1849.] AUSTEN ON THE VALLEY OF THE ENGLISH CHANNEL. 89 



Eastern counties. These rocks belong to the Northern ocean area, and 

 must have passed from that into the area of the English Channel. 

 We thus arrive at the precise date at which the English Channel be- 

 came sufficiently depressed so as to be occupied by sea, as well as at 

 the date of the subsidence of the chalk strata along the north and 

 south line before indicated, and which produced the Dover Straits. 

 The movement of the drift materials over the Northern and German 

 ocean area during the pleistocene period was from north to south ; 

 and when the Channel valley was opened to the waters of that period, 

 the drift was continued with a like direction into that area : in hke 

 manner the chalk-flints of the eastern portions were made to travel 

 west ; and in the meagre character of the marine fauna of the raised 

 beds of the Channel, we see that it was influenced by arctic currents, 

 and not southern ones as at present. 



The levels of the portions of the littoral zone of the pleistocene 

 period in the English Channel show the depression of that area to 

 have been rather lower at that time than it is at present. There would 

 also appear to have been an intermediate level, of which the shingle bed 

 between Brighton and Rottingdean is a familiar illustration — a level 

 which was of sufficient duration to allow of the formation of cliffs ; the 

 Elephant bed, as it is named by Dr. Mantell, belonging to a vast series 

 of deposits, to be noticed in the sequel, and of the age of the drift. 



Fig. 4. 



Fig. 3. 



The drift beds are the uppermost portion of the pleistocene group ; 

 and under the name of diluvium were long since traced down into the 

 Thames valley, and fully described as to their characteristic admix- 

 ture of northern materials by Dr. Buckland. On the south side of 

 the Thames they may be seen extending over the surface of the ter- 

 tiary district, in many instances overlapping it, and resting on older 

 denuded strata. But as we approach the district where the physical 

 features of the AVealden begin to show themselves, these accumula- 

 tions diminish in thickness, till at length we reach an area over which 

 no trace whatever of them is to be fomid. This termination of the 

 pleistocene drift takes place by a well-defined marginal bed, of which 

 clean sections have recently been exhibited in the cuttings of the 

 Reading and Reigate Railway. The detail of about twenty miles of this 

 coast-line, where it ranges across the county of Surrey, will be sufficient, 

 as all that I wish is to connect the pheenomena north of the Weald 

 with those on the south. If we commence with this line at Farnham, 



