Structure of the Eastern Alps. 329 



the northern mountains of the Canton of St. Gall; from which they descend 

 in a long succession of inclined terraces to the south shore of the Lake of 

 Constance. Whatever conclusions Professor Studer and other writers have 

 been enabled to establish, by the help of large suites of fossils, respecting the 

 age of the 7nolasse of Svt'itzerland, may therefore be extended to at least 

 a portion of the newer deposits of Bavaria. This inference is the more im- 

 portant, because the upper tertiary system of Bavaria is often buried under 

 great accumulations of alluvial matter; and in the places where it is laid bare, 

 we were often unable to find a single fossil, to assist us in making out its 

 relations. 



In other respects, the preceding section is comparatively imperfect; as we 

 have not determined the base line of the tertiary system, or derived a single, 

 well-preserved fossil from any bed of it * ; nor did we extend our examination, 

 so far up the right bank of the Rhine, as to see the junction of the green-sand 

 series with the Alpine limestone, 



2. Transverse Secttoti through the Valley of Sonthojen, and across a 

 Succession of Parallel Ridges on the Banks of the Iller. 



A part of the tertiary series, above described, after rising into a high, irre- 

 gular p/«^e«M, between the basins of the Rhine and the Danube, runs olf into 

 ridges composed of inolasse and conglomerate, ranging nearly parallel to the 

 secondary rocks of the chain ; generally, however, separated from them by a 

 longitudinal valley. In this way they cross the Iller at Immenstadt, nearly 

 shutting in, towards the north, the great transverse valley of the Allgau. They 

 there form what might almost be called an irregular, vertical wall of conglo- 

 merate and sandstone, entirely unconformable to the older system f; and 

 diminishing gradually both in inclination and elevation, they descend into the 

 newer deposits of Bavaria, containing tertiary shells and lignites. From their 

 place in the section, as well as from their mineral character, they are quite 

 distinct from any rocks entering into the newer, secondary system of the 

 Allgau ; we therefore continue to regard them, as an undoubted part of the 

 tertiary series;];. 



* In the prolongation of the molasse to the left bank of the llliine, near llheineck, organic 

 remains are much more abundant, and in a better state of preservation. In a single visit to a 

 quarry near that place we collected several Pectens, several Terebratula, one near to T. Man. 

 teUianu; two species of Cardium ; a Pholas ; &c. 



t Plate XXXVI. fig. 4. 



X In this conclusion we differ from Dr. Boue, who classes the conglomerates and grits of the 

 Rethenberg with the lowest part of the green-sand. 



VOL. 111. SECOND SERIES. 2 U 



