THE GEOLOGY OF THE ENGLISH CHANNEL. 177 



The southernmost find of New Eed Sandstone rocks among the 

 pebbles having been M. 18, S. 29" W. Edd., 23.4 miles, this trace of the 

 same in the sands shows in all probability an outward and downward 

 movement of small quantities of detritus, extending nearly twenty 

 miles, certainly fifteen miles. This is the only evidence of any but 

 very restricted movement among the mineral constituents of the sands, 

 and it must be remembered that Triassic sandstones and marls are 

 present in great quantity on their own area, and the amount of detritus 

 would be proportionately large, some might well have trespassed on to 

 other ground. 



In all but this matter the inorganic sands agree so precisely with 

 the closely adjacent coarse deposits, even in minute detail, and their 

 constituents are so exactly parallel, that great strength is given to the 

 previously urged view as to the value of the dredgings for approximate 

 geological mapping. 



In the gravels of some dredgings sharp chips of brown flints are 

 rather common. Such angular flint flakes were taken at M. 37, S. 41° 

 W. Edd., 171 miles, M. 71, M 40, M. 73, M. 56, M. 75, M 76, M. 65, and 

 M. 61, S. 25° W. Edd., 464 miles, extending thus over a long range. For 

 the more part the surfaces of the chips are practically undecomposed, 

 and all are of brown flint. (It is black flint which chiefly shows the 

 extreme alteration referred to in an earlier part of this paper.) These 

 chips do not, however, look quite recent. They are such as would be 

 formed by the mutual impact of subangular flints, possibly but rarely 

 of broken flint pebbles. They could never last long on a beach or in 

 any depth of water to which considerable wave action extended, 

 although such wave action might constantly create a fresh supply. 

 With a stationary shore-line a few such chips might be found a little 

 below low-water mark, but only rarely. On the other hand, with an 

 advancing shore-line and constantly deepening water it is quite easy 

 to imagine that, formed on beaches or in shallow water, they might be 

 placed in deeper water conditions soon enough to preserve many of 

 them from destruction. Taking the deposit at TIallsands as an 

 instance of a flint beach, long stationary, I may say that I have never 

 dredged off that shore any such flint chips, although it must be 

 imagined that some are at times formed. But probably one reason for 

 their absence at Hallsands is the extent to which the shingle has been 

 rounded, and a broken pebble is most rarely found ; while with the sea 

 advancing over a land surface covered with unrolled flints the process 

 of rounding these into pebbles or commencing such rounding would 

 give rise to very numerous chips. The fragments are therefore the 

 supplement of the subangular blocks of flint still associated with them, 



