122 THE RELATIVE POSITION OF THE [Ch. VII. 



Cornwall in the same direction. These facts may appear 

 to be trivial to those persons who have not paid much atten- 

 tion to this subject ; but they will be found hereafter to be 

 important, as furnishing some aid in the examination into the 

 nature of these rocks. 



In the Alps, and other granitic countries, the primary 

 slates are disposed near the granite, in a similar undulating 

 form; though the curves do not always run in the same 

 direction. In the isle of Arran, for instance, the primary 

 slates encircle the central mass of granite in the form of 

 undulating hills, with the exception of a part on the eastern 

 side, between North Sannox and the hills above Brodick 

 Wood; where the chain of schistose rocks is wanting, and 

 enormous masses of secondary conglomerate may be traced 

 nearly to the base of the precipices of granite.* It has been 

 supposed, that the primary slates are not only absent from the 

 surface, but that the secondary rock rests immediately upon 

 the granite : it may, in part, repose on granite ; but analogy 

 would lead us to conclude that it is also deposited on the 

 slate which, probably, is here continued beneath in the form 

 of a hollow curve. And the primary rocks of the central 

 axis of the Eastern Alps appear to be disposed in the same 

 manner ; descending in a curved line from the eastern 

 borders of the Tyrol, where they attain the height of more 

 than 12,000 feet, until they are lost beneath the Gratz and 

 Vienna basins : from these, however, they again emerge in 

 the low ridge of Leitha Gebirge, which separates Austria 

 from Hungary ; and after again disappearing under the 

 recent deposits, they rise once more in elevated curves near 

 Presburg, and are prolonged into the mountains which 

 range in a north-easterly direction towards the Carpathian 

 chain. The old rocks of the Leitha Gebirge ridge form a 

 true anticlinal axis, from which the tertiary deposits dip in 

 opposite directions ; and there can no longer be any doubt of 



* Geol. Trans. New Series, vol. iii. p. 22. 



