382 EHRENFELD— JOINTING AS A FUNDAMENTAL FACTOR 



proceeding by a method which can rationally be explained only 

 upon the basis of some generally determining cause such as the 

 jointing which is shown with practically universal distribution. 



That such block or fracture destruction is even now proceeding 

 over portions of the land masses is believed to be true; certain 

 structures in the British Isles (universally regarded as remnants 

 of the former wide extension of Europe) more especially in Scot- 

 land point to a decided indication of such block distintegration or 

 fracturing. The approximate parallelism of the Hebrides, the 

 Faroe, the Orkney and the Shetland islands ; the same parallel 

 identations of the coast lines, the remarkable series of firths which 

 find their greatest and most striking expression in the vast gash 

 which almost cuts Scotland into two parts as the firth of Moray 

 passes into Loch Sess and this on into Loch Linnhe and ends at 

 length in the firth of Lome, all these are so striking in their rela- 

 tions and occurrence that the conclusion is almost forced on us 

 that here also is to be seen the illustration of a land mass passing 

 into block disintegration by a series of fractures which exist inde- 

 pendently of surface agents of weathering or of erosion. 



As the whole mass of the northern hemisphere is contemplated 

 in its upper parts, with its widespread likenesses, its analogies of 

 structure and its broken remnants of former continuities to be ob- 

 served in the sediments of the arctic islands and in America and in 

 Europe, the reason for this unity of structure and unity of disin- 

 tegration must be sought not in the atmospheric elements which 

 have played upon it but must be sought for in the essential nature 

 of the lithosphere itself. 



As we journey round from lower Europe about the Canary and 

 Madeira islands up through the British islands to Scandinavia, on 

 through the arctic seas and islands and so on down the American 

 coast there is everywhere shown the same disintegration of the land 

 mass by a factor which controls all the atmospheric and erosion 

 agents ; there is seen a mechanism which whatever agent plays 

 upon it, whether glacier, frost, expansion and contraction from 

 change of temperature, or from the ceaseless pounding of the sea, 

 still runs always far in advance of them all and reaching even below 

 the level of the sea and the atmosphere determines in advance the 



