STRATIGRAPHICAL GEOLOGY. 521 



strated that calcareous and marly strata (Planerkalke) are 

 present between the Upper and Lower Quader Sandstone, and 

 contain in some localities a rich marine fauna. Cotta thought 

 these marine limestones were the time-equivalents of the 

 Gault clays. Geinitz published, between the years 1839-42, 

 an excellent Monograph on the Strata and the Fossils of the 

 Cretaceous Rocks in Saxony and Bohemia. His results con- 

 firmed Cotta's surmise, and upon paleeontological evidence 

 established the equivalents of the German and British de- 

 velopments: 



4. Upper Quader Sandstone . . = White Chalk. 



V Upper Planer Marls . . = (J?"? h! f- 



\Chalk Marl. 



2. Middle and Lower Planer Lime- f Upper Greensand 



stone and Marls . . ~ \ Gault. 



i. Lower Quader Sandstone . . = Lower Greensand. 



August Emmanuel Reuss, the famous Austrian authority on 

 the Cretaceous system, published in 1843 and 1844 the first 

 results of his detailed researches on the Cretaceous deposits 

 of Bohemia. Two years later, his monograph on the Bohemian 

 Cretaceous formations appeared, and this work has been 

 regarded as the fundamental stratigraphical work on the 

 Bohemian facies. The four chief divisions distinguished 

 by Reuss are : i, The Lower Quader Sandstone, present in 

 Bohemia in its full development ; 2, the Planer marls, richly 

 fossiliferous ; 3, the Planer limestones, together with the con- 

 glomerates reposing upon them ; 4, the Upper Quader Sand- 

 stone, poorly fossiliferous, but attaining very great thicknesses 

 in Bohemia. 



The insecurity of the systematic position of the Lower and 

 Upper Greensand in England induced Fitton to undertake a 

 renewed examination of those deposits in the Isle of Wight. 

 The result, published in 1847, showed conclusively that the 

 Lower Greensand was an equivalent of the Neocomian. 



A very great influence was exerted upon the systematic 

 arrangement of the Cretaceous system by the publication of 

 D'Orbigny's Paleontologie Francaise. In the second volume 

 of this gigantic work, D'Orbigny introduced a new classifica- 

 tion of the Cretaceous formations, which was based upon 

 intimate knowledge of the French development. He divided 

 the system into five stages, named in accordance with typical 



