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land elevations and subsidences, it has been connected 

 with and separated from Normandy on, at least, three occasions. 

 But its first separation — probably in late tertiary times — was 

 through erosion of softer rocks, by which, until then, it had been 

 covered. That it was once continuous with the plains of Nor- 

 mandy, and at much the same elevation, is shown by the yellow 

 clays which cover even the highest land, and bear clear evidence 

 of a diluvial origin, and, of course, could not have been derived 

 from such a limited insular area. 



The Rivers Seine and Somme (combined with tributaries from 

 the South and North) running to the Atlantic, formed the mouth 

 of the English Channel. Hurd's Deep, to the N.W. of Guernsey, 

 probably marks this old river channel. It will be readily under- 

 stood that Jersey and its neighbours must be made of some very 

 resistant substance to withstand the prolonged erosion of the 

 sea. And so, indeed, they are. For the north-western, south- 

 western, and south-eastern coasts consist of fairly coarse Syenitic 

 granite. Its eastern half consist of volcanic rocks, chiefly Felsite, 

 while the north-eastern cliffs and islets are formed of a peculiar 

 volcanic conglomerate, or agglomerate. Between the granite 

 areas of the north-west and south-west, and extending to about 

 the centre of the island is a large area of stratified Archaean shale, 

 a dark slaty-looking rock, which, from its regular lines of bedding 

 and the presence of ripple marks on some of the exposures, has 

 evidently been deposited in fairly shallow water. It must be very 

 ancient, as no trace of fossil organisation, macroscopic or micro- 

 scopic, has yet been discovered in it. Fragments of this rock are 

 very frequently found embedded in the granites which have 

 intruded upon them. The volcanic conglomerate already 

 mentioned, contains also about 80 per cent, of fragments of this 

 shale. From what pre-existing land this deposit can have been 

 derived it is impossible to conjecture, for these beds are a mile 

 in thickness. But it is thought they may represent the delta of 

 some inconceivably ancient river. The granites of the Island are 

 largely quarried for paving, and for ornamenting public buildings. 

 One valuable deposit in the north of the Island is called 

 Aplite, or China Stone, and is largely quarried for export to the 

 British Potteries. It is curious to notice in many places the com- 

 plex mixtures of granites of different degrees of coarseness, and 

 the intrusion of other rocks, such as diorite, and trap and quartz 

 in veins. In some places the Felsite rocks have a columnar 

 structure, similar to the basalt columns at Arthur's Seat, near 

 Edinburgh, and at Staffa. 



The superficial layers of the Island consist chiefly of yellow, 

 sandy clay, or brick earth. The deeper part of this is due to the 

 decomposition of the underlying rocks, but the surface layer 

 shews evidence of stratification and intercalated layers of stone 

 fragments and pebbles, suggesting a diluvial origin. 



One interesting recent deposit is an immense stretch of blown 



