502 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



geology the English nomenclature : Calcaire Portlandien, 

 Argiles Kimmeridgiennes and Oxfordiennes, Coralrag, Corn- 

 brash, Grand Oolite, etc. At the same time they varied the 

 English nomenclature on certain points where the French 

 development differed in any marked degree from the English. 



The General Survey of the Orographic and Geognostic Rela- 

 tions of North- Western Germany, a work published in 1830 

 by Friedrich Hoffmann, described the Jurassic succession 

 in that district in greater detail than a previous contribution 

 by Hausmann (1824). Roemer, Koch, and Dunker made 

 the German Jurassic fossils the subject of palaeontological 

 monographs, and their results, taken in conjunction with the- 

 geological map and sections of Hoffmann, showed that the 

 equivalents of the English Jurassic formations were well 

 represented in North-Western Germany. Thus it seemed as if 

 the English development of the Oolitic and Liassic formations 

 could be regarded also as a standard for the leading features 

 of the Terrain Jurassique in France, Switzerland, and North 

 Germany. 



While it was Thurmann who provided the clue to the 

 stratigraphy and tectonic structure of the Bernese Jura 

 mountains, to Gressly belongs the credit of having for the 

 first time elucidated the lithological and pakeontological 

 variations displayed in adjacent localities by deposits of the 

 same geological age. Gressly was the founder of the teach- 

 ing regarding rock facies, which afterwards played such an 

 important part in the unravelling of Alpine stratigraphy. 



In his investigation of the Solothurn Jura, Gressly 1 did not 

 confine himself to the determination of the chronological 

 succession of the Jurassic sub-divisions, but traced the 

 horizontal extension of the different members. He soon 

 became convinced that each particular petrographical develop- 



1 Amanz Gressly, bom 1814 in a remote valley near Laufon, in the 

 Jura mountains (Canton Solothurn), was intended for the Church, and 

 studied in Solothurn, Lucerne, Freiburg, and Strasburg. Stimulated by 

 his social intercourse with Voltz, Thirria, Thurmann, and Agassiz, he 

 devoted himself exclusively to geology, and especially to the research of 

 the Jura mountains. From 1840 to 1850 he geologised in the Solothurn 

 Jura region ; he supplied himself with means by the occasional 

 opportunities of delivering expert opinion, drawing up technical estimates, 

 etc. In 1859 he was sent by his patron Desor to Cette, where he studied 

 the mode of life of marine organisms. In 1861 he took part in the Berna 

 Expedition to the North Cape and Iceland; he died in 1865 



