1849.] AUSTEN ON THE VALLEY OF THE ENGLISH CHANNEL. 73 



flood. We have taken the Hne from Dieppe westward as the one 

 which indicates the hne of the Channel : it appears that at this place, 

 according to a register kept by M. de Breaute, extending over twelve 

 years, that the direction of the wind was 135 days between south 

 and west, and 94 days between west and north, or 229 days out of 

 the 365 during which the materials along some part or other of the 

 Channel might have an eastward movement. There are no observa- 

 tions to guide us as to the rate at which the marginal line of shingle 

 is made to travel forwards in this manner, but the distance at which 

 it occurs from its point of origin is occasionally very great. On the 

 Chesil beach may be collected pebbles of limestone, greenstone, trap, 

 and old red sandstone, derived from the older rocks of South Devon. 

 Much of the irregularity of the present outline of the Channel, 

 where it is independent of other causes, is due to the nature of the 

 beds which occur along it. Passing over minor examples, good illus- 

 trations of this are to be seen in the deep bay between Berryhead 

 and Portland, an interval which corresponds with that of certain 

 yielding sands and marls ; as also in the recess along the coast of 



Calvados. „. , 



Fig. 1. 



Good illustrations of the process of cutting back along the mar- 

 ginal sea zone, and of the depth to which this action is carried in the 

 case of hard compact beds, can be seen about the Channel Islands. 

 Sections of some of these groups of rocks show that they rise off plat- 

 forms, which have an uniform depth from the surface, and that from 

 their edges there is a rapid fall to the general sea-bed below. The 

 platform to the north of Ortach and Burhou comes nearly to the 

 surface, so that the projecting points are uncovered : when the wind is 

 fresh, the sea breaks violently on this platform ; the fall is immediate 

 into 18 fathoms water. Time being allowed, such a group as that 

 of the Caskets (fig. 1) would ultimately disappear, and be reduced to a 

 submarine shoal. Some of the actual shoals of these seas have pro- 

 bably at some former time existed as small groups of rocks ; — that of 

 the JPomier, two miles north-east of the Caskets, is apparently a good 

 instance of a mass of rock reduced to its utmost with relation to the 

 present sea-level. This shoal is a table-rock rising abruptly out of 

 170 feet water to within 36 feet of the surface, covered at top with 

 patches of coarse sand and shingle, and, as usual, vdth a vast growth 

 of sea-weed. Viewed in this way, the Channel Islands group, taken 

 collectively, will present instances of masses in every stage of abra- 

 sion ; and judging from the soundings round the several shoals, rocks, 

 and islands, the depths to which such masses may be reduced will 

 range down to between 40 and 50 feet at the very utmost. 



This process, by which masses of solid materials can be planed off 

 parallel with the sea-level, is due to the action of wind or surface 



