MINERALOGY OF THE OCHILS. 



11 



very distinct, and contain a fiesh-red variety of 

 felspar. 



This rock is traversed by veins of calcareous 

 spar, which exhibit a sea-green colour, when fresh 

 broken. 



III. Grey Sandstone. 



Above the amygdaloid*, beds of a yellowish 

 grey sandstone alternate with tuff and claystone, 

 which appear to be intimately connected with 

 some varieties of the amygdaloidal rock. It con- 

 tains a considerable quantity of scales of silver- 

 white mica, and decomposes into slaty masses. It 

 seems to pass almost imperceptibly into the varie- 

 ties of claystone to be hereafter described. One 

 variety of this rock has a very remarkable granitic 

 appearance, and does in fact contain all the con- 

 stituents essential to true granite. At the same 

 time, however, it retains the distinctive characters 

 of sandstone. 



The relations of this rock to the older rocks, is 

 not clearly made out, except at Wormit Bay, 

 where it seems to rest on amygdaloid. It occurs 

 frequently between Wormit Bay, and the village 

 of Dunning in Perthshire. It also occurs in the 

 course of the Devon, where it may be seen alter- 

 nating with the red sandstone, to which in all 

 probability it belongs. 



At the western extremity of Wormit Bay, 



