Geological Sociclij. 299 



But how (lifFerently is the history of tlie same great period told off 

 amone; the volcanic mountains of the Cantal and Auvergne ! Great 

 lacustrine formations, of the same age with the rock-marl of the Isle 

 of Wight, are there proved hy their organic contents to have been 

 formed and solidified at a time anterior to the trachytic eruptions 

 which upheaved and desolated the whole surface of the country. 

 How long these great eruptive forces were in action, it is useless to 

 conjecture ; but they were followed by ages of repose, during which 

 the surface of the land was reformed, and deep valleys were exca- 

 vated by the erosive power of water. A new period of volcanic 

 agency succeeded, marked by domes of cinders and scoriae, remain- 

 ing to this day almost unchanged, and by streams of lava, which 

 may be traced from them into the existing valleys. And even these 

 last operations, however recent in the order of geological events, 

 were anterior to the records of history; so that we can still only 

 approximate to their date, by a careful comparison of the effects 

 since produced upon these streams of lava by the destructive power 

 of the elements. 



A description by Mr. Murchison of the lacustrine strata and 

 fossils of CEningen is the last communication connected with ter- 

 tiary formations, which I am called upon to notice. He shows that 

 this deposit consists of horizontal beds of a considerable aggregate 

 thickness, laid bare in quarries on the side, and near the summit 

 of a ridge of hills, the base of which is washed by the waters of 

 the Rhine — that they do not alternate with the molasse but repose 

 upon it unconformably — and that from top to bottom they are of 

 freshwater origin. He enumerates in detail a great variety of fos- 

 sils (such as insects, plants, shells, fishes, tortoises, and mammalia,) 

 discovered at different times in these quarries ; and he adds a de- 

 scription (from the pen of Mr. Mantell) of a fossil fox not to be 

 distinguished from the Vidpes connnunis, found in the middle beds 

 of this system. From all these geological details, as well as from 

 the position of the strata, he concludes that they belong to a very 

 recent tertiary period. At the same time, the waters of the Rhine 

 descend from the lake of Constance at a level no less than 6('0 

 feet below that of the old lake, in which the Gilningen beds origi- 

 nated ; and there is not in the present outline of the country any 

 indication of the surface over which they once extended. 



Such, Gentlemen, have been the prominent subjects of discussion 

 during our meetings of the past year. Before I proceed to other 

 questions, let me express my thanks to Mr. Vernon, for the zeal 

 with which he has investigated, and the fidelity with which he has 

 described, a deep excavation at North Cliff in Yorkshire. Under 

 the ancient gravel of the district are found regular deposits of 

 river silt, containing bones of the mammoth, the horse, the urus, 

 the rhinoceros, the wolf, the ox, and deer ; mingled with thirteen 

 species of land or lacustrine shells, absolutely identical with those 

 now living in the neighbouring district. Phenomena like these 

 have a tenfold interest, when regarded as the extreme link of a 

 great chain, binding the present order of things to that of older 

 2 Q 2 piriods, 



