90 A DESCRIPTION OF PRIMARY SCHISTOSE ROCKS. [Ch. V. 



with gneiss, talc-schist, and quartz-rock. It appears again 

 farther towards the west, under similar circumstances ; it is 

 generally talcose, and passes insensibly from the protogine of 

 Corte into well-characterised protogine. 



M. Gueymard draws a line to separate the primary rocks 

 from the transition ; but at the same time states, that such a 

 distinction is not here to be found : for the line laid down 

 rather indicates the limits of certain prevailing rocks, than a 

 separation of geological epochs. The principal rock which 

 succeeds the foregoing, is a stea-schist : it encloses only a few 

 subordinate beds near the coast, but these become more 

 abundant in proportion as the central chain is approached. 

 They consist of blue limestone, more or less veined and 

 crystalline ; of ollareous serpentine ; of euphotide ; of dark- 

 coloured limestone, like that of the Alps; of compounds of 

 quartz and felspar; and, lastly, of porphyry. The quartz- 

 rock and limestone, near Ostriconi, appear to be enclosed in 

 the granitic series ; but the author is not quite certain on this 

 point. The granite, however, near Vivario, does contain 

 quartz-rock, and, near the village of the same name, is so 

 intimately connected with gneiss and schist, that they must 

 be all referred to the same epoch. 



Such is a brief sketch of the older rocks of Corsica : some 

 of which are extensively worked, and have been long cele- 

 brated as furnishing the most beautiful stones for architec- 

 tural and ornamental purposes. And with this sketch, we 

 terminate our descriptions of the foreign primary schists ; to 

 which we shall have repeated occasion to refer hereafter, in 

 our attempts to establish that they are analogous to the 

 Cornish slates. 



