TERTIARY FORMATIONS OF SWITZERLAND. 143 



Thus circumstanced, my observations will be found to relate chiefly to 

 the South-Western part of the Helvetic Basin, and not at all to the more 

 interesting portion extending Northwards and Eastwards from Berne, 

 and already somewhat minutely described in a work, published in 1825, 

 by Professor Studer, of Berne. My excursions were, as I have said, con- 

 fined to a small part of the Canton of Freyburg, and the greater part 

 of the Pays de Vaud. The limit of this district to the South is the 

 lake of Geneva. The Eastern and Western boundaries are sufficiently 

 defined by the abrupt elevation of mountains, forming the flanks of the 

 High Alps on the one side, and of the Jura on the other. 



The high road from Freyburg to Vevey is nowhere at any great dis- 

 tance from the line which separates the tertiary beds from those secondary 

 ones upon which they lie uncomformably, but the actual junction at any 

 point I did not perceive, as the country is for the most part covered 

 up, and the geological phenomena obliterated. Close to Vevey, however, 

 in a valley cut by a small stream coming down to the lake, we obtain 

 a glimpse of the extreme tertiary beds to the East, and it will be perhaps 

 best if, commencing with these, we trace the collocation of the beds as 

 they are exposed on the North side of the lake of Geneva, and mav 

 be observed in travelling from Vevey towards Lausanne and Geneva, 

 westwards. 



Close to the town of Vevey there occurs a hard conglomerate, very 

 coarse where it rests on the older rock below, but becoming gradually 

 finer, until after a few miles it is replaced by a very fine sandstone, which 

 spreads over the whole centre of the valley of Switzerland, and is the great 

 tertiary deposit of which I have chiefly to speak. Of these beds, the coarser 

 conglomerate is known generally by its German designation, " Nagelfluhe," 

 while the nature and peculiarities of the finer sandstone (which is the 

 most widely spread and extensive of all the European Tertiaries) are in- 

 dicated in the name " Molasse," by which the soft, incoherent tertiary 

 sandstone of this country and Germany is designated. 



The thickness of the Nagelfluhe is various, but never very great. From 

 near Vevey it may be traced towards the West for about a couple of 

 miles, gradually becoming a finer deposit, and imperceptibly changing 

 into the Molasse, without any definite line of separation. 



