﻿368 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



expressing my belief, that whilst the water-worn subjacent rounded- 

 pebble-bed (fig. 7, b) was really so formed, the overlying detritus was 

 accumulated under entirely different physical conditions. Although 

 very properly applied to the old shingle-bed, the explanation of a 

 "raised beach" fails entirely in regard to theoverlying drift and breccia. 



In some of those tracts where steep cliffs or even high hills slope 

 rapidly seawards, as on the south coast of Devonshire, there may be no 

 difficulty in admitting Mr. Austen's explanation*, viz. that the rubble 

 due to long diurnal action produced taluses on the sea-shore, the 

 materials of which have covered some of those beaches of whose 

 subsequent elevation geologists have noted so many examples. I must, 

 however, say, that I cannot admit the application of that view to the 

 north-west coast of Devonshire near Barnstaple any more than to the 

 Sussex coast. There Professor Sedgwick and myself describedf 

 the very remarkable raised beaches of Baggy Point covered by coarse 

 local drift, and showed how irregularly the ancient shore-deposit has 

 been thrown up northwards until it attains a height of about 90 feet 

 above the sea. Such cases of difference of level within a small area 

 cannot be reconciled with the view which would consider such sea- 

 beaches as any indication of the former level of the sea. 



Dwelling no further at present upon the North Devon sea-beaches, 

 I merely refer my readers to the memoir in the ' Geological Trans- 

 actions,' reproducing on this occasion the opposite woodcut, formerly 

 used, to show the analogy of this North Devonshire case — a coarse 

 drift overlying regular beds — to that of Brighton J. 



In Sussex, at all events, the wide spread of the debris over the low 

 and undulating tracts to the west of Brighton, and its relations to the 

 inferior marine shingle-bed, as well as to the nearest chalk-hills, quite 

 exclude the hypothesis of the diurnal descent of rubble from high 

 ground. There, whether in the form of piles of angular flint, lumps 

 of broken grey -wether-sandstone, or masses of clay or loam with some 

 included angular flints, the varied accumulation lies at very different 

 altitudes. At the west end of Brighton it rises from Hove to the 

 summit-level of the railroad and to the highest windmills, a mile and 

 a half inland. By no imaginable process of the longest continued 

 diurnal action could any portion of this detritus have been gradually 

 derived during ages from the low chalk-hills. There is a total absence 

 of the steep inclined plane which is required in all such cases, and 

 the hypothesis is therefore necessarily excluded. As soon as you 

 throw off the heaps of flints (or of clay and sand with fragments, as 

 the case may be) which cover the chalk, the latter is found to be 

 deeply eroded and channeled, with its fissures irregularly filled up, 

 — the detritus usually very ferruginous ; and without the intervention 



* See Memoir On the Superficial Accumulations of the Coasts of the English 

 Channel, &c, Quart. Journ. Geol. Soc. vol. vii. p. 118 et seq. 



f See Description of a Raised Beach in Barnstaple or Bideford Bay, &c, 

 Trans. Geol. Soc. N.S. vol. v. p. 279 et seq. 



% I here give to the subjacent rocks their proper term " Devonian " instead of 

 " Silurian," for which, judging from their external aspect and slaty character, they 

 were mistaken in the year 1835. See Memoir, supra cit. 



