GEOLOGY. 



This, wc believe, is now admitted by all thofe who have 

 had the moil extciifive range of obfervation. 



«' The fecondary ftrata are local formations, and lome ot 

 the upper ftrata were evidently formed in detached lakes or 

 inland feas. A ftiU more comprehenfive view will prove 

 that even all the ftratified rocks above the red fand-itone 

 and alpine lime-ftone are alfo local formations, which had 

 their origin in detached hollows or feas of great extent, but 

 which were limited to certain portions of the globe. i he 

 obfervation of travellers in different parts of the world m- 

 contellibly prove that thefe formations are local. I am even 

 inclined to confider tlie red fand-ttone and alpme lime-ftone 

 as local formations, but of greater extent than any of the 

 ftrata above them. If this view of the fubjeft were ad- 

 mitted, geologifts would be relieved from the great difficul- 

 ties under which the fcience labours at prefent, and it would 

 go far to eftablifli a iimple and perfpicuous fyftem, which 

 will at once account both for the fimilarity and diverfity of 

 rock formations in various parts of the world. If the 

 mountains were once much higher than at prefent, it muft 

 be admitted, that before the formation of the fecondary 

 ftrata the valleys and hollows were deeper in a far greater 

 proportion, becaufe to the height of tlie furrounding moun- 

 tains we muft add the whole depth of the fecondary ftrata 

 which were then wanting. By whatever procefs the fecond- 

 ary ftrata were formed, the exiftence of organic remains in 

 them inconteftibly proves that they were depofited in fuc- 

 cefiion, and the regular manner in which they are fpread 

 over each other further proves that the greatec-part of them 

 were depoilted in a fluid medium. As there are incontefti- 

 ble proofs that water once covered nearly all the exifting 

 continents, it follows, that when the ocean retired, or, 

 wliich is the fame thing in effeft, when the dry land emerged 

 from the fea, vaft inland lakes or feas would be left at the 

 bottom, of which tlie fecondary ftrata were formed. As 

 the fea retired further, the higher grounds being left dry, 

 thefe inland feas or lakes would become contradled, and a 

 number of fmaller lakes would occupy the loweft cavities 

 and depreffions, in each of which feparate depofitions of 

 ftrata might take place. The lower ftrata would be the 

 moft widely fpread, and the upper would conftitute de- 

 tached or infulatcd formations of greater or lefs extent, in 

 which there might be a great ilmilarity in fome fituations, 

 and a great diverfity in others. Now fuch is found to be the 

 faft." (Bakewell's Introduction to Geology, 2d ed. chap.x.) 

 This view of the fubjeft, we think, receives much fupport 

 from the pofition of the mountain ranges in Europe, as 

 may be feen in Mr. Arrowfmith's excellent map, in which 

 the phyfical geography is diftinftly marked. Thefe ranges 

 form the borders of numerous bafms, which muft evidently 

 have once been the boundaries of inland feas when the 

 ocean retired from the prefent continents. 



Though great diverlity may prevail in the fuccelTion of 

 the ftrata in different parts of the world, yet there are cer- 

 tain rock formations that we may regard as univerfal, 

 without afferting that they were formed at the fame epoch 

 in very diftant countries ; for it is only where organic re- 

 mains of the fame fpecies occur in rocks that we may infer 

 that their formation was cotemporaneous. In the prefent 

 ftate of our information, we may regard granite as the 

 loweft and moft extenfive rock, forming the foundation of 

 all other rocks or ftrata, where we have opportunities of 

 tracing their fucceffion. With granite we include gneifs, 

 and alfo mica-date, which may be regarded as granite in a 

 fchiftofe form, but with one or other of the ingredients 

 nearly wanting, or occurring in a very fmall proportion. 

 (See Rocks, Granite, Gneiss, and Mica-Slate.) 



Clay-flate (fee Slate) generally covers the granite, 

 gneifs, or mica-date, and may be regarded as a univerfal 

 formation, or, pei-haps more correftly, as a general cover- 

 ing of granite, gneifs, and mica-date. The date form- 

 ation contains various anomalous beds of porphyry, 

 compaft felfpar, lime-ftone, hornblende, ferpentine, and 

 fienite. ( See Pokphyry, Felsi'AR, &c. ) No obfervable 

 regularity has yet been difcovered in the fucceffion of thefe 

 latter rocks in different countries, and fome of them may 

 often be obierved paffmg by gradation into each other. 

 They have generally a cryftalhne ftrufture in the vicinity of 

 granite (fee Rocks), and have not been obferved to contain 

 organic remains. 



The beds of rock which cover date appear, many of them, 

 to be a coarfer kind of date, with an intermixture of quartz, 

 or other minerals, until at laft they lofe the charafter of 

 date, and become fand-ftone. This coarfe date, in its paf- 

 fage from date to fand-ftone, forms that kind of rock which 

 has been denominated grey wackc or wacce. Various beds 

 of lime-ftone occur in the coarfer date. Of thefe, the 

 moft confiderable in England is called the mountain 

 lime-ftone : it has a fubcryftalline ilrutlure ; it abounds in 

 organic remains in many parts, and contains metalliferous 

 veins, principally of lead and zinc. This lime-ftone lies below 

 all the principal coal formations in England and Wales. 

 (See Strata.) Between this lime-ftone, and a dark grey 

 compaft lime-ftone called lias, occur the coal ftrata, with the 

 various beds of fand-ftone and ftiale. The order of fuccef- 

 fion of thefe beds is not fimilar in different diitricts. The 

 lias ftratum is the moft remarkable in England, both for its 

 regularity and extent, and the organic remains which it 

 contains. The fame ftratum occurs in Flanders. The 

 ftrata above the lias were firft correftly defcribed by Mr. 

 Farey, whofe account we have given in the article Strata. 

 ( See Strata. ) The ftrata above the lias occur with remark- 

 able regularity over a great part of the eaftern fide of 

 England, defcribed by Mr. Bakewell, in his Geology, as the 

 ' low diftrift,' extending in a waving line from Dorfetftiire to 

 the county of Durham, and delineated in his map. Thefe 

 ftrata confift of a fucceffion of beds of roe-ftone, or oolite, 

 (fee Roe-stone,) and coarfe lime-ftone, with thick beds of 

 fand and clay, over which occurs the chalk. Thefe beds 

 are arranged with great regularity compared with the beds 

 that occur between the lias and the mountain lime-ftone ; but 

 the order of fucceffion and thicknefs, particularly of the 

 oolite, is variable ; for in many parts, beds of vaft thicknefs 

 occur which are not found in other fituations, and in fome 

 fituations the oolite is entirely wantijig, and the green fand, 

 inftead of covering it, refts immediately on the lias. See 

 Mr. Bakewell's feftion of the ftrata, Plate III. fg. 2. 

 Geology. 



A tabular arrangement of the ftrata of England, given 

 by Mr. Buckland, profeffor of mineralogy at Oxford, has 

 recently been pubhdied, which we fhaU prefent to our 

 readers. At the fame time we muft obferve, that they 

 would be greatly miftaken were they to fuppofe that the 

 whole of thefe rock formations had ever been obferved in 

 any one fituation in England or elfewhere, or that the 

 ftrata preferve the thicknefs here given throughout their 

 whole extent. There is no part of England, we believe, 

 in which all the ftrata here enumerated could be found, 

 were it poffible to perforate through them. The table may 

 be regarded as an approximation to the true order of fuc- 

 ceffion whenever feveral of thefe formations occur in the 

 fame diftrift, and the localities annexed will make it both 

 interefting and ufeful. Perfons who ftudy nature in their 

 clofets are difpofed to behcve, that the tliicknefs of the 



ftrata 



