38 THE OLIGOCENE BEDS 



There is a fine section of the molasse in a quarry at Vintue, 

 near Iiltrechy, where it occurs in beds compact enough to form 

 good ashlar stone. Fig. 12, p. 36, is a resume of this section 

 from details by MM. Cossmann and Lambert. This section is 

 very useful as showing the relations of the Molasse of Etrechy to 

 the falun of Jurre and the ISIeulieres of Brie ; and it also exhibits 

 the exceedingly variable character of the whole of this portion of 

 the Paris basin Oligocene. 



We may here remark that we consider these Oligocenes to 

 have been too minutely subdivided, and that at best many of the 

 formations mentioned have a local value only. We do not 

 recognise, for instance, that the Ostrea-xs\-dj\a and Molasse of 

 Etrechy, or the Sands of Vauroux, have the same geological, or 

 pal^ontological, value as, say, the Calcaire Grossier or the Sables 

 Moyens in the Eocenes. At the same time it is convenient to 

 treat of them in detail because of the assistance they afford in 

 correlating Oligocene beds in other parts of the basin. As in 

 England and elsewhere, the alternation of marine with fresh- 

 water beds has led to much difficulty in classification. 



For other details concerning this formation consult Lambert, 

 Bull. Soc. G'eoL Fr , 36. sen, t. ix. (1881), p. 501 ; Noiiv. Arch, dit 

 Museum (1880), p. 265. 



4. FALUN OF JEURRE. 



This horizon of the Etampes Oligocenes is typically developed in 

 a large sand pit near Jeurre church, on the right-hand side of the 

 road from Etrechy to Etampes (see p. 56). Here the majority 

 of the Oligocene mollusca described by M. Deshayes* were 

 found; and when studying the strata in this district in 1889 we 

 came to the conclusion that Jeurre is the best fossiliferous 

 locality at present available, though Pierrefitte would not be 

 bad, if perchance the section there should be re-opened. 



The details we noted do not differ from the published 

 accounts of the exposure, except that on the occasion of our visit 

 the lowermost beds were not clearly definable. 



in. 



Section at Jeurre-\. ft 



Drift 6 6 



Fine quartzose grey sand with fragments of 

 Axiiura, and having reddish bed with 

 bhick pebbles at the base . . . i 7 



,' Ouartzose grey sands with Meretrix sp/endida, 

 Sands \ _ Liicina Heherli ; falun and sands with 

 of s ^.v/w^rfZ o/^oT/rt/a/ yellowish fine quartzose 



Morigny. I sands with Cominella Gossardi, ike. ..59 



( Red falun with Axincea obovata . . . i ^ 



* Dcsliayes, CoquiUes foss. dcs cnn. dc Paris; and Aiiiin. sans vert, die Basin de Paris. 

 t Abridged frum Cossman and Lambert, o/t. cit.. p. I3. 



