60 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



tion of the nummulitic series of the Isle of Wight was deposited, — that 

 it extended to the west and south of it, — and that streams hrought 

 down pehhles of its component strata, and deposited them in that 

 basin *. I beheve that the older materials found in the upper tertiary 

 deposits of the Sussex-levels were derived from rocks now lying 

 within the limits of the present Channel-area, and that physical 

 arrangements of old date were continued down, with modified pro- 

 minency, even to the period of the large pachyderm mammals. 



To such geologists as may have had opportunities of examining 

 the relations of the oolitic strata to the subjacent palaeozoic rocks 

 along the valley of the Dives (Calvados), and have seen the slight 

 distance from the present coast-line at which these old rocks come 

 to the surface, the view here taken may have already suggested itself ; 

 but even to such as may not have visited this part of Normandy, the 

 study of a good geological map will be quite sufficient to satisfy them 

 of the very great probability that this relation of the two series may 

 be continued beneath the adjacent sea. 



With the waters of the Channel at their present level, the process of 

 coast-line waste will some day reach great masses of old palaeozoic 

 slates and sandstones, and project them on the cliff-sections of the 

 French coast. These masses will supply shingle and detritus to the 

 sea-bed then forming, and these will be in part identical with much 

 that is now found in the Sussex deposits : this will happen on a part 

 of the French coast opposite to, or on the meridian of Brighton. Or, 

 if at some past time, not remote, a tract contiguous to a sea-bed 

 so composed has been placed at the sea-level, it must in like 

 manner have caused a similar association of materials in its marginal 

 detritus. 



The case here taken, and which thus far is purely hypothetical, 

 becomes extremely probable, if we can show that a portion of 

 the east end of the English Channel area has experienced depression 

 since the period of the large pachyderm fauna. 



Starting from the coast-line of France, and applying the same rule 

 as in the case of the Dorset coast (p. 41), namely, that terrestrial 

 surfaces between tide-levels do not prove change of level, but that, 

 when they pass down beneath low-water, they necessarily do, we 

 have evidences of depression extending along a line 50 miles in extent. 

 The most striking of these are from Benerville to Villers, between the 

 Toucques and the Dives, and again, on a grand scale, east of Vier- 

 ville, where a wood of trees of large size is seen to pass down beneath 

 the lowest tidal level. In these cases, as in those on our own coasts, 

 the line of depression seems to incline towards the central area of the 

 Channel. Whether this depression was local, such as merely gave 

 greater depth and width to the valley of the Channel, or whether, the 

 whole remaining relatively unchanged, some much larger area was so 

 moved that the Channel-valley was at one time in the condition of 

 dry land, and at another occupied by water, is not a consideration 

 affecting the present question in the least, which resolves itself 



* Some beds in the fluvio-marine series of the Isle of Wight are wholly com- 

 posed of small quartjj-pebbles. 



