74 RAMBLES OF A NATURALIST. 



of tolerable thickness run through the general mass 

 in an almost constant direction from north-east to 

 south-west. Here and there quartz occurs in de- 

 tached masses of a dull white colour, or in veins as 

 transparent as the purest crystal; Avhilst grains of 

 iron in the state of peroxide are occasionally met 

 with in these rocky formations. I could nowhere 

 observe the homogeneous and compact structure 

 which has made the granite of Chausey so deservedly 

 celebrated ; indeed the rock of Brehat appears, from 

 the numerous veins which intersect it, and from the 

 diversity of its character at every few feet, to be 

 utterly valueless in a commercial point of view. 



This difference of structure in the rocks of Brehat 

 and Chausey explains the difference observable in 

 the general aspect of the coasts of the two islands. 

 At Chausey, the massive strata of granite, after un- 

 dersioino; a slow disinteo-ration under the action of the 

 currents and waves, leave enormous blocks standing 

 isolated from the general mass, which, from the very 

 disorder of the formations around them, present a 

 certain appearance of imposing grandeur. There is 

 nothincy of this kind to be seen at Brehat, where the 

 isolated rocks are little more than large detached 

 stones. There are many points along the coasts of 

 Chausey where the sea breaks against the rocks with 

 a violence that gives the observer the idea of some 

 vast convulsion of nature; for the scene around seems 

 to suggest an analogy with the fragments of an up- 

 heaved and broken world. Now, althouo;h there are 

 such fragments at Brehat, they have nothing striking 

 in their character, and I have seen many a feudal 



