Ch. VII.] THE GRANITIC AND SCHISTOSE ROCKS. 141 



the bridge over the Fou, to a place where the Gly enters 

 into a narrow and deep gorge opened in the nearly vertical 

 beds of crystalline limestone, the characters of the latter rock 

 are such as have been described ; but here, at the distance of 

 about a thousand feet from the granite, the limestone is per- 

 fectly saccharoid, and does not contain a trace of organic 

 remains. Here the following disposition of the rocks may be 

 observed. The strata dip towards the E. 25 S., at an angle 

 of 75, appearing to repose on the granite which forms the 

 hills of St. Martin; This crystalline limestone continues to 

 within about a hundred yards of the main mass of granite, 

 and, indeed, within a hundred feet of a branch of this rock, 

 which will be presently described. Then succeeds, 



1. A reddish ferruginous limestone, about fifty feet in 

 thickness, and disposed in beds regularly stratified. It is 

 worthy of remark, that no passage can be observed between 

 this rock and the grey limestone by which it is covered. 

 The line which separates them is well defined ; which is not 

 the case with the rock immediately subjacent. 



2. Beneath the red limestone, is a dolomite, which is very 

 solid, although composed of small distinct rhomboids aggre- 

 gated together. This rock is more than fifty feet in thick- 

 ness, and is not stratified. It decomposes in a very irregular 

 manner : its surface is deeply coloured, although in a fresh 

 fracture it is of a light yellowish tint. It contains some very 

 irregular veins of spathose iron ore. 



3. The dolomite rests on a very quartzose felspar rock, 

 which forms a kind of venous bed, or floor, about sixty-five 

 feet in thickness. It is difficult to convey an exact idea of 

 this rock : it seems to have been produced by the penetration 

 of the granite into these strata, and is, consequently, a mixture 

 of very different elements. This mass is in nowise stratified. 

 It contains spathose iron ore, pyrites, and a little iron glance. 



4. The compound of dolomite and spathose iron ore, 

 already described as superimposed on the quartzose felspar 

 rock, again occurs beneath the latter, in a layer about two 

 yards thick ; and this, again, rests on, 



