162 Dr. Mac Culloch's Supplement to the 



The whole series presents from one end to the other a repetition 

 of the same parts, although the several substances are in different 

 places differently proportioned, the one exceeding in one place, 

 while in another a different member of the series will be found 

 predominant. One exception to this rule will afterwards be 

 noticed. 



The rocks which compose the series are the following. 



Red sandstone, more or less indurated, of which the general 

 characters were formerly described. 



Quartz rock, or, as some may prefer to name it, indurated sand- 

 stone, passing from lead blue to grey and brown, sometimes pure, 

 at others containing felspar. 



Schist, which is sometimes not to be distinguished from ordinary 

 clay slate, and at other times contains particles of quartz and mica. 

 If one term is to be used for the whole it must probably be called 

 graywacke schist. 



White compact quartz rock : this substance is found only in one 

 part of the series. 



In the original paper I described the red sandstone as following 

 the blue rock and schist in conformable order, which it in fact does 

 throughout a considerable tract without any repetition of the two 

 latter. But on pursuing these beds further than I then did, whether 

 backwards or forwards, according to their relative inferiority or 

 superiority, repeated alternations of all those substances occur. 



The dip which I also described as constant and westerly, is only 

 thus regular from that part of Loch Eishort whence my exami- 

 nation at that time commenced, to its upper portions, ascending 

 according to the order of the beds. In tracing from that point 

 towards the last, or downwards according to the order of the beds, 

 through those parts of the country respecting which I formerly 



