﻿244 Canadian Record of Science. 



and this is the reason wliy just this place has attained! 

 such a historical significance in Carnuntum and Vienna. 



Such depressions are found in many places. It seems^ 

 indeed, as though the younger mountains were approach- 

 ing the same condition that the older ones have reached. 



Permit me now briefly to summarize all that we have- 

 so far said : 



The earth is decreasing in volume. Hence proceed in 

 one place subsidences, in another place foldings ; if sub- 

 sidences occur, stratified table-horsts are produced with 

 depressed areas. 



If the subsidences occur in mountainous districts of 

 folded rocks, folded horsts are formed. In each such 

 horst may be seen a portion of the old folded structure, 

 often indeed only in an indistinct, ruinous condition.. 

 The geologist, however, can from the fragments thus- 

 obtained restore the original structure, just as a student 

 of art frequently finds a portion of moulding sufficient to 

 enable him to restore to his mind's eye the whole 

 monument. 



If we put together all these results, and attempt to 

 follow them out on the map of Europe, we arrive at the 

 conclusion that Europe may be divided into a series of 

 zones, which are separated from one another by lines of 

 overthrust, and that from north to south we ever meet. 

 younger and younger phases of mountain formation. 



In the far north we have the Hebrides and Lofotens,. 

 composed entirely of Archaean rocks ; south of these the 

 Caledonian mountain district. The Caledonian mountain 

 district is divided up into horsts. 



Then comes the second period, that of the Armorican 

 and Variscian mountains. These mountains also are 

 shattered. Folds are present, and the overthrust regions 

 may be traced for great distance. This mountain system 

 reaches into the Carboniferous formation. All this has- 

 been broken up, and then new and more complicated 



