained in doubt concerning them. 294. Another inftance of a real granite, difpo- fed in regular beds, but without any character of gneifs, is one which I faw in Berwickthire, in Lammermuir, near the village of Prieftlaw. The little river of Faffnet cuts the beds acrofs, and HUTTONIAN THEORY. 329 ‘and renders it eafy to obferve their ftructure. The beds are not very thick; they run from about S. S. W. to N. N. E. like the fchiftus on either fide of them. I was in company with — | Sir James Hall when I faw thefe rocks; we ex- i amined them with a good deal of attention, and _ traced them for more than a mile in the bed of the river; and, if I miake not, our opinions concerning them were precifely the fame. 295. What exifts in two inflances may exiftin many, and, after thefe obfervations, I fhould be _ guilty of great inconfiftency, in refufing to affent to the accounts of Pallas, De Luc, Sauffure, and many other. mineralogifts, who fo often reprefent _ granite as formed into ftrata. In fome cafes, how- iil eyer, it is certain, that the ftratification they de- fcribe is extremely unlike that in the two inftan- _ ces juft mentioned, and indeed very unlike any _ thing that is elfewhere known by the name of ftra- í tification. For example, the ftratification muft _ be very ambiguous, and very ob{curely marked, __ that was not difcovered till after a feries of ob- fervations, continued for more than twenty ‘years, by a very fkilful and diftinguifhing mi- neralogift. Yet fuch undoubtedly is the ftra- _ tification of Mont Blanc, and of’ the granite mountains in its neighbourhood, as it efcaped ‘the eyes of Sauffure, in the repeated vifits which he made to them, during a period of no 330 ILLUSTRATIONS OF THE no lefs extent than has juft been mention. ed. It was not till near the conclufion of thofe labours, to which the geologifts of every age will confider themfelves as highly indebted, that, having reached the fummit of Mont Blanc, he perceived, or thought that he per- ceived, the ftratification of the granite moun- tains. The Aiguilles or Needles which border the valley of Chamouni, and even Mont Blanc itielf, appeared to be formed of vaft tabular mafies of granite, in pofition nearly vertical, and fo exactly parallel, that he did not hefitate to call them by the name of ftrata. Till this mo- ment, thefe fame mountains, viewed from a lower point, had been regarded by him as com- pofed of great plates of rock, nearly vertical indeed, but applied, as it were, round an axis, and refembling the leaves of an artichoke*; and the fiffures by which they are feparated from one another, had been confidered as effects of wafte and degradation. “ But now,” (fays he, {peaking of the view from the top of Mont Blanc), “ I was fully convinced, that thefe mountains are entirely compofed of vaft plates of granite, perpendicular to the horrzon, and directed from N. E. to S. W. Three of thefe plates, feparated from each other, formed thẹ top * Voyages aux Alpes, tom. ii, § 910, &c. HUTTONIAN THEORY. 331 i top of the diguille du Midi, and other fimilar j plates, decreafing gradually in height, compofe ‘iy its declivity to the fouth *.” 296, Sauffure was fo ftrongly imprefled with the j appearances of what he accounted regular ftra- tification, fuch as water only can produce, and 7 fuch as muft have been in the beginning hori- T zontal, that, placed as he now was, on one of T the higheft points of the earth’s furface, he form- F ed the bold conception, that the faummit on which he was ftanding had been once bu- T ried under the furface, to the depth at leaft of half the diameter of the mountain, and horizon- T tally diftant from its prefent place by a line not 4 lefs than the whole height of the mountain ; ;z-thg {i granite beds which compofe that mountain, having been raifed by fome enormous power from their horizontal pofition, and turned as on i an axis, till they were brought into the vertical f plane. In this notion, which fuits fo well with the nature of mountains really compofed of vertical trata, and which does credit to the extent of Sauffure’s views, it is wonder- ful that he did not fee the overthrow of the | geological fyftem he had adopted, which is pro- _ vided with no means whatfoever of explaining f thefe great effets. Such, * Voyages aux Alpes, tom. iv. § 1996. 332 ILLUSTRATIONS OF THE Such, then, were the ideas fuggefted toSauffure, by viewing the mountains of the Alps from the higheft of their fummits. His great experience, his accurate knowledge of the objects before him, and the power he had acquired of difi- pating thofe illufions, to which, in viewing mountainous tracts, the eye is peculiarly fub- ject, all confpire to give great weight to his opinion. Yet, as this opinion is oppofed by that which he himfelf had fo long entertained, before it can be received with perfect confi- dence, it will require to be verified by new ob- fervations. It feems certain, that the beds of | rock here defcribed, differ from all ordinary ftrata, both horizontal and vertical, in the cir- cumftance of their vaft thicknefs, three of them being fo large as to form the main body of a mountain. ‘Their parallelifm cannot eafily be afcertained; and they have at beft but a very flight refemblance to fuch beds as water is known to produce. 297. Their parallelifm is difficult to be afcer- tained ; for, on account of the magnitude and in- - aceceffibility of the objects, it is impoflible to place the eye in any fituation, where it fhall not be much nearer to one part of the planes whereof the parallelifm is to be eftimated, than to another. Indeed, one can perceive a caule which HUTTONIAN THEORY. 333 : q which may have rendered the parallelifm of the : ` 4 plates of granite which compofe the aiguilles, | more accurate in appearance than in reality, : _when viewed from a point fo elevated as the iy _ fammit of Mont Blanc. For, even on the fup- | pofition that the comparifon of thofe plates to i, leaves of artichokes was juft, and that the planes ». of their feparation converged toward one ano- "ther, in afcending to the top, when they were ` viewed from a point more elevated than that top, this convergency would be diminithed, and, | by the force of the perfpective, might even be | converted into parallelifm. We cannot at pre- OIT fent afcertain what effec this caufe of deception n may have actually produced. 298. The obfervations of Sauffure concerning WE the ftratification of granite, are not, however, in tt all inftances, liable to thefe obje&tions ; and it ti feems to be on much lefs exceptionable grounds WE that he pronounces the granite of St Gothard to 4 fbe ftratified. The gneifs and micaceous fchiftus W which conftitute the lower part of that mountain, i are fucceeded bya granite without any {chiftofe if j appearance, but divided into large plates, exa&ly i! i parallel to the beds of the former gneifs. Thefe if - he regards as real ftrata. On ftudying them in A detail, he fays, confiderable irregularities were j tobe obferved, but not greater than in the cafe i of 334 ILLUSTRATIONS OF THE of limeftone or micaceous {chiftus*. It may be inferred from this, that thefe plates of granite are not fo thick but that they admit of compa. rifon with beds that are known with certainty to be of aqueous formation, and I am therefore difpofed to believe, that the granite of St Go. thard, in this part at leaft, is ftratified. The tran. fition from gneifs to granite en ma/fs, is not un. common, as Sauffure has obferved in other in- ftances, and as we are juft about to confider more particularly. | 299. In the mountains of our own country, fome difficulties concerning the ftratification of gra- nite have alfo occurred. In Arran, for inftance, the mountain of Goatfield, which I have men- tioned above as affording an inftance of granite fending out many veins into the ‘fchiftus, and rivetted, as it were, by means of them to the fuperincumbent rock, when I vifited it, with a view of verifying on the fpot the interefting obfervations which Dr Hutton had there made, appeared to me to be without any vettige of ftra- tification in its granitic part, as did alfo the whole group of mountains to which it belongs. It was, therefore, not without a good deal of fur- prife, that I lately read, in an account of that ifland, by a very accurate and ingenious mine- ralogift, # Voyages aux Alpes, tom. iv. § 1830. HUTTONIAN THEORY. 335 ralogift, that Goatfield confifts of firatified gra- nite*. The impreflion which the appear- ance of that mountain made on my mind, is jut the reverfe; and though I faw large tabu- lar mafles, fometimes nearly vertical, feparated by fiffures, they appeared to be much too irre- gular, too little extended in length and height, ` and vaftly too much in thicknefs, to be reckon- ed the effects of ftratification. For all this, I ~ would by no means be underftood to fet my ob- fervations in oppofition to thofe of Mr Jamie- fon, In my vifit to Arran, I did not dire& my Mf inquiries much toward this point; the general appearance of the rocks did not fuggeft the ne- ich Thay ceffity of doing fo, and I was not perfectly aware | q how much the firatification of granite had been i) infited on by fome mineralogifts; fo that I W applied myfelf entirely to ftudy fome other of | the interefting phenomena which this little wa iland offers in fo great abundance. I there- ' fore carry my confidence in the appearan- ces which feemed to indicate a want of ftra- tification in the granite of Arran no further than to remain {ceptical both as to Mr Jamie- fon’s conclufions and my own, till an oppor- tunity itt _ * Mineralogy of the Scottifh Ifles, vol. i. p. 35, 36. 336 ILLUSTRATIONS OF THE tunity fhall occur of verifying the one or the other by actual obfervation. 300. The ftratification of granite, though it made no part of Dr Hutton’s fyftem, does by no means embarrafs his theory with any new difficulty. Rocks, of which the parts are highly cryftallized, are already admitted as belonging to the ftrata, and are. exempli- fied in marble, gneifs, and veined granite. In the two laft, we have not only {tratification, but a {chiftofe, united with a cryftallized ftruc. ture, and the effects of depofition by water, and of fluidity by fire, are certainly nowhere more fingularly combined. The ftratification of thefe fubftances is therefore more extraordinary than even that of the moft highly cryftallized gra- nite. Neither the one nor the other can be ex- plained but by fuppofing, that while fuch a degree of fluidity was produced by heat, as en- abled the body when it cooled to cryttallize, the whole mafs was kept in its place by great preflure acting on all fides, fo that the fhape was preferved as originally given to it by the fea. As we cannot, however, fuppofe, that the intenfity of the heat, or the fufibility of the fubftance through all the parts of a ftratum, were precifely the fame, we may expect to find in the fame ftratum, or in the fame body of ftrata, that in fome parts the marks of ftratification are | completely Ne È tte iy Mey nf Ti thy, teady n Sala “INE ea a Eed vi, y iri, Sà tA cylin tf dep *Pailtion by m BE Certainly note The ratificat More extraordin the mo highly ryti the one nor the other at y fsppoling, that while k ay së produced by hei = it cooled to j gns kept in its pleh byi gs e fo a i f Hence a fudden tranfition from ae eee HUTTONIAN THEORY. 337 Ji completely obliterated, while in others they re- It is thus that veined granite, or fhould be called granitic {chiftus, gra- main entire. what I think often graduates into granite in ma/s, that is, nite without any {fchiftofe or fiffile texture. Sauflure fays, that to be veined or not vein- ed, is an affection of granite, that feems, in ma- ny cafes, accidental *; as, in the midh of rocks of that fubftance, moft clearly fiffile d {tratifica- , large por» tions appear without any veftige tion. Of this phenomenon, which is frequent in the Alps, inftances are alfo to be met with in the granite rocks of Scotland, and the adja- cent ifles; and I know that Dr Hope, in a mi- neralogical excurfion which he lately made among the Hebrides, obierved many interefting and curious examples of it. Indeed, when rocks were fo much fufed as to cryftallize, and fo comprefled, at the fame time, as to re- they were evidently on the two oppofite forces were very main ftratified, verge of change ; nearly balanced, and each carried as far as it could go without entirely overcoming the other ; fo that a {mall alteration in the conditions may have made a great alteration in the effects. a ftratified to an a Voyages aux Alpes, tom. iv. § 2143. 338 ILLUSTRATIONS OF THE an unftratified texture, which is only found jn rocks highly cryftallized, and fuch as have en. dured the moft violent a@tion of the minerali- zing powers. 301. Now, though the ftratification of granite, or the mixture of the ftratified with the unftra- tified rocks of that genus, is not only reconcile. able with the principles of the Huttonian geolo- gy, but might even have been deduced as a corol. lary from thofe principles, before it was aćtual- ly obferved, it may be confidered as inconfiftent with the theory of granitic veins that has juft been given. A ftratum, though foft or fluid, could not invade the furrounding ftrata with violence, nor fend out veins to penetrate into them. It might, if ftrongly compreffed by — another ftratum lefs fluid than itfelf, fill up any fiffures or cracks that were in that other, but this would hardly produce fuch large veins, and of fuch confiderable length, as often penetrate from the granite into the fchiftus, — nor could it give rife to any appearance of di- _ fturbance. If, therefore, veins were found pro- ceeding from fuch ftratified granite as that of Chorley Foreft or Lammermuir, I fhould think, that the explanation of them was ftill a defide- ratum in geology. The Neptunian theory of infiltration would indeed be as applicable to them though fof yi lutroundig tray MRS out veins to pene ght, if roagly comp oe bets faid chan ikli y cach that were in tht: Jd hardly produce id i ble length s into the p ; 4 arate pikwa pr di eins were spect 4 grant sb HUTTONIAN THEORY. 339 them as to any other veins; for it is but little affected by the condition of the phenomena to be explained. Indeed, it is very difficult to fet any limits to the explanations which this theory affords ; and it would certainly puzzle a Neptu- nit, to aflign any good reafon why infiltration has not produced veins of one ichiftus running into another, er veins of {chiftus running into granite, as well as of granite running into {chif- tus. He will find it a hard tafk to reftrain the activity of his theory, and to confine its expla- nations to thofe things that really exif. 302. As the Huttonian fyfiem cannot boaft of theories of equal verfatility, it would be not a little embarraffed to account for veins of great magnitude proceeding from a rock diftin@ly ftratified, and accompanied with marks of ha- ving difturbed the rocks through which they pafs. Lam, however, inclined to believe, that this em- barraffment will never occur ; and that the grae nite veins do not proceed from the rocks that are really ftratified, but from fuch as have never been depofited by water, and where the appearances of {tratification, if there are any, are altogether il- lufory. This anticipation, however, requires to be verified by future obfervation ; and it remains to be feen, whether granitic veins ever accompany real granitic ftrata, or are peculiar to thofe in Y2 which 340 ILLUSTRATIONS OF THE which the appearances of regular beds are either ambiguous, or are entirely wanting. The de. cifion of this queftion is an object highly wor. thy of the attention of geologitts. 303. An argument, directed at once againft the igneous origin and unftratified nature of all gra. nite, is given in a work already mentioned: “ If granite had flowed from below, how does it happen, that, after it had burft through the ftrata of micaceous {chiftus, &c. it did not over- flow the neighbouring country ? If this hypo- thefis were true, Mont Blanc could never have exifted *.”? A theory is never more unfairly dealt with, than when thofe parts are feparated which were meant to fupport one another, and each left to ftand or fall by itfelf. This, however, is pre- cifely what is done in the prefent. inftance ; for Dr Hutton’s theory of granite would not de- ferve a moment’s confideration, if it were fo in- artificially conftructed, as to fuppofe that gra- „nite was originally fluid, and yet to point out no means of hindering this fluid from diffufing itfelf over the ftrata, and fettling in a horizon- tal plane. The truth is, that his theory, at the fame time that it conceives this ftone to have been dnan * * Mineralogy of the Scettith Ifles, vol. ii, p. 166. 4 ee te . | = UD Wy ADe could ay A aent more unfairly dei Oh parts are fence ii Pet one another, and eu) betel This, hover done in the prelent infu theory of granite woul i g's ouabderatio0, if it we! ss to foppot he gly fo, snd yet OF this 4yid fr 4 a HUTTONIAN THEORY. 341 been in fufion, fuppofes it to have been, in that ftate, injected among the ftrata already confo- lidated ; to have heaved them up, and to have een formed in the concavity fo produced, as in a mould. Thus Mont Blanc, fuppofing that it is unftratified, is underftood to confilt of a mafs that was melted by fubterraneous heat under the ftrata, and being impelled upwards by a force, that may ftand in fome comparifon with that which projected the planets in their orbits, heaved up the ftrata by which it was covered, and in which it remained included on all fides. 304. The covering of ftrata, thus raifed up, may have been burft afunder at the. fummit, where the curvature and elevation were, the ereateit; but the melted mafs underneath may have already acquired folidity, or may have been fuftained by the beds of fchiftus incum- bent on its fides. This fchiftus, forming the exterior cruft, was immediately acted on by the caufes of wafte and decompofition, which have long fince ftripped the granite of a great part of its covering, and aré now exercifing their power on the central mafs. That even Mont Blanc itfelf, as well as other unftratified moun- tains, was once covered with fchiftus, will ap- pear to have in it nothing incongruous, when we confider the height to which the fchiftus ftill rifes on its fides, or in the adjacent mountains ; Y3 and 342 ILLUSTRATIONS OF THE and when we refle&, that, from the appearances of wafte and degradation which thefe moun- tains exhibit, it is certain, that the fchiftus muĝ have reached much higher than it does at pre- fent. It is obvious, therefore, that when the cor- re{fponding parts are brought together, and pla- ced in their natural order, no room is left for the reproach, that this fyftem is inconfiftent with the exi/fence of granite mountains. I have no pleafure in controverfial writing ; and, not- withftanding the advantages which a weak at- tack always gives to a defender, I cannot but ‘regret, that Dr Hutton’s adverfaries have been fo much more eager to refute than to under. ftand his theory. 7 EE 305. A remark which Dr Hutton has made on the quantity of granite that appears at the furface, compared with that of other mineral bodies, has been warmly contefted. Having affirmed, that the greater part of rocks bear marks of being formed from the wafte and de- compofition of other rocks, he alleges that gra- nite, (a ftone which does not contain fuch marks), does not, for as much as appears from actual obfervation, make up a tenth, nor perhaps even mie iga i Caper to refute than y u ,, < $ which Dr Hutton bss that app! df ge Fhe HUTTONIAN THEORY. 343 even a hundredth part of the mineral kingdom *. Mr Kirwan contends, that’ this is a very erro- neous eftimate, and that the quantity of granite vifible on the furface, far exceeds what is here fuppofed}. The queftion is certainly of no mate- rial importance to the eftablifhment of Dr Hut- ton’s theory : it is evident, too, that an eftimation, which varies fo much as from a tenth toa hun- dredth part, cannot have been meant as any thing precile ; yet it may not be quite fuperfiuous to fhow, that the truth probably lies nearer to the leaft than the greateft of the limits juft mentioned. 306. Though granite forms a part, generally the central part, of all the great chains of moun- tains, it ufually occupies a much lefs extent of furface than the primary fchiftus. Thus in the Alps, ifa line be drawn from Geneva to Ivrea, it will be about eighty-five geographical miles in length, and will meafure the breadth of this formidable chain of mountains, at the place of its greateft elevation. Now, from the obferva- tions of Sauffure, who croffed the Alps exactly in this direction, it may be collected, that lefs than nine miles of this line, or not above a tenth part of it, in the immediate vicinity of Mont Blanc, is occupied by granite. Y 4 307% In * Theory of the Earth, vol.i. p. 211. t Geol, Effays, p. 480. 344 ILLUSTRATIONS OF THE 307. In fome fe&tions of the Alps, no granite” at all appears. Thus, in the rout from Cham, bery to Turin, acrofs Mont Cenis, which mea- {ures by the road not lefs than ninety miles, no granite is found, at leaft of that kind which i is diftinally i in mats, and ‘different from gneifs or veined granite *. 308. In fome other places of the fame moun- tains, the granite is more abundant. A line from the lake of Thun, along the courfe of the Aar, and over the mountains to the upper end of Lago Maggiore, croffes a very elevated trad, and pafles by the fources of the Rhone, the Rhine, and the Teffino, which laft runs into the Po. A good deal of granite is difcovered here, in the mountains of Grimfel and St Gothard ; | but by far the greater part of it is the va 7 granite, the granite in mafs being confined chiefly to the north fide of the Grimfel. Both together do not occupy more than one-third of the line, and therefore the fatter lefs than one- fixth. 309. The effay on the ae of the Py- rences, by the Abbé Patasso, contains a mine- ralogical chart of thofe mountains. From this chart I have found, by computation, that the granite does not occupy one- fifth of the hori- zontal * Voyages aux Alpes, tom, iii. § 1190, Ke. t cal | Me i Sof the lana í Tha, nm Mund Re ti 4 to the Ute PS A VETY eleva, ' the PAIS of the i tT Which lat ri dea. of granite is difton a of Grime! and SG Pee part of it is tke pant in mais being ct woth Gide of the Grin } g oop Dore than onet gime the latter lels tw ai spineralog! j HUTTONIAN THEORY. FAE JF) zontal furface on the north fide of the ridge, In- deed, many great tracts, even of the central reckoning from one end of it to the other. tain no granite what- the higheft mountains A large deduction fhould be made from the fra¢tion +, parts of the Pyrenees, con foever ; and not a few of confift entirely of calcareous {chiftus. on account of the fubftances unknown, which, from the conftruction of the chart, are often confounded with the granitic trad. 310. I might add other eftimations of the fame kind, all confeffedly rude and imper- fe&, but ftill conveying, by means of num- bers, a better idea of the limit to which our knowledge approximates, than could be done fimply by words; and, on.the whole, it would appear, that if we ftate the proportion of gra- nite to {chiftus to be that of one to four, we fhall certainly do no injuftice to the extent of the former. 3 It remains to form a rough eftimate from maps, and from the accounts of travellers, of what proportion of the earth’s furface confifts of primary, and what of fecondary rocks. After fupplying the want of accurate meafurement by what appeared to me the moh probable fuppo- fitions, I have found, that about —, of the fur- face of the old continent may be conceived to be occupied by primitive mountains; of which, if $ 346 ILLUSTRATIONS OF THE if we take one-fifth, we have 35 for the part of the furface occupied by granite rocks, which differs not greatly from the leaft of the two li- mits afligned by Dr Hutton. 311. In eftimating the granite of Scotland, Dr Hutton has certainly erred confiderably in defect *, and Mr Kirwan, who always: differs from him, is here neareft the truth ; though he is right purely by accident, as the information on which he proceeds is vague and erroneous, The places in Scotland where granite is found, are very well known; but the extent of fome of the moft confiderable of them is not accurately afcertained. In the fouthern parts, except the granite of Galloway, which is found in two pretty large infulated tracts, there is no other of any magnitude. The gra- nite of the north extends over a large di- ftri&. If we fuppofe a line to be drawn, from afew miles fouth of Aberdeen to a few miles | fouth * Dr Hutton in this cafe no doubt made a very loofe eftimate. He fays, the granite does not perhaps occupy more than a 5ocdth part of the whole furface. The whole furface of Scotland is not much more than 23,000 geographical miles, the seodth part of which is exactly 46; and this is exceeded by the granite in Kirkeud- brightfhire alone, as may be gathered from what iş faid § 202. ey wel known: byt b | a di Be wel condendi q i By akertained. In ih k Ete granite of Galowy, imo pretty large inl ther of any magnitude. T worth extends over 3 | scope » line to be de sath of Aberdeen 1 "ag GA ee | yp! . | HUTTONIAN THEORY. 347 fouth of Fort-William, it will mark out the cen- tral chain of the Grampians in its full extent, pafling over the moft elevated ground, and by F the heads of the largeft rivers, in Scotland. Along this line there are many granite moun- ,. tains, and large tracts in which granite is the prevailing rock. ‘There are, however, large {paces alfo in which no granite appears, though, if we were permitted to fpeak theoretically, and if the queftion did not entirely relate to a matter of obfervation, we might fuppofe, that, in no part of this central ridge is the gra- nite far from the furface, notwithftanding that in fome places it may be covered by the fchif- us. 312. A great part of the Grampian mountains is on the fouth fide of the line juft mentioned, but hardly any granite is found in this divifion of them, except fuch veins as thofe of Glentilt. On the north fide of the line, the granite extends in various directions; and, if from Fort-Wil- liam a line is drawn to Invernefs, the quadri- lateral figure, bounded on two fides by thefe lines, and on the other two by the fea, will be found to contain much granite, and many di- ftris confifting entirely of that ftone. This is in faét the great granite country of Scotland: it is a large tra, containing about 3170 {quare geographical miles, or about a feventh part et 348 ILLUSTRATIONS OF THE part of the whole : but the proportion of it occy. pied by granite cannot at prefent be afcertained with any exactnefs, nor will, till fome minera. logift fhall find leifure to examine the courfes of the great rivers, the Dee, the Spey, &c. which traverfe this country. If we call it one-fourth of the whole furface, its extent is certainly not under-rated, and will amount to 790 {quare miles nearly ; to which adding 150, as a very full al- lowance for all the other granite contained in | Scotland, exclufive of the ifles, we fthall have 940 fquare miles, between a twenty-fourth and twenty-fifth part of the furface of the whole, This computation, it muft be obferved, aims at nothing precife, but I think it.is fuch, that a more accurate furvey would rather diminith than increafe the proportion ailigned in it to the gra- nite rock. 313. This refult may perhaps fall as much fhort of Mr Kirwan’s notion, as it exceeds the — eftimate made by Dr Hutton. If it fhall not, and if the former has, in this inftance, come neareft the truth, it cannot be afcribed to the accuracy of his information, or the foundnefs of the prin- ciples which directed his refearch. Mr Wir- L1AMS, whom he quotes, was a miner, of great fkill and experience in fome branches of his profeflion, to which, if he had confined him- felf, he might have written a book full of ufe- 3 | ful the € ille es, | We a Wer A| at = ' 4 twenty- ~ion ‘ uTiace o Ot Ethe nhi S Dat d think itis fhi | ey would rather dim 00 ail Tenet init tote g tot + may pernp filla! a =s ° de Hot! ffon. If ith okt fa Na on di Í jo A p S 4 Eiei > R mnf > A Mit de oben n tion, as 1 a HUTTONIAN THEORY. 349 ful information. What he fays on the fubje& of granite, is, in the main I believe juft ; but it is far too general to author rife the conclufion which Mr Kirwan derives fromit. Dr Asun, for whofe judgment I have great refpect, cannot, I think, have meant, when he ufed the expref- fion granitic rocks, at fo called. He fays, Mr Kirwan, that and Berwick, there is a to defcribe granite ftridily in the paffage quoted by ‘‘ from Gallow ay, Dumfries, chain or Moul tains Dy Now, the fact is, that the great belt ¢ rock, here alluded to, of Scotland, rious kinds ; but except in Galloway, and again commonly ee eee but often alfo granitic.” of primary which traverfes the fouth confifts of vertical {chiftus of va- in Lammermuir, near Prieftlaw, it appears, as already mentioned, to contain no granite what- foever. If the German mineralogift quoted by Mr Kirwan, when he fays that the Grampian mountains confift of mica ceous limeftone, gneuls, D Se ee e $ ith ; and granite, aiternating wit e^ porphyry, argillite one another, means only to affirm that all t ftones are found in the Grampians, he is certain- ly in the right, and the catalogue might eafily be enlarged ; but, if thefe are nearly in equal abundance, or that the granite is abies found in ftrata alternating with other { he either means to fay trata, I muf fay, that thefe are pro- ILLUSTRATIONS OF THE pofitions quite contrary to any thing I have evet feen or heard of thofe mountains. -But it is pro- bable that this is not meant, and that the fault lies in underftanding the expreffions much too literally. Mr Kirwan accufes Dr Hutton of not knowing where to look for the granite; not aware of how much, notwithftanding any error committed in the prefent eftimate, he was {killed in the art of mineralogical obfer- vation ; an art, which thofe who have not prac- tifed do not always know how to appreciate, But, however imperfe& Mr Kirwan’s know- ledge of this fubjeét has been, he has here had the good fortune to correct a mineralogift of very fuperior information. The mete difpofi- tion to oppofe is not always without its ufe: no man i$ in every thing free from error, and, to controvert indifcriminately all the opinions of any individual, is an infallible fecret for being fometimes in the right. Nore xvi. § 100. Rivers and Lakes. 314. Rivers are the caufes of wafte moft vi- fible to us, and moft obvioufly capable of producing HUTTONIAN THEORY. 331 n | producing great effets. It is not, however, in the greateft rivers, that the power to change and wear the furface of the land is moft clearly Y Ry q feen. It is at the heads of rivers, and in the » % feeders of the larger ftreams, where they defcend over the moft rapid flope, and are moft fubje& to irregular or temporary increafe and diminu- tion, that the caufes which tend to preferve, and thofe that tend to change the form of the earth’s My furface, are fartheft from balancing one another, i and where, after every feafon, almoft after eve- Ty flood, we perceive fome change produced, Wk) for which no compenfation can be made, and _fomething removed which is never to be replaced. When we trace up rivers and their branches toward their fource, we come at laft to rivulets, that run only in time of rain, and that are dry at other feafons. It is there, fays Dr Hutton, that I would wifh to carry my reader, that he may be convinced, by his own obfervation, of this great fa, that the rivers have, in general, hollowed out their valleys. The changes of the valley of the main river are but flow; the plain indeed is wafted in one place, but is repaired in another, and we do not perceive the place from whence the repairing matter has proceeded. That which the fpe@ator fees here, does not | therefore immediately fuggeft to him what has A been the ftate of things before the valley was j hollowed $52 ILLUSTRATIONS OF THE hollowed out. But it is otherwife in the valley of the rivulet; no perfon can examine it with. out feeing, that the rivulet carries away matter which cannot be repaired, except by wearing away fome part of the furface of the place upon _which the rain that forms the ftream is gathered, The remains of a former ftate are here vifible; and we can, without any long chain of reafon- ing, compare what has been with what is at the prefent moment. It requires but little fludy to replace the parts removed, and to fee nature at work, refolving the moft hard and folid maffes, by the continued influences of the fun and at- mof{phere *. We fee the beginning of that long journey, by which heavy bodies travel from the fummit of the land to the bottom of the ocean, and we remain convinced, that, on our continents, there is no {pot on which a river may not formerly have run +. 315. The view thus afforded of the ope- rations, in their nafcent ftate, which have fha- ped out and fafhioned the prefent furface of the land, is neceflary to prepare us for fol- lowing them to the utmoft ‘extent of their effets. From thefe effects, the truth of the propofition, that rivers have cut and formed, not the aa oneal * Theory of the Earth, vol. ii. p. 294, N eS ard and fil t wdoences of the fan ae the bezinning oi j Beary bodies travel ty id to the bottom of te fumced, that, on our cue thich a river may nijn ibas afforded of feat fate, ped e P yy t9 prepar { i f n refent M ) W g TH 7 hich bait i to the Danube. HUTTONIAN THEORY. 353 the beds only, but the whole of the valleys, or rather fyftem of valleys, through which they flow, is demonftrated on a principle which has a clofe affinity to tl ufually calculated, § go. tightly the courfe of a great river, and the com- munication fubfifting between the main trunk and its remoteft branches, let us take the in- tance of the Danube, and cat our eyes on one of the maps conftructed by Marsicut, fox illuftrating the natural hiftory of that great ri- ver*, When it is confidered, that over all the valt and uneven furface, which reaches from the Alps to the Euxine, and from the mountains of Crapack to thofe of Hæmus, a regular commu- at on which chances are In order to’ conceive nication is kept up between every point and the line of greateft depreffion, in which the ri- ver flows, no one can hefitate to acknowledge, “that it is the agency of the waters alone which has opened them a free paflage through all the intricacies of this amazing labyrinth. In effeĝ, fuppofe this communication to be interrupted, “fand that fome fudden operation of nature were to erect a barrier of mountains to oppofe the Theife or the Drave, as they rolled their waters From this what could poflibly refult, but the damming up of thofe rivers till L their ie * Hiftoire du Danube, tom. i. tab. 34. 354 ILLUSTRATIONS OF THE their waters were deep, or high enough to find a vent, either under the bafes or over the tops of the oppofing ridge. ‘Thus there would be form. ed immenfe lakes and immenfe cataracts, which, by filling up what was too low, and cutting down what was too high, would in time reftore fuch a uniform declivity of furface as had before prevailed. Juft fo in the times that are paft, whatever may have been the irregularities of the furface at its firt emerging from the fea, or whatever irregularities may have been produced in it by fubfequent convulfions, the flow ac- tion of the ftreams would not fail in time to create or renew a fyftem of valleys commu- nicating with one another, like that which we at prefent behold. Water, in all circumftan- ces, would find its way to the loweft point; though, where the furface was quite irregu- lar, it would not do fo till after being dammed _ up in a thoufand lakes, or dafhed in cataracts over a thoufand precipices. Where neither of thefe is the cafe ; and where the lake and the ca- taract are comparatively rare phenomena ; there we perceive that conftitution of a furface, which water alone, of all phyfical agents, has a tenden- cy to produce; and we muft conclude, that the probability of fuch a conftitution having. arifen from another caufe, is, to the probability of its having se ee ee ee E ENE E oa a a ee ee a ee oe ae Oe HUTTONIAN THEORY. 555 having arifen from the running of water, in fuch E, proportion as unity bears to a number infinite- E dy great. _ 316. The courfes of many rivers retain marks _™ that they once confifted of a feries of lakes, W which have been converted into dry ground, by ‘the twofold operation of filling up the bottoms, " and deepening the outlets. This happens, efpe- by cially, when fucceffive terraces of gravelly and di Aat land are found on the banks of a river, § 100. q Such platforms, or haughs as they are called in i i this country, are always proofs of the wafte and li t 1 detritus produced by the river, and of the dif- but they wh J fometimes lead us farther, and ake it cer- alc tain, that the great mafs of grav el which forms the fucceflive terraces on each fide of the ri- me | ver, was depofited in the bafon of a lake. If, “from the level of the higheft terrace, down ssf to the prefent bed of the river, all is alluvial, and formed of fand and gravel, it is then evi- dent, that the {pace as low as the river now runs l muĝ have been once occupied by water; at the i fame time, it is clear, that water muft have ftood, i ; or flowed as high at leaft, as the uppermoft fur- 7 face of the meadow. Itis impoflible to recon- L j cile thefe two facts, which are both undeniable, : | but by fuppofing a lake, or body of ftagnant wa- E ter, to have here occupied a great hollow, AF 3 (which by us muft be held as one of the origi- 2 nal 336. ILLUSTRATIONS OF THE nal inequalities of the globe, becaufe we can trace it no farther back), and that this hollow, in the courfe of ages, has been filled up by the gravel and alluvial earth brought down by the river, which is now cutting its channel through materials of its own depofiting. There is no great river that does not afford inftances of this, both in the hilly part of its. courfe, and where it defcends firft from thence into the plain. Were there room here for the minuter details of topographical defcription, this might be il- luftrated by innumerable examples. 317. It is faid above, that the water muft have run or ftood, in former times, as low as the prefent bottom of the river; but there ts often clear evidence, that it has run or ftood much lower, becaufe the alluvial land reaches far be- low the prefent level of the river. This is known to hold in very many inftances, where it has happened that pits have been funk to confider- able depths on the banks of large rivers. By that means, the depth of the alluvial ground, under the prefent bed of the river, has been dif- covered to be great; and from this arifes the difficulty, fo generally experienced, of finding good foundations for bridges that are built ovet rivers in large vallies, or open plain, the ground being compofed of travelled materials to an un- known depth, without any thing like the native or HUTTONIAN THEORY. 357 or {olid flrata. In fuch cafes, it is evident, that | q formerly the water muft have been much low- er, as well as much higher, than its prefent level, and this is only confiftent with the notion, that Í the place was once occupied by a deep lake. = 318. If, following the light derived from thefe - indications, we go back to the time when the "river ran above the higheft of thofe levels at ` which it has left any traces of its operations, we fhall fee it compofed of a feries of lakes and ca- 1 taracts, from which, by the filling up of the one, _ and the wearing down of the other, the waters j have at length worked out to themfelves a quiet , and uninterrupted paffage to the ocean. We wl may, indeed, on good evidence, go back fill wi farther than the fucceffion of fuch meadows or ii} terraces, as are above mentioned, will carry us, and may confider the whole valley, or trough of iti), the river, as produced by its own operations. _ The original inequalities of the furface, and the : m - difpofition of the ftrata, muft no doubt have de- termined the water-courfes at firt; but this does not hinder us from confidering the rivers as i 4 l having modified and changed thofe inequalities, and as the proximate caufes of the fhape and con- _ figuration which the furface has now affumed. 319. From this gradual change of lakes into # Tivers, it follows, that a lake is but a temporary = and accidental condition of a river, which is L 3 every 359 ILLUSTRATIONS OF THE -every day approaching to its termination; and the truth of this is attefted, not only by the lakes that have exited, but alfo by thofe that conti: nue to exiit. “Where any confiderable ftream enters a lake, a flat meadow is ufually obferved increafing from year to year. The foil of this meadow is difpofed in horizontal ftrata: the meadow is terminated by a marth ; which marth is acquiring folidity, and is foon to be converted into a meadow, as the meadow will be into an arable field. All this while the fediment of the river makes its way flowly into the lake, forming a mound or bank under the furface of the wa- ter, with a pretty rapid flope toward the lake. . This mound increafes by the addition of new earth, fand, and gravel, poured in over the flope; and thus the progrefs of filling up continually advances. ) 320. In {mall lakes, this progrefs may eafily be traced ; and will be found fingularly confpicuous in that beautiful affemblage of lakes, which fo highly adorns the mountain fcenery of Weft- moreland and Cumberland. Among thefe a great number of inftances appear, in which lakes are either partially filled up, or have entirely difappeared. In the Lake of Kefwick, we not only difcover the marks of filling up at the up- per end, which extend far into Borrowdale, from which valley a {mall river flows into the lake ; but we have the cleareft proof, that this lake was once united i lar ; Be ¥ is Inn, 4 R | M to be COs i -wk lii T the fedir ma M bow! I mt to Maly els ake fp = rhace of I Ii nmi ne toward th, taies Oy the addition BPC, poured in overt peas Of nuog up cont res. | this prog pe of th n . phani ue m it HUTTONIAN THEORY. 359 united to that of Baffenthwa'te, and occupied the whole valley from Borrowdale to Oufe- Bridge. Thefe two lakes are at prefent joined only by a ftream, which runs from the former into the latter, and their continuity is inter- rupted by a confiderable piece of alluvial land, compofed of beds of earth and gravel, without rock, or any appearance of the native ftrata. This feparation, herefore, feems no other than a bar, formed by the influx of two rivers, that enter the valley here from oppofite fides, the Greata from the eaft, and Newland’s Wa- from the weft. ‘The furface of this mea- dow is at prefent twelve or fifteen feet at leaft above the level of either lake ; and a quantity of water of that depth muft therefore have been drawn off by the deepening of the iffue at Oufe-Bridge, through which the water of both lakes paffes, in its way to the ocean. Many more examples, fimilar to this, may be collected from the fame are In- deed few places from which, in lakes 3 there this branch of geology, more information may be collected. 321. The larger lakes e: se ogee the fame pro- erefs. Where the Rhone enters the Lake of Ge- neva, the beach has been obferved to receive an annual increafe; andthe Portus Valefiz, now Pre- vallais, which is at pretent half a league from the lake, was formerly clofe upon its bank. Indeed, the fediments of the Rhone uppear clearly to Z A. have è g60 . ILLUSTRATIONS OF THE have formed the valley through which it runs, to a diftance of about three leagues at leaft from the place where the river now difcharges itfelf into the lake, The ground there is perfectly ho. rizontal, compofed of fand and mud, little raifed above the level of the river, and full of marfhes, The depofition made by the Rhone after it en- ters the lake, is vifible to the eye; and may be feen falling down in clouds to the bottom. The great lakes of North America ate under- going the fame changes, and, it would feem, even with more rapidity. As the rivers, however, which fupply thefe vaft refervoirs, are none of them very great, the filling up is much lefs re- markable than the draining off of the water, by the deepening of the outlet. An intelligent travel- ler has remarked, that in Lake Superior itfelf the diminution of the waters is apparent, and that marks can be difcovered on the rocks, of the furface having been fix feet higher than it is at prefent. In the fmaller lakes this diminution is fill more evident *. In fome of thofe far inland, the ground all round ea gaps to the fame tra- wie to be the depofite from the rivers, of which the lakes ea Aes may be confidered as mere expanfion +. et pasadi 322. Tn * Mackenzie’s Voyages through the Continent. of North America to the Frozen and Pacific Oceans, pe xlii, and xxxvi. t lb:d. p. 122. A > Ming up 1S much hers raur uz BU { pi fof the Water, i Kiet. An intelligent m oh ub Lidl ikat in Lake Superi be Waters 15 appari: 0 prened on the rock ix i bet higher th nit ler | this sa ame gi we pct tot we 7 t 1c rivers, a” p” ‘ La confit’ py” tf cataracts are entirely obliterated ; rT Tr AT TINE TISLAYQY XF ria À Bia e Y ahr HU LT T ON TI AD Ae H AG, Nie 20 s 322. In order to uniform the rivers, the lakes r Jay ritip : give ceciivities to 7 muft not only be filled up or y k ~ 3 S & S d ye $ A 3 A drained, but the cataract, wherever there is one, t, The latter is an operation The ftream, as it precipi- tates itfelf over the rocks, hurries along with it, not only fand and gravel, but occafionally large ftones, which grind and wear down the rock with a force proportioned to their magnitude and acceleration. The fmooth furface of the waterfalls, their rounded furface, and curious excavations, are the moft fatisfac- tory proofs of the conftant attrition which they endure; and, where the muft be worn away. in all cafes vifible. rocks in all rocks are deeply in- terfeted, thefe marks often reach to a great height above tl on which the water now flows. The phenomena, in fuch inftances, are am ong 1e level the arguments beft calculated to remove all redali ty refpećđting the wafte which ri- vers have produced, and produce. They fuffer no doubt to remain, that the height and afperity of every waterfall are continually diminifhing ; that innumerable that thofe which remain are verging toward the fame end, and me the Falls of Montmorenci and Niagara muft ultimately difappear 523. Eck thane can be no doubt of the juft- nefs of the precedin or wAAA LS oO are continuing to conciuiions, when ay pplied to 362 ILLUSTRATIONS OF THE to lakes in general, fome apparent exceptions occur, in which the progrefs of draining and filling up feems to have been fufpended, or even to have gone in a contrary direction. Thete exceptions confift of the lakes which appear to have received a greater quantity of materials than was fufficient to have filled them up. Such, for example, is the Lake of Geneva, which re- ceives the Rhone defcending from the Vallais, one of the deepeft and longeft vallies on the fur- face of the earth. Now, if this valley, or even a large proportion of it, had been excavated by the Rhone itfelf, as our theory leads us to fup- pofe, the lake ought to have been entirely fill- ed up, becaufe the materials brought down by the river feem to be much greater than the lake, on any reafonable fuppofition concerning its ori- ginal magnitude, can poflibly have received. What, then, it may be faid, has become of all that the Rhone has brought down and depofit- ed in it? The lake, at this moment retains, in fome places, the depth of more than 1000 feet; and yet, of all that the Rhone carries in- to it, nothing but the pure water iflues. Ks it has been continuing to diminifh, both in fuperficial extent and in depth, from the time when the Rhone began to run into it, what mut have been its original dimenfions °. [ HUTTONIAN THEORY. 363 I cannot pretend to remove entirely the dif- culty which is here ftated; yet I think the following remarks may go fome length in doing fo. 324. It is certain, that from the prefent ftate of the lake of Geneva, and of the ground round it, we can hardly draw any inference as to its original dimenfions. Sauflure has traced, with his ufual fkill, the marks of the courfe of the Rhone, on a level greatly above the prefent ; and, by obfervations on the fide of Mount Saleve, has found proofs of the running of water, at leaft 200 toifes above the prefent fuperficies of the lake. But, if ever the fuper- ficies of the lake ftood at this height, or at this height nearly, though we can conjecture but ™ little concerning the ftate of the adjacent coun- ™ try, which no doubt was alfo on a higher level, the lake may very well be fuppofed to have been pwn ate of far greater dimenfions than it is now. It may have occupied the whole fpace from Jura to Sa- leve, and included the Lake of Neufchatel; fo that it may have been of magnitude fufficient to receive the {poils of the Valais, which, as the f furface of its waters lowered, may have been | wafhed away and carried down to the fea. Thus = it may have afforded a temporary receptacle for | the debris of the Alps, and may have ferved for an entrepot, as it were, where thole debris were A depofited, 364 ILLUSTRATIONS OF THE depofited, before they were carried to the place of their ultimate deftination. : 325. But the great depth which the lake hag at prefent, {till remains to be explained, becaufe no mud or gravel could be carried beyond the gulf, of a thoufand feet deep, which was here ready to receive it. The reality of this difi- culty muft be acknowledged ; and fome caufe feems to act, if not in the generation, yet cer- tainly in the prefervation of lakes, with which we are but little acquainted. We can indeed imagine fome caufes of that kind to occur in the courfe of the degradation of the land, which may produce new lakes, or increafe the di- mentions of the old. The wearing away of a ratum, or body of ftrata, may lay bare, and render acceffible to the water, fome beds of mi- neral fubftances foluble in that fluid. The di- ftrict, for inftance, in Chefhire, which contains rock-falt, extends over a tract of fourteen or fif- teen miles, and is covered by a thick ftratum of clay, more or lefs indurated, which defends the íalt from the water at the furface, and preferves the whole mafs in a ftate of drynefs. Should this covering be broke open by any natural con- vulfion, or fhould it be worn away, as it muft be in the progrefs of the general detritus, the water would gain admiffion to the faline ftrata, would a E ENES NA HUTTONIAN THEORY. 365 would gradually diffolve them, and form of courfe a very deep and extenfive lake, where all was before dry land. This event is not only poflible, but it fhould feem, that in the courfe of things it muft neceffarily happen. 326. Something of this kind may have taken place in the track of the Rhone, and may have _ produced the Leman Lake. It is not impoflible, that, at a very remote period, the Rhone de- feended from the Alps without forming any lake, or at leaft any lake of which the remains are now exifting ; and this fuppofition, which is _ more probable than that of § 324, we fhall foon find to be conformable to appearances of another kind. The river may have wore away the fecon- dary limeftone ftrata over which it took its eourfe after it left the {chiftus of the mountains ; and, in doing fo, may have reached fome ftra- tum of a faline nature, and this being wafhed out, may have left behind it a lake, which is but modern compared with many of the revolutions that have happened on the furface of thé earth *. This explanation is no doubt hypothetical ; but it is propofed in one of thofe cafes, in which * There are falt fprings at Bex, near Aigle, about ten miles from the head of the lake: faline ftrata, there- fore, are probably at no great diftance. 366 ILLUSTRATIONS OF THE which hypothetical reafonings are warranted by the ftricteft rules of philofophical inveftigation, It is propofed in a cafe, where the caufes vifi- ble to man feem inadequate to the effeé, and where we muft therefore have recourfe to an agent that is invifible. If the operations aferi- bed to this agent are conformable to the analo- i gy of nature, it is all that can in rekin be re- quired. 327. Another circumftance may alfo influence the generation and prefervation of lakes ; but it is allo one with which we are but little ac. quainted. The ftrata, and indeed the whole body of mineral fubftances which forms the bafis of our land, have been raifed up from the bottom of the fea, by a progrefs that fhould feem in general to have been gradual and flow. Ap- pearances, however, are not wanting, which fhew, that this progrefs is not uniform; and that both rifing and finking in the furface of the land, or in the rocks which are the bale of it, have happened within a period of time, which is by no means of great extent. In this progrefs, the elevations and depreffions may not be the fame for every fpot. They may be partial, and one part of a ftratum, or body of ftrata, may rife to a greater height, or be more depreffed, than another. It is not impof- fible, that this procefs may affed the depth of lakes, HUTTONIAN THEORY. 367 “fakes, and change the relative level of their Fides and bottom. 328. All lakes, however, do not involve the difficulty which the preceding conjectures are in« tended to remove. The great lakes of North F America do not, for inftance, receive their fup- i ply from very large rivers. Of courfe, it is not from a tract great in comparifon of themfelves, | that the wafte and detritus is brought down l into them; and it feems not at all wonderful, in that, without being filled up, they have been f able to receive it. The fame, in a degree at ~ leaft, is true of many other lakes. It fhould alfo be contidered, that we may im) err greatly in the eftimate we make of the ma- f terials actually carried down and depofited in i! any lake. To judge of their entire amount, we @ © thould know the original form of the inequali- Pan 7 ties on the earth’s furface ; of the quantity of de- _ preffion which exifted, independently of the ri- 1m vers; and though, in general, thefe original ine- qualities may be overlooked, and the prefent _ confidered as made by the running of water, 4 yet, in particular inftances,.this may be far from 4 true. The Vallais, for example, which we con- fider as the work of the Rhone, may, when the ‘Alps rofe out of the fea, have included many (| depreflions of the furface, which the river join- ed together, and, from being a feries of lakes, _. formed into one great valley. 329. The 368 ILLUSTRATIONS OF THE < 329. The mouths by which rivers on bold rocky coafts difcharge their waters into the fea, afford a very ftriking confirmation of the con. clufions concerning the general fyftem of wafte and degradation which have been drawn above, At thefe mouths we ufually fee, not only the bed of the river, but frequently a confiderable valley, cut out of the folid rock, while that rock perlerves its elevation, and its precipitous afped, wherever it is not interfected. by a run of water. No convulfion that can have torn afunder the © rocks; no breach that can have been madein them, antecedent to the running of the waters, will account for the circumftance of every ri- ver finding a correfponding opening, by which it makes its way to the fea; for that opening being fo nearly proportional to the magnitude — of the river, and for fuch breaches never oc- curring but where ftreams of water are found. 330. The actual furvey of any bold and rocky coaft, will make this clearer than any general ftatement can poffibly do. Let us take, for an example, the coaft of the Britifh Channel, from Torbay to the Land’s End, which is faced by @ continued rampart of high cliffs, formed of much indurated and primeval rock. If we con- fider the breaches in this rampart, at the mouths Q EAER E Te y a ron gy! fnk M hiat can have benng tto the ranning of then, the circumttance of m ` ponein: opening, bi to the fa; for thtye ‘opal to the oat for foch breaches m of water at? ant HUTTONIAN THEORY. 369 of the Dart, of the Plym and Tamer, of the ri- yer at Fowey, of the Fal, the Hel, &c. it will ap- pear perfedtly clear, that they have been produ- ced by their refpective ftreams. Where there js no ftream, there is no breach in the rock, no foftening in the bold and ftern afpe& which this fhore every where prefents to the ocean. If we look at the {maller ftreams, we find them working their way through the cliffs at the pre- fent moment; and we fee the fteps by which the larger valleys of the Dart and the Tamer have been cut down to the level of the fea. If we would have {till clearer evidence, that no breaches made antecedently to the running of the rivers have opened a way for them, we need only look to the oppofite fide, or northern fhore, of the fame promontory, where we alfo find a feries of outlets, all originating in the ridges of the country, and becoming deeper as they ap- proach the fea, but altogether unconnect: d with the openings on the fouth fide ; and this could hardly have been the cafe, had they been the effects of previous concuffions, or of any pecu- liarity in the original ftruCture of the rocks. 331. In contemplating fuch coafts as thefe, When we go back to the time when the rivers ran upon a level as high as the higheft of the cliffs on the fea-fhore, we muft fuppofe, that the land then extended many miles farther into what is Aa now 370 ILLUSTRATIONS OF THE now occupied by the fea. When at Plymou for inftance, the Tamer and the Plym flowed the level of Mount Edgecombe or of Sta Heights, if the rivers ran with a moder declivity into the fea, the coat muft hi advanced many miles beyond its prefent li Thus the land, when higher, was alfo more | tended, and the limits of our ifland in that ; cient ftate, were doubtlefs very different fr thefe by which it is at prefent circumf bed. : If with the fame views we confider any ther of the bold coafts which the map of - world prefents us with, we fhall quickly rema that wherever a deep interfection of the fea made into the land, as on the weftern fhores our own ifland, or on thofe of Norway, a ri runs in at the head of it, and points out by wl means fuch inlets are formed, viz. by the uni powers of the fea and of the land, the waters the latter having opened the way by wh thofe of the former have penetrated fo far i the country. Ae 332. It is not meant affuredly to deny i irregularities of the fea-coaft, as it may hi originally exifted ; thefe irregularities no dot determined the initial operations of that we and decay, by which, in procefs of time, th were themfelves entirely effaced. The line c HUTTONIAN THEORY. 39% Ny, 3 our coafts may be compared to one of thofe ‘i. curves, which are fometimes treated of in the A higher geometry, where the ordinates are func- : tions, not only of their abfciffee, but alfo of the . Dr $ time elapfed fince a certain epocha. The form of i ; the curve at that epocha, or when the time began R = to flow, correfponds to the original form of the i Í fea-coaft, on its emerging from the ocean, and _ | before the powers of wafting and decay had be- ` gun to act upon it. To fpeak ftri@ly, the ori- | ginal figure, in both cafes, influences all the fub- À ; fequent; but the farther removed from it} in "VE point of time, the lefs is that influence; fo that, + * in phyfical queftions, and for the purpofe of fuch Mii approximations as fuit the imperfeGtion of our ‘en knowledge, the confideration of ihe original Nomi’ figure may be wholly left out. Note xvi. § 105. Remains of Decompofed Rocks. Ps 33. Tue plain of Crau was the Campus La- im i _pideus of the ancients; and, as mythology al- _ ways feeks to connect itfelf with the extraordi- y J Mary faéts in natural hiftory, it was faid to be es? y| the {pot where Hercules, fighting with the fons Aa2 of 3472 ILLUSTRATIONS OF THE of Neptune, and being in want of weapons, was fupplied from heaven by a fhower of ftones: hence it was called Campus Herculeus. This plain is on the eaft fide of the Rhone, between Salon and Arles: it is of a triangu- lar form, about twenty fquare leagues in ex. tent, and is covered almoft entirely with quart. zy gravel. ‘This immenfe collection of gra- vel has been fuppofed by fome to have been brought down by the Durance from the Alps of Dauphiny; by others it has been afcribed to the Rhone; and by many to the fea, as being a work too great for any river. The explanation mentioned above, 4 105, namely, that the loofe gravel on the plain arifes from the decompofition of a great ftratum of pudding- ftone, which is the bafis of the whole, is the — opinion of Sauffure, and is founded on his own obfervations *. 334. The theories that have been contrived for explaining the phenomena of the plain of Crau, afford an inftance of the neceflity of generaliz- ing our obfervations before we can explain a par- ticular appearance: in other words, they prove the * See Voyages aux Alpes, tom. iii. § 1592, et 1597: See alfo on this fabje@ a Memoir by Lamanon, Journal de Phyfique, tom. xxii. p. 477; and another by M. De Servieres, zbzd. p. 270. be h meat for any im, Mi above, 4 10, m pared on the plain xiki p ofa great ratono pi the babs of the wh! pre, aad is founded cal nf se that have been . 3 of the pat peeli # Ia! fore we can ep : a” wots „jp 0 l HUTTONIAN THEORY. 373 the truth of Lord Bacon’s maxim, That the ex- planation of a phenomenon fhould not be fought for from the ftudy of that phenomenon alone, but from the comparifon of it with others. One of the theories of this plain is, that the breccia, which’ is the bafe of it, is formed from the con- folidation of the loofe gravel of the plain, by water percolating through it, and carrying fome cementing fubftance along with it, or fome Za- pidific juice, as it is called. And indeed, whe- ther the gravel is formed from the breccia, or the breccia from the gravel, is a queftion which probably could never be refolved by the mere examination of the plain itfelf. But the que- ftion is very foon decided, when we compare what is obferved here with other appearances in the natural hiftory of the earth’s furface, and confider how much more frequent the decom- pofition of folids is, than their reconfolidation, in any place above the level of the fea. 335. The argument for the decompofition of ftony fubftances which is afforded by the ftate of this fingular plain, may be confirmed by the ap- pearances obferved in many extenfive traéts of land all over the world, and efpecially in fome parts of Great Britain. The road to Exeter from Taunton Dean, between the latter and Honiton, paffes over a large heath or down, confiderably elevated above the plain of Taunton. The rock > which 374. ILLUSTRATIONS OF THE which is the bafe of this heath, as far as can be difcovered, is limeftone, and over the furface of it large flints, in the form of gravel, are very thickly fpread. There is no higher ground in the neighbourhood from which this gravel can be fuppofed to have come, nor any ftream that can have carried it, fo that no explanation of it remains, but that it is formed of the flints contained in beds of limeftone, which are now worn away. ‘The flints on the heath are pre- cifely of the kind found in limeftone; ma- ny of them are not much worn, and cannot have travelled far from the rock in which they were originally contained. It feems cer- tain, therefore, that they are the debris of lime- ftone ftrata, now entirely decompofed, that once lay above the ftrata which at prefent form the bafe of this elevated plain, and proba- bly covered them to a confiderable height. This explanation carries the greater probability with it, that any other way of accounting for the fac in queftion, as the travelling of the gra- vel from higher grounds, or the immerfion of the furface under the fea, will imply changes in the face of the country, incomparably greater than are here fuppofed. Our hypothefis feems to give the minimum of all the kinds of change that can pofiibly account for the phenomenon. 330. The HUTTONIAN THEORY. 375 TA d © 336. The fame remarks may be made on the f° high plain of Blackdown, which the road paffes hy, _ over in going from Exeter to the weftward. The thy.’ flints there are diffeminated over the furface as ? À thickly as in the other inftance, and can be ex- an 4 plained only on the fame fuppofition. , 4 — Again, in the interior of England, beginning MAU from about Worcelter and Birmingham, and iy _ proceeding north-eaft through Warwickhhire, AN a ] Leicefterfhire, Nottinghamfhire, as far as the Miglin fouth of Yorkthire, a particular {pecies of high- ly ly indurated gravel, formed of granulated quartz, is found every where in great abun- | dance. This fame gravel extends to the weft nf 3 and north-weft, as far as Afhburn im Der- “iy. bythire, and perhaps {till farther to the north. »| The quantity of it about Birmingham is very yj. Temarkable, as well as in many other pla- wy fes; and the phenomenon is the more fur- < a prifing, that no rock of the fame fort is. feen in 14, its native place. It is fuch gravel as might be | i expected in a mountainous country, in Scotland, A] for inftance, or in Switzerland, but not at all in m® the fertile and fecondary plains of England. "| This enigma is explained, however, when it ‘| is obferved, that the bafis of the whole tra@ juft defcribed is a red fandftone, often contain- ing in it a hard quartzy gravel, perfe@ly fimilar to that which has juft been mentioned. From i Aag the 370 ILLUSTRATIONS OF THE the diffolution of beds.of this fandftone, which - formerly covered the prefent, there can be no doubt that this gravel is derived. But, as the gravel is in general thinly difperfed through the fandftone, and abounds only in fome of its layers, it fhould therefore feem, that a vaft bo. dy of {trata muft have been worn away and de- compoted, before fuch quantities of gravel as now exift in the foil could have been let loofe, 337. I have faid, that a rock capable of afford: ing fuch gravel as this, is not to be found in the tract of country juft mentioned. This, however, is not ftri@ly true; for in Worcefterthire, be- tween Bromefgrove and Birmingham, about feven miles from the latter, a rock is found confifting of indurated ftrata, greatly eleva- ted, and without doubt primitive, from the detritus of which fuch gravel as we are now {peaking of might be produced. Thefe ftrata feem to rife up from under the fecondary, where they are: interfected by the road; and, for as much as appears, are not of great thicknefs, fo that they cannot have afforded the materials of this gravel dire@ly, though they may have donë fo indirectly, or through the medium of the red fandftone ; that is to fay, a primary rock of which they are the remains, may have afforded materials for the gravel in the .andftone ; and this fandftone may in its turn have afforded the ma- terials HUTTONIAN THEORY. 377 l 4 4 terials of the prefent foil, and particularly the ) gravel contained in it. 338. Pudding-ftones being very liable to de- compofition, have probably, in moft countries, af afforded a large proportion of the loofe gra- yel now found in the foil. The mountains, or at leaft hills, of this rock, which are found in many places, prove the great extent of fuch de- compofition. Mount Rigi, for inftance, on the fide of the Lake of Lucerne, is entirely of pud- ding-ftone, and is 742 toifes in height, meafured — i from the level of the lake. By the defcriptions _ it given of it, as well as of other hills of the fame kind in Switzerland, we may, without due at- ‘Mk ; tention, be led to fuppofe that they are entirely 1 formed of loofe gravel. Even M. Sauflure’s de~- | feription is chargeable with this fault, though, when attended to, it will be found to contain a fufficient proof, that this hill is compofed of real pudding-ftone*. The nature of the thing ‘i i alfo, would be fufficient to convince us, that a hill, more than 4000 feet in height, could not - eonfift of loofe and unconfolidated materials. “If, then, we regard Mount Rigi as the re- ains of a body of pudding-ftone firata, we mutt conclude, that thefe {trata were originally more extenfive, and the adjacent valleys and plains will ; ferve, * Voyages aux Alpes, tom, iv. § 1941s 378 ILLUSTRATIONS OF THE ferve, in fome degree, to meafure the quantity of them which time has deftroyed. 339. If the theory of unftratified mountains, namely thofe of whinftone, porphyry, and gra. nite, be admitted as laid down above, it will furnifh a meafure of the deftru€tion which has taken place in the ftratified rocks, and of the vaft depredations which have been made upon them fince they were raifed up from the bottom of the fea. - Like every other meafure, however, of wafting, by a thing that is itfelf fubje@ to wate, it. can only give a minimum, or a limit which the quantity wafted muft neceflarily ex- ceed. The abrupt face of a whinftone rock muft be underftood as an evidence, that fome body of ftrata which fupported it when fluid, remain- ed in contact with it, when it was become fo- lid; and if this part of the mould in which the whinftone was caft, has difappeared, it muft generally be afcribed to the operation of wafte and decompofition. Such a face, for inftance, as that which Salifbury Craig pre- fents tothe weft, viz. a perpendicular wall ef whin- ftone, about ninety feet high, raifed on a body of fandftone ftrata of the height of about 300 feet, can have been produced only by having been abut- ted againft fome ftratified rock, equally abrupt, and ~HUTTONIAN THEORY. 379 and of the fame elevation with itfelf. Of this rock no part remains. : The bafaltic rock of Edinburgh Caftle is near- ly in the fame ftate. Its perpendicular fides on the fouth, weft, and north, are now difengaged from the ftrata by which they were once en- compafied. 340. The granite mountains alfo, where they are quite unftratified, give rife to the fame con- clufion. Thofe central chains which we find in fo many inftances towering above the {chiftus which cover their fides, have probably been once completely enveloped by the latter , and, on this fuppofition, an eftimate may fometimes be formed of the original height of fuch mountains. _ In thefe eftimations, however, fome uncer- tainty muft arife, from our being unable to di- ftinguifh between the effects which are to be aferibed to the fracture and diflocation that took place when the compound body of ftrati- fied and unftratified rocks was raifed up from the bottom of the fea, and the effects produced by the fubfequent wafte and decompofition at the furface.- In this, as in many other inftances, we are not always able to feparate between the original inequalities of the furface, and thofe which wearing has produced. 341. It would be important to afcertain the rate _. atwhichthe elevation of mountains decreafes, and this 386 ILLUSTRATIONS OF THE this is what we may perhaps expect to be aga complithed, by the progrefs of geological {cience, and the multiplying of accurate obfervations, It has been fuppofed, that the Pyrenees dimi. nifh about ten inches ina century ; but what confidence is to be put in this eftimate, I am unable to determine *, A very unequivocal mark of the degradation of mountains is often to be met with in the heaps of loofe ftones found on their tops. Thefe ftones, it is obvious, cannot have come from any other place by natural means, and they are ac- cordingly always fharp and angular, and have none of the charaéters of tranfported rocks; They are faid fometimes to have been brought by men’s hands ; but this is highly improbable, their quantity is often fo confiderable, and the dif. ficulty of tranfportation fo great. Where any pur- pofe was to be ferved by heaping them together, men have availed themfelves of the ftones that they found ready prepared on the fummit, and have conftru@ted from them cairns, which have ferved as fignals, ufeful in their paftoral, and fometimes in their military occupations. Note * Effai fur le Mineralogie des Pyrenées, p. 87. -HUTTONIAN THEORY. Nore XVIIL § 112. Tranfportation of Stones, Se. 342. Nature fupplies the means of tracing with confiderable certainty the migration of fof- fil bodies on the furface of the earth, as only the more indurated ftones, and thofe moft ftrongly characterifed, can endure the accidents that muft befal them in travelling to a diftance from their native place. | wl -Itis a fa@ very generally obferved, that where the valleys among primitive mountains open into large plains, the gravel of thofe plains confifts of ftones, evidently derived from the mountains. The nearer that any fpot is to the mountains, the larger are the gravel ftones, and the lefs rounded is their figure ; and, as the di- ftance increafes, this gravel, which often forms a ftratum nearly level, is covered with a thick- er bed of earth or vegetable foil. This pro- greffion has particularly been obferved in the valleys of Piedmont and the plains of Lombardy, where a bed of gravel forms the bafis of the foil, from the foot of the Alps to the fhores of the Hadriatic, 382 ILLUSTRATIONS OF THE Hadriatic *. We may colleé& from GUETTARD, that a fimilar gradation is found in the gravel and earth which cover the great plain of Poland, from Mount Krapack to the Baltic +. The rea. fon of this gradation is evident ; the farther the ftones have travelled, and the more rubbing they have endured, the fmaller they grow, the more regular is the figure they affume, and the greater the quantity of that finer detritus which conititutes the foil. The wathing of the rains and rivers is here obvious; and each of the three quantities jat mentioned, if not diredtly proportional to the diftance which the ftones have migrated from their native place, may be faid, in the language of geometry, to be at leaft proportional to a certain function of that diftance, 343. The immenfe quantity of cailloux roulés, or rounded gravel, collected in the immediate vi- cinity of mountainous tracts, has led fome geo- logifts to fuppofe the exiftence of ancient cur- rents, which defcended from the mountains, in a quantity, and with a momentum, of which there is no example in the prefent. ftate of the world. Thus Sauffure imagines, that the hill of Su- pergue, near Turin, which is formed of gravel, can only be explained by fuppofing fuch cur- rents * Voyages aux Alpes, tom. iii. § 1315. + Mém. Acad. des Sciences, 1762, p. 234; 293, &c- HUTTONIAN THEORY. 383 yents as are juft mentioned, or what he terms a debacle, to have taken place at fome former pe- riod *. If, however, we afcribe to the moun- tains a magnitude and elevation vaftly greater than that which they now poffefs ; if we regard the vallies between them as cut out by the ri- yers and torrents from an immenfe rampart of folid rock, neither materials fufficiently great, nor agents fufficiently powerful, will appear to I be wanting, for collecting bodies of gravel and other loofe materials, equal to any that are found onthe furface of the earth. The necefflity of W introducing a debacle, or any other unknown agent, to account for the tran{portation of foffils, feems to arife from under-rating the effects of of that dit _ action long continued, and not limited by fuch j fhort periods as circumfcribe the works, and f even the obfervations, of men. 344. The fupply of gravel and cailloux roulés, for the plains extended at the feet of primitive mountains, is doubtlefs in many cafes much in- creafed by the pudding-ftone, interpofed between the fecondary and the primary ftrata. The beds of pudding-ftone contain gravel already formed on the fhores of continents, that ceafed to exift before. the prefent were produced; and the cement of this D ¥ Voyages aux Alpes, tom, iii. § 1303. 384 ILLUSTRATIONS OF THE this gravel, yielding eafily to the weather, al, lows the ftones included in it to be wafhed down by the torrents, and fcattered over the plains, I know not if the hill of Supergue, above men. tioned, is not in reality a mafs of the pudding. ftone which forms the border of the Alps, and of which the materials have fuffered no tranf. portation fince the time of their laft confolida. tion. This at leaft is certain, that Sauffure, not. withftanding his accuracy, has fometimes con- founded the loofe gravel on the furface with that which is confolidated into rock ; an inace curacy which is to be charged, as I have elfe. where obierved, rather againft his fyftem than himfelf. 345. The loofe ftones found on the fides of hills, and the bottoms of valleys, when tra- ced back to their original place, point out with demonftrative evidence the great chan- ges which have happened fince the com- mencement of their journey; and in particular ferve to fhow, that many valleys which now deeply interfect the furface, had not begun to be cut out when thefe ftones were firft detached from their native rocks. We know, for inftance, that ftones under the influence of fuch forces as we are now confidering, cannot have firft de- {cended from one ridge, and then afcended on . the fide of an oppofite ridge. But the me ol HUTTONIAN THEORY. 385 of Mont Blanc has been found, as mentioned above, on the fides of Jura, and even on the fide of it fartheft from the Alps. Now, in the pre- fent ftate of the earth’s furface, between the central chain of the Alps, from which thefe pieces of granite muft have come, and the ridge _ of Mont Jura, befides many fmaller valleys, there is the great valley of the Rhone, from the bot- tom of which, to the place where they now lie, isa height of not lefs than 3000 feet. Stones F could not, by any force that we know of, be U made to afcend over this height. We mut _ therefore fuppofe, that when they travelled from Mont Blanc to Jura, this deep valley did not = f exif, but that fuch a uniform declivity, as water i) can run on with rapidity, extended from the ff one fummit to the other. This fuppofition ac- _ cords well with what has been already faid con- i) © cerning the recent formation of the Leman Lake, @ and of the prefent valley of the Rhone. i 346. We can derive, in a matter of this fort, but little aid from calculation; yet we may Tai - difcover by it, whether our hypothefis tranf- À ull greffes materially againft the laws of probabi- ag) lty, and is inconfiftent with phyfical principles d already eftablifhed. The horizontal diftance f _ from Mont Jura to the granite mountains, at the f head of the Arve, may be accounted fifty geo- bb graphic 386 ILLUSTRATIONS OF THE | graphic miles. Though we fuppofe Mont Blane, and the ref of thofe mountains, to have been ori- ginally much higher than they are at prefent, the ridge of Jura muft have been fo likewHfe; and though probably not by an equal quantity, yet it is the fairefk way to fuppofe the difference of their height to have been nearly the fame in for- mer ages that it is at prefent, and it may there- fore be taken at 10,000 feet. The declivity of a plane from the top of Mont Jura to the top of Mont Blanc, would therefore be about one mile and three quarters in fifty, or one foot in thirty; an inclination much greater than is neceffary for water to run on, even with extreme rapidity, and more than fufficient to enable a river ora torrent to carry with it ftones or fragments of rock, almoft to any diftance. Sauffure, in relating the fa& that pieces of granite are found among the high paffes near the fummits of Mont Jura, alleges, that they are only found in fpots from which the central chain of the Alps may be feen. But it fhould feem that this coincidence is accidental, be- caufe, from whatever caufe the tranfportation of thefe blocks has proceeded, the form of the mountains, efpecially of Mont Jura, muft be too much changed to admit of the fuppofition, that the places of it from which Mont Blanc is now vifible, HUTTONIAN THEORY. 387 vifible, are the fame from which that mountain was vifible when thefe ftones were tran{ported hi- ther. It may be, however, that the paffes which now exift in Mont Jura are the remains of val- leys or beds of torrents, which once flowed weft- ward from the Alps; and itis atural, that the fragments from the latt r m untains fhou d be found in the neighbourhood of thofe ancient water-tracks. : 347. Sauffure obferved in another part of the Alps, that where the Drance defcends from the fides of Mont Velan and the Great St Bernard, to join the Rhone in the Vallais, the valley it runs in lies between mountains of pri- mary {chiftus, in which no granite appears, and yet that the bottom of this valley, toward its lower extremity, is for a confiderable way co- vered with loofe blocks of granite *. His fa- miliar acquaintance with all the rocks of thofe mountains, led him immediately to fulpect, that thefe ftones came from the granite chain of Mont Blanc, which is weftward of the Drance, and confiderably higher than the intervening mountains. ‘his conjecture was verified by the obfervations of one of his friends, who found the ftones in queftion to agree exactly with a Bb2 rock iaa * Voyages aux Alpes, tom. il. § 1042. 388 ILLUSTRATIONS OF THE rock at the point of Ornex, the neareft part of the granite chain. In the prefent ftate of the furface, however, the valley of Orfiere lies between the rocks of Ornex and the valley of the Drance, and would certainly have intercepted the granite blocks in their way from the one of thefe points to the other, if it had exifted at the time when they were pafling over that tra. The valley of Or- fiere, therefore, was not formed, when the tor- rents, or the glaciers tranfported thefe fragments from their native place. Mountainous countries, when carefully ex- amined, afford fo many fats fimilar to the pre- ceding, that we fhould never have done were we to enumerate all the inftances in which they occur. ‘They lead to conclufions of great ufe, if we would compare the machinery which na- ture actually employs in the tranfportation of rocks, with the largeft fragments of rock which appear to have been removed, ‘at fome former period, from their native place. 348: For the moving of large maffes of rock, the moft powerful engines without doubt which nature employs are the glaciers, thofe lakes or — rivers of ice which are formed in the higheft valleys of the Alps, and other mountains of the firft order. Thefe great maffes are in perpetual motion, wt, : HUTTONIAN THEORY, 369 the lug 3 = motion, undermined by the influx of heat from i bety t, hn, the earth, and impelled down the declivities on ia teng _ which they reft by their own enormous weight, s S together with that of the innumerable fragments of rae of rock with which they are loaded. I hefe ak ty fragments they gradually tran{port to their ut- * tea moft boundaries, where a formidable wall alcer- e valey tains the magnitude, and attefts the Ore; of the great engine by which it waserected. ‘The im- ported thet fy menfe quantity and fize of the rocks thus tranf- w ported, have been remarked with aftonifhment by every obferver *, and explain fufficiently how fragments of rock may be put in motion, even where there is but little declivity, and where the actual furface of the ground is confiderably un- even. In this manner, before the valleys were cut out in the form they noware, and when the moun- tains were {till more elevated, huge fragments of rock may have been carried toa great diftance; and it is not wonderful, if thefe fame maffes, greatly diminifhed in fize, and reduced to gravel or fand, have reached the fhores, or even the bottom, of the ocean. 349. Next in force to the glaciers, the torrents are the moft powerful inftruments employed in Bb 3 the * The ftones collected on the Glacter de Miage, when Sauflure vifited it, were in fuch quantity as to conceal the ice entirely. Voyages aux Alpes, tom. ii, § 554. 390 ILLUSTRATIONS OF THE the tranfportation of ftones. Thefe, when they defcend from the fides of mountains, and even where the declivity of their courfe is not very great, produce effes which nothing but dire@ experience could render credible. The frag- ments of rock which oppofe the torrent, are ren- dered fpecifically lighter by the fluid in which they are immerfed, and lofe by that means at leaft a third part of their weight: they are, at the fame time, impelled by a force proportional to the fquare of the velocity with which the water rufhes againft them, and proportional alfo to the quantity of gravel and ftones which it has already put in motion. Perhaps, after ta- king all thefe circumftances into computation, in the midft of a fcene perfe@ly quiet and undi- fturbed, a philofopher might remain in doubt as to the power of torrents to move the enormous bodies of rock which are feen in the bottom of the narrow valleys or deep glens of a mountain- ous country ; but his incredulity, fays an expe- rienced traveller, will ceafe altogether, if he has been furprifed by a ftorm in the midft of fome Alpine region; if he has feen the number and impetuofity of the cataracts which rufhed down the fides of the mountains, and beheld the ruin which accompanied them ; and if, when the tem- peft was paffed, he has viewed thofe meadows, which HUTTONIAN THEORY. 391 which a few hours before were covered with verdure, now buried under heaps of ftones, or overwhelmed by maffes of liquid mud, and the fides of the mountains cut by deep ravines, where the track of the fmalleft rivulet was not before to be difcovered *. It is but rarely, however, even on occafions like thefe, that fuch vaft maffes of rock can be feen actually in motion, as are often found on the furface, apparently removed to a great di- ftance from their native place. The magnitude of thefe is fo great, in many inftances, that their tran{portation cannot be explained without fup- pofing, that the furface was very different when thefe tranfportations took place from what it is at prefent ; that the elevation of the mountains was greater, and the ground {moother and more uniform, at leaft in fome directions. If thefe fuppofitions are admitted, and they are counte- nanced, as we have already feen, by almoft every phenomenon in geology, the difficulties which prefent themfelves here will not appear infur- mountable. | 350. One of the largeft blocks of granite that we know of, is on the eaft fide of the lake of Bb4 Geneva, * See an account of a thunder ftorm near Bareges, in the Effai fur la Mineralogie des Pyrenées, p. 134. 392 ILLUSTRATIONS OF THE Geneva, called Pierre de Gouté, about ten feet in height, with a horizontal feétion of fifteen by twenty *. Another block not far from it, and nearly of the fame fize, has fome remains of {chiftus attached to it. Thefe ftones very much refemble thofe which have fallen from the Aiguilles, in the valley of Chamouny. The di- ftance from their prefent fituation to thofe 4i- guilles is about thirty Englith miles, with many mountains and valleys at prefent interpofed. By whatever means, therefore, thefe blocks were tran{ported, their motion muft have been over a furface of much more uniform declivity than the prefent. If the furface was without great ine- qualities, and its general declivity about one foot in thirty, as already computed, the gla- ciers, in the firft place, and the torrents after- wards, may have ferved for the tranfportation even of thefe rocks. | 351. Again, in the narrow vale or glen which feparates the Great from the Little Saleve, the ftra- ta are all calcareous, but a great number of loofe blocks of granite and primary {chiftus are {catter- ed over the furface. A block of the former, near the lower end of the valley, is about the fize of 1200 cubic feet. Two other large blocks of the fame kind of ftone reft on a bafe of horizontal limeftone, /* Voyages aux Alpes, tom. i. § 308. HUTTONIAN THEORY. 303 limeftone, elevated two or three feet above the ret of the furface. This elevation arifes no doubt from the protection which the ftones have afforded to the calcareous beds on which they lie, fo that thefe beds do not wear away fo faft as thofe which are fully expofed to the weather. But it is furely to take a very limited view of the operations on the furface, to fup- pofe, with Saufflure, that the parts of the cal- careous rock under thefe ftones has fuffered no wafte whatfoever, fo that the ftones remain now in the identical fpot where they were pla- ced by the great debacle which brought them down from the high Alps *. For my part, I have no doubt that the Arve, which is ftill at no great = diftance, when it ran on a higher level, and in _ a line different from the prefent, aided by the i) glaciers and fuperior elevation of the mountains, was an engine fufficiently powerful for effe&ing the tranfportation of thefe ftones. 352. Thefe phenomena are not peculiar to the Alps, but prevail, in a greater or lefs degree, in the vicinity of all primary or granite mountains. In the ifland of Arran, a fragment of the fame kind with that which conftitutes the upper part of Goatfield, is found on the fea-fhore, at leaft three miles from the neareft granite rock, and with Mee * Ibid. § 227. 394 ILLUSTRATIONS OF THE with a bay of the fea intervening. Its dimen: fions are not far from thofe of the pierre de gouté. In fome former ftate of the granitic mountains in that ifland, the declivity from the top of Goatfield may have been very uniform, and more rapid than it is at prefent. 333. Befides glaciers and torrents, which have no doubt been the principal inftruments in produ- cing thefe changes, other caufes may have oc- cafionally operated. Large ftones, when once detached, and refting on an inclined plane, from the effects of wafte and decompofition, may ad- vance horizontally, at the fame time that they defcend perpendicularly, and this will happen though they be not urged by any torrent, or any thing but their own weight ; for the furface of the ground, as it waftes, remains higher un- der the ftone, and for a little way round it, than at a greater diftance, on account of the protection which it receives from the ftone, as in the inftances at Saleve, juft mention- ed. The ftone itfelf alfo becomes rounded at the bottom; and thus the furface in contact with the ground is diminifhed in extent, and the two furfaces rendered convex towards one another. It muft therefore happen, that the fupport, continually weakening, will at length give way, and the ftone incline or roll toward the lower fide, and may even roll con- fiderably, pk er HUTTONIAN THEORY. 395 fiderably, if its centre of gravity has been high above its point of fupport, and if its furface has had much convexity: Thus the horizontal may very far exceed the perpendicular motion; and, in the courfe of ages, the ftone may travel to a great diftance. A ftone, however, which tra- yels in this manner, muit diminifh as it pro- ceeds, and muft have been much greater in the beginning than it is at prefent. 354. This kind of motion may be aided by particular circumftances. W hen a ftone refts on an inclined plane, fo as to be in a ftate not very remote from equilibrium, if a part be taken away from the upper fide, the equilibrium will be loft, and the ftone will thereby be put in mo- tion. That ftones which lie on other ftones, may, by wearing, be brought very near an equi- librium, is proved by what are called rocking- flones, or in Cornwall Logan /tones, which have fometimes been miftaken for works of art; but that are certainly nothing elfe than ftones, which have been fubjected to the univerfal law of wafting and decay, in fuch peculiar circum- = ftances, as nearly to bring about an equilibrium _ Of that ftable kind, which, when flightly difturb- ed, re-eftablifhes itfelf*. The logan ftone at the * I do not prefume fo far as to fay, that all rocking. ftones are produced by natural means: I have not fufli- cient 396 ILLUSTRATIONS OF THE the Land’s End, is a mafs of granite, weighing more than fixty tons, refting on a rock of gra. nite, of confiderable height, and clofe on the fea-fhore. The two {tones touch but in a fmall fpot, their furfaces being confiderably convex towards one another. The uppermott is fo near- ly in an equilibrium, that it can be made to vi. brate by the ftrength of a man, though to over. fet it entirely would require a valt force. This arifes from the centre of gravity of the ftone being fomewhat lower than the centre of cur- vature of that part of it on which it has a ten- dency to roll; the confequence of which is, that any motion impreffed on the ftone, forces its centre of gravity to rife, (though not very con- fiderably), by which means it returns whenever | the force is removed, and vibrates backward and forward, till it is reduced to reft. Were it re- quired to remove the ftone from its place, it might cient information to juftify that affertion ; but the great fize of that at the Land’s End, its elevated pofition, and the approaches toward fomething of the fame kind which are to be feen in other parts of that fhore, prove that it is no work of art. They who afcribe it to the Druids, do not confider the rapidity with which the Cornifh granite waftes, nor think how improbable it is, that the conditions neceflary to a rocking-ftone, whether produced by nature or art, fhould have remain- ed the fame for fixteen or feventeen hundred years. HUTTONIAN THEORY. 307 might be moft eafily done, by cutting off a part from one fide, or blowing it away by gun- powder ; the ftone would then lofe its balance, would tumble from its pedeftal, and might roll to a confiderable diftance. Now, what art is here f{uppofed to perform, nature herfelf in time will probably effet. If the wafte on one fide of this great mafs fhall exceed that on the op- pofite in more than a certain proportion, and it is not likely that that proportion will be always maintained, the equilibrium of the Logan ftone ` will be fubverted, never to return. Thus we perceive how motion may be produced by the combined action of the decompofition and gra~ vitation of large maffes of rock. 355. Befides the gradual wafte to which ftones expofed to the atmo/phere are neceflarily fubje&, thofe of a great fize appear to be liable to fplit- ting, and dividing into large portions, no doubt from their weight. This may be obferved in almoft all ftones that happen to be in fuch cir- cumftances as we are now confidering ; and from this caufe the fubverfion of their balance may be more fudden, and of greater amount, than could be expected from their gradual decay. Thus, if to the wafting of a {tone at the bot- tom, we add the accidents that may befal it in the wafting of its fides, we fee at leaft the phy- fical poffibility of detached ftones being put in motion, 398 ILLUSTRATIONS OF THE motion, merely by their own weight. It is in, deed remarkable, that fome of the largeft of thefe ftones reft on very narrow bafes. Thofe at the foot of Saleve touch the ground only in a few points: The Boulder-ftone of Borrowdale is fupported on a narrow ridge like the keel of a fhip, and is prevented from tumbling by a ftone or two, that ferve as a kind of fhores to prop it up. Very unexpected accidents fometimes hap- pen to difturb the reft of fuch fragments of rock as have once migrated from their own place. Sauflure mentions a great mafs of Zapis gllaris *, that lies detached on the fide of a de- clivity in the valley of Urferen, in the canton of Uri. The people ufe this ftone as a quarry, and - are working it away on the upper fide, in confequence of which it will probably be foon overfet, and will roll to the bottom of the val- ley. 356. In many inftances it cannot be doubted, that ftones of the kind here referred to are the remains of maffes or veins of whinftone or granite, now worn away, and that they have travelled but a very fhort way, or perhaps not at all, from their original place. Many of the large blocks of whinftone which we find in this country, fometimes fingle, and fometimes fcat- tered ee al * Voyages aux Alpes, tom, iv. § 1851. HUTTONIAN THEORY. 399 tered in confiderable abundance over a particu- lar fpot, are certainly to be referred to this caufe. But the moft remarkable examples of this fort are the ftones found at the Cape of Good Hope, on the hill called Paarlberg, which takes its name from a chain of large round ftones, like the pearls of a necklace, that paffes over the fummit. Two of thefe, placed near the higheft point, are called the Pearl and the Diamond, and were mentioned feveral years ago in the Phi- lofophical Tranfactions *. From a more recent account, thefe ftones appear to be a fpecies of granite, though the hill on which they lie is compofed of fandftone ftrata}. The Pearl isa naked rock, that rifes to the height of 400 feet above the fummit of the hill; the Diamond is higher, but its bafe is lefs, and it is more inac- ceffible. From the above ftones forming a regular chain, as well as from the immenfe fize. of the two largeft, it is impoflible to fuppofe that they have been moved ; and it is infinitely more pro- bable, that they are parts of a granite vein, which runs acrofs the fandftone ftrata, and of which fome parts have refitted the action of the weather, while the reft have yielded to it. The whole * Vol. Ixvill. p. 102. + Barrow’s Travels into Southern Africa, p. 60. 4oo ILLUSTRATIONS OF THE whole geological hiftory of this part of Africa feems highly interefting, fince, as far as can be collected from the accounts of the ingenious traveller juft mentioned, it confifts of horizontal beds of fandftone or limeftone, refting immediate- ly on granite, or on primary fchiftus. Loofe blocks of granite are feen in great abundance at the foot of the Table Mountain, and along the fea-fhore. ee ea 357. The fyflem which accounts for fuch phenomena as have been confidered in this and fome of the preceding notes, by the operation of a great deluge, or debacle as it is called, has been already mentioned. In Dr Hutton’s theo- ry, nothing whatever is afcribed to fuch acci- dental and unknown caufes; and, though their exiftence is not abfolutely denied, their effects, whatever they may have been, are alleged to be entirely obliterated, fo that they can be re- ferred to no other clafs but that of mere pofi- _ bilities. A minute difcuffion, however, of the queftion, Whether there are, on the furface of the earth, any effects that require the interpo- fition of an extraordinary caufe, would lead in- to a longer digreffion than is fuited to this place. I fhiall briefly fate what appear to be the prin- cipal In Dr Hotot alcribed to fc iff fes; and, thought y denied, ther ; been, ae alef HUTTONIAN THEORY. AOL cipal objections to all fuch explanations of the phenomena of geology. 358. The general ftructure of valve among mountains, is highly unfavourable to the notion that they were produced by any fingle great tor- rent, which {wept over the furface of the earth. In fome inflances, valleys diverge, as it were from a centre, in all directions. In others, they originate from a ridge, and proceed with equal depth and extent on both fides of it, plainly in- dicating, that the force which produced them was nothing, or evanefcent at the fummit of that ridge, and increafed on both fides, as the diftance from the ridge increafed. The work- ing of water collected from the rains and the fnows, and feeking its way from a higher to a lower level, is the only caufe we know of, which is fubje& to this law. 359. Again, if we confider a valley as a fpace, which perhaps with many windings and irre- gularities, has been hollowed out of the folid rock, it is plain, that no force of water, fud- ‘denly applied, could loofen and remove the great mafs of ftone which has actually difap- peared. The greateft column of water that could be brought to act againft fuch a mals, whatever be the velocity we aferibe to it, could not break afunder and difplace beds of rock Many leagues in length, and in continuity with Ce the 402 ILLUSTRATIONS OF THE the rock on either fide of them. The flow work. ing of water, on the other hand, or the powers that we fee every day in aćłion, are quite fuff- cient for this effect, if time only is allowed them. 360. Some valleys are fo particularly con- ftructed, as to carry with them a ftill ftronger refutation of the exiftence of a debacle. Thefe are the longitudinal valleys, which have the openings by which the water is difcharged, not at one extremity, but at the broadfide, Such is that on the eaft fide of Mont Blanc, deeply excavated on the confines of the granite and {chiftus rock, and extending parallel to the beds of the latter, from the Col de la Segne to the Col de Ferret ; its opening is nearly in the middle, from which the Dorea iffues, and takes its courfe through a great valley, nearly at right angles to the chain of the Alps, and to the valley jut mentioned. From the ftruéture of thefe valleys, Sauffure has argued very juftly againft Buffon’s hypothefis, concerning the for- ‘mation of valleys by currents at the bottom of the fea*. It affords indeed a complete refutation of that hypothefis ; and it affords one no lefs com- plete of the fyftem which Sauffure himfelf feems on fome occafions fo much inclined to fupport. For if it be faid; that this valley was cut out by the current * Voyages aux Alpes, tom. il. § 920. Eo HUTTONIAN THEORY. 403 eurrent of a debacle, that current muft either have run in the direction of the valley of Ferret, orin that of the Dorea, which iffues from it. Ifit had the direction of the firft, it could not cut out the fecond ; and if it had the diretion of the fe- cond, it could not cut out the firft. Befides, the force which excavated this valley muft have been nothing at the two extreme points, viz. at the Col de Segne and the Col de Ferret, and muft have increafed with the diftance from each. It can have been produced, therefore, only by the run- ning of two ftreams in oppofite directions, on a furface that was but flightly uneven, thefe "| ftreams at meeting taking a new dire@ion, near- ly at right angles to the former. A clearer ) proof could hardly be required than is afforded # inthis cafe, that what is now a deep valley was "formerly folid rock, which the running of the } waters has. gradually worn away; and that p | the waters, when they began to run, were on ) alevelas high, at leaft, as the tops of thofe moun- _ tains by which the valley is bounded toward the lower fide. 361. Longitudinal valleys, with the water burfting out tranfverfely from their fides, like the preceding, are by no means confined to moun- tains of the firft order. We have a very good example, though on a fmall fcale, of a val- ley of this fort, within a few’miles of Edin- Cc2 burgh, 404 ILLUSTRATIONS OF THE burgh. The Pentland Hills form a double ridge, feparated by a {mall longitudinal valley, that runs from N. E. to S. W., the water of which iffues from an opening almoft in the middle, and directed towards the fouth. This, there- fore, is not the work of any great torrent, which overwhelmed the country; for no one direc. tion, which it is poflible to afflign to fuch a tor- rent, will afford an explanation, both of the valley and its outlet *. | | 362. They * In Scotland there is one valley, of a kind that I be- lieve is extremely rare in any part of the world, in ac- counting for which, the hypothefis of a torrent or debacle might, if any where, be employed to advantage. This is the valley which extends acrofs the ifland, from Invernefs to Fort-William, or from fea to fea, being open at both ends, and very little elevated in the middle. It is nearly ftraight,andofa veryuniform breadth,except that towards each end it widens confiderably. The bottom, reckon- ` ing tranfverfely, is flat, without any gradual flope from the fides towards the middle. From the fides the moun- tains rife immediately, and form two continued ridges of great height, like ramparts or embankments on each fide of a large foflé. A great part of the bottom of this fingular valley is occupied by lakes, namely, Loch Nefs, Loch Oich, and Loch Lochy. Its length is about fixty-two miles, and the point of partition from which the waters run different ways, viz. north-eaft to the German aii = ee HUTTONIAN THEORY. 405 362. They who maintain the exiftence of the debacle, will no doubt allege, that though thele i Ces valleys German Ocean, and fouth-weft to the Atlantic, is be- tween Loch Oich and Loch Lochy; and, by the eftima- tion of the eye, I fhould hardly think that it is elevated more than ten or fifteen feet above the furface of either lake. The country on both fides is rugged and moun- tainous, and the ftreams which defcend from thence into the valley, either fall direétly into the lakes, or turn off almoft at right angles when they enter the val- ley. Though the bottom of this valley, therefore, is every where alluvial, with the exception, perhaps, of a few rocks which appear at the furface, it is certainly not excavated by the rivers which now flow init. The direction of the valley, it is to be obferved, is the fame with that of the vertical ftrata which compofe the moun- tains on either fide. Here, then, we have a valley, not cut out by the f working of any ftreams which now appear; and we may therefore make trial of the hypothefis of a de- bacle. This, however, will afford us no affiftance; be- caufe, if we fuppofe what is now hollow to have been once occupied by the fame kind of rock which is on either fide, no force of torrents can have fuddenly loofen- ed and removed from its place a body of fuch vaft mag- nitude. A greater column of water, than one having for its bafe a tranfverfe fection of the valley, could hot act againft it, and this would have to overcome the 406 ILLUSTRATIONS OF THE valleys were not cut out by means of it, yet others may. But it muft be recolleGed, that if fome the cohefion and inertia of a column of rock of the fame fection, and of the length of fixty-two miles, It is not hazarding much to affirm, that no velocity which could be communicated to water, not even that which it could acquire by falling from an infinite height, could give to it a force in any degree adequate to this great effect. The explanation of this valley, which appears to me the moft probable, is the following. It will be hewn hereafter, that there is good reafon to fuppofe, that, in moft parts of our ifland, the relative level of the fea and land has been in paft ages confiderably higher than it is at prefent. In fuch circumftances, this valley may have been under the, furface of the fea, the higheft part of it being fcarcely 100 feet above that level at prefent, It may have been a kind of found, therefore, or ftrait, which conneéed the German Sea with the Atlantic; and the ftrong currents, which, on account of the different times of high water in thefe two feas, muft have run al- ternately up and down this ftrait, may have produced that flatnefs of the bottom, and firaightnefs of the fides, and that widening at the extremities, which are men- tioned above. In this way, too, fome difficulties are re- moved relative to Loch Nefs, which is fo deep as hard- ly to be confiftent with the indefinite length of the period of wafte that mutt be afcribed to the mountains on each fide of it. Its depth is faid, where greateft, not te HUTTONIAN THEORY. 407 fome of the greateft and deepeft valleys on the face of the earth, fuch as that juft mentioned, on the eaft fide of Mont Blanc, are thus fhewn to be the work of the daily wafting of the fur- face, what other inequalities can be great enough to require the interpofition of a more powerful caufe? If a dignus vindice nodus does not exift here, in what part of the natural hiftory of the earth is it likely to be found? 363. The large maffes of rock fo often met with at a diftance from their original place, are one of the arguments ufed for the debacle. It has, how- ever, been fhewn, that, fuppofing a form of the earth’s furface confiderably different from the prefent, efpecially, fuppofing the abfence of the valleys which the rivers have gradually cut out, the tranfportation of fuch ftones is not impoffi- ble, even by fuch powers as nature employs at prefent. Now, without the fuppofition that the furface was more continuous, and that its pre- fent inequalities did not exift, no force of tor- rents, whatever their velocity and magnitude may have been, could have produced this tranf- portation. No force of water could raife a ftone like the pierre de goutté from the bottom of a Cc4 valley, to be lefs than 18c fathoms. According to this hypo- thefis, it may, at no very diftant period, have been a part of the bottom of the fea. 408 ILLUSTRATIONS OF THE valley, to the top of a fteep hill. Indeed, if we fuppofe a great fragment of rock to be hurried along on a horizontal or an inclined plane, by the force of water, the moment it comes to a deep valley, and has to rife up over an afcent of a certain fteepnefs, it will remain at reft ; the water itfelf will lofe its velocity, and the heavy bodies which it carried with it will pro- ceed no farther. Thus, therefore, we have the following dilemma. If the furface is not fup- pofed to have had a certain degree of uniformi- ty in paft times, a debacle is infufficient for the tran{portation of ftones : If it is fuppofed to have had that uniformity, a debacle is unneceflary. 364. Another faé&, which has been fuppofed favourable to the opinion of the action of great torrents at fome former period, is, that in coun- tries like that round Edinburgh, where whin- ftone hills rife up from among fecondary ftrata, a remarkable uniformity is obferved in the di- reion of their abrupt faces. ‘Thus, in the country juft mentioned, the fteep faces general- ly front the weft, while, in the oppofite direction, the flope is gentle, and the hills decline gradual- ly into the plain. Hence it is fuppofed, that a torrent, fweeping from weft to eaft, has carried off the ftrata from the weft fide of thefe hills, but, being obftruéted by the whinftone rock, has HUTTONIAN THEORY. 409 has left the ftrata on the eaft fide in their natu- ral place. But, befides that no force which can ever be 17 afcribed to a torrent could have removed at once bodies of ftrata 300 or 400 feet, nay even 869 or 1000 in thicknefs, which muft have been th. “tthe cafe if this were the true explanation of the fact, there is a circumftance which may perhaps enable us to explain thefe phenomena without the afliftance of any extraordinary caufe. - The fecondary ftrata in which the whinftone hills are found in this part of Scotland, are not hori- zontal, but rife or bead towards the weft, dip- ping towards the eaft. The fide, therefore, of i) the whinftone hills which is precipitous, is the - fame with that towards which the ftrata rife. imp Now, from the manner in which thefe hills are fuppofed to have been elevated, the {trata are te likely to have been moft broken and fhattered aie towards that fide, while, on the oppofite, they go) had the fupport of the whinftone rock. They a) would become a prey, therefore, more eafily to the common caufes of erofion and wafte on the upper fide than onthe lower. The ftreams that flowed from the higher grounds would wear _ them on the former moft readily ; and the action of thefe ftreams would be refifted by the fupe- tior hardnefs of the whinftone, juft as the great torrent of the debacle is {uppofed to have been, It 410 ILLUSTRATIONS OF THE It fhould alfo be obferved, that this fa& of the uniform direCtion of the abrupt faces of mountains, is often too haftily generalized. In primitive countries, it is no farther obferved than by the fteep faces of the mountains being moft frequently turned toward the central chain. Ip Scotland, as foon as you leave the flat country, and enter the Highlands, the {carps of the hills face indifcriminately all the points of the com- pafs, and are directed as often to the eaft as to the weft. 365, Where the ftrata are nearly horizontal, they afford the moft diflin@ information concern- ing the direction and progrefs of the wafting of the land. The inclined pofition of the ftrata, which in all other cafes muft enter for fo much into our eftimate of the caufes which have produced the prefent inequality of the earth’s furface, dif- appears there entirely ; and the whole of that inequality is to be afcribed to the operations at the furface, whether they have been fudden or © gradual. A very important fact from a coun: try of this fort, is related by Barrow, in his Travels into Southern Africa, The moun- tains about the Cape of Good Hope, and as far to the north as that ingenious traveller profecu- ted his journey, are chiefly of horizontal ftrata of fandftone and limeftone, exhibiting the ap- pearance, on their abrupt fides, of regular layers of mafonry, of towers, fortifications, &c. Now, among HUTTONIAN THEORY. 41 among all thefe mountains, he obferved, that the high or fteep fides look conftantly down the rivers, while the floping or inclined fides have juft the oppofite dire@tion. When, in tra- yelling northward, he paffed the line of parti- tion, where the waters from running fouth take their direction to the north, he found, that the gradual flope, which had hitherto been turned to the north, was now turned to the fouth: The abrupt afpect of the mountains, in like manner, from facing the fouth, was directed to the north 5 fo that, in both cafes, the hills turned their backs on the line of greateft elevation *. It is evident, therefore, that the form of this land has been determined by the flow working of the ftreams. The caufes which produced the effets here defcribed, began their action from ‘the line of greateft elevation, and extended it from thence on both fides, in oppofite directions. This is the moft precife character that can mark the alluvial operations, and diftinguifh them from the overwhelming power of a great debacle. 306. Laftly, If there were any where a hill, or any large mafs compofed of broken and fhapelefs ftones, thrown together like rubbifh, and neither worked into gravel nor difpofed with any regu- larity, we muft afcribe it to fome other caufe than e * Barrow’s Travels into Southern Africa, p. 245. s P245 412 ILLUSTRATIONS OF THE than the ordinary detritus and wafting of the land. This, however, has never yet occurred ; and it feems beft to wait till the phenome- non is obferved, before we feek for the explana- tion of it. 367. Vhefe arguments appear to me conclufive again{t the neceflity of fuppofing ‘the a&tion of fudden and irregular caufes on the furface of the earth. In this, however, I am perhaps deceived : neither Pallas, nor Sauflure, nor Dolomieu, nor any other author who has efpoufed the hypothefis of {uch caufes, has explained his notions with any precifion ; on the contrary, they have all fpoken with fuch referve and myftery, as feemed to betray the weaknefs, but may have concealed the ftrength of their caufe. I have therefore been combating an enemy, that was in fome re- {pects unknown; and I may have fuppofed him diflodged, only becaufe I could not pene- trate to his ftrong-holds. The queftion, how- ever, is likely foon to affume a more determinate form. A zealous friend of Dr Hutton’s theory, has lately * declared his approbation of the hy- pothelis which has here been reprefented as fo adverfe to that theory; and, from his ability and vigour of refearch, it is likely to receive every improvement of which it is fufceptible. OTE * Tranf, Royal Society Edin. vol. v. p. 68. HUTTONIAN THEORY. 413 NOTE xix. § 117. Tranfportation of Materials by the Sea. 368. Tue exiftence of the great and exten- five operations, by which the {poils of the land are carried all over the ocean, and fpread out on the bottom of it, may be fuppofed to requiré {fome further elucidation. We muf attend, therefore, to the following circumftances. When the detritus of the land is delivered by the rivers into the fea, the heavieft parts are depofited firft, and the lighter are carried to a greater diftance from the fhore.. The accumu- lation of matter which would be made in this manner on the coaft, is prevented by the farther operation of the tides and currents, in confe- quence of which the fubftances depofited con- tinue to be worn away, and are gradually re- moved further from the land. The reality of this operation is certain ; for otherwife we fhould have on the fea-fhore a conftant and unlimited accumulation of fand and gravel, which, being perpetually brought down from the land, would continually increafe on the fhore, if nature did not employ fome machinery for removing the advanced. 414 ILLUSTRATIONS OF THE advanced part into the fea, in proportion to the fupply from behind. The conftant agitation of the waters, and the declivity of the bottom, are no doubt the caufes of this gradual and widely-extended depofition, A foft mafs of alluvial depofite, having its pores filled with water, and being fubje& to the vi- brations of a fuperincumbent fluid, will yield to the preffure of that fluid on the fide of the leaft refiftance, that is, on the fide toward the fea, and thus will be gradually extended more and more over the bottom. This will happen not only to the finer parts of the detritus, but even to the groffer, fuch as fand and gravel. For fuppofe that a body of gravel refts on a plane fomewhat inclined, at the fame time that it is covered with water to a confiderable depth, that water being fubje& not only to moderate re- ciprocations, but alfo to fuch violent agitation as we fee occafionally communicated to the wa- ters of the ocean; the gravel, being rendered lighter by its immerfion in the water, and on that account more moveable, will, when the un- dulations are confiderable, be alternately heaved up and let down again. Now, at each time that it is heaved up, however fmall the {pace may be, it muft be fomewhat accelerated in its de- {cent, and will hardly fettle on the fame point where it refted before. Thus it will gain a lit- tle HUTTONIAN THEORY. 415 tle ground at each undulation, and will flowly make its way towards the depths of the ocean, or to the loweft fituation it can reach. ‘This, as far as we may prefume to follow a progrefs which is not the fubject of immediate obfervation, is one of the great means by which loofe materials of every kind are tranfported to a great dift and fpread out in beds at the bottom of the ocean. 369. The lighter parts are more eafily carried to great diftances, being actually fufpended in the water, by which they are very gradually and flowly depofited. A remarkable proof of this is furnifhed from an obfervation made by Lord Mulgrave, in his voyage to the North Pole. In the latitude of 65° nearly, and about 250 miles diftant from the neareft land, which was the coaft of Norway, he founded with a line of 683 fathoms, or 4098 feet; and the lead, when it ftruck the ground, funk in a foft blue clay to the depth of 10 feet*, The tenuity and finenefs of the mud, which allowed the lead to fink fo deep into it, muft have refulted from a depofi- tion of the lighter kinds of earth, which being fufpended in the water, had been carried toa ance, great diftance, and were now without doubt forming * Phipps’s Voyage, p. 74, 141. 416 ILLUSTRATIONS OF THE forming a regular ftratum at the bottom of the fea, o< 370. The quantity of detritus brought down by the rivers, and diftributed in this manner over the bottom of the fea, is fo great, that feveral narrow feas have been thereby rendered fenfi- bly fhallower. The Baltic has been computed to decreafe in depth at the rate of forty inches in a hundred years. The Yellow Sea, which is a large gulf contained between the coaft of China and the peninfula of Corea, receives fo much mud from the great rivers that run into it, that it takes its colour, as well as its name, from that circum- fiance; and the European mariners, who have lately navigated it, obferved, that the mud was drawn up by the fhips, fo as to be vifible in their wake to a confiderable diftance *, Com- putations have been made of the time that it will require to fill up this gulf, and to with- draw it entirely from the dominion of the ocean: but the data are not fufficiently exact to afford any precife refult, and are no doubt particular- ly defective from this caufe, that much of the earth carried into the gulf. by the rivers, muĝ be carried out of it by the currents and tides, and the finer parts wafted probably to great di- flances * Staunton’s Account of the Embafly to China, vol. i P. 448. HUTTONIAN THEORY: 419 fiancés in the Pacific Ocean*. The mere at- tempt, however, towards fuch a computation, fhews how evident the progrefs of filling up is to every attentive obferver ; and, though it may not afcertain the meafure, it fufficiently declares the reality of the operations, by which the wafte of the prefent continents is made fubfervient to the formation of new land. - 371. Sand-banks, fuch as abound in the Ger- man Ocean, to whatever they owe their origin, are certainly modified, and their form determi- hed, by the tides and currents. Without the ope- ration of thefe laft, banks of loofe fand and mud could hardly preferve their form, and remain interfected by many narrow channels. The for- mation of the banks on the coaft of Holland, and even of the Dogger Bank itfelf, has been afcribed to the meeting of tides, by which a ftate of tranquillity is produced in the waters, and of confequence a more copious depofition of their mud. Even the great bank of Newfoundland feems to be determined in its extent by the action * Peroufe, in failing along the coaft of China, from Formofa to the ftrait between Corea and Japan, though generally fifty or fixty leagues from the land, had found. ings at the depth of forty-five fathoms, and fometimes at that of twenty-two. Atlas du Voyage de la Peroufe, No, 43. 418 ILLUSTRATIONS OF THE action of the gulf-ftream. In the North Sea, the current which fets out of the Baltic, has evi- dently determined the fhape of the fand-banks oppofite to the coaft of Norway, and produced a circular {weep in them, of which it is impofli- ble to miftake the caufe. In proof of the adion here afcribed to the waters of the fea, in tranfporting materials to an unlimited extent, we may add the well-known obfervation, that the ftones brought up by the lead from the bottom of the fea, are generally round and polifhed, hardly ever fharp and an- gular. This could never happen to ftones that were not fubje& to perpetual attrition. 372. Currents are no doubt the great agents in . diffufing the detritus of the land over the bottom of the fea. ‘Thefe have been long known to ex- ift; but it is only fince the later improvements in navigation, that they have been underftood to conftitute a fyftem of great permanence, regu- larity and extent, connected with the trade- winds, and ether circumftances in the natural hiftory of the globe. The gulf-ftream was ma- ny years fince obferved to tranfport the water, and the temperature of the tropical regions into the climates of the north; and we are indebted to the refearches of Major RENNEL, for the know- ledge ofa great fyftem of currents, of which it is only a part. That geographer, who is fo eminent for a aid as HUTTIONIAN THEORY. 419 for enriching the details of his:fcience with the moft interefting facts in hiftory or in phyfics, has fhewn, that along the eaftern coaft of Africa, from about the mouth of the Red Sea, a current fifty leagues in breadth fets continually towards the fouth-weft *. It doublesthe Cape of Good Hope, runs from thence north-weft, preferving on the whole the direction of the coatt, but reaching fo far into the ocean, that, about the parallel of St Helena, its breadth exceeds 1009 miles. From thence, as it approaches the line, its direction is more nearly eaft , and meeting in the parallel of 3° north, with a current which has come along the weftern coaft of Africa from the north, the two united ftretch acrofs the At- lantic, in a line fomewhat fouth of weft, and in a very wide and rapid ftream. This ftream meets the American land at Cape St Roque, where it is joined by another coming up along the eaftern fhore of that continent, and direét- ed towards the north. They proceed north- ward together till they enter the Gulf of Flo- rida, from which being as it were reflected, they form the Gulf-ftream, pafling along the coaft of North America, and ftretching acrofs the At- lantic to the Britifh Ifles. From thence the cur- rent turns to the fouth, and, proceeding down Dea. | the * Geography of Herodotus, p.672, 420 ILLUSTRATIONS OF THE the coaft of Spain and Africa, meets the ftream afcending from the fouth, as already defcribed, and thus continues in perpetual circulation, The velocity of thefe currents is not lefs remark- able than their extent. At the Cape of Good Hope, the rate is thirty nautical miles in twenty- four hours ; in fome places forty-five; and un- der the line feventy-feven. When the Gulf-ftream iffues from the Straits of Bahama, it runs at the rate of four miles an hour, and proceeds to the diftance of 1800 miles, before its velocity is re- duced to half that quantity. In the parallel of 38°, near 1000 miles from the above ftrait, the water of the ftream has been found ten degrees warmer than the air. 373. The courfe of the Gulf-ftream is fo fixed and regular, that nuts and plants from the Weft Indies are annually thrown afhore on the Weft- ern Iflands of Scotland. The maft of a man of war, burnt at Jamaica, was driven feveral months afterwards on the Hebrides *, after per- forming a voyage of more than 4000 miles, un- der the direction of a current, which, in the midft of the ocean, maintains its courfe as ftea- dily as a river does upon the land. The great fyftem of currents thus traced through the Atlantic, has no doubt phenomena correfponding :* Pennant’s Arctic Zoology, Introd. p. 70: rown ashore on tele among the foffils of another. ™ volutions of the globe, the economy of nature it" has been uniform, in this refpe&, as well as in f fomany others, and her laws are the only thing _ that have refifted the general movement. — HUTTONIAN THEORY. 421 correfponding to it in the Indian and Pacific Oceans, which the induftry of future navigators may difcover. The whole appears to be con- nected with the trade-winds, the figure of our continents, the temperature of the feas them- felves, and perhaps with fome inequalities in the ftructure of the globe. The difturbance pro- duced by thefe caufes in the equilibrium of the fea, probably reaches to the very bottom of it, and gives rife to thofe counter currents, which have fometimes been difcovered at great depths under the furface *. The great tran{portation of materials that muft refult from the action of thefe combi- ned currents is obvious, and ferves not a little _ to diminifh our wonder, at finding the produc- jaod plants from lee tions of one climate fo frequently included Amid all the re- The rivers and the rocks, the feas and the continents, have been changed in all their parts; but the _ laws which dire& thofe changes, and.the rules Dd 3 to * Hiftoire Naturelle de Buffon, fupplément, tom. ix. P 479. 8vo, 422 ILLUSTRATIONS OF THE to which they are fubjé€t, have rémained inva- riably the fame. 374. Objections have been made to that tranfla- tion of materials by the waters of the ocean which is fuppofed in this theory, particularly by Mr Kirwan, in his Geological Effays; and, though — I might perhaps content myfelf with the remark already made, that-the Neptunian fyftem inə volves fuppofitions concerning the tranfportation of folid bodies by the fea, in the early ages of the world, as wonderful as thofe which, accord- ing to our theory, are common to all ages, I am unwilling to remain fatisfied with a mere ar- gumentum ad hominem, where the fallacy of the reafoning is fo eafily detected. 375. One of Mr Kirwan’s objections to the dé- pofition of materials at the bottom of the fea, is thus fated: “ Frist has remarked, in his ma- thematical difcourfes, that if any confiderable mafs of matter were accumulateéd in the interior of the ocean, the diurnal motion of the globe would be difturbed, and confequently it would be perceptible; a phenomenon, however, of which no hiftory or tradition gives any ac- count *.”’ The. appeal made here to Frifi is fingularly unfortunate, as that philofopher has demonftra- ted * Geol. Effays, p. 441. HUTTONIAN THEORY. 423 ted the very contrary of Mr Kirwan’s pofi- tion, and has proved, that the difturbance gi- yen to the diurnal motion by the caufes here referred to may be real, but cannot be percepti- ble. Having inveftigated a formula exprefling the law which all fuch difturbances muft ne- ceflarily obferve, he concludes, “ Hac autem formula manifeftum fiet, ex iis omnibus varia- tionibus que in terreftri fuperficie obfervari fo- lent, montium et collium abrafione, dilapfu cor- porum ponderofiorum in inferiores telluris finus, nullam oriri poffe variationem /enfibilem diurni motûs. Nam fi ftatuamus data aliqua annorum periodo terreftrem fuperficiem ad duos ufque pedes abradi undique, eam vero materiæ quan- titatem ad profunditatem pedum roco dilabi ; erit omne quod inde orietur incrementum velo- $5090 a I MET (19638051)* ~ 12855068184 ` Here, it is evident, that Frifi admits thofe very changes on the furface which we are con- tending for, and fhews, that their tendency is to accelerate the earth’s diurnal motion, but, by a quantity fo fmall, that, in a fpace of time amount- ing at leaft to 200 years, the increafe of the diur- nal motion would only be fuch a part of the Dd4 whole citatis diurni motis * Frifi Opera, tom. ili, p. 269. 424 ILLUSTRATIONS OF THE whole as the preceding fra&tion is of unis ty *. 376. The * The time requifite for taking away by wafte and erofion two feet from the furface of all our continents, and depofiting it at the bottom of the fea, cannot be rec- koned lefs than 200 years. The fraction vsyrrosrron reduced to parts of a day, is yz,-;_ of a fecond; fo that it would require 200 years to fhorten the length of the day, by the above fraction of a fecond; and there- fore it would require 148554 times 200 years, or 29710800 years, to diminifh it an entire fecond. The accumulated effect, however, of all the diminutions du- ring that period, would amount to much more: and if we had any perfectly uniform ftandard to compare the motion of the earth with, its difference from that ftand- ard would increafe as the fquares of the time, and the total acceleration would amount to one fecond in “4080 years. Whatever relation this bears to the age of the globe itfelf, it exceeds more than ten times the age of any hiftorical record. Though Frifius concludes, as is ftated here, that the acceleration produced in the diurnal motion of the earth, is far too inconfiderable to become the objet of aftronomical obfervation, he makes a fuppofition diffi- cult to be reconciled with this conclufion. namely, that the acceleration has had a fenfible effect on the figure of the earth, or rather of the fea, having increafed the cen- : trifugal force, and thereby accumulated the waters un- der the equator, in the prefent, more than in former ages. Such an accumulation, he thinks agreeable to certain HUTTONIAN THEORY. 425 376. The inftance juft given may ferve as one of many, to fhew what confidence is to be placed jn that indigefted mafs of facts and quotations which Mr Kirwan, without difcrimination, and without difcuffion, has brought together from all quarters. He has no intention, I believe, to deceive his readers; but we may judge, from this fpecimen, of the precautions he has taken againft beins `. ceived himfelf. In fome refpects, the refult of Frifi’s invefti- gation muft be confidered as imperfect. If there were no relative motion in the parts of our globe, but that by which things defcend from a high- er toa lower level, a continual acceleration of its rotation, though extremely flow, would take place, as above computed. But as, in the in- terior of the earth, there are undoubtedly mo- tions of a tendency oppofite to thofe on the fur- face, and directed from the centre towards the circumference, certain appearances that have been obferved ref{pecting the ancient level of the fea. Thefe appearances will be afterwards confidered : it is fufficient to remark here, that though the fraction, exprefling the increment of the centrifugal force, muft be double that which expreffes the acceleration, it muft be too fmall to have any per- ceptible effect in elevating the fea, except after an im- - menfe interval of time; and the compenfations which arife from other caufes, probably muft prevent it from becoming fenfible in any length of time whatfoever, 426 ILLUSTRATIONS OF THE circumference, they muft produce a retardation in the diurnal revolution; and from this muft arife an inequality, not uniformly progreffive in the fame direction, but periodical, and confined within certain limits, as the caufes are by which it is produced *. 377. Mr * Even in the defcent of bodies from a higher to a lower level at the furface of the earth, the whole ten- dency is not to increafe the velocity of the earths rota- tion, and many compenfations take place, which, when the matter is confidered only in general, are neceflarily overlooked. This will appear evident, if we refled; that it is not fimply the approach of a body towards the centre of the earth, or its removal from that centre, which tends to difturb the rotation of the earth; but its approach to the axis of the earth, or its removal from that axis. The velocity with which a particle of mat- ter revolves, whether on the furface, or in the interior ef the globe, is proportional to its diftance from the axis of rotation; 'and therefore, when a body comes nearer to the axis, it lofes a part of the motion which it had before; which part, of confequence, is communica- ted to the whole mafs of the earth, and therefore tends to increafe the velocity with which it revolves, ‘The contrary happens when a body recedes from the axis; for it then receives an addition to its velocity, which, of courfe, is taken away from the rotatory motion of the earth. Hence, bodies moving in a horizontal plane, may in- creafe or diminifh the fwiftnefs of the diurnal motion; according HUTTONIAN THEORY. 427 377. Mr Kirwan’s fecond objection is founded pn the mifapprehenfion of a well-known fact in the according as they move towards the poles or towards the equator; and thofe which defcend from a higher toa lower level, difturb the earth’s rotation, much more in confequence of their horizontal, than of their perpendi- cular motion. The Ganges, for inftance, though its fource is probably elevated no lefs than 7000 feet above the level of the fea, tends to retard the earth’s rotation, by bringing its waters, and the mud contained in them, from the parallel of 31° to that of 22°, and fo increa- fing their diftance from the earth’s axis by more than yzth part. “Had the Ganges flowed towards the north, as the Nile does, its effect would have been juft the con. trary. In the fame manner, a ftone defcending from the top of a mountain, may accelerate or retard the earth’s rota- tion, according to the direCtion in which it defcends. If it defcend on the fide of the elevated pole, it will then produce acceleration, becaufe its diftance from the axis will be diminifhed ; but if it defcend on the fide of the feprefled pole, and if the diretion in which it is mo- ved, be over a line lefs inclined, than a line drawn from the fame point to the deprefled pole, it will then pro- duce a retardation, becaufe its diftance from the axis will be increafed. Let us fuppofe, for example, that the top of Mount ` Blanc is in latitude 45° 49%, and that its height is 2450 toifes above the level of the fea. The point at which @ line drawn from the top of this mountain, parallel to the 428 ILLUSTRATIONS OF THE the natural hiftory of the earth. “ Rivers,” fays this author, “ do not carry into the fea the fpoils which they bring from the land, but employ them in the formation of deltas of low alluvial land at their mouths, according to what Major Rennell has proved.” The fat of the formation of del. tas from the fpoils which the rivers carry from the the earth’s axis, will meet the fuperficies of the fea, (fuppofing that fuperficies continued inland from the Mediterranean), muft be about 2382 toifes in horizontal diftance, or about 24 minutes fouth of the fummit} that is, in the parallel of 45° 46%’; and if this parallel be continued all round the globe, the points of the earth’s furface between it and the equator, are all more diftant from the earth’s axis than the top of Mount Blanc is; whereas all the points to the north of it are nearer to that axis. A ftone, therefore, from the top of Mount Blanc, if carried any where to the fouth of the above parallel, will retard the earth’s diurnal motion; but if carried any where to the north of the fame line, will ac- celerate that motion. ? The fame quantity of matter, however, carried an equal diffance toward the pole, and toward the equator, from any point, will lofe more velocity in the former cafe than it will gain in the latter, as eafily follows from the nature of circle. ‘Therefore, fuppofing an équal difperfion of the detritus of a mountain in all di- rections, the parts that go toward the pole will moft di- {turb the diurnal motion; and hence a balance on their fide, or in favour of acceleration, as already obferved. ea, aia i the tp of Mork) of it we ap HUTTONIAN THEORY. 429 the higher grounds, is perfectly afcertained ; and the detail into which Major Rennel has entered in the paffage referred to by Mr Kirwan, does credit to the acutenefs and accuracy of that ex- cellent geographer. But it is not there afferted, that rivers employ all the materials which they carry with them, in the formation of thofe del- tas, and deliver none of them into the fea. On the contrary, they carry from the delta itfelf mud and earth, which they can depofite nowhere but in the fea; and it is this circumftance chiefly that limits the increafe of thofe alluvial lands, and makes them either ceafe to increafe, or makes them increafe very flowly after a cer- tain period, though the fupply of earth from the higher grounds remains nearly the fame. To make Mr Kirwan’s argument conclufive, it would be neceflary to prove, that aX the mud carried down by the Nile or the Ganges, was depofited on the low lands before thefe rivers enter the fea; a thing fo obvioufly abfurd, that nothing but his hafte to obtain a conclufion un- favourable to the Plutonic fyftem, could have prevented him from perceiving it *. 378. A * The inftance mentioned in the Geological Effays, from the travels of the Abbé Fortis, concerning urns thrown into the Adriatic, upwards of 1400 years ago, and 430 ILLUSTRATIONS OF THE 378. A remark which Major Rennell has made concerning the mouths of rivers, in his Geogra- phy of Herodotus, deferves Mr Kirwan’s atten- tion, though perhaps he may not be able to put on it an interpretation quite fo favourable to his fyftem. The remark is, that the mouths of great rivers are often formed on principles quite oppofite to one another, fo that fome of them have a real delta or triangle of flat land at their mouths, while others have an eftuary, or what may, not improperly be called a negative delta. Of the latter kind are fome of the greateft rivers in the world, the Plata, the Oroonoko and the Maranon, and by far the greateft number of our European rivers. Nobody can doubt, that the three rivers juft named carry with them as much earth as the Nile, or the Euphrates, or any other river in the world. All this they have depofi- ted in the fea, and committed to the currents, which {weep along the fhore of the American continent, and by thefe they have been fpread out over the unlimited tracts of the ocean. Indeed, and not yet covered with mud, muft be explained from peculiar circumftances, or local caufes, with which we are unacquainted, as it makes againft the depofition of earth near the fhore, and in narrow feas; a general fact, which, I think, every body admits. ore of the ol p Bore of the ia bees Asoftieor | mise f HUTTONIAN THEORY. 431 Indeed, nothing can be more juft than Dr Hutton’s obfervation, that where low land is formed at the mouths of rivers, there the rivers bring down more than the fea is able to carry away; but that where fuch land is not formed, it is becaufe the fea is able to carry off imme- diately all the depofite which it receives. 379. Mr Kirwan has denied on another princi- ple the power of the fea to carry to adiftance the materials delivered into it: “ Notwithftanding,”’ fays he, “ many particles of earth are by rivers. conducted to, the fea, yet none are conveyed to any difiance, but are either depofited at their mouths, or rejected by currents or by tides; and the reafon is, becaufe the tide of flood is always more impetuous and forcible than the tide of ebb, the advancing waves being prefled forward by the countlefs number behind them, whereas the retreating are prefled backward by afar {maller number, as muft be evident to an attentive fpectator ; and hence it is that all float- ing things caft into the fea, are at laft thrown on fhore, and not.conveyed into the mid regions of the fea, as they fhould be if the reciprocal undulations of the tides were equally power- ful *.”? 380. But * Kirwan’s Geol. Effays, P- 439- 432 ILLUSTRATIONS OF THE 380. But if the attentive fpectator, inftead of trufting to a vague impreflion, or liftening to fome crude theory of undulations, refle&s on one of the moft fimple facts refpecting the ebb- ing and flowing of the tides, he will be very little difpofed to acquiefce in the above conclu- fion. He has only to confider, that the flowing of the tide requires juft fix hours, and the ebb- ing of it likewife fix hours; fo that the fame body of water flows in upon the fhore, and re. treats from it, in the fame time. The quantity of matter moved, therefore, and the velocity with which it is moved, are in both cafes the fame; and it remains for Mr Kirwan to thew in what the difference of their force can pofli- bly confift. The force with which the waves ufal break upon our fhores, does not arife from the velo- city of the tide being greater in one direction than in another. In the main ocean, the waves have no progreflive motion, and the columns of water alternately rife and fall, without any other than a reciprocating motion: a kind of equilibri- um takes place among the undulations, and each wave being equally acted upon by thofe on op- pofite fides, remains fixed in its place. Near the fhore this cannot happen; the water on the — land fide from its fhallownefs being incapable of ofall, without! is: be pla HUTTONIAN THEORY. 433 of rifing to the height neceffary to balance the great undulations which are without. The wa- ter runs, therefore, as it were, from a higher to a lower level, fpreading itfelf towards the land fide. ‘This produces the breakers on our fhores, and the furf of the tropical feas. A rock ora fand-bank coming within a certain diftance of the furface, is fufficient, in any part of the ocean, to obftruct the natural fucceflion of undulations ; and, by deftroying the mutual reaction of the waves, to give them a progreflive inftead of a reciprocating motion. 381. It is, however, but from a {mall diftance, that the waves are impelled againft the fhore with a progreflive motion. The border of break- F ers that furrounds any coaft is narrow, compa- F xed with the diftance to which the detritus from the land is confeffedly carried ; the water, while it advances at the furface, flows back at the bot- tom; and thefe contrary motions are fo nearly equal, that it is but a very momentary accumu- lation of the water that is ever produced on any fhore. If it were otherwife, and if it were true that the fea throws out every thing, and carries away nothing, we fhould have a conftant accumula- tion of earth and fand along all fhores whatfo- ever, at leaft wherever a ftream ran into the fea. Ee This, 434 ILLUSTRATIONS OF THE This, as is abundantly evident, is quite contra- ry to the fad. So, alfo, the bars formed at the mouths of ri- vers, after having attained a certain magnitude, increafe no farther, not becaufe they ceafe to receive augmentations from the land, but be- caufe their diminution from the fea, increafing with their magnitude, becomes at length fo great, as completely to balance thofe augmen- tations. When properly examined, therefore, the phenomena, which have been propofed as moft inconfiftent with the indefinite tran{porta- tion of ftony bodies, afford very fatisfactory proofs of that operation. 382. It is true, that bodies which float in the wa- ter, when carried along on the tops of the waves towards a fhelving beach, having acquired a cer- tain velocity, are thrown farther in upon the land than the diftance they would have floated to, if they had been fimply fuftained by the water. The depth of water, therefore, at the place where they take the ground, is not likely to be fuch as to float them again, and to carry them out towards the fea. They are, therefore, left behind; and this produces an appearance of a - force impelling floating bodies towards the land, much greater and more general than really takes place. 7 Thefg would pro tom did n The fać vigation v had very { | that they But from hitly ded | tom of th but little Dut even tlon from lead broy Siege š SA ; HUTTONIAN THEORY. 435 Thefe obfervations may ferve to fhow, how unfound the principles are from which Mr Kir- wan’s conclufions are deduced: they are per- haps more than is neceflary for that purpofe : it might have been fufficient to obferve, that the in- creafe of land on the fea-fhore is limited, though the augmentation from the land is certainly in- definite, a proof that the diminution from the fea is conftant and equal to the increafe. 383. “Mariners,” fays Mr Kirwan, “ were accu- ftomed, for fome centuries back, to difcover their fituation, by the kind of earth or fand brought up by their founding plummets ; a method which would prove fallacious, if.the furface of the bot- tom did not continue invariably the fame *.”’ The fact here ftated, that mariners, when na- vigation was more imperfect than it is now, had very frequent recourfe to this method, and that they ftill ufe it occafionally, is very true. But from this, the only inference that can be fairly deduced is, that the changes at the bot- tom of the fea are very flow, and the variation but little; not merely from one year to another, but even from one century to another. The rules by which the mariner judged of his pofi- tion from the quality of the earth which the lead brought up, and which were deduced no Ecs doubt * Geol. Effays, p. 440. 430 ILLUSTRATIONS OF THE doubt from obfervations made at no very great diftance of time, might be fufficient for his pur- pole, though a flow change had been all the while going forward. Such obfervations could at beft have little accuracy, and could not be ` affected by {mall variations. Itis the flownefs of the change, that makes the experience of one age applicable, in this, as in innumerable other inftances, to the obfervations of the next. Ifa long interval is taken, we will look in vain for the fame uniformity of refults. A pilot, who would at prefent judge of his pofition in the German Ocean, by comparing his foundings with thofe taken by Pyrueas, (f{uppofing them known) in his navigation of that fea, more than 2000 | years ago, could hardly be expected to deter- mine his latitude and longitude with great ex- acinefs; and I know not if the moft zealous advocate for the immutability of the earth’s furface, would be willing to truft his fafety in a fhip that was guided by fuch antiquated rules. ‘ Nore Es qn ios, W “gence fers t apra je pel ‘pe prii - emati - tations “te con 1 faltei dits of pot if the mot wy gutability of the to rule his cd by fuch w Di a a wo HUTTONIAN THEORY. 4 Note xx. § 118. Inequalities in the Planetary Motions. 334. The affertion that, in the planetary mo- tions, we difcover no mark, either of the com- mencement or termination of the prefent order, refers to the late difcoveries of La Grancz and ~ La Prace, which have contributed fo much to the perfection of phyfical aftronomy. From the principle of univerfal gravitation, thefe ma- thematicians have demonftrated, that all the va- riations in our fyftem are periodical ,; that they are confined within certain limits; and confift of alternate diminution and increafe. The or- bits of the planets change not only their po- fition, but even their magnitude and their form : the longer axis of each has a flow angular mo- tion; nd, though its length remains fixed, the fhorter axis increafes and diminifhes, fo that the form of the orbit approaches to that of a circle, and recedes from it by turns. Inthe fame man- ner, the obliquity of the ecliptic, and the incli- Nation of the planetary orbits, are fubject to change ; but the changes are fmall, and, being firft in one direction, and then in the oppofite, Eeg F they 438 ILLUSTRATIONS OF THE they can never accumulate fo as to produce a per- manent or a progreffive alteration. Thus, in the celeftial motions, no room is left for the introduc- tion of diforder ; no irregularity or difturbance, arifing from the mutual action of the planets, is permitted to increafe beyond certain limits, but each of them, in time, affords a correction for it- felf. The general order is conftant, in the midft of the variation of the parts; and, in the lan- guage of La Place, there is a certain mean con- dition, about which our fyftem perpetually o/c7/- lates, performing {mall vibrations on each fide of it, and never receding from it far*. The fyftem is thus endowed with a ftability, which can refift the lapfe of unlimited duration; it can only perifh by an external caufe, and by the introduction of laws, of which at prefent no vef- tige is to be traced. 385. The fame calculus to which we are indebt- ed for thefe fublime conclufions, informs us of two circumftances, which mark the law here treated of as an effect of wife defign, to thé entire exclufion both of neceflity and chance. One of thefe circumftances confifts in the planetary motions being all in the fame direction, or all in confequentia, as it is called by the aftrono- | mers. * Expofition du Syftéme du Monde, par La Place, Livre iv. chap. 6. p. 199. 2d edit. cul that 1 is th) soils P girl d A by wi ; wi y” i Ga HUTTONIAN THEORY. 439 mers. This is effential to the compenfation and ftability above mentioned * : had one planet circulated round the fun in a direction from eaft to weft, and another in a direction from weft to eaft, the difturbances they would have produ- ced on one another’s motion would not necet- farily have been periodical ; their irregularities might have continually increaled, and they might have deviated in the courfe of ages from their original condition, beyond any limits that. can be affigned. | The other circumftance, on which the ftability of our fyftem depends, is the fmall eccentricity of the planetary orbits, or their near approach to circles. Were their orbits very eccentric, an opening would be given to progreflive change, that might fo far increafe, as to prove the de- ftruction of the whole. But neither the move- ment of all the planets in the fame direction, nor the {mall eccentricity of their orbits, can be afcribed to accident, fince that either of thefe fhould happen by chance, in as many inftances as there are planets, both primary and fecondary, is almoft infinitely improbable. Again, that any neceflity in the nature of things fhould have either determined the direction of the planetary ` motions, or proportioned the quantity of them Beg to * La Place, zdid. 440 ILLUSTRATIONS OF THE to the intenfity of the central force, cannot be admitted, as thefe are things unavoidably concei- ved to be quite independent of one another. It remains, therefore, that we confider the laws, which make the difturbances in our fyftem cor- rect themfelves, and by that means give firm- nefs and permanence to it, as a proof of the con- fummate wifdom with which the whole is con- ftructed. 386. The geological fyftem of Dr Hutton, re- fembles, in many refpects, that which appears to prefide over the heavenly motions. In both, we perceive continual viciffitude and change, but confined within certain limits, and never depart- ing far from a certain mean condition, which - is fuch, that, in the lapfe of time, the deviations from it on the one fide, muft become juft equal to the deviations from it on the other. In both, a provifion is made for duration of unlimited extent, and the lapfe of time has no effet to wear out or deftroy a machine, conftru@ed with fo much wifdom. Where the movements are all fo perfect, their beginning and end muft be alike invifible. Nore HUTTONIAN THEORY. 44t Norte xx; § 122. Changes in the apparent Level of the Sea. 387. In {peaking of the natural epochas mark- ed out by the phenomena of the mineral king- dom, we have fuppofed a greater fimplicity, and feparation of effects from one another, than pro- bably takes place in nature. We have, for in- ftance, abftracted, in {peaking of the wafte and degradation of the land, from that elevation which may have been carried on at the fame time. This appeared neceflary to be done, in order to fimplify as much as poflible the view that was to be given of the whole; but there can be no doubt, that, while the land has been gradually worn down by the operations on its furface, it has been raifed up by the ex- panfive forces acting from below. There is even reafon to think, that the elevation has not been uniform, but has been fubject to a kind of ofcillation, infomuch, that the continents have both afcended and defcended, or have had their level alternately raifed and deprefled, inde- _ pendently of all action at the furface, and this | : within 442 ILLUSTRATIONS OF THE within a period comparativel¥ of no great ex- tent. It will be eafily underftood, that the fads we are going to ftate, each taken fingly, prove no- thing more than a change of the line in which the furface of the fea interfects the furface of the land, leaving it uncertain to which of the two the change ought really to be afcribed. Ta- ken in combination, however, thefe fas may determine what each of them feparately cannot afcertain. I fhall firft, therefore, mention fome of the principal obfervations relative to the change above mentioned, and fhall then com- pare them, in order to difcover whether it is moft probable that this change has been produced by the motion of the land or of the fea. 388. If we begin with examining the coafts of our own ifland, we fhall find clear evidence every where, that the fea once reached higher up up- on the land than it does at prefent. The marks of an ancient fea-beach are to be feen beyond the prefent limits of the tide, and beds of fea-fhells, not mineralized, are found in the loofe earth or foil, fometimes as high as thirty feet above the prefent level of the fea. Some of thefe on the fhores of the Frith of Forth are very well known, and have been often mentioned. Fn- deed, on the fhores of that frith, many monu- ments appear, which would feem to carry the difference | HUTTONIAN THEORY. 443 difference between the prefent and the ancient level of the fea, to more than forty feet. The É ground on:which the Botanic Garden of Edin- burgh is fituated, after a thin covering of foil is removed, confifts entirely of fea-fand, very regularly ftratified, with layers of a black car- bonaceous matter, in thin lamellz, interpofed between them. Shells I believe are but rarely found in it, but it has every other appearance of a fea-beach. The height of this ground above the prefent level of the fea is certainly not lefs than 40 feet. z 389. Onalmoft every part of the coaft where the = rocks do not rife quite abrupt and precipitous _ from the fea, fimilar marks of the lowering of the fea, or the rifing of the land, may be obfer- ved. On the fhores oppofite to ours, the fame appearances are remarked. The author of the Lettre Critique to M. de Buffon, tells us, that , i _ he had found the bottom of a bafon at Dunkirk, which he had reafon to think was dug about 950 years ago, ten feet and a half above the prefent low-water mark, though it muft have been originally under it. The bottom of this bafon is in the native chalk. From this, the fame author concludes, that the fea at Dunkirk lowers its level at the rate of an inch nearly m feven years. The obfervation was made in | 1702, 444 ILLUSTRATIONS OF THE 1762, (Lettre a M. le Comte de Buffon, &c: pr) feo 390. The fhores of the Low Countries, and of Holland, have been often inftanced in proof of the fame kind of changes, and it has been fup- pofed, that, independently of thofe artificial bar- riers which at prefent exclude the waters of the ocean from overflowing a great part of this tract, nature herfelf has brought it near- er to the furface than it had formerly been. It is indeed certain, that thofe countries, to a ve- ry great extent inland, have either been un- der the fea at fome period, by no means re- mote if compared with the great revolutions of the globe, or that they are entirely alluvial, and of the fame fort with the Deltas formed at the mouths of rivers. The relative changes, however, of the fea and land on this tract, have been differently reprefented, and I am unwilling, on * In the county of Suffolk, near Wood Bridge, at the diftance of feven or eight miles from the fea, are the Crag-pits, in which prodigious quantities of fea-fhells are difcovered, many of them perfe& and quite folid, (Pennant’s Aréctic Zoology, Introd. p. 6.). Lincoln- fhire affords various proofs of the fame kind; but fome other circumftances in the appearance of that coaft, juft about to be taken notice of, indicate changes of a more complicated nature. d graver HUTTONIAN THEORY. 445 on that account, to found any argument on them. 391. If we proceed farther to the north, tothe fhores of the Baltic for inftance, we have un- doubted evidence of a change of level in the fame direction as on our own fhores. The le- vel of this fea has been reprefented as lowering at fo great a rate as 4o inches in a century. Celfius obferved, that feveral rocks which are now above water, were not long ago funken rocks, and dangerous to navigators ; and he par- ticularly took notice of one, which, in the year 1680, was on the furface of the water, and in —) the year 1731 was 204 Swedith inches above it. From an infcription near Afpô, in the lake Me- lar, which communicates with the Baltic, en- graved, as is fuppofed, about five centuries ago, the level of the fea appears to have funk in that time no lefs than 13 Swedifh feet *. All thefe facts, with many more which it is unneceflary to enumerate, make the gradual depreffion, not only of the Baltic, but of the whole northern ocean, a matter of certainty. 392. Suppoting thefe changes of level between the fea and land to be {ufficiently aicertained, the fuppofition which at firft occurs is, that the mo- tion * Friii Opera, tom. ili. p. 274. 446 ILLUSTRATIONS OF THE tion has been in the fea rather than in the land, and that the former has actually defcended to a lower level. The imagination naturally feels lefs difficulty in conceiving, that an unftable fluid like the fea, which changes its level twice every day, has undergone a permanent depref- fion in its furface, than that the land, the terra firma itfelf, has admi‘ted of an equal elevation. in all this, however, we are guided much more by fancy than reafon; for, in order to deprefs or elevate the abfolute level of the fea, by a gi- ven quantity, in any one place, we muft deprefs or elevate it by the fame quantity over the whole furface of the earth; whereas no fuch neceflity exifts with refpe& to the elevation or depreffion of the land. To make the fea fubfide 30 feet all round the coaft of Great Britain, it is neceflary to difplace a body of water 30 feet deep over the whole furface of the ocean. The quantity of matter to be moved in that way is incomparably greater than if the land itfelf were to be elevated; for though it is nearly three times lefs in fpecific gravity, it is as much great- er in bulk, as the furface of the ocean is greater — than that of this ifland. 393. Befides, the fea cannot change its level, without a proportional change in the folid bottom on which it refts. Though there be reafon to fup- pofe alt of Great Bash a body of wate pth fice of the oct | EIIE HUTTONIAN THEORY. 447 pofe that fuch changes in the bottom do adual- ly take place, yet they are probably much flower and more imperceptible than thofe which we are here confidering. It is evident, therefore, that the fimpleft hypothefis for explaining thofe changes of level, is, that they proceed from the motion, upwards or downwards, of the land it- felf, and not from that of the fea. As no ele- vation or depreflion of the fea can take place, but over the whole, its level cannot be affected by local caufes, and is probably as little fubje@ to variation as any thing to be met with on the f furface of the globe. 394. Other dobfervations, however, made on dif- ferent fhores from the preceding, give greater certainty to this conclufion, and make it clear, that the motion or change which we are now treating of is not to be afcribed to the fea itfelf. The obfervations juft mentioned prove, that the level of the North Sea is lower now than it was heretofore ; but it appears, that in the Me- diterranean, the oppofite takes place. Very ac- curate obfervations made by ManFrepI, render it certain, that the fuperficies of the Hadriatic was higher about the middle of the laft century, than toward the beginning of the Chriftian æra. Some repairs that were carrying on in the ca- thedral church of Ravenna, in the year 1731, afforded 448 ILLUSTRATIONS OF THE afforded him an opportunity of obferving, that the ancient, and probably original, pavement, was four feet and a half below the prefent, and nearly a foot under the level of the fea at high water *. Now, when the church was built, this cannot have been the pofition of the pave- ment, relatively to the level of the fea, for it would have fubje@ted the floor to be under wa- ter twice in twenty-four hours, and muft have done fo the more unavoidably, becaufe at that time (the beginning of the 5th century) the walls of Ravenna were wafhed by the fea. The fact that this pavement is under the high-water mark, by the quantity juit mentioned, was afcer- tained by actual levelling. This refult was con- firmed by fimilar faéts, obferved by LENDRINŞ at Venice. | 395- Manfredi himfelf attributes all this to the elevation of the furface of the fea, and has enter- ed into a long calculation to afcertain at what rate that furface may be fuppofed to rife, on ac- count of the earth and fand brought down by the rivers, and fpread out over the bottom of the fea. But as the fad of the rife of the level of * Commentarii Academie Bononienfis, tom. ii. ars ima, D. 2 &c. and pars 2da, p. 1. &c- ? ? ? ibfide HUTTONIAN THEORY. 449 of the fea is not general, and as the contrary is obferved in the north feas, as already proved, | this hypothefis will not explain the apparent rife in the level of the Hadriatic. 396. Though a local fubfidence, or fettling of the ground, could hardly account for this change, _ the pavement being perfect in its level, and the walls of the cathedral without any fhake, yet a | fubfidence that has extended to a great tract, as tothe whole of Italy, if the mafs moved has continued parallel to itfelf, and changed its place flowly, will agree very well with the appearances. _ The facts here ftated are alfo the more defer- ving of attention, that about Ravenna, the land, "| atthe fame time that it has funk in its level, "| has extended its furface, and has encroached on H the fea. Since the time of Aucustus, the line of iti) the coaft has been carried farther out by about i i three miles *. This laft is the undoubted effect of the degradation of the land by the rivers; and here we have very clear evidence of the forces, both under and above the furface, pro- ducing their refpective effects at the fame time, fo that while the furface is raifed by earth brought down by the rivers, every given point in Ff the P ‘ * Manfredi, zbid: 450 ILLUSTRATIONS OF THE the ground is depreffed and let down to a lower level *. 397. On the fouthern coaft of Italy fimilar faĉts have been obferved. BrerrsLAac, in his Topo- grapbia Fifica della Campania di Roma +, from certain appearances in the gulfs of Bajia and Naples, concludes, that at the beginning of the Chriftian æra, the level of the fea was lower on that part of the coaft than it is now. The facts which he mentions are the following: 1mo, The remains of an ancient road are now to be feen in the Gulf of Bajia at a confiderable diftance from the land. 2do, Some ancient buildings be- longing to Porto Julio are at prefent covered by the fea. 3ti0, Ten columns of granite at the foot 7 of Monte Nuovo, which appear to have belong- ed to the Temple of the Nymphs, are alfo near- ly covered by the fea. 4to, The pavement of the Temple of Serapis is now fomewhat lower than the high-water mark, though it cannot be fuppofed that this edifice when built was expo- fed to the inconvenience of having its floor fre- — quently under water. 50, The ruins ofa palace, built % On the coaft of Dalmatia alfo, the rifing of the le« vel of the fea has been remarked, particularly at the — ruins of Diocletian’s palace of Spalatro. + Cap. vi. p. 300- r y m a EN ai Soe Áa J HUTTONIAN THEORY. 451 built by Tiberius in the ifland of Caprea, are now entirely covered by the fea. Thus, it appears that the level of the fea is finking in the more northern latitudes, and ri- fing in the Mediterranean, and it is evident that this cannot happen by the motion of the fea itfelf. The parts of the ocean all com- municating with one another, cannot rife in one place and fall in another; but, in order to maintain a level furface, muft rife equally or fall equally over the whole of its extent. If, there- fore, we place any confidence in the preceding = obfervations, and they are certainly liable to no objection, either from their own nature or the character of the obfervers, we muft confider it as demonftrated, that the relative change of le- vel has proceeded from the elevation or depref- fion of the land itfelf. This agrees well with the preceding theory, which holds, that our © continents are fubject to be acted upon by the expanfive forces of the mineral regions; that by thefe forces they have been actually raifed up, and are fuftained by them in their prefent fituation. 398. According to fome other facts ftated by the fame ingenious author, it appears, that on the coaft of Italy the progrefs of the fea in afcending, or of the land in defcending, has not Efso been 452 ILLUSTRATIONS OF THE ' been uniform during the period above mentioti- ed, but that different ofcillations have taken place; fo that, from about the beginning of the Chriftian æra, till fome time in the middle ages, the fea rofe to be fixteen feet higher than at pre- fent, from which height it has defcended till it = became lower than it is now, and from that ftate _of depreffion it is now rifing again. Breiflac in- fers this from two facts, which he combines ve- ry ingenioufly with the preceding, viz. the re- mains of fome ancient buildings, at the foot of Monte Nuovo, five or fix feet above the prefent level of the fea, in which are found the fhells of fome of thofe little marine animals that eat into ftone: And again, the marble columns of the temple of Serapis, which are alfo perforated by pholades, to the height of fixteen feet above the ground. All thefe changes Breiflac afcribes to the motion of the fea itfelf; a fuppofition which, as we have feen, cannot poflibly be ad- mitted, fince nothing can permanently affect the level of the fea in one place, which does not af- fect it in all places whatfoever. 399. Appearances, which indicate fuch alterna- tions as have juft been mentioned in the level of the fea, are to be met with on fome other coafts. In England, on the coaft of Lincolnfhire, the re- mains of a foreft have been oblerved, which are ` now oa Yh, tf eet a Tiia HUTTONIAN THEORY. 453 now entirely covered by the fea*. The fub- marine ftratum which contains the remains of this foreft, can be traced into the country to a _ great diftance, and is found throughout all the fens of Lincolnfhire. The ftratum itfelf is a- bout four feet thick; it is covered in fome pla- ces by a bed of clay fixteen feet thick, and un- der it for twenty feet more is a bed of foft mud, like the {courings of a ditch, mixed with fhells and filt. l Here then we have a ftratum which muft have been once uppermoft on the furface of the dry land, though one part of it is now immerfed under the fea, and another covered with earth, to the depth of fixteen feet. A change of level in the fea itfelf will not explain thefe appearan- ces: they can only be explained by fuppofing the whole tract of land to have fubfided, which is the hypothefis adopted by the author of the defcription in the Tranfactions, M. Corria DE SERRA; the fubfidence, however, is not here _underftood to arife from the mere yielding of fome of the ftrata immediately underneath, but is conceived to be a part of that geological fy- ftem of alternate depreffion and elevation of the furface, which probably extends to the whole mineral kingdom. ‘To reconcile all the differ- <3 ent * Phil, Tranf. 1799. p. 145. 454 ILLUSTRATIONS OF THE ent facts, I fhould be tempted to think, that the foret which once covered Lincolnfhire, was _ immerfed under the fea by the fubfidence of the land to a great depth, and at a period con- fiderably remote ; that when fo immerfed, it was covered over with the bed of clay which now lies on it, by depofition from the fea, and the wafhing down of earth from the land; that it has emerged from this great depth till a part of it has became dry land; but that it is now fink- ing again, if the tradition of the country de- “ ferves any credit, that the part of it in the fea is deeper under water at prefent than it was a few years ago. This might alfo ferve to recon- cile, in fome meafure, the phenomena of this fub- marine foret with the appearances which indi- cate an extenfion of the land on the coaft of Lincolnfhire. Indeed the extenfion of the land is no dire&t proof, either of its own elevation, or of the depreffion of the fea, as we may conclude from the inftance of Ravenna already mention- ed. 400. We have concluded from the facts {lated above, that the level of the fea rifes in the Mediterranean, and finks in the more northern latitudes ; and thence fome have fufpected, that the level of the fea had in general a tenden- cy to rife towards the equator, and to fink to- wards b i | ’ HUTTONIAN THEORY. 455 wards the poles. This is the notion of Frifi, as has been already remarked, and he fuggetts, that this rife of the fea may be owing to a flight acceleration in the earth’s diurnal motion. . But there are facts which fhew, that between the tro- pics the relative level of the fea and land has funk, and is lower at prefent than it was at fome former period, probably not extremely re- mote. The opinion of Frifi, therefore, is un- fupported by obfervation, and, as has been al- ready fhewn, cannot be juftified from theory. Between the tropics, iflands are formed from the mere accumulation of coral; and it is the peculiarity of thofe regions, to produce rocks that have not pafled through the ufual procefs of mineral confolidation *. The iflots, however, which are thus formed, muft have their bafes laid on a folid rock, though perhaps at a great depth; and it is not probable, that after they are once raifed above the furface of the fea, they can ftill rife farther, except by fome eleva- tion of the rock which ferves as their founda- Ff4 tion. * Dr Fofter, in his Voyage round the World, (vol. ii. p.146.) gives an inftance in the South Sea Iflands, where the furface of the ifland, though entirely a coral rock, was raifed forty feet above the level of the fea, 456 ILLUSTRATIONS OF THE tion*, Now, at Palmerfton ifland, which com- prehends nine or ten low iflots, that may be reckoned the heads of a great reef of coral rock, Captain Cook informs us of his having feen, “ far beyond the reach of the fea, e- ven in the moft violent ftorms, elevated co- ral rocks, which, on ination, appeared to have been perforated in the fame manner that the rocks are that now compofe the outer edge of the reef. This evidently fhews,’’ he adds, ‘‘ that the fea had formerly reached fo far; and {ome of thefe perforated rocks were almoft in the centre of the ifland 4.2" , The fame excellent navigator, giving an ac- count of the peninfula at Cape Denbigh, re- marks: “ It appeared to me, that this peninfula muf have been an ifland in remote times; for — there were marks of the fea having flowed over the ifthmus.”’ : 401. Weare here touching on one of thofe fub- jects, where we feel much the want of accurate and ancient obfervations, and where it is not from the infancy, but the maturity of fcience that any thing approaching to certainty can be looked fore Lhe utmoft that we can expedt at prefent, is o * A very curious account of the formation of fuch iflands is given by A. Dalrymple Efq; in the Philofo- phical Tranfaétions, vol. lvii. p. 394. | + Cook’s Third Voyage, vol. i. p. 221. HUTTONIAN THEORY. 457 js an anticipation, which future ages muft cer- tainly modify, and corre. The beft thing, in the mean time, that can be done for the advancement of this branch of geological know- ledge, is to afcertain with exactnefs the re- lative level of the fea, and of fuch points upon the land as can be diftinétly marked, and point- ed out to fucceeding ages. ‘This is not fo eafy as it may at firt appear. Where every obje&t changes, it is difficult to find a meafure of change, or a fixed point from which the compu- tation may begin. The aftronomers already feel this inconvenience, and when they would refer their obfervations to an immoveable plane, that — fhall preferve its pofition the fame in all ages, _ they meet with difficulties, which cannot be re- moved but by a profound mathematical invetfti- gation. , In geology, we cannot hope to be delivered _ from this embarraffment in the fame manner ; and we have no refource but to multiply ob- fervations of the difference of level; to make them as exact as poflible, and to fele& points of comparifon that have a chance of being long diftinguifhed. The improvements in barome- trical meafurements, which give fuch facility to the determination of heights, along with fo con- — fiderable a degree of accuracy, will furnifh an accumulation of faéts that muft one day be of great value to the geologift. à NoTE 458 ILLUSTRATIONS OF THE NOTE XXII. § 123. Foffil Bones. 402. The remains of organifed bodies, at pre- fent included: in the folid parts of the globe, may be divided into three claffes. The firft confifts of the fhells, corals, and even bodies of fih, and amphibious animals, which are now converted into ftone, and make integrant parts of the folid rock. All thefe are parts of animals that exift- ed before the formation of the prefent land, or . even of the rocks whereof it confifts. Thefe re- mains have been already treated of, and the evi- dence which they furnifh muft ever be regarded as of the utmoft importance in the theory of the earth. The fecond clafs confifts of remains, — which, by the help of ftalactitical concretions, are converted into ftone. Thefe are the exuvie of animals, which exifted on the very fame conti- nents on which we now dwell, and are no doubt the moft ancient among their inhabitants, of which any monument is preferved. In compa- rifon of the firft clafs, they muft, neverthelefs, be - confidered as of very modern origin. 403. The third clafs confifts of the bones of animals found in the loofe earth or foil; thefe have not acqiiired a ftony character, and their na- | ture Thel HUTTONIAN THEORY. 459 ture appears to be but little changed, except by the progrefs of decompofition and of mouldering in- to earth. No decided line can be drawn between the antiquity of this and the preceding clafs, as there may be between the preceding and the firt. In fome inftances, the objects of this third clafs may be coeval with thofe of the fecond ; in general, they muft be accounted of later ori- gin, as they are certainly not preferved ina man- ner fo well fitted for long continuance. 404. The animal remains of the fecond clafs, are generally found in the neighbourhood of lime- ftone ftrata, and are either enveloped or penetra- ted by calcareous, or fometimes ferruginous matter. Of this fort are the bones found in the ! rock of Gibraltar, and on the coaft of Dalmatia. The latter are peculiarly marked for their num- ber, and the extent of the country over which they are fcattered, leaving it doubtful whether they are the work of fucceffive ages, or of fome fudden eataftrophe that has affembled in one place, and overwhelmed with immediate deftruction, a vaft multitude of the inhabitants of the globe. Thefe remains are found in greateft abundance in the iflands of Cherfo and Ofero; and always in what the Abbé Fortis calls an ocreo-ftalattitic earth. The bones are often in the ftate of mere fplin- ters, the broken and confufed relics of various animals, concreted with fragments of marble and 460 ILLUSTRATIONS OF THE and lime, in clefts and chafms of the ftrata *, Sometimes human bones are faid to be found in thefe confufed maffes. 405. A very remarkable collection of bones in this {tate is found in the caves of Bayreuth in Fran- conia. Many of thefe belong, as is inferred with great certainty from the ftruCture of their teeth, to a carnivorous animal of vaft fize, and having very little affinity to any of thofe that are now known. The bones are found in different ftates, {fome being without any ftalactitical concretion, and having the calcareous earth ftill united to the phofphoric acid, fo that they belong to the third, rather than the fecond, of the preceding di- vifions. In others, the phofphoric acid has wholly difappeared, and given place to the carbonic. The number of thefe bones, accumulated in ~ the fame place, is matter of aftonifhment, when it is confidered, that the animals to which they belonged were carnivorous, fo that more than two can never have lived in the fame cavern at the fame time. The caves of Bayreuth feem to have been the den and the tomb of a whole dy- nafty of unknown montfiers, that iffued from this central fpot to devour the feebler inhabitants of the woods, during a long fucceffion of ages, be- . fore * Travels into Dalmatia, P. 449. the ee, E HUTTONIAN THEORY. 46 fore man had fubdued the earth, and freed it from all domination but his own. 406. The foffil bones of the fecond and third clafs, but chiefly of the third, have now afford- ed matter of conjecture and difcuffion for more than a century. The facts with refpect to them are very numerous and interefting, but can be confidered here only very generally. The remains of this kind, confift of the bones only of large animals, fo that they have gene- rally been compared with thofe of the elephant, the rhinoceros, the hippopotamus, or other ani- mals of great fize. The bones of {maller animals have alfo been found, but much more rarely than the other. It is ufually remarked, that the bones _ thus difcovered in the earth are larger than thofe of the fimilar living animals. | Another general fact concerning thefe remains, js, that they are found in all countries whatfo- ever, but always in the loofe or travelled earth, and never in the genuine ftrata. Since the year 1696, when the attention of the curious was called to this fubje&, by the fkeleton of an e- lephant dug up in Thuringia, and defcribed by Tentzelius*, there is hardly a country in Europe which has not afforded inftances of the * Phil. Tranf. vol. xix. p. 757. 462 ILLUSTRATIONS OF THE the fame kind. Foffil bones, particularly grind- ers and tufks of elephants, have been found in other places of Germany, in Póland, France, Italy, Britain, Ireland, and even Iceland *. - Two countries, however, afford them in greater abundance by far than any other part of the known world; namely, the plains of Siberia in the old continent, and the flat grounds onthe banks of the Ohio in the new +}. | 407. When the bones in Siberia were firft dif- covered, they were fuppofed to belong to an ani- mal that lived under ground, to which they gave the name of the mammouth , and the credit be- ftowed on this abfurd fiction, is a proof of the ftrong defire which all men feel of reconciling ex- traordinary appearances with the regular courfe of nature. Much {kill, however, in natural hi- ftory was not required to difcover that many of the bones in queftion refembled thofe of the ele- phant, particularly the grinders and the tuiks of that animal. Others refembled the bones of the rhinoceros; and a head of that kind, having the - hide * A grinder of an elephant found in Iceland, is de- feribed by Bartholinus, Actor. Hafniens. vol. i. p. 383. + The foflil bones on the Ohio are defcribed in two papers by Mr P. Collinfon, Phil. Tranf. vol. lvii. p. 404. and 468. a, HUTTONIAN THEORY. 463 hide preferved upon it, was found in Siberia, and is till in the imperial cabinet at Peterfburgh. Pallas has defcribed the foffil bones which he found in the mufeum at Peterfburgh, on his be- ing appointed to the fuperintendence of it, and enumerates, not only bones that belong, in his opinion, to the elephant and rhinoceros, but others that belong to a kind of buffalo, very dif- ferent from any now known, and of a fize vaftly greater *. He has alfo defcribed, in ano- ther very curious memoir, the bones of the fame kind that he met with in histravels through the north-eaft parts of Afia. The foffil bones found on the banks of the Ohio, refemble in many things thofe of Siberia ; like them they are contained in the foil or allu- vial earth, and never in the folid ftrata; like them too they are no otherwife changed from their natural ftate, than by being fometimes flightly calcined at the furface , they are alfo of 4 great fize, and in great numbers, being’ proba- bly the remains of feveral different {pecies. 408. Two inquiries concerning thefe bones have excited the curiofity of naturalifts ; firft, to difcover among the living tribes at prefent inha- biting * Novi Comment. Petrop. tom. xiii. (1768) p. 436» and tom. xvii. p. 576, &c. 464. ILLUSTRATIONS OF THE biting the earth, thofe to which the foi res mains may with the greateft probability be re- ferred; and, fecondly, to find out the caufe why thefe remains exift in fuch quantities, in countries where the animals to which they be- long, whatever they be, are at prefent unknown. The folution of the firft of thefe queftions, is much more within our reach than the fecond, and at any rate muft be firft fought for. On the authority of fo eminent a naturalift as Pallas, the bones from Siberia may fafely be re- ferred to the elephant, the rhinoceros, and buf- falo, as mentioned above, though perhaps tova- rieties of them with which we are not now ac- quainted. With refpec to the bones of North America, the queftion is more doubtful, for,they have this particular circumftance attending them, viz. that along with the thigh-bones, tufks, &c. which might be fuppofed to belong to the ele- phant, grinders are always found ofa ftruĉture and form entirely different from the grinders of that a- nimal *. Some naturalifts, particularly M. D’ Av- BENTON, referred thefe grinders to the hippopota- mus; but Dr W. Hunrer appears to have proved, in a very fatisfactory manner, that they cannot have * See Mr Collinfon’s papers. above referred to, Phil. Tranf, vol. lvii. tuk thigh bones, J to belong to ted fundatam” othe snders tt yD alae an HUTTONIAN THEORY. 465 have belonged to either of the animals juft men- tioned, but to a carnivorous animal of enormous fize, the race of which, fortunately for the prefent inhabitants of the earth, feems now to be entire- ly extinct *. The foundation of Dr Hunter’s opinion is, that in thefe grinders the enamel is merely an external covering; whereas, in the elephant, and other animals deftined to live on vegetable food, the enamel is intermixed with the fubftance of the tooth +. 409. Though this argument appears to be of confiderable weight, yet CAMPER, who was great- ly {killed in comparative anatomy, and who had ftudied this fubje&t with particular attention, was of opinion, that thefe grinders belong to a fpecies of elephant. This opinion he ftates in a let- ter to Pallas, who had found grinders and o- ther bones of this fame animal, on the weftern Gg declivity oO * Phil. Tranf. vol. lviii. p. 3, &c. + A foffil grinder in the colle&tion of Joun Maccow- AN, Efq; of Edinburgh, anfwers nearly to Mr Collinfon’s defcription, and -is very well reprefented by the figure which accompanies it. This grinder weighs four pounds one-fourth avoirdupois ; the circumference of the corona is eighteen inches; the coat of enamel is one-fourth of an inch thick ; there are five double teeth; in Mr Col- linfon’s {pecimen thete are only four. 466 ILLUSTRATIONS OF THE declivity of the Oural mountains *. Camper denies that the animal is carnivorous, becaufe the incifores, or canine teeth, are wanting; and he argues farther, from the weight of the head, which may be inferred from the weight of the grinders, that the neck muft have been fhort, and the animal muft have been furnifhed witha probofcis. He afterwards abandoned the latter hypothefis, and gave it as his opinion, that the incognitum was neither carnivorous, nor a fpecies of the elephant +. 410. Neverthelefs, Cuvier, in a mémoire read before the National Inftitute of Paris, maintains, that the foffil bones of the new continent, as well as moft of thofe of the old, belong to certain {pecies of the elephant; of which, at leaft, two do notnow exift, and are only known from remains preferved in the ground. He diftinguifhes them thus f: Elephas mammonteus,—maxilld obtufiore, lamel- lis molarium tenuibus, rectis. Elepbas Americanus,—molaribus multicufpidi- bus, lamellis poft detritionem quadri-lobatis. The latter fpecies, which is meant to include the animal incognitum, is faid to have lived, not only * A&a Acad. Petrop. tom. i. (1777) pars pofterior, p- 213, &c. + Ibid. tom. ii, (1784) p- 262. + Mémoires de l'Inftitut National, Sciences Phyfiques, tom. ll. p. 19., &c, HUTTONIAN THEORY. 467 , only in America, but in many parts of the old continent. Yet fome late inquiries into the W | ftructure of the teeth of graminivorous animals, E and particularly of the elephant, make it very l improbable that the incognitum has belonged to F this genus*. The grinders of the elephant have T been found to confift of three fubftances, ena- mel, bone, and what is called the cru/ta petrofa, ] applied in layers, or folds contiguous to one ano- ther; and no veftige of this ftructure appears in og the perioders of the unknown animal ofthe Ohio +. B Gg2 At 5 * See Mr Home's obfervations onghe teeth of gramini- --yorous animals, Phil. Tranf. 799. Alfo, An sects on the ftrudure of the teeth, by Dr Blake. + Ina paper inferted in the fourth volume of the A- , “merican Philofophical TranfaGtions, an account is given of two different grinders that are found at the Salt-Licks near the Ohio. One of them refembles the grinder of the elephant, and may have belonged to the elephas Americanus of Cuvier; the other agrees pretty nearly with the grinder of Dr Hunter’s animal incognitum. The author of the paper thinks that the animal incognitum was “not wholly carnivorous, as the inci/ores, or canine teeth, “are never found. At the Great Bone. Lick, bones of {maller animals, particularly of the buffalo kind, have been difcovered. The faline impregnation of the earth at thefe Licks muft no doubt have contributed to the pre- _fervation of the bones. Tranf. American Phil. Soc. vol, iv. (1799) p. 510, &c. 468 ILLUSTRATIONS OF THE At the fame time, Dr Hunter’s affertion, that this animal was carnivorous, is rendered doubtful, not only by the want of canine teeth, but alfo from the refemblance between its grinders and thofe of the wild boar, which Mr Home has ob- ferved to be confiderable *. The grinder of the boar is fimilar to that of the elephant, in the ex- tent of the mafticating furface, but not at all in the internal ftructure; and the fame is true of the tooth of the animal incognitum, fo that a confidera- ble probability is eftablifhed, that it and the boar are of the fame genus, and both deftined to live occafionally‘either on animal, or vegetable food. 411, Another anignal incognitum found in South America has been deferibed by Cuvier, and ap-. pears to be of a different genus from the incogni- tum of the North. Thus, if we include the two incognita of America, the elephas mammonteus, the unknown buffalo of Pallas, and the great animal of Bayreuth, we have at leaft five di- ftinct genera, or fpecies of the animal kingdom, which exifted on our continents formerly, but do not exit on them now. The number is probably much greater: Pallas mentions foffil horns of a gazelle, of an unknown fpecies ; and horns of deer aré often found, that cannot be re- ferred to any fpecies now exilting. Thole ex- tinct * Obfervations on the grinding teeth of the wild boar and animal incognitum. Phil, Tranf, 1801, p. 319. 5 HUTTONIAN THEORY. 469 tind races have been remarkable for their fize: fome of the ancient elephants appear to have ] been three times as large as any of the prefent *. 412. The inhabitants of the globe, then, like all F the other parts of it, are fubje& to change: Itis not only the individual that perifhes, but whole i fpecies,and even perhaps genera, are extinguifhed. - It is not unnatural to confider fome part of this _ change as the operation of man. The extenfion = of his power would neceflarily fubvert the balance that had before been eftablifhed between the in- if habitants of the earth, and the means of their fub- ly fiftence. Some of the larger and fiercer animals | might indeed difpute with him, for a long time, _ the empire of the globe; and it may have requi- _ red the arm of a Hercules to fubdue the montfters _ which lurked in the caves of Bayreuth, or roamed l on the banks of the Ohio. But thefe, with others of the fame charaéter, were at length extermina- ; ted: the more innocent fpecies fled to a diftance _ from man ; and being forced to retire into the | moft inacceffible parts, where their food was _ feanty, and their migration checked, they may have degenerated from the fize and ftrength of _ their ancettors, and fome fpecies may have been i ply extinguifhed. But befides this, a change in the animal king- dom feems to be a part of the order of nature, Gg3 . and * Camper, Nov, Acta Petrop. tom. ii. (1784) p. 257 4yo ILLUSTRATIONS OF THE and is vifible in inftances to which human pow- er cannot have extended. If we look tothe — mof ancient inhabitants of the globe, of which the remains are preferved in the ftrata them- felves, we find in the fhells and corals of a for- mer world hardly any that refemble exadly thofe which exift in the prefent. The fpecies, except in a few infltances, are the fame, but fub- ject to great varieties. The vegetable impref- fions on flate, and other argillaceous ftones, can feldom be exaétly recognifed ; and even the in- feéts included in amber, are different from thofe of the countries in which the amber is found. 413. Suppofing, then, the changes which have taken place in the qualities and habits of the ani- mal creation, to be as great as thofe in their ftruGure and external form, we can have no rea- fon to wonder if it fhould appear, that fome have formerly dwelt in countries from which the fi- milar races are now entirely banifhed. The power of living in a different climate, of endu- ring greater degrees of cold or of heat, or of fubfifting on different kinds of food, may very well have accompanied the other changes. Though one fpecies of elephant may now be confined to the fouthern parts of Afia, another may have been able to endure the feverer cli- mates of the north ; and the fame may be true of the buffalo or the rhinoceros. In all this no phy- - : fical HUTTONIAN THEORY. 471 T fical impoflibility is involved ; though whether f jt is a probable folution of the difficulty concern- T ing the origin of thefe animal remains, can only | be judged of from other circumftances. _. 414. If weconfider attentively the facts that re- {pect the Siberian foffil bones, there will appear jnfurmountable objections to every theory that fuppofes them to be exotic, and to have been prought into their prefent fituation from a di- = ftant country. The extent of the tra& through which thefe bones are fcattered, is a circumftance truly won- | derful. Pallas affures us *, that there is not a » river of confiderable fize in all the north of Afia, from the Tanais, which runs into the Black Sea, to the Anadyr, which falls into the Gulf of Kamtchatka, in the fides or bottom of which bones of elephants and other large animals have not been found. This is efpecially the cafe _ where the rivers run in plains through gravel, fand, clay, &c.; among the mountains, the bones are rarely difcovered. The extent of the tract juft mentioned exceeds four thoufand miles ; and how the bones could be diftributed over all that extent, by any means but by the animals having Gg4 lived * De Reliquiis Animalium exoticorum, per Afiam i Borealem repertis.—Nov. Comment. Petrop. tom, xvii. j j (1772) p. 576. 472 ILLUSTRATIONS OF THE lived there, it feems impoflible to conceive. No torrent nor inundation could have produced this effect, nor could the bones brought in that way have been laid together fo as to form complete ikeletons, 415. One fac recorded by the fame author, feems calculated to remove all uncertainty. Itis that of the careafe of a rhinoceros, almoft entire, and covered with the hide, found in the earth in the banks of the river Wilui, which falls into the Lena below Jacutfk *. Some of the mufcles and tendons were actually adhering to the head when Pallas received it. The head, after being dried in an oven, is ftill preferved in the mu- feum at Peterfburgh. The prefervation of the fkin and mufcles of this natural mummy, as Pal- las calls it, was no doubt brought about by its being buried in earth that was in a ftate of per- petual congelation ; for the place is in the pa- rallel of 64°, where the ground is never thawed but to a very {mall depth below the furface. But by what means can we account for the carcafe of a rhinoceros being buried in the earth, on the confines of the polar circle? Shall we a- {fcribe it to fome immenfe torrent, which, {weep- ing acro{s the defarts of Tartary, and the moun- tains of Altai, tranfported the produ@ions of In- dia * Pallas, ub: jupra, p. 86, Alfo, Voyages de Pallas, tom. 1v. p. 13m. ly HUTTONIAN THEORY. 473 dia to the plains of Siberia, and interred in the mud of the Lena the animals that had fed on the banks of the Barampooter or the Ganges? Were all other objections to fo extraordinary a fuppofi- tion removed, the prefervation of the hide and mufcles of a dead animal, and the adhefion of the parts, while it was dragged for 2000 miles over fome of the higheft and moft rugged mountains in the world, is too abfurd to be for a moment ad- mitted. Or fhall we fuppofe that this.carcafe has been floated in by an inundation of the fea, from fome tropical country now fwallowed up, and of which the numerous iflands of the Indian _ Archipelago are the remains? The heat of a tropical climate, and the putrefcence naturally _arifing from it, would foon, independently of all other accidents, have ftripped the bones of their covering. Indeed this inftantia fingularis, as in every fenfe it may properly be called, feems cal- culated for the exprefs purpofe of excluding eve- ty hypothefis but one from being employed to explain the origin of foffil bones. It not only ex- cludes the two which have juft been mentioned, but it excludes alfo that of Buffon, viz. that thefe bones are the remains of animals which lived in Siberia, when the ar&tic regions enjoyed a fine climate, and a temperature like that which fouthern Afia now pofleffes. From the preferva- tion of the flefh and hide of this rhinoceros, it is plain, that when the body was buried in the earth, 474 ILLUSTRATIONS OF THE earth, the climate was much the fame that it is now, and the cold fufficient to refift the progrefs of putrefaction. Pallas takes notice of the inconfiftency of the fate of this fkeleton, with the hypothefis of Buffon; but he does not obferve that the incon- fiftency is equally great between it and his own hypothefis, the importation of the foffil bones by an inundation of the fea, and that flefh or mufcle muft have been entirely confumed long before it could be carried by the waves to the parallel of 64°, from any climate which the rhinoceros at prefent inhabits. 416. The prefence of petrified marine objects in places where fome of the foffil bones are found, is no proof that the latter have come from the fea, though it is produced as fuch both by Pal- las himfelf, and afterwards by Kirwan. Thefe marine bodies are the fhells and corals that have been parts of calcareous rocks, from which being detached by the ordinary progrefs of difintegra- tion, they are now contained in the beds of fand or gravel where the animal remains are buried. They have nothing in common with thefe re- mains; they are real ftones, and belong to ano- ther, and a far more remote epocha. Such objects being found in the fame place where the bones lie, argues only that the {trata in the higher grounds, from which the gravel has come, are calcareous; and nothing can fhew ina ftronger light + HUTTONIAN THEORY. 475 light the néceflity of diftinguifhing the different condition of fofal bodies, united by the mere circumftance of contiguity, before we draw any inference as to their having a common origin. If the marine remains were in the fame condi- tion with the bones ; if they were in no refpe& mineralized; then the conclufion, that both had been imported by the fea, would have great probability; but without that, their prefent union muft be held as cafual, and can give no spit into the origin of either. 417. On the whole, therefore, no conclufion re- mains, but that thefe bones have belonged to fpecies of elephants, rhinoceros, &c. which in- habited the very countries where their remains are now buried, and which could endure the feverity of the Siberian climate. The rhinoce- ros of the Wilui certainly lived on the confines of the Polar circle, and was expofed to the fame cold while alive, by which, when dead, its body has been fo long, and fo curioufly preferved. Thefe animals may alfo have lived occafion- ally farther to the fouth, among the valleys between the great ranges of mountains that bound Siberia on that fide. Foffil bones are but rarely found in thefe valleys, probably be- caufe they have been wafhed down from thence 3 into the plains. We muft obferve, too, that thofe animals may have migrated with the fea- fons, and by that means avoided the rigorous winter 476 ILLUSTRATIONS OF THE- winter of the high latitudes. The dominion of man, by rendering fuch migration to the larger animals difficult or impoffible, muft have greatly changed the economy of all thofe tribes, — and narrowed the circle of their enjoyments and exiftence. The heaps in which the foffil bones appear to be accumulated in particular places, efpecially in North America, have a great ap- pearance of being connected with the migrations of animals, and the accidents that might bring multitudes of them into the fame fpot. What holds of Siberia and of North America, is applicable, a fortiori, to all the other places where animal remains are found in the fame con- dition. Thus we are carried back to a time when many larger fpecies of animals, now en- tirely extin, inhabited the earth, and when varieties of thofe that are at prefent confined to particular fituations, were, either by the liberty of migration, or by their natural conftitution, ac- commodated to all the diverfities of climate. This period, though beyond the limits of ordinary chronology, is pofterior to the great revolutions on the earth’s furface, and the late among geological epochas. Note Cia acticin aa aii HUTTONIAN THEORY. 444 Nore xxtir. § 128. Geology of Kirwan and De Luc. 418. The two champions of the Neptunian fyftem, who have diftinguifhed themfelves moft by their hoftility to Dr Hutton, are De Luc and Kirwan. ‘They have carried on their at- tack nearly on the fame plan, and have em- ployed againft their antagonift the weapons both of theology and fcience. With a fpirit as in- jurious to the dignity of religion, as to the free- dom of philofophical inquiry, they have difre- ae garded a maxim enforced by the authority of Ba- {con and by all our experience of the paft ; “ Tan- a to magis bec vanitas inhibenda venit et coércenda, quia, ex divinorum et humanorum male-fana admix- tione, non folum educitur philofophia phantaftica, Jed etiam religio heretica. Itaque falutare admo- dum eft, fi mente Jobrid, fidei tantum dentur que fidei funt *,”’ Proceeding * The whole paflage is deferving of attention, and | it feems as if the prophetic fpirit of Bacon had addrefled E it to the cofmologifts of the prefent day. “ Peffima enim j res eft errorum APOTSEOSIS, et pro pefte intelleétis habenda i j eft, fi vanis accedat veneratio, Huic autem vanitati non- | j nullt ex modernis fummd levitate ita indulferunt, ut, in pri- mo capitolo GENESEQS, et aliis Scripturis Sacris, philofo- phiam naturalem fundari conati funt : Inter viva queren- tes MORTUA.” Nov. Organum, lib. i. aphor. 65. 478 ILLUSTRATIONS OF THE — Proceeding, accordingly, in direct oppofition te rules that have never yet been violated with im- punity, and miftaking the true obje& of a theory of the earth, they carry back their inquiries to a period prior to the prefent feries of caufes and effects, where, having neither experience nor analogy to direct them, they pretend to be guided by a fuperior light. They would have us to confider their geological {peculations as a commentary on the text of Moszs ; they endea- vour to explain the action of creative power, and, with indifcreet curiofity, would tear off the veil which the hand of the prophet has fo wifely re- fpected. But the veil cannot be torn off, and all that is behind it muft be to man as that which never has exitfted. | 419. M. de Luc has neverthelefs treated very diffufely of the hiftory of the folar fyftem, pre- vious to the eftablithment of the prefent laws of nature, and has dwelt on it with great compla- cency, and fingular minutenefs of detail. His tenth letter to La Mrerueriz has the follow- ing title : “ On the Hiftory of the Earth, from the time when that planet was penetrated by dight, till the appearance of the fun; a portion of time which includes the origin of heat, and of the figure of the earth; of its primeval ftrata, of the ancient fea, of our continents, as the bottom of that HUTTONIAN THEORY. 479 that fea, of the great chains of mountains, and of vegetation *.”’ I muft confefs that lam unacquainted with eve- ry thing of this letter but the title; and could not eafily be prevailed on to follow any man who pro- feffedly goes out of nature in fearch of knowledge; who pretends to give the hiftory of our planetary fyftem when there was no fun, and to enumerate the events which took place between the exift- ence of that lumimary, and the exiftence of light. The abfurdity of fuch an undertaking admits of no apology; and the {mile which it might excite, if addrefled merely to the fancy, gives place to indignation when it aflumes the air of philofophic inveftigation. 420. It fets, however, in a ftrong light, the in- confiftencies that may be obferved in the intellec- ` tual character of the fame individual, to confider that the author of this trange and inconfiftent reverie, * Journal de Phyfique, tom. 37. (1790) partie 2de, P. 332. As I may not have done juftice to this extra- ordinary title, it may be right to prefent it in the origi- nal. “ Sur PHiftoire de la TERRE, depuis que cette pla- nette fut penetrée de LUMIERE, jufqu’s l’apparition du SOLEIL; efpace de tems qui renferme les oRIGINES de la chaleur, et de la figure de notre globe; de fes couches primordiales, de L'ancienne mer, de nos continens, comme fond de cette mer, de leurs grandes chaînes de mon- tagnes, et de-la vegetation.” 480 ILLUSTRATIONS OF THE reverie is, neverthelefs, an excellent obferver, and well {killed in experimental inquiries. It will hardly be believed that he who writes the hifto- ry of the earth before the formation of the fun, is verfed in the principles of inductive reafoning 3 and that he has added much to the ftock of geo- logical knowledge, having obferved accurately, and defcribed with great perfpicuity and can- dour. His Lettres Phyfiques are full of valuable and juft obfervations, though accompanied with reafonings that do not feem always entitled to the fame praife; and in another work he has fuc- ceeded where many men of genius had failed, and has made confiderable improvements in a branch of the mathematics, without borrowing almoft any affiftance from the principles of that {cience *. 421. Some of the fame obfervations apply to Mr Kirwan. His Geological Effays have alfo for their object to explain the firft origin of things ; and to fay that he has not fucceeded, in an at- tempt where no man ever can fucceed, im- plies no reproach on the execution of his work, whatever it may do on the defign. We have indeed no criterion by which the execution of it can be eftimated: what would in any other place be a blemifh, may be here deferving of praife ; and if the work is full of confufion and perplexity — * Effai fur les Modifications de l’Atmofphere, HUTTONIAN THEORY. 481 perplexity, thefe are qualities inherent in the fubjec&t which it is intended to defcribe. It were, no doubt, to be wifhed, that after emerging into the regions of day, Mr Kirwan had been as fuc- cefsful in copying the beauty and fimplicity of nature, as in reprefenting the diforder and in- le | q commiftency of the chaotic mafs. But his cof- mology is without unity in its principles, or con- fiftency in its parts: the caufes introduced, are, for the moft part; fuch as will account for one fet of appearances juft as well as for another; or, if any of them is likely to prove inadequate | to the effed afcribed to it, a new and arbitrary _hypothefis is always ready to come to its aflift- ance. The information given is feldom exact: À a multitude of facts brought together, without the order and difcuffion effential to precife know- ledge; and an infinity of quotations, amaffed = Without criticifm or comparifon, afford proofs of extenfive reading, but of the moft hafty and fu- perficial inquiry. Thus we have feen paffages from Uxtoa and Frist, produced in fupport of opinions, which, when fairly ftated, they had the moft direct tendency to overthrow. 422. In one ref{peét, the geological writings of _ Kirwan are far inferior to De Luc’s: They are evidently the productions of a man who has not feen nature with his own eyes; who has ftudied Hh mineralogy 482 ILLUSTRATIONS OF THE mineralogy in cabinets, or in books only; but who has feldom beheld foffils in their native place. With the balance in his hand, and the external characters of WERNER in hjs view, he has examined minerals with diligence, and has difcovered many of thofe marks which ferve to afcertain their places, in a fyftem of artificia?ar- rangement. But to reafon and to arrange are very different. occupations of the mind; and a man may deferve praife as a mineralogift, who is but ill qualified for the refearches of geo- logy. 423. The fame hurry and impatience are vifi- ble in the manner in which his argument againft Dr Hutton is ufually conducted. He has feldora been careful to make himfelf mafter of the opi- nions of his adverfaries ; and what he gives as fuch, and directs his reafonings againft, have of- ten norefemblance to them whatfoever. With- out any intention to deceive others, but deceived himfelf, he ufually begins with mifreprefenting Dr Hutton’s notions, and then proceeds to the re- futation of them. In this imaginary conteft, it will readily be fuppofed, that he is in general fuccefsful: when a man has the framing both of his own argument, and that of his antagonift, he muit be a very unfkilful logician if he does not come off with the advantage. 424. It = E sso taii HUTTONIAN THEORY. 483 424. It is but juftice, however, to the Neptu- nifts, to acknowledge, that they are not all liable tothe cenfure of beginning their refearches from a period antecedent to the exiftence of the laws of nature. This abfurdity does not, fo far as I know, infect the fyftem of Werner. That mi- neralogift has not propofed to explain the firft o- rigin of things, though he has fuppofed, at fome former period, a condition of the globe very unlike the prefent, viz. the entire fubmerfion of the folid under the fluid part. Nore xxiv. § 129. Sytem of Burron. 425. The affinity of Dr Hutton’s theory to _ that of Buffon, is nothing more than what arifes from their making ufe of the fame agents, viz. fire and water, in producing the prefent condi- _ tion of the earth’s furface. In almoft all other refpeéts the two theories are extremely differ- ent, The order in which tho e agents are em- ployed in them, is dire@tly oppofite, as has al- ready been remarked ; Buffon introducing the action of fire firt, and of water only in the fe- cond place, to wafte and deftroy mineral bodies, Hi 2 and 484 ILLUSTRATIONS OF THE and afterwards to difpofe them anew, and ar- range them into ftrata. He makes no provi- fion for the confolidation of thefe ftrata, nor any for their angular elevation; he has no means of explaining the unftratified rocks; nor any, but one extremely imperfect, for explaining the in-. equalities of the earth’s furface. Again, Buffon miftook, in fome degree, the true object of a theory of the earth ; and though he did not go back, like the waclout Gatien named, to a time when the laws of nature were not fully eftablifhed, he begins from a condition of things too unlike the prefent to be the bafis of any rational fpeculation. He does not, indeed, undertake to examine the flate of our planetary fyftem before the fun exifted ; for from fuch ex- travagance, even when moft difpofed to indulge his fancy, he would furely have revolted. But he treats of the world, when the earth and the planets had juft ceafed to be a part of the fun, and were newly detached from the body of that lu- minary *. This E concerning the origin of the planets, contrived chiefly to account for the cir- cumftance * According to Buffon, the granite is the true folar matter, unchanged but by its congelation. HUTTONIAN THEORY. 48 cumftance of their motion being all in the fame direction, and in other refpects not only unfup- ported, but even inconfiftent with the principle of gravitation, has nothing in common with a theory, confined as Dr Hutton’s is, within the field which mult for ever bound our inquiries, and not venturing to fpeculate about the earth, when in a condition totally different from the prefent. 426. In what relates to the future, the two fyitems are not more like than in what relates to the paft. Buffon reprefents the cooling of our planet, and its lofs of heat, asa procefs conti- nually advancing, and which has no limit, but the final extinétion of life and motion over all the furface, and through all the interior, of the earth. ‘The death of nature herfelf is the di- ftant but gloomy obje@ that terminates our view, and reminds us of the wild fiGions of the Scandinavian mythology, according to which, an- -mbilation is at laft to extend its empire even to the gods. This difmal and unphilofophic vifion was unworthy of the genius of Buffon, and wonder- fully ill fuited to the elegance and extent of his underftanding. It forms a complete contrat to the theory of Dr Hutton, where nothing is to be feen beyond the continuation of the pre- fent order ; where no latent feed of evil threat- ens final deftru@ion to the whole; and where the Hh 3 movements 486 ILLUSTRATIONS OF THE movements are fo perfect, that they can never terminate of themfelves. This is furely a view of the world more fuited to the dignity of Na- TURE, and the wifdom of its Auror, than has yet beert offered by any other fyftem of cofmo- logy. 427. I have often quoted Buffon in the courfe thefe I/luftrations, and mot commonly for the purpofe of combating his opinions ; but I am very fenfible, neverthelefs, of the obligations un- der which he has laid all the fciences connect- ed with the natural hiftory of the earth. The extent and variety of his knowledge, the juftnefs of his reafonings, the greatnefs of his views, his correct tafte, and manly eloquence, qualified him, better, perhaps, than any other individual, to compofe the Hiftory of Nature. The errors into which he has fallen, are almoft all the unavoidable confequences of the circum- ftances in which he was placed ; and if their a- mount is eftimated by the proportion that they bear to the general excellence of the work, they will be reckoned but of fmall account. Buffon began to write when many parts of natural hifto- ry had made but little progrefs; when the quan- tity of authentic information was fmall, and when {cientific and corre@ defcription was hardly to be found. Many of the greateft and moft im- portant faéts in geology were quite unknown, and HUTTONIAN THEORY. 487 and {carcely any part of the mineral kingdom had been accurately furveyed ; and, with fuch ma- terials as this ftate of things afforded, it is not wonderful if fome parts of the edifice he.erected have not proved fo folid and durable as the reft. Had he appeared fomewhat later; had he been farther removed from the time when reafonings a priori ufurped the place of induction ; and had he been as willing to correct the errors into which he had been betrayed by imperfeét in- formation, as he was ingenious in defending them, his work would probably have reached as great perfection, as it is given for any thing | without the {phere of the accurate fciences to j a ee ee E ee ee ee ee aS ) attain. If he had examined the natural hiftory : of the earth more with his own eyes, and been as careful to delineate it with fidelity as force; if he had liftened with greater care to the philofo- _ phers around him ; had he attended to the de- -monftrations of Newron more, and defpifed the arrangements of Linnzus lefs; he would have produced a work, as fingular for its truth as fot its beauty, and would have gone near to merit the eulogy pronounced by the enthutiafm of his countrymen, MAJESTATI NATURÆ PAR INGE- NIUM. | Hh4 Norz an estar alin 488 ILLUSTRATIONS OF THE ju w Note x Bs XV. $ 1303 A ge 7 tb Figure of the Earth. ie E 428. That the earth is a fpheroidal body, gl compreffed at the poles, or elevated at the equa- Sn tor, is a fact eftablifhed by many accurate expe- tt riments ; and though thefe experiments do not P exactly coincide, as to the degree of oblatenefs y€ which they give to that fpheroid, they agree fuf- ficiently to put it beyond all difpute, that the ; ft earth, though folid, has nearly the fame figure which it would affume if fluid, in confequence of tts rotation on its axis. Now, it is not at all obvious, to what phyfical Eo ‘ caufe this phenomenon is to be afcribed. The l earth, as it exifts at prefent, has none of the conditions that render the affumption of the fi- | gure of equilibrium in any way neceffary to it. | Conftituted as it is, its parts cohere with forces incomparably too great to obey the laws of fta- tical preffure, or to aflume any one figure rather than another,’ on account of the centrifugal ten- dency which refults from its revolution on its axis. There is no neceflity that its fuperficies fhould be every where level, or perpendicular to the direction of gravity, nor that every two co- lumns, HUTTONIAN THEORY. 489 lumns, ftanding on the fame bafe, any where within it, and reaching from thence to any two points of the furface, fhould be of fuch weights as precifely to balance one another. Neither of thefe, indeed, is at all conformable to fad, They are, however, the very fuppofitions on which the determination of the {pheroid of e- quilibrium is founded ; and as they certainly do in no degree belong to the earth, it feems flrange that the refult deduced from them fhould be ia any way applicable to it. This coincidence remains, therefore, to be explained ; and it muft greatly enhance the merit of any geological fy- ftem, if it can connect this great and enigmati- cal phenomenon with the other fas in the na- tural hiftory of the earth. 429. To eftablifh fuch a connection, has, ac- cordingly, been a favourite object with geologitts, whether they have embraced the Neptunian or Vulcanic theory: both have thought that they were entitled to fuppofe the primeval fluidity of the globe, the one by water, and the other by fire; and in whatfoever way that fluidity was produced, the refult of it could be no other than the {pheroidal figure of the whole mafs, agree- _ ably to the laws of hydroftaties. If in this fluid ftate the earth was homogeneous, the {pheroid would be accurately elliptical, and the compref- fion at the poles would be Saat the radius of the goo ILLUSTRATIONS OF THE the equator ; if the fluid was denfer toward the centre, the flattening would be lefs : and in either cafe, the body, as it acquired folidity, may be fuppofed to have retained its fpheroidal figure with little variation. But though the fluidity of the earth will account for the phenomenon of its oblate figure, it may reafonably be queftion- ed, whether this fluidity can be admitted, in confiftency with other appearances. According to what is eftablifhed above, none of the appear- ances in the mineral kingdom indicate more than a partial fluidity in any former condition of the earth. The prefent ftrata, made up as they are of the ruins of former ftrata, though foftened by heat, have not been rendered fluid by it, and have even poffeffed their foftnefs in parts, and in fucceffion, not altogether, nor at the fame time. The unftratified, and more cryftallized fubs - (tances, were caft in the bofom of others, which were folid at the time when they were fluid. In all this, therefore, there is no indication of a fluidity prevailing through the whole mafs, or even over the whole furface of the earth, and therefore nothing that can explain the {pheroid- al figure which it has acquired. The fuppofi- tion, then, of the entire body of the earth, or even of its external cruft, having been fluid, though it might account for the compreflion at the \ es ee BE. E HUTTONIAN THEORY. 49% the poles, does not conneét that fact with the o- ther facts in the natural hiftory of the globe, and fails, therefore, in the point moft effential to a theory. It is liable, alfo, to other objections ; - whether it be conceived to have proceeded from fire or from water ; whether it has happened on the principles of Buffon or of Werner. 430. Firft, let us fuppofe that the fluidity of the earth, or of the external cruft of it, at leaf to a certain depth, proceeded from a folution of the whole in the waters of the ocean; and, waving all the objections that have been ftated to this hypothefis, on account of the abfolute in- folubility of many mineral fubftances in wa- ter, let us fuppofe them all foluble in a certain degree, and let us compute the quantity of the menftruum, which, on the fuppofitions moft fa- yourable to the fyftem, muft have been required to this great geologico-chemical operation. The filiceous earth, though not foluble in wa- ter per fe, yet, after being diffolved in that fluid by means of an alkali, was found by Dr Black, in his analyfis of the Geyfer water, to remain fufpended in a quantity of water, between 500 and 1000 times its own weight. This is one of the facts moft favourable to the Neptunian the- ory; and that every advantage may be given to that theory, we fhall take the leaft of the num- bers jut mentioned, and fuppofe that filiceous earth 492 ILLUSTRATIONS OF THE earth may be diffolved or fufpended in 500 times its weight of water. Taking this for the extreme degree of infolu- bility of mineral fubftances, (though there are many of which the infolubility is abfolute, or, to {peak in the language of calculation, infinitely great), we may fuppofe the infolubility of all the reft, or the quantities of water in which they are diffolved, to be ranged in a defcending feale from goo to o, the extreme degree of deliquet- cence. Then, taking the arithmetical mean be- tween thefe extremes, it will give us 250, as the proportion of water in which mineral fubftances may at an average be diffolved. But this ave- rage is much lefs than the truth ; for the quan- tity of filiceous earth is great in comparifon of any of the reft, and the mineral fubftances that are extremely foluble in water are but in a {mall quantity ; therefore, when we fuppofe mineral bodies, at a medium, to be foluble in 250 times their own weight of water, we make a fuppofi- tion extremely favourable to the Neptunian fy- ftem. : 431. This is the proportion between the weight of the folvent, and of the fubftances held in folu- tion: to have the proportion of their bulks, we may fuppofe the fpecific gravity of mineral bo- dies in general to be to that of water as 5 to 2, and then we have the ratio of bulks, that of 250 —— SO ls HUTTONIAN THEORY. 493 i 2509X 5 to 2x1, or of 625 to r. It follows, , then, that minerals in general cannot be fuppo- fed foluble in lefs than 625 times their bulk of ' water. 4 432. Again, it muft be allowed to the Neptunifts, that the fluidity of the whole earth is not ne- ceflary to account for its affuming the {pheroidal figure. Itis fufficient if the whole of that cruft or fhell of matter was fluid, which is contained between the actual furface of the terreftrial {phe- roid, and the furface of the fphere infcribed with- in it; that is, of the {phere which has for its diameter the polar axis of the earth. The whole ` ofthe minerals which compofe this fhell, mutt a at leaft have been diffolved in water, and have | formed the chaotic mafs of Mr Kirwan. The [ volume of the water required for this was not lefs than 625 times the bulk of the {pheroidal fhell that has juft been mentioned. But, eis the difference between the polar axis and the ‘equatorial diameter to be are the ‘latter, which i is the fuppofition moft kuuk to the phenomena, it is eafy to fhew that the mag- nitude of the above fpheroidal hell, or the dif- ference between the folid content of the earth, and the {phere infcribed in it, is greater than = and lefs than a of the whole earth; fo that 494 ILLUSTRATIONS OF THE that the earth is lefs than 151 times the fphe- roidal fhell. The volume of the water, therefore, neceflary to hold in folution the materials of this fhell, is to the volume of the whole earth as 625 to 151, or in a greater ratio than that of four to one: and fuch, therefore, at the very leaft, is the quantity of water which Mr Kirwan luppofes, after it cea- fed to a& in its chemical capacity, to have reti- red into caverns in the interior of the earth. Thus the Neptunifts, in their account of the fpheroidal figure of the earth, are reduced toa cruel dilemma, and are forced to choofe be- tween a phyfical and a mathematical impofli- bility. If we would inquire whether the opinion of the igneous origin of minerals, as commonly re- ceived by the Vulcanifts, is capable of affording a better folution of this difficulty, the theory of M. de Buffon is the firft that prefents itfelf. 433. That philofopher confiders the exiftence of the {pheroidal figure as a proof that the whole of the earth muft have been originally fluid ; and as the fluidity of the whole can only be afcribed to fufion, he has fuppofed that the earth was originally a mafs of melted matter ftruck off from the fun by the collifion of a comet; and that this. mafs, when made to revolve on its axis, HUTTONIAN THEORY. 498 axis, put on a fpheroidal figure, which it has retained, though now cooled down to congela- tion. : This fyftem need not be confidered in detail; the foundation of it is laid in fuch defiance of the principles of geometry and mechanics, that the architect, notwithftanding all the fertility of his invention, and all the refources of his genius, was never able to give any folidity to the ftruc- ture. But it will be faid, that we may take a part of the fyftem, without venturing on the whole, and may fuppofe that the earth, or at leaft the external cruft of it, has been fluid by fire, though we do not inquire into the caufe of this fire, or into the manner in which it was produ- ced. It is indeed true, that, when this is done, we have not the fame fort of abfurdity to encoun- ter that we met with in the Neptunian fy- ftem, and that the Vulcanic theory does not, like it, come into dire@ collifion with an axiom of geometry. There are, neverthelefs, great objections to it; for though all the pheno- mena of the mineral kingdom atteft a flui- dity of igneous origin, yet it is a fluidity that was never more than partial; and though it has been over all the earth, has been over it in {ucceflion only. Befides, we are not entitled to 496 ILLUSTRATIONS OF THE to aflume the exiftence, and again the difappear- ance of fuch a great quantity of heat, without af- figning fome caufe for the change. 434. Since, then, neither the hypothefis of the Neptunifts or the Vulcanifts, affords any good explanation of the figure of the earth, or fuch 4 one as can connect it with the other appear- ances in its natural hiftory, it remains to Im- quire, whether the fyftem that fuppofes a partial and fucceffive fluidity, like Dr Hutton’s, has any refource for explaining this great phenome- non. | Of this fabje& Dr Hutton has not treated; and when I was firk made acquainted with his fyfiem, it appeared to me a very ferious ob- jection to it, that it did not profefs to give an explanation of fo important a fact as the oblate figure of the earth: On confidering the matter more clofely, however, I found that there were principles contained in it from which a very fa- tisfactory folution (and, I think, the only fatis- faory folution) of that difficulty might be dedu- ced. This folution I fhall endeavour to explain, in as far, at leaft, as is neceffary for the purpofe of general illuftration. It is laid down in Dr Hutton’s theory, that the furface of the earth is perpetually changed by the detritus of the land; and that from the materials HUTTONIAN THEORY. 497 materials thus afforded, new horizontal ftrata are perpetually formed at the bottom of the fea. If this be true, and if the alternations of decay and renovation have been often repeated, it is certain, that the figure of the earth, whatever it may have originally been, muft be brought ° at length to coincide with the {pheroid of equi- librium. l 435. Here it is neceffary to remark, that the expreflions, figure of the earth, and /urface of the earth, are each of them occafionally taken in two different fenfes. The furface of the earth, in its moft obvious ` fenfe, is that which bounds the whole earth, and includes all its inequalities ; it is a furface ex- _ tremely irregular, rifing to the tops of the moun- tains, def{cending to the bottoms of the valleys, and having the continuity of its curvature often interrupted, or fuddenly changed. This may „be called the actual furface,and the figure bound- i T ed by it, the actual figure, of the earth. The furface of the earth, in another fenfe, is one that is every where horizontal, and is the fame which water affumes when at reft. This fuperficies is ‘determined by the cir- cumftance of its being conftantly perpendicular to the direction of gravity; it is the furface marked out by levelling, and may. be fuppo- fed to be continued from the fęa, through the ‘ | Ti ; interior 498 ILLUSTRATIONS OF THE interior of the land, till it meet the fea again. The figure bounded by this horizontal furface, may properly be called the /fatical figure of the . earth. When it is gi that the figure of the earth “is an oblate fpheroid, it is the ftatical, not the aftual figure which is meant; and the de- grees of the meridian which aftronomers mea- fure, -are alfo referred to the Sapir icma of the former. 436. Suppofe now a body like the. earth, but i its a@tual figure infinitely more irregular, having a fea circumfuled around it, the water will defcend into the loweft fituations, and will ` fo atrange itfelf, that its furface fhall be per- pendicular every where to the plumb-line, or to the direction of gravity, in which ftate only it can remain at reft. The figure of the fu- perficies which the fea muft thus take will be of a continuous curvature, and will return ins. a to itfelf; though it may, if the actual figure ~ is very irregular, be far either from a {phere or a fpheroid. If, however, we fuppofe the folid parts of this mafs fubje& to be diffolved or worn away, and carried down to the ocean, * there will be a tendency td give to the whole body the fame figure that it would have affumed, if it had been entirely fluid, and fubje& to the laws 4 = HUTTONIAN THEORY. 499 Jaws of hydroftatics. This tendency is the re- fult of two principles. 437. Let us fuppofe the body juft deferibed to have no rotation, fo that the particles of it are o auated only by the forces of cohefion and of attraction. It is then clear, that every particle taken away by attrition from the parts above the level of the fea, and depofited under the furface-of it, makes the general figure more compact, bring- ing the remoter parts nearer to the centre of gravity of the whole; fo that, in time, if the body is homogeneous, “all the points of the furs face will become equally diftant from. that cen- tre. Thus the affual figure changes continually, and approaches nearer to the ftatical, — _ While this change is going forward in the } Mual figure, there is another produced on the = ftatical, that tends very much to accelerate the ei coincidence of the two. rs The effect of the inequalities of the bind. that _ rife above the horizontal furface, i is, by their at- traction, to render the parts of that furface imme- - diately under them, more convex, ceteris pari- * bus, than the reft. Again, where there are parts of extraordinary depth in the fea, that is, where - the folid and denfer parts are far removed from the furface af the ocean, the curvature of the fu- - a lia ae Lpoticlee * BOO ILLUSTRATIONS OF THE perficies of the fea is thereby diminifhed, and that fuperficies is rendered lefs convex than it would be if the fea were fhallower. Thefe propofitions: are both capable of ftri& mathematical demon- itration. Hence the taking away of any particle ' of matter from the top of a mountain tends to di- minith the curvature of the horizontal furface un- der the mountain, where it is greateft; and the depofition of the fame particle at the bottom of the fea, tends to increafe the’curvature of this fuperficies where it is leaft. The general ten- dency, therefore, being to increafe the curva- ture.where it is leaft, and to diminith it where it is greateft, muft be to bring about an uniform curvature throughout, that is, a fpherical figure. Thus, by the wafte and fubfequent ftratification of the land, the direction of gravity is continu- ally altered ; it is more and more concentrated, and the figure brought nearer to that which a fluid would affume. 438. Ifnow we fuppofe the body to tee on its axis, all other things remaining as before, the furface bounding the fea will become different from what it was in the former cafe, and will be more fwelled out toward the middle or equatorial regions. The land above the level of the fea will itill, as before, be worn down and depofited in the bottom of the fea, fo as to form ftrata nearly parallel to its furface ; the tendency, therefore, : 1S os HUFTONIAN THEORY; sot is to render the real figure of the planet nearer to the ftatical, At the fame time the /fatical fi- gure is changed, as explained above; fo that the two figures mutually approach, and the limit, or ultimate figure to which they tend, is one. over which the ocean might be diffufed every where to the fame depth, for then the caufes of change would entirely ceafe. But this figure is no other thën the {pheroid of equilibrium, which, therefore, is the effet which the wafte and re- confolidation of the land would necefiarily pro- duce, if the procefs were continued indefinitely, without interruption, In this, asin many other ` inflances, when a body is fubje@ to the action _ of caufes by which its form is gradually chan- ged, the figure beft adapted to refift thofe chan- ges, is the figure which the changes themfelves ultimately produce, Alfo, whatever be the irregularities of denfi- s ty, the tendency to a change of figure will not ceafe till the body is moulded into that particu- lar fpheroid which admits of being covered with water every where to the fame depth *. Thus Bis. ite A * In the fame mariner as a tranfition i is thus made from an irregular figure toa fpheroid of equilibrium, fo, if the actual figure were at firft more Gimple than the {pheroid, it would ftill be changed into this laft by degrees, Let 602 ILLUSTRATIONS OF THE it appears, that a folid of an irregular figure, and of irregular denfity, provided it be in part co- ` vered De E EGRO e Let us conceive, for inftance, that the earth is at reff, and is a perfe& {phere of folid matter, furrounded by an ocean every where of equal depth, for example, of one mile. Then, if a rotatory motion be communicated to it, fo that it fhall revolve on its axis in twenty-four hours, in confequence of the centrifugal force, the water circum- fufed about the {phere will immediately rife up under the equator, and will become part of a {pheroidal furface, (not _ elliptical, but nearly fo), the equatorial diameter of which is greater than the polar axis, in the ratio of 588 to 577- By this means the water will be accumulated at the equa- tor to the depth of nearly 2.5 miles, and form a zone fur- rounding the earth, and extending about 37° on each fide of the equator. The remainder of the furface will be left dry, forming two vaft circumpolar continents, that reach 53° on.every fide of the poles, and that are: elevated in the middle more than four miles above the level of the fea. | Such would-be the ftate of our globe, on the hypothe- fis above laid down; and, if there were no wafte or de- ftru€tion of the land, this order of things would be per- manent, and neither the folid nor fluid part of the mafs: could ever acquire any other figure than that which has been defcribed. But, if the fame laws be fuppofed to regulate the action of the atmofphere in thofe circum- ftances, that do a€tually regulate it according to the pre- fent conftitution of the globe, the vapours raifed up from the furface of the fea, would be carried by the winds Over HUTTONIAN THEORY. 503 vered with water; and be at the fame time fub- ject to wafte above the furface of the fea, and reconfolidation under it; has a tendency to ac- quire, in time, the fame figure that it would have megurted h had it beeti entirely fluid, Tig 439. In A over the land, where they would be condenfed and preci- pitated in rain. Thus, all the agents of deftruétion would be let loofe on the two great circumpolar continents ; rivers would be formed; the land would become deeply interfected by ravines; thofe ravines would gradually open into wide valleys; the maffes of greateft refiftance would be fhaped into hills and mountains: and from a fuperficies originally {mooth and uniform, the fame inequalities would be produced which at prefent diver- fify the furface of the earth. While the parts of the {phere without the fpheroid _ are thus continually diminifhed, the loofe earth and fand wathed down from them, will be depofited at the bot- ` tom of the fea, and will form ftrata parallel to the fut- face of the fuperincumbent water: The actual and fta- tical figure are thus brought nearer one another; and, at the fame time the ftatical is changed, on the principle already explained (the change in the diré@ion of gravi- ty), and is made continually to approximate to a fate, which when it has attained, no farther change can take place, viz. an oblate elliptic {pheroid, of which the fur- face is perpendicular to the dire&ion of gravity, having the equatorial diameter to the polar axis in the ratio of 230 to 229. » 504 ILLUSTRATIONS OF THE 439. In the preceding reafonings, we have fup» pofed the procefs of decay and fubfequent ftratifi- cation to be carried on without interruption, till the whole of the land is covered by the fea. This fuppofition is ufeful for explaining the nature of the forces-which have determined the figure of the earth; but there is no reafon to think-that it has ever been realized in its full extent, the elevation of ftrata from the bottom of the fea in- terrupting the progrefs, and producing new land in one place as the old decays in another. The very fame land alfo, which is wafted at its furface, may perhaps be lifted up by the forces that are placed under it ; or it may be let down, ~ undergoing alterations of its level, from caufes - that we do not perceive, but of which the a@tion is undoubted (§ 387). But notwithftanding thefe interruptions, the general tendency to produce in the earth a {pheroidal figure may remain, and ` more may be done by every revolution, to bring about the attainment of that figure than to caufe a deviation from it. This figure, therefore, though never likely to be perfe@tly acquired, will be the miting or afymptotic figure, if it may be fo called, to which the earth will continually approach. 440. If the preceding conclufions are juft, and if the figure of equilibrium is only an afympto- tic figure, to which that of the earth may ap- proximate, ! x ) = = + I j n (| Y HUTTONIAN THEORY. 50% proximate, but cannot perfectly attain, we are not to be furprifed if confiderable deviations from it are actually obferved. This has accord- ingly happened, infomuch, that the refults de. duced from the moft accurate meafurement of degrees of the meridian, differ from ‘one ano- ther, in the oblatenefs they give to the earth, by nearly one-half of the quantity to be determi- ned. When we compare the degrees meafured in France, and in fome other countries of Eu- rope, with thofe meafured in Peru, we obtain for the compreffion at the poles, lefs than ig of _the radius of the earth. But when we compare „the degrees meafured in France with one ano- ther, and with thofe lately meafured in Eng- land, we find that-they are beft reprefented by a {pheroid that has its compreffion =a of its fe. mi-axis*, There is reafon to think, therefore, that the meridians are not elliptical ; and other obfervations feem to fhow, that they are not even fimilar to ‘one another ; or that the earth is not, ftrictly {peaking, a folid of revolution ; fo, alfo, _ the comparifon of the degree meafured at the Cape of Good Hope, with thofe meafured on the oppolite * Expofition du Syftéme du Monde, par La Place, P- 61. 2d edit, 266 ILLUSTRATIONS OF THE oppofite fide of the equator, creates a fufpicion; b that the northern and fouthern hemifpheres are A not perfectly alike, and that the earth is not e- fe qually comprefied at the Arétic and the Antarctic o! poles» Thefe irregularities, though they do not th affect the general fa&t of the earth’s compreflion ec at the poles, thew that the true ftatical figure is its but imperfe&ly attained; and though this may ot ~ be accounted for, without having recourfe to the he principles involved in our theory, it is in a mán- fir ner very unfatisfatory, and, by help of fuppofi- br tions, not at all confiftent with the original flui- or dity afcribed to the whole mals, or to the exte- di rior cruft of the earth. " ot 441. As the principles here iai down ii o'th how a folid body may attain very nearly the | pl figure which a fluid would acquire in order to ii preferve its parts in equilibrio ; and fince the i oblate figure belongs to other of the planets as | well as the earth, and the globular to all the a great bodies of the univerfe, this fuggefts an ana- in logy that goes deep into the economy, of na- Ky ture, and extends far beyond the limits within fa which the mineralogift is wont to confine his fs fpeculations. 442. That no very irregular figure is found ~ 4 S among the planetary bodies, may therefore be E confidered as a proof of the univerfality of that d ae fyftem of wafte and reconfolidationthatwehave | th been of HUTTONIAN THEORY. so% been endeavouring to trace in the natural hifto- ry of the earth. A farther proof of the fame ari- fes from confidering, that for every given mafs of matter, having a given period of rotation, there are two different {pheroids that anfwer the conditions of eftablifhing an equilibrium among its parts, the one near to the {phere, and the other very diftant from it, and fo oblate as to have a lenticular form. Thus the earth, fuppo- fing it homogeneous, might either be in equili- brio, by means of the figure which it actually has, or of one in which the polar was to the equatorial diameter as 1 to 768. The fame is true of the ` other planets; and yet we no where find that ad ‘this highly comprefled fpheroid is a&tually em- | ployed by nature. The reafon, no doubt, is, that in fo oblate a {pheroid, the equilibrium between "the gravitating and the centrifugal force is of the kind that does not re-eftablifh itfelf when dif- turbed ; fo that the parts let loofe, and not kept in their place by firm cohefion, would fly off al- together. In fuch a body, the wafte at the fur- face would lead to an entire change of form, and - therefore the conftitution here fuppofed could not be permanent. 443. In the fyftem of atara, we have a great deviation from the general order, which, never- _ thelefs, has led to a very unexpected verification of fome of the conclufions deduced above. A principle so8 ILLUSTRATIONS OF THE EP principle extremely like that which is the bafis | b of all the foregoing reafonings, led one of the | 8 greatet philòfophers of the prefent age to dif- | tl cover the revolution of Saturn’s ring on its axis, ~ | th and even to determine the velocity of that revolu- | ci tion, fuch as it has been fince found by obferva- là tion. La Pracer, laying it down as a maxim, that T pe nothing in nature’can exift, where there are cau- ow fes of change, not balanced or compenfated by br other caufes *, concluded, that the parts of the as ring muft be held from falling down to the body th of the planet by fome other force than their mere i cohefion to one another. Were it otherwife, every ‘s i K particle detached from the ring, by any means, g muf defcend in a Rraight line, almoft perpen-' ‘fo dicular to the furface of Saturn; and the final dı deftruction of the ring muft be inevitable. The | fe only force that could balance this effe& of gra- z E vitation, feemed to bea centrifugal force, ari- fing from the rotation of the ring on an axis ~~ pafling through its centre, and perpendicular to of its plane. La Place proceeded to inquire what f d celerity of rotation was adequate to this effet, = | be and found that one of ten hours and a quarter OV would be required, which is almoft precifely an the time afterwards determined by Dr Her- ` | di scHEL from actual obfervation. If, with this | ag : _ rotation, aa W —— ec > x fu * La Place, ubi fupra, p. 242. ` HUTTONIAN THEORY. 509 N rotation, the ring is a folid annulus generated by the rotation of a very flat ellipfis about a given point in its greater axis, coinciding with the centre of Saturn, it may be fo conftituted, that the attraction of Saturn, combined with the centrifugal force, may produce a force perpen- dicular to its furface, and may enable detached parts to remain at reft, animals, for inftance, to walk on its furface, and fluids to be in equili- brio. The fyftem of Saturn is thus fortified againit the lapfe of time, as effectually as that of _ the earth itfelf; and the means by which this is accomplifhed, feem to prove, that the weapons _ which time employs, are in both cafes the fame, „viz. the flow wearing and decompofition of the olid parts. This flow wearing may have pro- duced the figure by which its a&tion is moft e£- _, fefually refitted. : 444. Thus Dr Hutton’s theory of the earth comes at laft to connect itfelf with the refearches of phyfical aftronomy. The conclufion to be drawn from this coincidence is to the credit of both fciences. When two travellers, who fet out from points fo diftant as the mineralogift and the aftronomer, and who follow routes fo different, meet at the end of their journey, and agree in their report of the countries through which they have paffed, it affords no flight pre- fumption, that they have ‘kept the right way, : ee and ir . 4) i : » ee E >- f; 510 ILLUSTRATIONS OF THE and that they relate what they have 2aually | d > feen. i | wpe Nore xxvi. § 133. d tic | Prejudices relating to the Theory of the Earth, | A 445. Among the prejudices which a new the- | ory of the earth has to overcome, is an opinion, | held, or affected to be held, by many, that geo- | a logical fcience is not yet ripe for fuch elevated { to and difficult {fpeculations. ‘They would, there- 17 fore, get rid of thefe fpeculations, by moving the s ha previous queftion, and declaring that at prefent col th we ought to have no theory at all. We are not | fee yet, they allege, fufficiently acquainted with the pa phenomena of geology ; the fubje& is fo various al and extenfive, that our knowledge of it muft for _ i all a long time, perhaps for ever, remain extremely ; “ch imperfe&. And hence it is, that the theories th hitherto propofed have fucceeded one another fl with fo great rapidity, hardly any of them ith having been able to laft longer than the difcoyery ha ofa new fad, or a fa& unknown when it wasin- ' fo vented. It has proved infufficient to conneét this © : 2 fact with the phenomena already known, and has therefore been juftly abandoned. In this man- ner, they fay, have pafled away the theories of Je Woodward, Burnet, Whifton, and even of Buf- i Pi fon; TR ee a ‘HUTTONIAN THEORY. sır , & “fon; and fo will pafs,*in their turn, thake of Hutton and Werner. 446. This unfavourable view of geology, a not, however, to be received without examina- tion ; in fcience, prefumption is lefs hurtful than defpair, and inactivity is more dangerous than error. 3 One reafon of the rapid fucceffion of geolo- gical theories, is the miftake that has been made as to their object, and the folly of attempting to explain by them the firft origin of things. This miftake has led to fanciful {peculations that had nothing but their novelty to recommend them, and which, when that charm had cea- fed, were rejected as mere fuppofitions, inca- able of proof. But if it is once fettled, that a E assy of the earth ought to have ‘no other „aim but to difcover the laws that regulate the changes on the furface, or in the interior of the globe, the fubjeét is brought within the {phere either of obfervation or analogy; and _ there is no reafon to fuppofe, that man, who has numbered the ftars, and meafured their forces, fhall ultimately poe unequal to this in- = veftigation. 447. Again, theories = have a rational ob- je&, though they be falfe or imperfe&t in their principles, are for the moft part approximations to the truth, fuited to the information at the time LELEnE 5r2 ILLUSTRATIONS OF THE time when they were propofed. They are fteps, A therefore, in the advancement of knowledge, a and are terms of a feries that muft end when gr the real laws of nature are difcovered. It is, on | of this account, rath to conclude, that in the revo-’ | ing lutions of fcience, what has happened muft con- À tinue to happen, and becaufe fyitems have chan- T the ged rapidly in time paft, that they muft neceffa- — | ext rily do fo in time to come. ; | anc He who would have reafoned fo, aad who fes had feen the ancient phyfical fyftems, at firft all Wi ‘yivals to one another, and then {wallowed up by | gré the Ariftotelian; the'Ariftotelian phyfics giving thë way to thofe of Des Cartes; and the phyfics of | fe Des Cartes to thofe of Newton ; would have prez and di&ed that thefe laft were alfo, in their turn, to | dep give place to the philofophy of fome later period. . phe This is, however, a conclufion that hardly any , 6G one will now be bold enough to maintain, after | ae a hundred years of the moft f{crupulous exami- | cda nation have done nothing but add to the evie Th dence of the Newron1an System. It feems | s certain, therefore, that the rife and fall of theo- | 3 | ries in times paf, does not argue, that the fame i will happen in the time that is to come. pom 448. The multifarious and extremely diverfi- | adh fied object of geological refearches, does, no doubt, . the render the firft fteps difficult, and may very . Ply; well Te HUTTONIAN THEORY. = 373 well account for the inftability hitherto obfer- ved in fuch theories; but the very fame thing gives reafon for expecting a Very high degree of certainty to be ultimately attained in thefe inquiries. Where the phenomena are few and fimple, there may be feveral different theories that will explain them in a manner equally fatisfa@ory ; and in fuch cafes, the true and the falfe hypothe- fes are not eafily diftinguifhed from one another. When, on the other hand, the phenomena are greatly varied, the probability is, that among them, fome of thofe inflantie crucis will be found, that exclude every hypothefis but one, | E reduce the explanation given to the higheit degree of certainty. It was thus, when the _ phenomena of the heavehs were but imper- -fely known, and were confined to a few ge- neral and fimple faéts, that the Philolaic could claim no preference to the Ptolemaic fyfem : The former feemed a poflible hypothefis ; but as it performed nothing that the other did _ Mot perform, and was inconfiftent with fome of our moft natural prejudices, it had but few adherents. The invention of the telefcope, and the ufe of more accurate inftruments, by multi- plying and diverfifying the facts, eftablifhed its credit; and when not only the general laws, but alfo the inequalities, and difturbances of Kk the ? ee 514 ILLUSTRATIONS OF THE the planetary motions were wunderftood, all id phyfical hypothefes vanifhed, like phantoms, J” before the philofophy of Newron. Hence the A number, the variety, and even the complica- th tion of faéts, contribute ultimately to feparate. ia truth from falfehood; and the fame caufes which, ob in any cafe, render the firt attempts toward a 5° theory difficult, make the final fuccefs of fuch wi attempts juft fo much the more. probable. i oe This maxim, however, though a general en- tio couragement to the profecution of geological [ fec inquiries, does. not amount to a proof that we- an are yet arrived at the period when thofe inqui- in ries may fafely affume the form of a: theory. | the But that we are arrived at fuch a period, appears, ‘the clear from other circumftances. | a 449. It cannot be denied, that a great multi- bra tude of facts, refpecting the mineral kingdom, are the now known with confiderable precifion ; and. por that the many diligent and {kilful obfervers, who. ane have arifen in the courfe of the laft thirty years, at have produced. a great change in the ftate of geo- tole logical knowledge. It is unneceflary to enu- | ar merate them all; Frerper, Beraman, De Luc, Saussure, DoLomiev, are thofe on whom Dr | í Hutton chiefly relied; and it is on their obfer- j vations and his own that his fyftem is founded. p If it be faid, that only a fmall part of the earth’s furface has yet been Boba and defcribed. oh y with HUTTONIAN THEORY: BIg with fuch accuracy as is found in the writers juft named, it may be anfwered, that the earth is conftructed with fuch a degree of uniformity, that a tract of no very large extent may afford _ inftances of all the leading facts that we can ever © obferve in the mineral kingdom. The variety of geological appearances which a traveller meets with, is not at all in proportion to the extent of country he traverfes ; and if he take ina por- tion of land fufficient to include primitive and : fecondary trata, together with mountains, rivers, and plains, and unftratified bodies in veins and | in maffes, though it be not a very large part of the earth’s furface, he may find examples of all p moft important facts in the hiftory of foffils. Though the labours of mineralogifts have em- braced but a fmall part of the globe, they may _ therefore have comprehended a very large pro- portion of the phenomena which it exhibits ; and hence a prefumption arifes, that the outlines, at leaft, of geology have now been traced with tolerable truth, and are not fufceptible of great Variation. 450. When the phenomena of any clafs are in general ambiguous, and admit of being ex- plained by different or even oppofite theories ; if few of thofe exclufive fads are known, which admit but of one or a few folutions, then we f have no right to expe& much from our en- deavours to generalize, except the knowledge mT Bk of ae s16 ILLUSTRATIONS OF THE of the points where our information is moft de- i ficient, and to which our obfervations ought © chiefly to be directed. But that many of the bi exclufive and unambiguous inftances are known, I in the natural hiftory of the globe, I think is of evident from the reafoning in the foregoing pa- the ges, where fo many examples have occurred of Ve appearances that give the moft direct negative fte to the Neptunian fyftem, and exclude it from afl the number of poflible hypothefes, by which the phenomena of geology can be explained. The a be Ce) abundance of fuch inftances is an infallible fign, -Sa that the mais of knowledge is in that ftate of fer- i thg mentation, from which the true theory may be — tio expected to emerge. | he 451. Another indication of the fame kind, is the | po neat approach that even the moft oppofite theo- fer ries make, in fome refpects, to one another. p There are fo many points of contact between nal them, that they appear to approximate to an ùl- | the timate ftate, in which, however unwillingly, | in, they muft at laft coincide. That ultimate form, | of too, which all thefe theories have a tendency to put on, if Iam not deceived, is no other than that of the Huttonian theory. F 452. The firft example I fhall take from the ay fyftem of Sauffure. It is to be regretted, that ih this excellent geologift has no where given us a cs complete account of his theory. Some of the | i Ne leading si Sa HUTTONIAN THEORY. 517 leading principles of it are, however, unfold- ed in the courfe of his obfervations, and ena- ble us to form a notion of its general outline. It was evidently far removed from the fyftem of fubterraneous heat, and feems, efpecially in the latter part of the author’s life, to have been very much accommodated to the prevailing fy- ftem of Werner. Neverthelefs, with fo little affinity between their general views, Sauffure and Hutton agree in that moft important. ar- ticle which regards the elevation of the ftrata. Sauffure plainly perceived the impoflibility of the ftrata being formed in the vertical fitua- tions which fo many of them now occupy; and he takes great pains to demonftrate this im- poflibility, from fome facts that have been re~ ferred to above. He alfo believed that this ele- vation had been given to ftrata that were origi- nally level, by a force directed upwards, or by the refoulement of the beds, not by their falling in, as is the opinion of De Luc and fome other of the Neptunitts. Now, whoever admits this principle, and rea- fons on it confiftently, without being afraid to follow it through all its confequences, muft un- avoidably come very clofe to the Huttonian theory. He muft fee, that a power which, a&t- ing from below, produced this great effect, can never have belonged to water, unlefs rarefied Kk 3 into a s18 ILLUSTRATIONS OF THE ` into team by the application of heat. But if it | Di be once admitted that heat refides in the mine- ft ral regions, the great objection to Dr Hutton’s i fyftem is removed ; and the theorift, who was ii furnifhed with fo a&ive and fo powerful an agent, would be very unfkilful in the manage- ie ment of his own refources, if he did not employ ` it in the work of confolidating as well as in that lo of raifing up the ftrata. A little attention will | fhew, that it is qualified for both purpofes ; th though infuperable objeCtions mutt, no doubt, . offer themfelves, where the effets of compref- 9 fion are not underftood, We may fafely con- th clude, then, that the accurate and ingenious Ore- he ologift of Geneva ought to have been a Piu- | oe zonift, in order to give conliftency to the princi- hi ples which he had adopted, and to make them coa- af lefce as parts of one and the fame fyftem. If he | de embraced an oppofite opinion, it probably was it from feeling the force of thofe objections that ca arife from our difcovering nothing in the bowels D of the earth like the remains left by combuftion, ce or inflammation, at its furface. The fecret by th which thefe feeming contradictions are to be re- | th conciled, was unknown to this mineralogift, and a he has accordingly decided ftrongly againft the a action of fire, even in the cafe of thofe unftratified ae fubftances that have the ereateft affinity to vol- S canic lava. l f 453. The HUTTONIAN THEORY. s519 453. The theoretical conclufions of another ac- curate and {kilful obferver, Dolomieu, furnifh a ftill more remarkable example of a tendency to union between fyftems profefledly hoftile to one another. This ingenious mineralogift, obferving the in- terpofition of the bafalt between ftratified rocks, fo that it had not only regular beds of fandftone for its bafe, but was alfo covered with beds of the fame kind, faw plainly that thefe appearan- ces were inconfiftent with the fuppofition of =. common volcanic explofions at the furface. He therefore conceived, that the volcanic eruption had happened at the bottom of the fea, (the le- vel of which, in former ages, had been much higher than at prefent), and that the materials - afterwards depofited on the lava, had been in length of time confolidated into beds of ftone. ft is evident, that this notion of fubmarine vol- canoes, comes very near, in many refpedts, to Dr Hutton’s explanation of the fame appearan- ces. If the only thing to be accounted for were the phenomenon in queftion, it cannot be denied that Dolomieu’s hypothefis would be perfe@ly fufficient ; but Dr Hutton, to whom this phe- | nomenon was familiar, and who, like Dolomieu, conceived the bafalt to have been in fufion, was convinced that the retreat of the fea was not a fact weil attefted by geological appearances, and Kk4 if s20 ILLUSTRATIONS OF THE if admitted, was inadequate to account for the facts ufually explained by it. He conceived, therefore, that fuch lava as the preceding had flowed not only at the bottom of the fea, but in the bowels of the earth, and having. been forced up through the fiffures of rocks already formed, had heaved up fome of thefe rocks, and interpofed itfelf between them. This agrees - with the other facts in the natural hiftory both of the bafaltes and the ftrata. It is plain, that, in this, there is a great ap- proach of the two theories to one another : both maintain the igneous origin of bafaltes, and its affinity to lava; both acknowledge that this la- va cannot have flowed at the furfaee, and that the ftrata which cover it have been formed at the bottom of the fea. They only differ as to the mode in which the fubmarine or fubterra- neous volcano produced its effect, and that dif- ference arifes merely from the one geologift ha- ving generalized more than the other. Dolo- nieu fought to connect the bafalt with the la- vas that proceed from volcanic explofions at the furface; Dr Hutton fought not only to conned thefe ens appearances with one another, but al- fo with the other phenomena of mineralogy, particularly with the veins of bafaltes, and the elevation of the ftrata. - 454.In HUTTONIAN THEORY. sas - 454. In another point, the coincidence of Dolo- mieu’s opinions and Dr Hutton’s is ftill more ftriking. The former has remarked, that many of the extinguifhed volcanoes are in granite countries, and that, neverthelefs, the lavas that they have erupted contain no granitic ftones, ` There muft be, therefore, fays he, fomething un- der the granite, and this laft is not, at leaft in all cafes, to be confidered as the bafis of the miné- ral kingdom, or as the body on which all others reft. In this fyftem, therefore, granite is not always a primordial rock, any more than in Dr Hutton’s. : But Dolomieu makes a {till nearer advance to the Huttonian theory; for he {uppofes, that under the folid and hard cruft of the globe, there isa {phere of melted ftone, from which this bafaltic lava was thrown up. The fyftem of f{ubterraneous heat is here adopted in its ut- moft extent, and in that form which is confider- ed as the moft liable to objection, viz. the exift- ence of it at the prefent moment, in fuch a de- gree as to melt rocks, and keep them in a ftate of fufion. In this conclufion, the two theories agree perfectly; and if they do fo, it is only be- caufe the nature of things has forced them into union, notwithftanding the diffimilitude of their fundamental principles, This g22 ILLUSTRATIONS OF THE This ought to be confidered as a ftrong proof, that the phenomena known to mineralogifts are fufficient to juftify the attempts to form a theo- ry of the earth, and are fuch as lead to the fame conclufions, where there was not only no pre- vious concert, but even a very marked oppofi- as tion. Ihave already obferved, that there is a | greater tendency to agree among geological theo- ries, than among the authors of thofe theories. 455. Another circumftance worthy of confide- l ration is, that in the fearch which the Neptunifts have made, for facts moft favourable to the aque- ous formation of minerals, we find hardly any of ‘ a kind that was unknown to the author of the i fyftem here explained. The appearances on oe which WERNER grounds his opinion with re- i fpe& to bafaltes, and by which he would ex- ) clude the adion of fire from any fhare in the formation of it, are all comprehended in the ; alternation of that rock with beds, or ftrata ; obvioufly of aqueous origin. Now thefe ap- pearances were well known to Dr Hutton, and a are eafily explained by his theory, provided the | effets of compreflion are admitted. From this, and the other circumftances juft obferved, | am difpofed to think, that the great facts on which every geological fyftem muft depend, are now known, and that it is not too bold an anticipa- tion to fay, that a theory of the earth, which explaing _ HUTTONIAN THEORY. 523 explains all the phenomena with which we are at prefent acquainted, will be found to explain all thofe that remain to be difcovered. 456. The time indeed was, and we are not yet far removed from it, when one of the moft im- portant principles involved in Dr Hutton’s theo- ry was not only unknown, but could not be dif- covered. This was before the caufticity produ- ced in limeftone by expofure to fire was under- ftood, and when it was not known that it arofe from the expulfion of a certain aerial fluid, which before was a component part of the ftone. It could not then be perceived, that this aerial part might be retained by preflure, even in fpite of the action of fire, and that in a region where great compreflion exifted, the abfence of cautti- city was no proof that great heat had not been applied. The difcoveries of Dr Biack, therefore, mark an era, before which men were not qualified to judge of the nature of the powers that had ~ acted in the confolidation of mineral fubftances. Thofe difcoveries were, indeed, deftined to pro- duce a memorable change in chemiftry, and in all the branches of knowledge allied to it; and have been the foundation of that brilliant pro- grefs, by which a collection of praical rules, and of infulated facts, has in a few years rifen to the rank of a very perfect fcience. But even before they had explained the nature of carbo- nic z224 ILLUSTRATIONS OF THE pic gas, and its affinity to calcareous earth, I am i not fure but that Dr Hutton’s theory was, at ‘ leaft, partly formed, though it muft certainly f have remained, even in his own opinion, expo- f fed to great difficulties. His active and penetra- ting genius foon perceived, in the experiments £ his friend, the folution of thofe difficulties, and formed that happy combination of princi- ; ples, which has enabled him to explain the moft 5 enigmatical FRERE in the natural hiftory of $ ! the earth. . o i As we are not yet far removed from the time p * when our chemical knowledge was too imperfect ¥ to admit of a fatisfatory explanation of the phe- | t nomena of mineralogy, fo it is not unlikely that Š we are approaching to other difcoveries that ae. are to throw new light on this fcience. It Ls would, however, be to argue ftrangely to fay, ce. that we muĝ wait till thofe difcoveries are = made before we begin any theoretical reafon- a: ings. If this rule were followed, we fhould t not know where the imperfections of our fcience € lay, nor when the remedies were found out, Pee fhould we be in a condition to avail ourfelves of { them. Such condu& would not be caution, but í timidity, and an excefs of prudence fatal to all 1 philofophical inquiry. i 457. The truth, indeed, is, that in phyfical in- quiries, the work of theory and obfervation muft go HUTTONIAN THEORY. 525 go hand in hand, and ought to be carried on at the fame time, more efpecially if the matter is very complicated, for there the clue of theory is neceflary to direct the obferver. Though a man may begin to obferve without any hypothefis, he cannot continue long without feeing fome ge- neral conclufion arife ; and to this nafcent theo- ry it is his bufinefs to attend, becaufe, by feek- ing either to verify or to difprove it, he is led to new experiments, or new obfervations. He is led alfo to the very experiments and obferva- tions that are of the greateft importance, namely, to thofe inflantie crucis, which are the criteria that naturally prefent themfelves for the trial of every hypothefis. He is conducted to the places where the tranfitions of nature are moft percepti- ble, and where the abfence of former, or the pre- fence of new circumftances, excludes the action of imaginary caufes. By this correction of his firit opinion, a new approximation is made to the truth ; and by the repetition of the fame procefs, certainty is finally obtained. Thus theory and obfervation mutually affift one another; and the fpirit of fyftem, againft which there are fo ma- ny and fuch jut complaints, appears, nevertlic- lefs, as the animating principle of induive in- vettigation. The bufinefs of found philofophy is not to extinguifh this fpirit, but to reftrain and dire@ its efforts. | 458. It 226 ILLUSTRATIONS OF THE 458. It is therefore hurtful to the progrefs of phyfical fcience to reprefent obfervation and theory as ftanding oppofed to one another. Berg- — man has faid, ‘‘ Obfervationes veras quam in- geniofiffimas fictiones fequi preeftat ; nature my- {teria potius indagare quam divinare.” If itis meant by this merely to fay, that it is better to have fađts without theory, than theory without facts, and that it is wifer to inquire into the fecrets of nature, than to guefs at them, the truth of the maxim will hardly be controverted. But if we are to underitand by it, as fome may perhaps have done, that all theory is mere fiction, and that the only alternative a philofopher has, is _to devote himfelf to the ftudy of facts unconnect- ed by theory, or of theory unfupported by facts, the maxim is as far from the truth, as I am con- vinced it is from the real fenfe of Bergman. Such an oppofition between the bufinefs of the theorift and the obferver, can only occur when the fpeculations of the former are vague and in- diftinct, and cannot be fo embodied as to become vifible to the latter. But the philofopher who has afcended to his theory by a regular genera- lization of fas, and who defcends from it again by drawing fuch palpable conclufions as may be compared with experience, furnifhes the infalli- ble means of diftinguifhing between perfect fei- ence and ingenious fiction. Of a geological theory that HUTTCNIAN THEORY. 527 that has ftood this double teft of the analytic and fynthetic methods, Dr Hutton has furnifhed us with an excellent inftance, im his explanation of granite. The appearances which he obferved in that ftone led him to conclude, that it had been melted, and injected while fluid, among the ftratified rocks already formed. He then confi- dered, that if this is true, veins of granite muft often run from the larger mafles of that ftone, and penetrate the {trata in various directions ; and this muft be vifible at thofe places where thefe different kinds of rock come into conta& with one another. This led him to fearch in Arran and Glen-tilt for the phenomena in quef- tion; the refult, as we have feen, afforded to his theory the fulleft confirmation, and to himfelf the high fatisfaG@tion which muf ever accompa- ny the fuccefs of candid and judicious inquiry. 459. It cannot, however, be denied, that the impartiality of an obferver may often be affe&ted by fyftem; but this is a misfortune againtt which the want of theory is not always a com- plete fecurity. The partialities in favour of opi- nions are not more dangerous than the prejudi- ces againft them ; for fuch is the fpirit of fy ftem, and fo naturally a all men’s notions tend to re- duce themfelves into fome regular form, that the very belief that there can be no theory, becomes a theory itfelf, and may have no inconfiderable {way R < s . z pie EAE CAEN S f Í 228 ILLUSTRATIONS, &c. {way over the mind of an obferver. Befides, one | man may have as much delight in pulling down, as another has in building up, and may choofe to difplay his dexterity in the one occupation as well as in the other. The want of theory, then, does not fecure the candour of an obferver, and it may very much diminihh his fkill. The difci- pline that feems beft calculated to promote both, Gs a thorough knowledge of the methods of in- ductive inveftigation ; an acquaintance with the hiftory of phyfical difcovery ; and the careful ftudy of thofe fciences in which the rules of phi- lofophizing have been mof fuccefsfully applied. FINIS. RE SEES PEM E CAEN ED SSCA NF MARNE SALA RENE LP EEE ROR RS PRI LITRE IRN E DEEE ES LN \ V