260 AN ENQUIRY INTO THE NATURE OF [Ch. XIII. 



called false stratification, is not confined to deposits of fine 

 sand and comminuted shells, for we find beds of shingle 

 (pebbles of chalk flint, and of rolled pieces of white chalk) 

 disposed in the same manner, as is seen in the section at the 

 lighthouse near Happisborough." Consult this section, and 

 it will be found that the entire mass (overlooking the lines or 

 divisions by which it is traversed) presents a form very com- 

 mon on existing beaches ; and, as the irregular and ancient 

 deposits of sand on the Cornish shores acquire a subsequent 

 arrangement into horizontal layers, so these beds of sand and 

 of pebbles may have assumed the diagonal laminae, the differ- 

 ence of the angje depending on the composition or some other 

 modifying circumstance. This peculiar disposition of inclined 

 layers between the planes of the strata is found in rocks of 

 every geological era, and appears to depend (as stated in the 

 last chapter) on the manner in which the attraction of co- 

 hesion has operated, and not on the mode of deposition. 



We conjecture, therefore, that what occurs in these small 

 banks of pebbles, holds good with the larger masses of con- 

 glomerate; that is, that the inclined planes which these 

 exhibit are not always those of stratification, but are referrible 

 to the concretionary structure, the result of the aggregation 

 of the loose materials of which these rocks were once com- 

 posed. Lest this opinion should be deemed to rest too much 

 on bare assertion, we will refer to the page of Nature on this 

 subject, and quote the following examples. 



At Nare Point, Helford Harbour, in Cornwall, there is a 

 mass of conglomerate * occupying the hollows and irregulari- 

 ties of the adjacent schistose rocks ; the fragments and rolled 

 pieces of which it is composed are of the same nature as the 

 latter rocks ; and it also exhibits the same structure, being 

 traversed by systems of parallel lines, at elevated angles, but 

 wanting the fissile texture of the parent slate. According to 

 the received notion, the inclined planes of this conglomerate, 



* Cornish Geol. Trans., vol. iv. p. 320, 



