in reply to Mr. R. C. Taylor. 281 



superficially reposing on the slope of the hills. At page 14 

 of my Observations, I i-eferred to one bed, a section of which, 

 being laid open, showed "that it gradually shelved off to a 

 point as it receded from the valley, and soon terminated." 

 Since that time it has been completely cut away by the chalk- 

 diggers, and not a vestige of it is now left. In another pit I 

 noticed two layers ; the lowest not much above the surface of 

 the chalk, consisting of broken shells, mixed in an indurated 

 mass of gravel and ferruginous sand ; and the upper about ten 

 feet higher, composed principally of the Buccinum undatum'^ 

 and Turbo littoreus loosely imbedded in a white quartzose 

 sand. On my last visit to this spot I found the latter entirely 

 exhausted for the space of about fifty yards, except a small 

 portion not more than six inches deep and seven feet in length, 

 which it was evident, that the next excavation would altoge- 

 ther remove. If to these decisive cases we add the striking 

 fact, tliat no traces whatever of corresponding beds are dis- 

 cernible in any upland situations, where the strata have been 

 actually explored, we have a right to infer from such circum- 

 stances, that these marine deposits are confined to the basins 

 of the valleysf . It is far however from my object to contend, 

 that they are all of the same age ; I have on the contrary ad- 

 mitted, that the lowest are of a more ancient date, and appear 

 to have some affinity to what is called the Crag stratum ; it 

 was from the upper and more recent beds that my conclusions 

 were drawn. Not only is it evident that these are not buried 

 beneath thick beds of sand and gravel ; but we have the most 

 decided proofs, that they actually repose on the surface of that 

 mass which bears the name of diluvium. This I consider to 

 be the essential characteristic of that subsequent adventitious 

 Ibrmation, which has been with propriety termed alluvial ,- 

 and every circumstance connected with these beds tends to 

 corroborate this account of their origin. The uncompact and 

 loose arrangement of their materials distinguishes them at 

 once from the Crag, the structure of which, according to 

 Mr. Taylor's description, is in some places so solid and rock- 

 like, as to admit of its being hollowed into artificial caves and 



* The Mures struitus of Mr. Taylor. 



t The " diluvial agcncj/ " by whicli Mr. Taylor imagines them to have been 

 displaced from those situations, where, according to his theory, they ought to 

 be found, is a most convenient assistant, whenever a stubborn unaccommo- 

 dating difficulty is to be swept away, or a reason assigned for the absence 

 of material evidence. I should be almost disposed to regret having rejected 

 its services, did I not remember, that they would be of no avail, since that, 

 which viai) be made to account for every thing, pruucs nolhiiig. 



New Series. Vol. 2. No. 10. Oct. 1 827. 2 O grottos, 



