STRATIGRAPHICAL GEOLOGY, 517 



The Quader Sandstone and Greensand in North Germany 

 were united with the White Chalk by Hoffmann in 1830, 

 and recognised as the equivalents of the Cretaceous system. 

 He compared the- Quarter Sandstone with the upper and lower 

 greensand deposits; the marly, calcareous^ or siliceous rocks 

 between Quader Sandstone and Chalk in North Germany with 

 the Chalk Marl of the North- Western basin ; the grey, earthy 

 marls and white chalk with the Lower and Upper Chalk of 

 England. 



The discovery of older Cretaceous deposits in the Swiss Jura 

 mountains was an important step in advance. As far back as 

 1 803, Leopold von Buch had drawn up a very detailed catalogue 

 of the rocks in the neighbourhood of Neuchatel, but his manu- 

 script was not published until sixty-four years later, after the 

 death of the author. A copy of the manuscript had been, 

 however, presented by Ami Boue' to the library of the French 

 Geological Society, and geologists had tried in vain to find 

 equivalents for the series of strata described in it. 



In 1836 Auguste de Montmollin demonstrated that the 

 youngest Jurassic rocks were succeeded by a diversified com- 

 plex of strata comprising yellowish limestone and blue marls, 

 whose fossils resembled those of the English greensand ; 

 Montmollin called the complex " Terrain cretace du Jura," 

 and Thirria, who almost simultaneously found similar strata in 

 the neighbourhood of Besangon, applied the name of " Terrain 

 Jura-Cre'tace." 



But before the actual publication of Montmollin's treatise, 

 Thurmann had made the proposal at a Congress of the French 

 Geological Society in Besangon (1835) to introduce the designa- 

 tion of Neocomien for the newly-discovered complex of strata, 

 and this name was immediately adopted by Dufrenoy and Elie 

 de Beaumont, and received the authority of their geological 

 map and text. These two authors sub-divided the Cretaceous 

 formation into a Lower Group, comprising (a) Wealden, 

 Neocomian, and ferruginous sand ; (b] Greensand ; (<r) Chalk 

 Marl ; and an Upper Group represented by the White Chalk. 

 The chief divisions of the Cretaceous deposits having been 

 thus definitely fixed in France, the following years between 

 1835 and 1860 were signalised by the publication of an extra- 

 ordinary number of special papers devoted to the geology and 

 palaeontology of the Cretaceous system in French localities. 



Two valuable memoirs were published in 1841 and 1842 on 



