ORIGINAL ARTICLES. 
On Cycies of Sedimentation in the Eocene Strata of the 
Anglo-Franco-Belgian Basin. | 
By L. Duptry Stamp, M.Sc., A.K.C., F.G.S., King’s College, London. 
(Concluded from p. 157.) 
C. Tur Lonpon “ Basin ’”’. 
Landenian.—The Landenian is represented by the Thanet Sands 
and Woolwich and Reading Beds. The former seem to correspond 
to the two lower zones of the French Landenian, whilst the marine 
Bottom Bed of the Woolwich Series corresponds to the zone of 
Cyprina scutellaria. The present writer has given reasons for 
believing the pebble-bed separating the two to be due to a move- 
ment of uplift in the Wealden area! In the east of the 
London district the marine Bottom Bed passes up into clays and 
marls crowded with estuarine fossils (Woolwich Beds); to the west 
into unfossiliferous mottled clays and fluviatile sands (Reading Beds). 
The extensive transgression at the time of the zone of Cyprina 
scutellaria is noticeable in the London Basin as it is in the Paris 
and Hampshire Basins. 
Ypresian.—The Ypresian commences with the Oldhaven or 
Blackheath Beds. A shght upward movement of the Weald caused 
the sea to spread rapidly over the Upper Landenian estuarine flats, 
and at the same time great masses of pebbles tended to move from 
the northern flank of the Weald into the same area. In this disturbed 
marine region the invading Ypresian species lived side by side for 
a short time with the existing estuarine species of the lagoons, and 
so gave rise to the mixed Blackheath fauna. Continued transgression 
and more tranquil conditions resulted in the formation of the Base- 
ment Bed of the London Clay. The clay itself is much thicker in the 
east than in the west, and passes up gradually into sandy beds 
(Claygate Beds), and then into the continental Bagshot Sands. 
The latter are thicker in the west, and, as Mr. Whitaker showed many 
years ago, overlap the marine Ypresian, and come to rest on the 
continental Landenian, or even on the Chalk.2 The London Clay 
is only 15 feet thick at Great Bedwin in the extreme west, about 50 to 
60 feet at Newbury, but increases rapidly to over 400 feet in the 
North of London and about 490 feet in the Isle of Sheppey. In the 
London district it thins off rapidly southwards against the Wealden 
Dome. This is another proof that the Weald was being uplifted 
during Eocene times. 
1 Stamp and Priest, ‘“Geology of the Swanscombe Eocene Outlier ’’: Proc. 
Geol. Assoc., vol. xxxi, 1920, p. 191. - 
2 Whitaker, ‘‘ On the Western End of the London Basin”’: Quart. Journ. 
Geol. Soc., vol. xviii, 1862, p. 258. 
