250 AN ENQUIRY INTO THE [Ch. XII. 



has surely been quoted to show that all rocks that are per- 

 fectly consolidated are, like the primary, traversed by lines, 

 which cross each other at various angles, dividing the mass 

 into forms more or less geometrical. 



This we all admit, some may argue, but it furnishes 

 weapons against the conclusion, in favour of which it has 

 been advanced. Not so, we think : it establishes that the 

 same structure is common to the primary and sedimentary 

 rocks, but does not prove that the former are, therefore, 

 stratified, in the usual acceptation of the term. Indeed, it 

 rather leads us to doubt whether the parallel layers of the 

 sedimentary rocks do owe their form to the mode in which 

 they have been deposited. It cannot be questioned, that the 

 concretionary surfaces are sometimes coincident with those of 

 deposition, as is evident when each layer is separated by an 

 uniform surface of shells, scales of mica, or other substances 

 which have been arranged by water ; and more especially, 

 when the stratum only consists of one layer, succeeded by 

 another of a different nature, but similarly circumstanced. 

 These instances, however, are few compared to those in which 

 the stratified rock is of considerable extent, nearly homo- 

 geneous throughout, and yet divided by layers in various 

 directions. The principal lines which mark these layers are 

 generally horizontal, or inclined at angles, which, in a great 

 measure, correspond with those of the subjacent rock. 

 Now these layers are supposed to mark the successive de- 

 posits from water, either in their original position, or tilted 

 up by some power acting from beneath. But let us turn our 

 attention to the actual state of such deposits, previous to their 

 consolidation : can we detect any thing like what is called 

 stratification, when the mass has been accumulated by the 

 same agency operating under precisely the same conditions ; 

 that is, when the sedimentary mass consists throughout of the 

 same materials, whether it be of clay, of sand, or of pebbles ? 

 Now such a mass, taken as a whole, may be evenly spread 

 over an extensive space, having its upper and under surfaces 



