1852.] 



NICOL ON THE GEOLOGY OF CANTYRE. 



413 



distance from it increases. The change even in the deepest beds is 

 not very great, having apparently only driven off the carbonaceous 

 matter from the black shales, and modified the state of oxidation of 

 the iron in the ferruginous red beds below, which are at the same 

 time somewhat hardened and converted into a kind of porcellanite, 

 yet the heat seems to have extended through from 20 to 30 feet of 

 conglomerate and probably twice that thickness of shales. Further 

 down the stream the same black friable shales are seen in cliffs some- 

 times 60 feet or more high. They are intermixed with beds of sand- 

 stone and impure coal, which has been mined in several places. In 

 the shales I only observed a few obscure indications of fossils. 



Fig. 1. — Section in Tirfergus Burn. 



ft. in. 



Black shale, becoming lighter below. . 1 ; 



Grey shale, slightly altered 

 Reddish-white shale 



3 

 2 6 



Bluish shale. 



Bluish-grey sandy shale 



Reddish-purple shale. 

 Reddish-yellow shale. 

 Dark-purple shale . . . 



7 



7 



1 



1 1 



Greyish-brown and purple shale, morel 

 than J 



On the west coast south of Losset, beds of sandstone and lime- 

 stone, much altered by intrusive igneous rocks, are seen in the high 

 cliffs. Similar altered masses occur near Killellan and in other por- 

 tions of the tract laid down on the map as trap. Before noticing 

 these, we must describe the igneous rocks seen in this district with 

 which they are intimately connected. 



VOL. VIII. — PART I. 2 E 



