STRATIGRAPI1ICAL GEOLOGY. 535 



brackish and fresh-water deposits of the Mainz basin, and 

 the brown-coal deposits of Hesse and-Rhineland. In Upper 

 Oligocene, Beyrich included the Marine formations of Crefeld, 

 Diisseldorf, Cassel, etc. These are succeeded by the typical 

 Miocene formations of the Lower Elbe district, Holstein and 

 Schleswig. 



Beyrich's differentiation of the Oligocene formation was 

 supported by Lyell and other eminent geologists, and proved 

 very helpful in the systematic arrangement of the Tertiary 

 deposits. It is noteworthy that there is no marine equivalent 

 in Belgium, France, or England for the Upper Oligocene strata 

 of North Germany. Probably these correspond in age with 

 the fresh-water limestone of Beauce, which is usually classified 

 as Lower Miocene by French geologists. Emendations in 

 Beyrich's sub-division were made by Sandberger in 1863, when 

 he pointed out that the "Cyrena" marls belonged to Upper 

 Oligocene, and that the Lower Miocene should begin with the 

 littoral and brackish-water series, the " Cerithia " and land-snail 

 limestones, and the leaf-sands of the Miinzenberg. 



The Tertiary basin of the Swabian-Bavarian plateau and the 

 neighbouring margin of the Jura mountains and the Alps is 

 connected on the one side with the Austrian development, on 

 the other side with the North Swiss development of the Tertiary 

 formations, and its relations could only be properly understood 

 after the knowledge of these formations in adjacent areas was 

 fairly well advanced. The monograph of the Molasse deposits 

 in Switzerland, written by Studer (1825), contains a remark- 

 ably accurate description of the different formations according 

 to their petrographical constitution and stratigraphical posi- 

 tion, but at the time of publication it was quite impossible to 

 assign definite ages to the successive strata. The observa- 

 tions of the Bernese geologist were supplemented by the 

 researches of Escher von der Linth, Braun, and Oswald 

 Heer, so that Studer in 1853, in the second volume of his 

 famous work, Geologic der Schweiz, was in a position to 

 give an almost exhaustive exposition of the Swiss Tertiary 

 deposits. 



From the composition and stratigraphical position of the 

 parti-coloured Nagelflue deposits, Studer concluded that the 

 materials composing this conglomeratic rock and the Molasse 

 sandstones had been derived from a marginal Alpine chain 

 which was afterwards bent inward at the further folding and 



