110 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



The palpable features in these sections are the preponderance of 

 clays, the decreased importance of these clays as they range eastward 

 and southward, and the increasing importance of the quartzose sands 

 in the same direction. If now we turn our attention to the extreme 

 range eastward in France of the " Sables Moyens," we shall find no 

 apparent relation with the English series. In the neighbourhood of 

 Rheims they consist of siliceous sands a few feet thick, and with but 

 few fossils : as they trend towards Paris they gradually become 

 thicker, and at La Ferte-sous-Jouarre they present the following 

 section (D'Archiac), underlying 195 feet of the green marls and 

 freshwater limestones of the gypseous series : — 



Ft. in. 



Calcareous freestone, with marine remains 5 



White shelly sand (siliceous?) 19 6 



Beds of sandstone 6 6 



31 



and overlying 114 feet of " Calcaire grossier," under which are 

 107 feet of "Sables Inferieurs * ." Further westward the sands 

 rapidly expand ; and, near Villers- Cotterets, attain an exceptional 

 thickness of 1 75 feet, consisting throughout of siliceous sands and 

 sandstones with few or no fossils. 



M. D'Archiac gives as the principal fossils in this eastern part of 

 the Paris basin (the department of the Aisne) — Astrcsa stylophora, 

 Nummulites variolarius, Corbula angulata, Cyrena deperditay Venus 

 solida, Paludina globulus, Cerithium thiara, Fusus minax, Voluta 

 labrella, and Portunus Hericarti. 



Immediately west of this spot a marked change takes place : the 

 thickness of the series decreases again to 80 or 90 feet, and certain 

 divisions and physical features, which become still more prominent 

 in the Oise, set in. In places in the vicinity of Beaumont and Auvers 

 there occurs at the base of the " Sables Moyens," in a bed of 

 white sand with flint-pebbles, numerous fossils derived from older 

 tertiary beds, almost all broken and much worn. Above this there 

 is often a variable bed of laminated sandy green clay without fossils. 

 This is overlied by 30 to 40 feet of white sand, the upper part con- 

 solidated into a siliceous sandstone. These are succeeded at Auvers 

 by the celebrated shelly and conglomerate beds of that locality. In 

 1854 this section presented in descending order the following suc- 

 cession of strata under the surface-soil : — 



Section of Stone-pit at Auvers, Oise. 



Feet. 



Broken sandstone and sands, with a few shells 3 



Yellow sands full of shells, and with small pebbles ; la- 

 minae with a subdip eastward 3 



White sandstone : white sand and shells 1 



Light-coloured sand (sometimes the lower part stained fer- 



* Hist, des Prog. vol. ii. p. 571. 



