^ HUTTONIAN THEORY. 291 



^lii 



'fi 



mafles 



lie I Where whinflone rocks are found in 



'P%* bounded by the flrata, and infulated among 



'^gUreii' them, thej fubjed the Neptunian fyflem to great 



^%^| difficulties. For, fuppofing it true that this 



..,,3^, ftone may be produced by the precipitation and 



Xl! cryftaliization of mineral fubftances dilTolved in 



water, yet it feeras unaccountable, that this ef- 



I 





fed has been fo local and limited in extent, 

 as often to be confined to an irregular figure 



cludel'I °^ ^ ^^^ ^^^^^' ^^^^^' ^^^ ^°^^"^^' ^^^^ fubftan- 

 I ''■ ces depofited have had no tendency to cry 



'^m 



-'"/. \k 



K. 



flallization, and have been formed into the 



common fecondary flrata. The rock of Sa- 

 ^""^'y hlbury Craig, for infiance, is a mafs of whin- 

 ^"^^ Hone, having a perpendicular face eighty or 



ninety feet high tou^ard the weft, and ex- 

 jfurL tending from north to fouth with a circular 



fweep about 900 yards. The whole of this rock 

 ; beeiii reds on regular beds of fecondary fandflone, not 

 luflfti horizontal, but confiderably depreffed toward 

 rocbiSi' the north-eaft : the rock is loftieft in the mid- 

 0^,^: ^^^^ ^"d decreafes in thicknefs toward each end, 

 ^^gt terminating at its northern extremity in a kind 



,[i3tfo^' of ^'edge. It is covered at top, toward that 



tremity, with regular beds of fandftone, per- 

 fcaiy fimilar to thofe on which it is incumbent ; 



probable, that this covering for- 



d 



ly extended over the whql 



T 2 Now, 





-Jh - r -- 



