164 Dr. Mac Culloch's Supplement to the 



Meeting near Loch Eishort with the white compact quartz rock 

 which was described in the original paper, I concluded that here, 

 as elsewhere, it was a member of the primary rocks, and therefore 

 without hesitation laid it down among the series which I considered 

 to be micaceous schist, concluding also that I had in reaching it 

 arrived at the bottom of that series which contained the blue quartz 

 rock and schist. That white quartz is however a member of this 

 very series, holding a parallel course with it, and being preceded 

 as it is followed by red sandstone, blue quartz rock, and gray wacke 

 schist. This circumstance forms a material addition to the history 

 of quartz roek, and an alteration no less material in that of the 

 series to which the red sandstone belongs. 



I must here remark that in calling so complicated a series of rocks 

 by the title of only one of its members, the red sandstone, I have 

 done so only on account of the necessity of using one term for the 

 temporary purpose of a geological description, and that this one 

 was chosen from the predominance of that substance. I can only 

 add that this predominant member corresponds in mineral character 

 with the other red sandstones which in Scotland occupy the inter- 

 mediate place between the primary rocks and the secondary strata 

 containing organic remains, and that it is connected by visible 

 indications with many similar portions of the same rock to be 

 found not only in Sky but in the neighbouring islands. As it is 

 also followed in a conformable order by the limestone series for- 

 merly described, it possesses anothtV common character with the 

 usual red sandstone of other districts. If any person shall think 

 that the whole of this series should be ranked under gray wacke 

 and called a transition series, I can have no objection, but am at the 

 same time unable to see what advantage is gained by the substitu- 

 tion, or in what respect the science is aided by it ; while at the 

 same time the red sandstone will be as much transferred from its 



