112 L. Dudley Stamp— 
frequently regarded as of lagoon origin; this is called P1m, the 
Paniselian having been divided into two cycles, Pl and P2. It 
seems probable that this scheme of nomenclature has been carried 
too far by the Belgian Survey, for example in the Devonian, where 
the artificial grouping of the deposits of each division (Coblentzian, 
etc.) has obscured the more or less continuous marine transgression 
of Lower Devonian times. However, even there it has the 
advantage of giving some indication of the EON) of the beds, by 
a single symbol. 
The application of the principle to the classification of the Hocene 
strata of the Paris Basin is due especially to Professor Leriche.1 As 
will be seen later these deposits are especially suitable for 
classification in this way. 
IJ. THE ANGLO-FRANCO-BELGIAN BASIN. 
The Hocene rocks of the area under consideration occur in four 
principal districts—the so-called “‘ Basins’? of Paris, Northern 
France and, Belgium, London, and Hampshire. Separating these 
four areas of Kocene rocks there are uplands of Cretaceous or older 
rocks. It is now quite certain that they are not original basins of 
deposition, but formed part of one great basin—the Anglo-Franco- 
Belgian Basin. The folding which has affected this extensive area 
and caused its separation into the present “ basins”’ took place, for 
the most part, in post-Kocene times. One finds, for example, in 
the monocline of the Isle of Wight 2 and the anticline of the Pays de 
Bray ® that the Eocene beds are involved in the movements. Their 
thickness is quite independent of the folding. Hence it may be 
inferred that the movements did not commence until after Hocene 
times. On the other hand, there is a large amount of evidence that 
the uplift of the Wealden Dome commenced even before Hocene 
times, and went on gradually throughout the early Tertiary period. 
The effects of the movement can be clearly seen in the character of 
the Eocene deposits of the London Basin. The areas of uplift 
between the present “ basins”? have been stripped by denudation 
of their Kocene rocks, and only a few scattered outliers remain to 
indicate the former continuity of the deposits. 
The Paris Basin is situated mainly to the north of Paris. South- 
wards the Hocene series becomes incomplete, since some of the marine 
invasions did not penetrate beyond the latitude of Paris. The Paris 
Basin is separated from the Kocene region of Northern France and 
Belgium by the Chalk uplands of Artois, Picardy, and Champagne, 
and one only finds a few patches of Lower Hocene rocks from the 
1 Leriche, ‘‘ Observations sur la Classification des assises paléocenes et 
éocénes du Bassin de Paris’’: Ann. Soc. géol. Nord, vol. xxxiv, 1905, p. 383. 
- 2 Bristow, Geology of the Isle of Wight (Mem. Geol. Surv.), 2nd ed., 1889, 
p. 242. 
3 Dollfus, ‘‘ Essai sur la détermination de l’Age du soulevement du Pays 
de Bray’: Bull. Soc. géol. France, sér. m1, vol. ix, 1881, p. 112. 
