38 

 of the cretaceous system. 



THE LOWER OREENSAXD. 



This formation ought to be well known to us ; but a few 

 observations as to the origin, lithological composition, and 

 fossil contents of this rock will, perhaps, be acceptable. 

 This deposit is described by Dr. Fitton as a triple alterna- 

 tion of sands and sandstones, with beds of chert and fuller's 

 earth in some localities, and it consists of ordinary beds of 

 sand, clay, and impure limestone, the materials of which re- 

 sulted from the wearing down of pre-existing rocks, and the 

 nature of which rocks we learn from finding in the green- 

 sand pebbles of quartz, quartzose sandstones, and green 

 grains of silicate of iron, chlorite, and mica. This de- 

 posit is formed partly of green and partly of ferruginous 

 sand and sandstone, with some limestone ; and these rocks 

 are classified thus (in ascending order) : — 



Calcareous stone called Kentish rag. .60 to 80 feet thick. 



Sand with c;rcen matter 70 to 100 „ 



Sand— white, yellowish, or ferrugi- 

 nous, with concretions of limestone 

 andchert about 70 70 „ 



200 or 250 „ 



At the base of the lower greensand, we find, at Ash ford, 

 the Atherfield clay, a thin bed of dark clay, not very dif- 

 ferent in appearance from the weald clay, but its fossils 

 ai-e of marine origin. The only specimen I have 

 from this deposit is a large oyster, Gryphwa sinmta, found 

 by the late Mr. Mark Dorman in clay from a well at the 

 bottom of Ashford town. I believe it was at Eaglan-place, 

 ■where these oysters were numerous. Mr. Dorman brought 

 away five or sis of them and gave me three, which were 

 eagerly caught after by my geological friends in London, to 

 whom I gave two of the specimens reserving the one I 

 now submit for inspection. I do not know what other 

 shells might have been found there if I had been on the 

 spot, but the well was finished and covered in before Mr. 

 Dorman called on me, and my object in mentioning these 

 facts is to draw the attention of resident geologists to the 



