PRESTWICH — BRITISH AND FOREIGN TERTIARIES. 1 11 



Feet, 

 ruginous) with pebbles of flint, of sandstone, and of Cal- 

 caire grossier, the latter often pierced by boring shells ; 

 laminae with a subdip westward ; organic remains nu- 

 merous 5 



Light yellow soft sandstone 2 



White sand and shells 1 



Light-coloured saccharoid sandstone, with a few seams of 

 shells and some pebbles : base not exposed 20 



35 



At Hadancourt near Chaumont the " Sables Moyens " appear to 

 be, as well as I could judge from a well-section, about 70 feet thick, 

 but I could not there ascertain its subdivisions*. A cutting on the 

 side of a road above Triel gave me in 1855 the following section : — 



Road-side Section^ Triel, Seine et Oise. 



Feet. 

 Thick-bedded freshwater limestones. Base of Calcau'C lacustre ? 



Laminated freshwater marl and limestone ? 3 

 Light-green marly sands, with numerous 



small shells in patches at top ; fewer in 



the lower part 8 



Shelly sandstone 3 



Sables Moyens. These 

 beds seem to belong 

 to the upper part of 



Unfossiliferous clayey sands 4 )■ this deposit, and that 



Hard tabular sandstone, no shells 3 



Light-yellow and greenish sandy clay, with 

 few or no fossils 3 



the lower beds are 

 wanting. 



24^ 



White marls and freshwater limestones, Upper part of the Cal- 

 with a subordinate bed of sand 9 caire grossier. 



The general section of the " Sables Moyens," as given by M. 

 Chas. D'Orbigny in his Tableau synoptique, and including more 

 especially the district within 30 to 40 miles of Paris, is as under : — 



Ft. in. 



1. Thin beds of greenish marl and brown clay, with an 



intercalated bed of shelly greenish sand — Avicula 

 fragilis, Cerithium mutabile, Fusus subcarinatus ... G 6 



2. Calcareous sandstone, very shelly, sometimes passing 



down into a calcareous and sandy freestone — Ceri- 

 thium lapidum, Natica m,utabilis, Melania hordeacea, 

 Cytherea elegans, Portunus Hericarti, &c 10 



3. Sand full of fossils, many rolled — Astrcea stylophora, 



Nummulites variolarius, Cyrena deperdita, Cardium 

 obliquum, Valuta labrella, LimncBa 6 6 



4. Quartzose sands and sandstone in places mixed with 



green sand, and containing masses of fossil wood, 

 and sometimes a considerable number of shells — 



* Another well at Cuvergnon, mentioned by M. Graves (p. 445), gives a thick- 

 ness of 110 feet to the " Sables Moyens." 



