GEOLOGY. 



tive-trap ; 7, serpentine ; 8, porphyry ; 

 9, sienite * 10, topaz rock; II, quartz 

 rock ; 12, primitive flinty slate ; 13, pri- 

 mmve g> psuin ; 14, white stone. The 

 circumstances which chiefly mark the 

 high antiquity of these rocks are, that 

 they form the fundamental rock of the 

 other classes ; and that the outgoings of 

 their strata are generally higher than 

 those of the other classes. Having been 

 formed in the uninhabitable state of the 

 gloue, they contain no petrifactions; 

 and, excepting the small portions which 

 sometimes accompany those which will 

 be next mentioned, they contain no me- 

 chanical deposits, but are throughout 

 pure chemical productions. Small por- 

 tions of carbonaceous matter occur only 

 in the newer members of the class. 



Before the summits of the mountains 

 appeared above the level of the ocean, 

 and before the creation of vegetables and 

 animals, a rising of the waters is supposed 

 to have taken place, during which that 

 class of rocks which are said to be of the 

 second porphyry and sienite formation 

 was deposited. The rocks of this forma- 

 tion are of clay-porphyry, pearl-stone 

 porphyry, obsidian porphyry, sienite, and 

 pitch-stone. They contain very little 

 mechanical depositions, are of complete 

 chemical formation, and contain little or 

 no carbonaceous matter, and never any 

 petrifactions. 



On the appearance of land, or during 

 the transition of the earth from its chao- 

 tic to its habitable state, rocks, which, 

 from this circumstance, are denominated 

 transition rocks, were formed. In these 

 rocks the first slight traces of petrifac- 

 tions, and of mechanical depositions, are 

 to be found. The species of rocks which 

 come under this class are, the transition 

 lime-stone, transition-trap, gray-wacke, 

 and flinty slate. The petrifactions are, 

 corallites, encrinites, pentacrinites, en- 

 trochites, and trochites. The lime-stone 

 of Derbyshire is said to be of this kind. 

 As the former class of rocks were purely 

 of chemical formation, so the contents of 

 these are chiefly chemical productions, 

 mingled with a small proportion of me- 

 chanical depositions. To explain the cause 

 of this mixture we are referred to the pe- 

 riod of their formation, that at which the 

 summits of the primitive mountains just 

 appeared above the waters, when, by the 

 attrition excited by the* motion of the 

 waves, and which we are reminded ex- 

 tends to no great depth, particles of the 

 original mountains were worn off and de- 

 posited. 



As the height of the level of the ocean 

 diminished, so would the surface on which 

 its waves acted increase, and of course 

 the quantity of the mechanical deposi- 

 tions. Hence these are much more abun- 

 dant in the rocks of the next formation, 

 which are denominated floetz rocks, on 

 account of their being generally disposed 

 in horizontal or flat strata. In these, pe- 

 trifactions are very abundantly found, 

 having been formed whilst vegetables and 

 animals existed in great numbers. These 

 rocks are generally of very wide extent, 

 and commonly placed at the feet of pri- 

 mitive mountains. They are seldom of 

 very great height, from whence it may be 

 inferred, that the water had considerably 

 subsided at the time of their formation, 

 and did not then cover the whole face of 

 the earth. Countries composed of these 

 rocks are not so rugged in their appear- 

 ance, nor so marked by rapid inequalities, 

 as those in which the primitive and tran- 

 sition rocks prevail. The formations of 

 this class are supposed to be, 1, first or 

 old red sand-stone ; 2, first or oldest floetz 

 lime-stone ; 3, first or oldest flostz gyp. 

 sum ; 4, second or variegated sand-stone ; 

 5, second floetz gypsum ; 6, second iioetz 

 or shell lime-stone ; 7, third floetz sand- 

 stone ; 8, rock-salt formation ; 9, chalk 

 formation ; 10, floetz-trap formation ; 11, 

 independent coal formation ; 12, newest 

 floetz-trap formation. 



Most of the rocks which have been just 

 enumerated are covered by a great for- 

 mation, which is named the newest floetz- 

 trap. This formation also covers many 

 of the high primitive mountains : it has 

 but little continuity, but is very widely 

 distributed. It contains considerable 

 quantities of mechanical deposits, such 

 as clay, sand, and gravel. The remains 

 both of vegetables and animals also occur 

 very abundantly in these deposits. Heaps 

 of trees and of parts of plants, and an 

 abundance of shells and other marine pro- 

 ductions, with the horns of stags, and great 

 beds of bituminous fossils, point out the 

 lateness of the period when this formation 

 was deposited. In this formation several 

 rocks occur, which are also met with in 

 other floetz formations; but the following 

 are supposed to be peculiar to this class, 

 basalt, wacke, gray-stone, porphyry, slate, 

 and trap tuft'. These rocks are said to 

 have been formed during the settling of 

 the water consequent to a vast deluge, 

 which is supposed to have taken place 

 when the surface of the earth was cover- 

 ed with animals and vegetables, and when 

 much dry land existed. From various ap- 



