Structure of the Eastern Alps. 363 



Tornatella gigantea, Fungia poltjmorpha, t^c.) and abut against the opposite 

 wall of Alpine limestone called the Telschbeig ; their absolute contact is how- 

 evei'j for the most part^, hidden by a talus of fragments from the mountain side. 

 This southern ridge consists of red, melalliferous, encrinite-limestone, which 

 we are disposed to refer to the lower system of the oolitic series. 



The northern wall of secondary limestone called the Gros-Berg, is chiefly 

 composed of a compact grey rock, with obscure impressions of some bivalves 

 and Ammonites. The face of this rock is singularly scooped out into grooves 

 or furrows, which, wherever the surface is nearly vertical, are straight, semi- 

 cylindrical, and deeply engraven ; but where the limestone sweeps down in 

 a slope, they are wider and shallower, and increase in number, branching out 

 from each main trunk so as to look like gigantic arms with expanded and 

 pendent fingers. These furrows offer an instructive example of the gradual 

 erosion produced by the almost continued descent of water during the summer 

 months from the melting snow, and may, indeed, be considered as so many 

 rude, independent chronometers to help us in counting the periods of time 

 during which the surfaces of the neighbouring rocks have been exposed to 

 the action of the elements. 



The Gros-Berg shuts out the valley from the beautiful, narrow lake called 

 Griindel-See, the level of which is about 2500 feet below that of the Weissen- 

 bach in Zlam ; and by this we may form some estimate of the intensity of the 

 moving powers by which the shelly marls were lifted up to such snowy Alpine 

 elevations as we have here described. 



No drawing or description can convey more than a faint idea of the extra- 

 ordinary contortions and dislocations of the rocks which surround the little 

 upland valley of Zlam. The geological phenomena, however modified by 

 local causes, are obviously of the same kind with those of the valley of Gosau : 

 and we have the more pleasure in submitting them to the notice of the 

 Society, as they appear, so far, to have escaped the observation of those who 

 have written on the structure of the Eastern Alps. 



3. Section of the Overlying Strata of Windischgarsten, S^c. 



We now proceed briefly to describe some other insulated groups of strat'^ 

 in the prolongation of the Eastern Alps, cited in various memoirs by Dr. Boue : 

 and though we fully agree with him in referring them all to a common system, 

 we deny that they offer any evidence subversive of the conclusions we have 

 drawn from the shelly deposits of Gosau. 



The first example we wish to notice is seen among the ramifications of the 



3 a2 



