1848.] 



MURCHISON ON THE STRUCTURE OF THE ALPS. 



233 



Freshwater Deposits of (Eningen. 



In following the surface of the uppermost beds of the nagelflue and 

 molasse from the lofty hills which flank the chain of the Hoher Sentis, 

 &c., the formation as it spreads over the lower grounds, extending 

 from thence, and from the lake of Zurich to the lake of Constance 

 and the Rhine, is chiefly characterized (where fossils and lignites have 

 been detected) as a great terrestrial or estuary deposit. On the right 

 bank of the Rhine, between Constance and Schaffhausen, the cele- 

 brated freshwater deposit, which I visited for the third time, has, 

 it still appears to me, been formed in a depression of pre-existing 

 molasse and nagelflue*. In revisiting this locality I was anxious to 

 see what discoveries had been made, and what influence they might 

 have, in conjunction with the recent description of the fossils, on the 

 conclusions respecting the age of that formation which I formerly 

 entertained. In regard to its overlying position I am happy to say 

 that my former general view is supported by M. Studer, M. Escher, 

 and all the Swiss geologists; viz. that these freshwater sands, marls 

 and limestones are younger than the chief masses of molasse and 

 nagelflue of Switzerland. As in my previous communication a very 

 small woodcut only was given, I beg to annex another which better 

 represents my present ideas. 



Fig. 27. 



U'angen. 



Marls and detritus (with volcanic tuff of Escher). 

 Upper quarries of freshwater limestone. 

 Lower quarries of freshwater limestone. 

 Regenerated soft moiasse (marine molasse of Escher). 



Rhine. 



The area over which the sandy marls, marlstone and limestone of this 

 deposit extend, is of much greater dimensions than the spots where 

 quarries have been opened and wherein the fossils have been found. 

 This area, as far as it can be traced, is of an elongated elliptical form, 

 extending \^ith the Rhine from Berlingen, on the right bank of the 

 river, to Wangen and (Eningen near Stein on the left bank, a distance 

 of not less than ten miles from east to west. This is inferred because 

 freshwater shells have been found in the soft recomposed sandstone of 

 Berlingen, which rock is of the very same character as that which 



* On this occasion I was accompanied by Professor Brunner. For my previous 

 description of (Eningen see Trans. Geol. Soc. Lond. 2nd Ser. vol. iii. p. 277. In the 

 little woodcut there given the surrounding molasse and nagelflue were indicated by 

 inclined lines, though I then knew perfectly that in this tract such strata were not 

 there incHned. These lines were only inserted to mark more strongly my belief that 

 such rocks, so highly inclined in the neighbouring country, were of age anterior to 

 the overlying marls and limestones of (Eningen. See also the account of this 

 deposit by M. Eschervon der Linth, given by Herman von Meyer in his Palsologica, 

 1845, and my observations thereon, Journal of the Geol. Soc. Lond. vol. iii. p. 54. 



