158 



than three or four distinct zones of coal or lignite, separated from 

 each other by sedimentary deposits of enormous thickness ; as some 

 of these zones occur in the lower, and some in the higher parts of 

 the tertiary group, they infer that the existence of lignite is, of itself, 

 no general test of the age of a tertiary deposit. 



7. Section through the hills at the east end of the Lake of Con- 

 stance. — After making some remarks upon the great elevation of the 

 tertiary formations in the south-western extremity of Bavaria, the 

 authors proceed to describe the transverse section exhibited by the 

 hills above Bregenz. They commence with a description of the 

 nummulite-rocks of Haslach, which are associated with, and form a 

 prolongation of, the secondary system of the Stauffen and the Salz- 

 burg chain. They also refer the nummulite-rocks and marl-slate 

 above Oberdorf to the same system, and compare them with the 

 nummulite-ironstone of Sonthofen. In consequence of the de- 

 rangement of the strata, and the accumulations of transported 

 materials, the first commencement of the tertiary beds is obscure; 

 but they rise into hills of the elevation of about 2.500 feet above 

 the Lake of Constance, and mark the prolongation of the secon- 

 dary series, on the northern extremity of a ridge called Rexberg, 

 ten or twelve miles S. E. of Bregenz. The lower part of the 

 tertiary system, is composed of green, micaceous sandstone, to 

 which certain beds of conglomerate are subordinate, and it is de- 

 scribed as perfectly identical with the great deposit of adjoining mo- 

 lasse which forms the base of the tertiary formations of Switzerland 

 This sandstone occupies the successive ridges which extend from the 

 neighbourhood of Oberdorf to Bregenz. And, as in the greater 

 part of this long range the beds are highly inclined and have an 

 undeviating dip towards the north, their united thickness must be 

 enormously great. — The authors afterwards describe, with many 

 details, the great complex deposit of conglomerates alternating 

 with greenish sandstone and variously coloured marls which consti- 

 tute the upper tertiary group, and compose the whole mass of the 

 mountain ridge extending northwards from Bregenz. This whole 

 section is considered of importance, partly from the great scale upon 

 which the formation is developed, and still more from its forming a 

 connecting link between the tertiary deposits or molasse of Swit- 

 zerland and those which are exhibited in the several sections de- 

 scribed in this paper. 



Finally, the authors give a short summary of the conclusions 

 which seem to follow from the facts stated in the memoir. 



1. The tertiary formations of Austria and Bavaria appear to 

 have been formed in an ancient mediterranean sea, the limits of 

 which may be in a considerable measure ascertained ; and the 

 great mechanical deposits above described seem to have origi- 

 nated in the gradual degradation of the Alpine chain, partly by the 

 action of the sea on the flanks, and partly by the erosion of the 

 torrents descending from the mountains, and carrying great masses 

 of transported materials below the level of the waters. 



2. In some instances the tertiary beds are unconformable to the 



