98 



PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



the current was reduced, the finer materials might be deposited. 

 There is no evidence of any change of level during these deposits ; 

 and the river must have risen 50 feet at least in times of flood. 



Fig. 33. — Sect on on Brading Down, Isle of Wight, showing blocks of 



Chalk in Gravel. 



In conclusion I may mention that the beds described above as 

 pluvial have been referred to by Mr. Godwin-Austen under the 

 name of Head, or Subaerial beds ; and I quite admit the propriety 

 and importance of his terms in many respects ; but I was obliged to 

 use the term "pluvial," in order specially to introduce the notion of 

 rain-water action, as I was treating of deposits made on slopes by 

 the action of water (probably by a non- continuous action) and thus 

 necessarily to be separated from the ordinary aqueous action, such as is 

 performed by rivers, lakes, and seas ; as well as from ordinary sub- 

 aerial action. While the pluvial beds, as I have shown in my sections, 

 pass down into the aqueous beds, they pass upward into Mr. Godwin- 

 Austen's subaerial beds, and the stones which have been head at one 

 time, and weathered by subaerial action, pass down into what may 

 be termed pluvial beds, which in their turn are being constantly 

 despoiled, and carried into the purely aqueous beds at lower levels. 

 Although Mr. Godwin-Austen's term subaerial is an excellent one, 

 I submit that it does not suificiently define the kind of action for 

 the purpose I have in view, and still less so for the paper I have 

 prepared on the formation of valleys, and the denudation of the 

 surface. 



When the Crayford and Erith beds have been as fully examined as 

 those at Grays, the numerical superiority of the MoUusca in the latter 

 deposit (as shown in the following Table) will probably disappear. 



The list of shells from Salisbury is principally on Dr. Blackmore's 

 authority. The Grays list is compiled from Mr. Pickering's table, 

 the Ilford one partly from Mr. Morris's ; the remainder by Mr. A. 

 Bell, who has revised the list, and omitted the doubtful species. 



