252 AN ENQUIRY INTO THE [Ch. XII. 



certainly a case in point ; and it may also be stated, that the 

 siliceous sandstones, on the southern shore, present the same 

 phenomenon. Thus we found " at the foot of Pendowa Cliffs, 

 at the head of Gerrans Bay, near Veryan, a recent deposit of 

 considerable thickness, the lowest part of which consists of 

 pebbles similar to those of the adjacent shore, intermixed 

 with sand, and some scattered fragments of slate. These 

 pebbles gradually diminish in quantity upwards, till the de- 

 posit is composed entirely of sand, an intimate mixture of 

 siliceous and argillaceous particles with minute scales of mica : 

 this sand in its turn becomes more and more argillaceous, 

 until it terminates in a bed of clay of considerable thickness. 

 The under part of this deposit, for about ten or twelve feet 

 in depth, including the pebbles and sand, is consolidated into 

 horizontal layers of conglomerate and sandstone of a reddish 

 brown colour. These layers average about nine inches in 

 thickness, and have a very interesting appearance. The 

 upper layers, being softest, have suffered most from the action 

 of the elements, so that the lower ones successively extend 

 farther from the cliff, forming an irregular flight of stairs : 

 some of the layers, however, project, and are of sufficient 

 tenacity to bear the weight of the body." * 



In both these instances, the beds of pebbles and sand are 

 evidently ancient beaches; and, like the existing ones, are 

 placed on inclined slate, sloping down to the sea at a consider- 

 able angle. On these considerations, we think that it may 

 be fairly concluded, that the lines marking the layers of the 

 sedimentary rocks, though sometimes coincident with those 

 of deposition, are not referrible to this cause, but depend on 

 the mode in which the particles of these rocks have been 

 aggregated during their consolidation. 



This opinion is no new doctrine, though it is now pro- 

 posed to extend it further, perhaps, than will be generally 

 admitted. Most geologists, of late years, whenever they 



* Cornish Geol. Trans., vol. iv. p. 271. 



