﻿238 Canadian Record of Science. 



are not indicated, but these play no very important part 

 in the general relief. Iceland is such a mass of volcanic 

 origin, young rock ejected from the interior of the earth; 

 I shall not deal with it any further. We proceed 

 immediately to the first zone of old rocks. This forms the 

 Hebrides and the Lofoten Islands, two areas forming the 

 extreme north-west of the continent and made of the 

 oldest rocks, the Archaean. Here the first boundary-line 

 may be drawn. This line goes through the extreme 

 north-western foothills of Scotland and Loch EriboU, west 

 of the Orkney and Shetland Islands, and then from the 

 great Westfjord in Norway through the peninsula and 

 islands of the north to Mangeroe ; it is indicated in 

 Scotland by a great overthrust, the limit of the first 

 element which takes part in the construction of Europe. 

 It is the gneiss of the Hebrides and Lofotens. 



Next we come to a second, much larger area, which 

 includes a series of mountain fragments, colored blue on 

 the map. This is a region of ancient folding, much of 

 which has subsided, leaving folded horsts represented by 

 the blue spots. 



The north of Ireland shows two small horsts, which find 

 their continuation in the north of Scotland. The Scotch 

 Highlands form the transition to Western Norway, where 

 rocks of similar kind stretch far to the north. These are 

 fragments of a great ancient mountain system. 



The folds in these horsts all liave a north-easterly 

 strike, and the whole area is known as the Caledonian 

 Mountain System. To this system belongs a spur further 

 south, which reaches to the English boundary, and also 

 includes the greater part of the principality of Wales and 

 a portion of southern Ireland. 



The two northern horsts are separated by a portion of 

 central Scotland having subsided, and having thus formed 

 a huge ditch. 



If tlie folds in these horsts are more closely studied, we 



