EXISTENCE OF MECHANICAL DEPOSITS. 19 



POSTSCRIPT. 



Since writing the inclofed, I have examined one of thofe 

 appearances, which are considered by Dr. Hutton and Pro- 

 feflbr Playfair, as demonftrating the exiftence of petrefaclions 

 in primitive mountains. Dr. Hutton, at p. 334- of his Theory 

 of the Earth, remarks, " I have already obferved, that one Dr . Hutton's 

 fingle example of a (hell, or of its print, in a fchiftus, or in a {^^iLtvr tht 

 ftone unratified among thofe vertical or erected mafles, fuffices mechanical ori* 

 to prove the origin of thefe bodies to have been, what I hadS inof P rin l itive 



r o countries from 



maintained them to be, water formed ftrata created from the the exiftence of 



bottom ol the lea, like every other confolidated ftratum of the or S anic remains. 



earth. But now, I think, I may affirm that there is not, or 



rarely, any confiderable extent of country of the primary kind, 



in which fome mark of this origin will not be found, upon 



careful examination ; and now I will give my reafon for this 



aflertion. I have been examining the fouth alpine country of 



Scotland occafionally, for forty years back, and I could not 



find any mark of an organized body in the fchiftus of thofe 



mountains. It is true, that I knew of only one place where 



limeftone is found among the ftrata : this is upon Tweedfide 



near the Crook. This quarry I had carefully examined long 



ago, but could find no mark of any organized body in it. I 



fuppofe they are now working fome other of the vertical ftrata 



near to thofe which I had examined : for, in the fummer of 



1792, I received a letter from Sir James Hall, which I fhall 



now tranfcribe. It is dated Moffat, June 2, 1792. 



" As I was riding yefterday between Noble Houfe and the Sir James Hall't 



Crook, on the road to this place, I fell in with a quarry of a ? count °. f orga ' 



' . c nic remains in a 



alpine limeftone; it confifts of four or five ftrata, about three limeftone ftated 



feet thick, one of them fingle, and the reft contiguous ; they t0 be P rimitive » 



all ftand between the ftrata of flate and fchift, that are at that 



place nearly vertical. In the neighbourhood, a flate quarry 



is worked of pure blue flate ; feveral of the ftrata of flate near 



the limeftone, are/filled with fragments of limeftone fcattered 



about like the fragments of fchift in the fandftone, in the 



neighbourhood of the junction on our coaft. Among the 



mafTes of limeftone lately broken off for ufe, and having the 



fracture frem, I found the forms of cockles quite diftinct, and 



in great abundance. I fend you three pieces of this kind," 



&c, 



C2 It 



