﻿The Structure of Eitrope. 239 



make the remarkable discovery that the Caledonian 

 Mountain System was completely established by Devonian 

 time, because the deposits of the Devonian formations lie 

 horizontally on the Caledonian horsts. The folding which 

 formed this system may therefore be placed at the 

 junction of the Silurian and Devonian. Subsequently, at 

 different times, portions of these folds subsided, forming 

 the low-lying parts of Ireland and England and the North 

 Sea. Denudation has removed from the upper portions 

 of the horsts most of later formations deposited horizon- 

 tally upon them whereas they still remain for the most 

 part in the depressions. 



To these deposits still existing belong first and foremost 

 the Scotch coal measures. And it may here be parentheti- 

 cally stated that the development of the industries and 

 the large towns of Scotland is connected with the above- 

 mentioned depressed belt : here lie Edinburgh and Glasgow. 



The Caledonian folds terminate towards the south at a 

 line which is indicated by the following points : The 

 boundary line begins south of the mouth of the river 

 Shannon in western Ireland, enters the southern part of 

 Wales, embraces the southern peaks of that country, 

 reaches England at the Bristol Channel, and may again 

 be recognized between Boulogne and Calais and in the 

 Belgian coal measures. From this point it cannot be 

 actually traced until it is again met with not far from 

 Ostrau in Mahren. 



This line separates the Caledonian horsts from a second 

 group of horsts which are depicted red on our map. 

 These latter are very numerous, and embrace that area 

 which has been designated as the Massengebirge of central 

 Europe. To it belong Portugal and a large part of Spain, 

 the plateaux of the so-called Meseta ; then, in France, 

 Brittany and a part of Normandy; Cornwall; in Germany, 

 the mountains of the middle Ehine, Taunus, Vogesen, 



