328 Professor Sedgwick and Mr. Murchison on the 



the incoherent sandstone, and left many knotty protuberances of the less de- 

 structible conglomerates, standing out upon the crests and sides of the moun- 

 tains. 



The beds we have so far described, to the north of the river Ach, may be 

 considered as the middle group of the tertiary system, exposed in this section. 

 The upper group may be supposed to commence about three miles north of 

 Bregenz : for bands of white sandstone containing some green grains there 

 begin to prevail, and the conglomerate beds to diminish in thickness and in 

 number. On reaching the castles of Hofen and Halberstein, a most marked 

 change was observed ; for the conglomerate series was found to pass under 

 thick beds of variegated, argillaceous marls, A magnificent, vertical section 

 of these argillaceous beds, is exhibited in the upper extremity of the Russ- 

 bach stream, in the face of the Hand Reutti hill. The beds (which gradually 

 diminish in inclination to the north of Bregenz) are there nearly horizontal, 

 and are seen in regular superposition in the face of escarpments several hun- 

 dred feet high. 



The prevailing masses in these escarpments, are composed of bands of varie- 

 gated marls, some of which are very unctuous, alternating with thin courses 

 of white sandstone, which occasionally passes into a hard and nearly compact 

 gritstone. Among these beds traces of the conglomerates are still met with ; 

 and near the summit of the hill there are some considerable bands of it, sub- 

 ordinate to the marl and the sandstone. 



With these beds our transverse section terminates ; and we may remark 

 that they are of a structure analogous to that of the upper part of the tertiary 

 system of Bavaria, especially as it is exposed on the banks of the Lech near 

 Schongau, This agreement might almost have been anticipated ; for the strata 

 of the Hand Reutti, being at a great elevation and inclined at a comparatively 

 small angle, are probably in their range tovvards the north, spread over a con- 

 siderable portion of the lower plains of Bavaria. 



The preceding section places in a striking point of view, the position and 

 enormous development of the tertiary system on the north flank of the Alps; 

 but it derives its chief interest from the green, micaceous sandstone (niolasse), 

 which enters so largely into the composition of the lower and middle groups 

 above described. In this way the sandstones and conglomerates of the high 

 plateau of south-western Bavaria, become connected with, and pass into, the 

 tertiary series of Switzerland. Nor is this conclusion founded upon a merely 

 accidental, mineralogical resemblance ; for the beds of molasse, composing so 

 large a portion of the hills south-east of Bregenz, reappear with the same 

 Mrike and dip on the other side of the broad valley of the Rhine, and rise into 



