Identifier: quarterlyjourna371881geol (find matches)
Title: The Quarterly journal of the Geological Society of London
Year: 1845 (1840s)
Authors: Geological Society of London
Subjects: Geology
Publisher: London (etc.)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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eat mass of the 300 ft.and occupying the valleys, will represent the undoubted Oxford Clay.The series 3 b (1) then commences the group of rocks now understudy. If for siliceous limestone we read its equivalent, calca-reous grit, we have the term which will exactly suit the Englishgeologist, who at once recognizes in it a representative of his LowerCalcareous Grit. At the base, as seen in quarries on the road fromthe station of Launois to Neuvizy, is hard blue calc-grit; and abovethis, nodular beds of grit in a subargillaceous matrix. Some ofthese are very light, like the Upper Calcareous Grit of Yorkshire, andare said by Sauvage and Buvignier to be soluble in potash, indicatinga possible organic origin, like the Renulina-grits of Scarborough ;the fossils, however, are in some cases beekized. These nodularbeds, which begin to present some of that peculiar feature indicated * See list of works above. 502 J. F. BLAKE ON THE UPPEE Pig. 1.—Map of Country near Neuvizy. (Scale 1 : 80,000.)
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by the term terrain a chailles**, contain a characteristic fauna, viz.Ammonites cordatus, Modiola bipartita, Perna quadrata, Pecten ji-brosus,Aviculaexpansa, Exogyra spiralis, Ostrea dilatata, 0. rastellarisBhynehonella Thurmanni, and several others less certainly identified,but all indicating a horizon similar to that of the No the grits andclays or of the Lower Calcareons Grit of Yorkshire. At the top thisseries becomes much more calcareous, and finally contains abundantoolitic grains, while a change of fauna takes place. This has beenvery imperfectly examined; but the three chief species are Ammo- * This term terrain a chailles is a misleading one. It is often used as ifindicating a fixed horizon ; but it appears from French writers that there is oneof these terrains in the Oallovian, another in the Oxfordian (the presentone), and a third in the Corailian; so that it is really a mere petrologieal phrasesimilar to nodular beds . JURASSIC OF THE PARIS BASIN. 503 nites cculatus of the

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