Ixxii PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



wards returned to Germany, he devoted himself from 1816 to 1819 

 to the study of the Vienna Basin, in which he discovered a series of 

 tertiary deposits, very similar to those of the Paris Basin, thus 

 extending the discoveries of his early masters to other and distant 

 regions. He published his work on the Vienna Basin in 1820, and, 

 comparing its deposits with those of Paris, pointed out that they 

 were either more recent than the Parisian beds, or at least equivalent 

 to the upper portion of them, thus advancing an opinion now recog- 

 nized as a fact, that there are tertiary deposits more recent than any 

 of those which constitute the Paris formation, and suggesting to 

 geologists the means of more accurately determining the epoch of 

 the tertiaries of Italy and of the South of France. In the next 

 year he published a work on the Geology of Normandy, the coasts 

 of which he had carefully examined with the view of determining 

 the geological succession of the secondary rocks of this part of 

 France, and comparing them with those of England, so that it has 

 been justly claimed for him that he shared with the early English 

 geologists in laying the first firm foundations of the science. From 

 1821 to 1829, he was Professor of Geology at the Athenaeum at 

 Paris. In 1820 he had first communicated his observations on the 

 occurrence of marine shells in the muds of freshwater deposits, and 

 of freshwater shells in the marine deposits of the Paris Basin ; and 

 in 1829 he resumed the discussion of these facts ; and, opposing the 

 theory of alternating elevations and depressions of the surface, he 

 maintained that such mixtures of the organisms of freshwater 

 and marine life were the consequence of river-freshets on the one 

 hand, and of tidal overflows on the other, in a large estuary. This 

 theory he afterwards applied to the Sub-Pyrenean Basin in his paper 

 on the bone-beds of Sansan, near Auch. In 1829 he was the pro- 

 jector and one of the founders of the Geological Society of France, as 

 has been commemorated by M. Deshayes in the following very for- 

 cible words : " It so chanced," he says " that M. Prevost, his brother- 

 in-law, M. Jules Desnoyers, and myself, were lodging together in 

 the Rue de Paradis, when Constant Prevost conceived the idea 

 of founding an independent society, under the title of The 

 Geological Society of France, which was intended to advance and 

 spread abroad the science by collecting together its scattered elements. 

 The idea of such an association was eagerly embraced by a small 

 number of the most eminent men of the epoch, who became thus the 

 first founders of the Society. Around them were speedily grouped a 

 large number of native and foreign men of science, who felt honoured 

 by being associated in their labours. The success of this happy 

 thought of Constant Prevost is no longer doubtful, and more than 

 five hundred colleagues, spread over every part of the earth, will be 

 associated in the grief which all must feel at the loss of our founder." 

 How much must these words recall the early formation of our own 

 Society, although the customs of our country have not permitted 

 those public exhibitions of grief at the loss of its founders which are 

 so characteristic of our French neighbours. 



In 1831 he taught Mineralogy and Geology at the Central School 



