44 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



the superficial accumulation consists in its very marked horizontal 

 bedding, with layers of drifted sand ; I here found pebbles of quartz. 

 Two sets of gravel-accumulations may be observed here, — one 

 overlying the furrowed surface of that just described ; both may 

 be considered distinct, as to age and circumstances of origin, from 

 the clayey angular gravel which covers much of the chalk-area inland. 

 With reference to our own coast, the gravel-beds of Sainte Mar- 

 guerite with quartz-pebbles may perhaps be of the same age as those 

 of the high levels near Poole (see p. 45). 



The chalk attains its greatest elevation at Fecamp. About ten 

 miles further the strata begin to rise. The lower cretaceous beds 

 there appear on the sea-level, and thence continue to the mouth of 

 the Seine. 



The beds subjacent to the chalk are visible for a greater distance 

 along the right bank of the Seine, than they are on the seaboard ; 

 they rise in the same direction, or towards Cap la Heve. The rapid 

 reduction in the thickness of the chalk which accompanies this rise 

 of the beds is very remarkable, and with it there is a corresponding 

 increase in the superficial beds of angular flint-gravel. 



Wells which have been sunk at Havre show that an old terrestrial 

 surface lies considerably below the water-level in that valley, buried 

 beneath sand and shingle ; and like evidences of depression are to be 

 met with along the coast of Calvados. 



Whatever may be the age of the accumulations of the platforms of 

 chalk of this part of France, thus much is clear, that they are an- 

 terior to the formation of the valleys which have been cut through 

 them*. Thick beds of subaerial detritus are to be found on the 

 sides and the lower slopes of these valleys. Sections of such masses 

 may be seen where the valleys open out on the coast-section ; but 

 they do not contain any true gravel-beds, showing the action of 

 moving water, as is the case with so many of the gravel-valleys of 

 this country. Even the great valley which extends from the coast 

 at Dieppe to the denuded district of the Pays de Bray has not the 

 slightest trace of them. 



Eure. — Beyond, or south of the Seine, the chalk does not appear 

 in the upper part of the cliffs, but the same rapid diminution in its 

 thickness is continued across the Department. All the circumstances 

 under which this takes place — such as the very irregular surface, pro- 

 duced by lines of deep troughs — agree in a remarkable manner with 

 what may be observed over the Blackdown range of Devon, particu- 

 larly in the cliff-sections E. and W. of Sidmouth. In the Department 

 of the Eure, as in the west angle of that of the Seine Inferieure, the 

 accumulation of angular flint-gravel which accompanies the reduction 

 of the chalk-strata often exceeds 1 00 feet in thickness : it is not 

 limited to the chalk, but outspreads it, and covers up the beds of the 

 lower cretaceous series. It diminishes in thickness, however, with 

 its distance from the chalk, so that the oolitic platforms of the 

 Department are mostly free from it. As also in 

 Calvados, — where the detritus on the surface of the country, between 

 * Quart. Journ. Geol. Soc. vol. xi. p. 118» 



