408 LOWEST RED SANDSTONE. 



The prevailing colour of this rock is that 

 whence its name has been derived. The red 

 varies from a bright ochre down to the darkest 

 brown, and even to a blackish purple. Many 

 varieties of grey, also occur, from dark blueish to 

 the lightest ash colour, at length passing to an 

 imperfect white. 



But the most remarkable modifications of 

 colour, consist of intermixtures of red and white; 

 and these varieties have been distinguished by 

 the name of the mottled or variegated sandstone, 

 as if they formed a distinct geological mass. 

 That this is not the case, however, is proved by 

 their occurring in alternation and intermixture 

 with all the other varieties. The most remark- 

 able of these, exhibits white circular spots of 

 different sizes, more or less abundantly disse- 

 minated in the red ground ; and they are proved, 

 by the fracture of the stone, to be spheroidal. 

 In other examples, the white is disposed in veins, 

 or in other ways intermixed with the red colour : 

 and it is remarkable, that where these characters 

 prevail, they generally also pervade the accom- ^ 

 parrying shales. 



