352 ORIGIN OF MOUNTAIN CHAINS. 



the deposit of the tertiary strata. This is the effect that lateral con- 

 traction should produce. 



Lateral Displacement as the Sole Cause of the Formation of 

 Mountain Chains. Professor Heim states that a contraction of only 

 Y^yth of the earth's circumference would be sufficient to fold all the 

 rocks in the mountain masses which would be crossed by a meridian 

 traversing the Alps. Even the central crystalline mass of the Alps 

 has undergone enormous lateral compression, and is now reduced by 

 crumpling to half the width to which it once extended. These 

 phenomena of compression have been especially studied in the moun- 

 tain mass of the Toedi, which is an enormous block of Jurassic lime- 

 stone in the Orisons, separated by prodigious denudation from the sur- 

 rounding masses. In this neighbourhood many of the folds are highly 

 complicated. One great contortion, bent over towards the north, 

 piles upon the Nummulitic rocks, the Jurassic rocks, the Verrucano, 

 which is partly of Carboniferous age, the porphyry of "Windgselle, and 

 gneiss. In the direction of the Windgselle mountains, this fold breaks 

 up into a number of minor folds ; and at the southern border of the 

 central mass, the chain of the Piz Tumbrif is formed from a fold 

 which has itself been folded, by which the middle zone forms greatly 

 compressed synclinals. 



Mountains of the European Basin. 



The Ural Chain forms the western limit of the European basin. 

 It is a water-parting, which must have come into existence as a long 

 island, whose eastern slope the older geographers separated from the 

 western slope, as though they were distinct parts of the world. This 

 chain is one of the older features in geological history, though certainly 

 newer than the western contour of the continent. Broken as that 

 contour is by the inlets of the North Sea and the Bay of Biscay and 

 the isolation of Britain, it needs but the help of a geological map of 

 Europe, and a map of the hundred-fathom soundings, to recognise 

 that the Scandinavian chain, now ending with the peninsula, strikes 

 away south-west to Shetland, the western Highlands of Scotland, and 

 north of Ireland, and is prolonged further south beneath the sea, so as 

 to have outlined the eastern side of the great Atlantic Valley, or to 

 have formed a ridge parallel to the Dolphin ridge, before the Atlantic 

 was denned by land. 



Old ridges, generally rising to the west of Britain, but sometimes 

 elevated also to the east, come again and again under notice of the 

 British physical geologist, as parent masses from which the sedimen- 

 tary materials of primary and secondary rocks were derived, and vary- 

 ing elevation of which governed the succession of British strata. 



But the European basin in its present form is essentially a product 

 of forces which began to operate with the Tertiary period. This eleva- 

 tion runs eastward through Europe and Asia, and links the south 

 of Europe with the north of Africa, in a way of which the Mediter- 

 ranean, at first sight, gives no indication. Grand contractions of the 



