﻿1851.] AUSTEN ON THE PLEISTOCENE PERIOD. 123 



most particularly to pi. 9. fig. 4, and borrow a few lines from his 

 account. " In a creek called Tor-nanven in the parish of St. Just, 

 Penuith, near Cape Cornwall, in the north part of the cliff, inserted 

 under clay and rubble, are ranged horizontally many rows of large 

 and small rounded pebbles of the granite kind*. The covering of 

 the pebbly stratum is 50 feet on the north, but only 20 feet on the 

 south, consisting of rough yellow clay, charged with large and small 

 stones, all with their angles on." (p. 76.) 



Besides the local character of this accumulation of earthy and an- 

 gular materials, there is another allied fact of some value — viz. the 

 absence of the slightest indications of any moving agent, such as that of 

 a body of water in motion ; this is shown in a very striking manner in 

 many places, as on the west of Pendennis Point, where the beds attain 

 a great thickness, are coarse and fragmentary, and are seen resting on 

 a former upper sea-zone of loose sands ; these sands are still as little 

 coherent as if they had been thrown there by the last gale, but their 

 surface is not in the least grooved or eroded along the line of junction. 



The thickness which these accumulations attain is frequently very 

 great ; the mass described from Borlase varied as we have seen from 

 50 to 20 feet. West of Pendennis it may be estimated at nearly 30 

 feet, and reaches to 20 feet in the district of the Prawle. In the 

 coast sections of the Channel Islands, I have measured it from a few 

 feet to as much as 40. And everywhere about the shores of the western 

 entrance into the Channel it is of sufficient thickness to constitute the 

 line of low under-cliffs represented in figure 3. 



These beds everywhere range inland above and beyond the level of 

 the sea-beds on which they rest in the coast sections ; and this position, 

 with relation to two lines of definite sea-level, is one of the most inter- 

 esting points in their history, as but for such intercalation the por- 

 tions of the mass extending inland would be referred to that body of 

 loose materials which is so constantly found resting on the funda- 

 mental rock strata, and whose age, but for this, would never be clearly 

 ascertained. 



As the beds which are here described are purely local, it may be 

 as well, before speculating on the conditions under which they have 

 been produced, to call attention to the very distinct character of the 

 agencies now modifying the earth's surface, as compared with those 

 which these older accumulations must have required. The general 

 description of these beds already given has been derived from coast 

 sections ; in their extension inland, and to higher levels, they pre- 

 serve the same characters, are earthy, fragmentary, and show a like 

 decrease of the larger fragments in the upper, as compared with the 

 lower portions. The upper surfaces of these masses of detritus are 

 now necessarily receiving annually the accession of materials, from the 

 joint operation of decomposition, and the transference of the products 

 to lower levels ; but, as may be seen in numerous valley sections, par- 

 ticularly over the slate districts of the south of Devon generally, the 

 distinction between the coarse angular detritus below, and the fine 

 earthy materials above, is always distinct : the nature and scale of 

 * Old sea-bed of the age of those to be next described. 



K 2 



