694 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



in the nineteenth century Lower Cretaceous shales, limestones, and marls had 

 been recognized as resting on uppermost Jurassic deposits in the Jura Alps of 

 eastern France and in 1835 these rocks and their fauna were described and desig- 

 nated as Neocomian. The Cretaceous rocks and faunas in particular areas of 

 France were studied by Leymerie, d'Archiac, and others and compared and cor- 

 related with the divisions established in England, Germany, and Switzerland. 



During the first half of the nineteenth century, the Cretaceous deposits of 

 Germany were studied by F. A. Roemer and Hans Geinitz. The former in 1841 

 published his great work on the Cretaceous of North Germany, with a descrip- 

 tion of the faunas and a classification of the rocks. At approximately the same 

 time Geinitz described the Cretaceous faunas and rocks of Saxony and Bohemia. 

 By the middle of the century the first volumes of d'Orbigny's PaUontologie 

 frangaise had appeared. In this work the French Cretaceous was divided into 

 seven stages designated as Neocomian, Urgonien, Aptien, Albien, Gault, Ceno- 

 manien, Upper Greensand, Turonien, and Senonien. Additional investigations 

 by Geinitz and Beyrich extended the German classification to the Cretaceous 

 deposits farther east in Hungary and north into the Baltic region. 



The results of early investigations of the richly fossiliferous Tertiary deposits 

 of the Paris Basin led to a preliminary classification of the strata and a knowl- 

 edge of the stratigraphic relationships of the invertebrate faunas occurring in 

 the beds which later were to be designated as Eocene and Oligocene. An impor- 

 tant contribution by Cuvier and Brongniart was published in 1808 and reprinted 

 in 1811, in which the faunas were listed and the rocks described. Accompanying 

 preliminary geologic maps and stratigraphic sections revealed the relatively 

 simple structural features of the strata and some information concerning chang- 

 ing lithologic facies. The recognition of lower beds of plastic clay, followed by 

 sandstones and limestones forming a group characterized by great numbers of 

 Nummulites, led to the introduction of the term Nummulitic Series for strata 

 which later were to be classified as Eocene. Above was a second group, which in 

 upward succession consisted of gypsum, fresh water marls, and clays, passing 

 upward into marine limestones and sandstones alternating with fluviatile and 

 lacustrine beds. From such evidence Cuvier and Brongniart concluded that at 

 the close of the Cretaceous, the area of the Paris Basin was only slightly above 

 sea level and that it possessed an irregular surface formed by erosion of the Up- 

 per Chalk and that it was traversed by several streams. A local, differential, 

 slight downwarping of the surface at the close of the Cretaceous permitted ma- 

 rine waters to transgress slowly into the river valleys and ultimately over the 

 intervening land areas, thus permitting the deposition of fluviatile and lagunal 

 deposits and the plastic clay. Intermittent advances and retreats of the sea were 

 regarded as being responsible for the alternations of continental and marine 

 beds and variations in sedimentary facies. 



The Tertiary of the Belgian Basin was laid down in the northeast extension 

 of the Paris Basin. One of the most important studies on these deposits was by 

 A. Dumont (1849) in which the entire Belgian Tertiary succession was classi- 

 fied stratigraphically upward as the Heersien, Landenien, Ypresien, Paniselien, 

 Bruxellien, Laekien, Tongrien, Rupelien, Bolderien, Diestien, and Scaldisien. 



Among the more important contributions made to the Tertiary stratigraphy 

 and paleontology of Italy was a work published in 1814 by Giovanni Brocchi 



