MODE VIII. ARGILLACEOUS GLUTENlTE. 287 



stone. Those beds themselves are very regular, 

 well connected, and of different thickness, from 

 half an inch to several feet. Those which are thin 

 contain few, and sometimes no foreign pebbles ; 

 and some alternations are observed of thin beds 

 without pebbles, and thick ones which contain 

 them. The colour of the base of this schistus 

 varies considerably; it is grey, greenish, most 

 often violet, or reddish ; some is also found 

 marbled with these different colours. These beds 

 are in a direction from north to south, exactly like 

 those of granitoid rocks, which are under them ; 

 but the inclination of the schistus in much greater, 

 its beds are often nearly vertical ; and when they 

 are not, they rise some degrees on the same side as 

 the rocks I have just mentioned, that is, towards 

 the west. 



" The pebbles buried in this schistus are, as I 

 have said, of different sizes, from a grain of sand 

 to six or seven inches diameter ; they all belong 

 to that class of rocks which I call primitive ; yet 

 I have not observed massive granite ; only laminar 

 granite, laminar rocks, blended with quartz and 

 mica; even fragments of pure quartz, but posi- 

 tively no schistus purely argillaceous, nor any 

 lime-stone ; nothing which effervesces with aqua- 

 fortis, and even the paste which contains these 

 stones does not. Their form differs; some are 



