226 



Notices of Memoirs — 



The following abstract gives M. Hebert's views respecting the cor- 

 relation of the Lower Eocene strata, but which are not in accordance 

 with other geologists, including Mr. Prestwich, whose opinion will 

 be found in " Memoire sur la position geologique des sables et du 

 calcaire lacustre de Eilly " (Marne), Bull. Soc. Geol. France, 2 ser. 

 torn, X. p. 300 ; and also " On the Structure of the Strata between 

 the London Clay and the Chalk in the London and Hampshire 

 Basin" (Quart. Journ. Geol. Soc. 1853, vol. 6, p. 252, and 1865, 

 vol. 8, p. 255). 



Table showing the Synchronism of the Lower Eocene in the Basins of 

 Paris, Belgium, and England. 



o 

 o 



o 



1-^ 



1 



A J 

 W 1 



Ph 

 a. 



pi 

 P 



o 

 O _ 



Ay 



Paris Basin. 

 Lower Calcaire Grossier. 



Belgium. 

 Bruxellien. 



England. 

 Bracklesham. 



Sands with Nummulites 



planulatus 



Sands without fossils 



Wanting 



Wantino" 



Paniselien 



Lower Bagshot 



Sands. 

 London Clay. 

 Oldhaven Beds. 

 Woolwich Beds. 

 Thanet Beds, 



Upper Tpresien. 



Clay of Ypres 





Plastic clay and Lignites 

 Sands of Bracheux 



Upper Landenien 



Lower Landenien 





Denudation. 



Denudation. 



-Wanting. 



Marl of Dormans. ^ 

 Conglomerate of Meudon. j 

 Calcaire de Billy, Strontian 



Marls of Meudon 



Sands of Eilly 



Poudingue de Nemours 



Wanting. 



Heersien Marine Marls. 



Upper Heersien Sands . 

 Lower Heersien Sands . 



Gap and Denudation 



Calcaire de Mens 



General remarTcs. — It is to be observed that during the period 

 corresponding to the lower group of the preceding table, the basin 

 of Paris as well as that of Belgium have undergone considerable 

 denudation, so that the deposits of this period no longer exist as 

 continuous strata, but only as outliers, as is shown by the limestone 

 of Mons, the Heersien marl, the Eilly limestone, etc. These 

 districts have been, during the early Tertiary period, the seat of 

 oscillations, by which they have been alternately emerged and 

 submerged. In the stationary interval of these movements deposits 

 have taken place, but the incoming and retiring waters have carried 

 off the greater portion of these deposits. 



It had been the same at the close of the Cretaceous period. The 

 different strata of the Upper Chalk ( Craie Superieure) posterior to 

 the chalk of Meudon, — the chalk of Ciply, the Maestricht chalk, the 

 pisolitic limestone, have been deposited and denuded under similar 

 conditions to those above described. It is the cause of the numerous 

 lacunse that are observed, specially in the Paris basin, in the transi- 

 tion from the Cretaceous to the Tertiary period. M. Hebert points out 

 that he has frequently shown how the sea, at the time of the Chalk of 

 Meudon, the Upper Chalk and Lower Eocene, penetrated into the 

 Paris basin by Belgium. The basin of Paris at these periods was 



