70 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



east into the western districts of this country pass over the edge of all 

 the lower tertiary strata, must be obviously referable to some period 

 intermediate between the upper fluvio-marine series of the Isle of 

 Wight and the Crag : such may also be the case as to the gra- 

 vel-beds next in succession, in respect of age; but with reference 

 to the question as to what were the conditions under which this 

 wonderful outspread of detritus took place, and what were its equi- 

 valents elsewhere, we know nothing whatever ; we have not even any 

 certain indication as to whether the mass of water by which it was 

 effected was salt or fresh. The vast accumulations of angular chalk- 

 flints which progressively thicken as the chalk is reduced, both in 

 Devon and in the Department of the Eure, as if they had been dis- 

 solved out, but not moved, are inexplicable by any agencies with 

 which we are as yet familiar. 



The British area had however become, at least in part, a terrestrial 

 one at the period of the fauna marked by the Rhinoceros Schleier- 

 macheri and the Mastodon angustidens, anterior to the accumulation 

 of those marine deposits of the Germanic area which are known 

 as the Crag. This terrestrial fauna occupies a distinct place over a 

 large European area. 



The next group of terrestrial forms is that of the Elephas primi- 

 genius, Rhinoceros tichorhinuSy &c. with which, as we have seen, 

 the marine deposits of Selsea were contemporary : and, according to 

 the present state of our knowledge, these two assemblages of terres- 

 trial animals differed more from one another than the existing mam- 

 malian fauna of our area does from that of the Elephas primigenius. 



The next question which arises relates to the condition of the 

 English Channel area at the period of the Crag-deposits of the 

 German Ocean. As far back as the year 1825, M. Desnoyers gave 

 an account of certain tertiary strata which occur in parts of the Co- 

 tentin ; and, referring more particularly to the beds which are found 

 at Santenay and at Auxais, he then stated that he considered them 

 as " analogue aux terrains du basin de la Loire." Sir Charles Lyell, 

 in 1841, after an examination of the several localities described by 

 M. Desnoyers, and a comparison of the fossil shells with those of the 

 Crag and Faluns deposits, suggested that the beds of the Cotentin 

 belonged to the Crag, and were the equivalents of the Faluns, and 

 that all were referable to his miocene period.* The beds in the 

 neighbourhood of Carentan, by the presence of Terebratula grandisy 

 suggest comparisons with the Crag. With this exception, there are 

 no deposits on any part of the western shores of the Channel, none 

 certainly on our coasts, which can be compared with that formation. 

 All the raised marine beds on our western coasts are clearly referable 

 to a period during which the marine fauna was excessively poor ; 

 and, with the exception of Terebratula grandis, the other shells of 

 the Carentan deposits, such as Lucina horealis and Pecten pusio, are 

 such Atlantic shells as are now found abundantly about the Channel 

 Islands. 



* Subsequently Mr. Wood and Sii- C. Lyell have referred the Crag to the plio- 

 cene period. 



