Cycles of Sedimentation in the Eocene. 113 
neighbourhood of Laon to the neighbourhood of Lille. In the drift 
and clay-with-flints which partly covers the Chalk, however, Leriche 
has found fossiliferous remanié blocks proving the former presence 
of all the Eocene deposits. 
In Belgium Eocene rocks occupy the whole of the northern and 
western parts of the country, and this “ basin” extends into the 
adjoining regions of Northern France. It stretches northwards into 
Holland, but the Eocene rocks are there covered by a great thickness 
of later deposits. To the south-east the Ardennes apparently 
formed an area of dry land during most of the Eocene period, and 
the deposits tend to assume a littoral character as they are traced 
in this direction. 
On the extreme west of the North France - Belgium region, near 
Calais and St. Omer, the succession is so similar to that on the 
opposite side of the Straits of Dover in the Isle of Thanet and near 
Herne Bay that there seems little doubt concerning the former 
continuity of the deposits. One sees, resting on the Chalk, the 
glauconitic marine Thanet Sands (Landenian) with harder beds 
(“ tuffeau ’’) in the lower part and the “‘ Bullhead Bed” of green- 
coated, unrolled flints at the base, both near Ramsgate and St. Omer. 
The succeeding Ypresian commences at Reculvers (Herne Bay)? 
with a pebble-bed and about 20 feet of very fine brownish sand 
(Oldhaven Sand), followed by the great mass of stiff blue clay 
(London Clay). Around Calais? there is the same succession—first 
the pebble-bed, then the bed of very fine brownish sand, and then the 
great mass of London Clay (Argile yprésienne). Moreover, the faunal 
evidence corroborates the lithological. 
The London Basin is too well-known to need any introductory 
remarks. There is every reason to believe that the Hampshire Basin 
was originally joined to the extreme western end of the London 
Basin. The existence of a few small outliers as well as relict blocks 
(“sarsens”’) on the intervening Chalk lands and the close lithological 
resemblance between the two areas are sufficient proof. The central 
portion of the Wealden Dome probably formed an island of low relief 
or a submerged area within the reach of wave action during the 
greater part of Eocene times. 
The outliers at the eastern end of the Hampshire Basin, especially 
at Newhaven, form a connecting link with the small outliers on the 
other side of the Channel near Dieppe. In many respects the Eocene 
beds of Dieppe resemble the Hampshire deposits more clearly than 
they do the Paris deposits. Not only are the Dieppe deposits 
1 Leriche, Ann. Soc. géol. Nord, vol. xxxii, 19035) pps) 12055; 239) 
vol. xxxviii, 1909, pp. 74,421. C.r. Ass. Frang. Avan. Sci., Cherbourg, 1905, 
p. 394; ibid., Lille, 1909, p. 408. Bull. Soc. géol. France, sér. Iv, vol. xii, 
1912, p. 690 et seq. 
* Whitaker, Geology of the London Basin (Mem. Geol Surv.), vol. iv, 1872, 
p. 170, etc. 
° Briquet, “ Observations sur la Composition des Terrains Eocénes inférieurs 
du Nord de la France’”’: Ann. Soe; géol. Nord, vol. xxxv, 1906, p. 132. 
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