Mineralogy of Sky, 37 



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arrangement even one step further, since I have shown that perfectly- 

 characterized clay slate is here a member (to use the Wernerian 

 language) of ihQ Jloetz rocks; the sandstone here described being 

 analogous to the old red sandstone of that school, and a member of 

 a continuous series of stratified rocks, of which the uppermost con- 

 tain shells and other undoubted characteristics of their rank in the 

 order of rocks. 



The extent of this rock on the shore is not great, but it may be 

 seen occupying a continuous line both on the shore of the sound 

 of Soa and within the entrance of Loch Scavig, forming the foot 

 of Garsven, one of the highest of the Cuchullin group. 



These are the only places in which I have found this rock, and 

 I have no great reason to expect that it will be found any where 

 else, as its dip does not any where indicate its probable re-appear- 

 ance ; yet I should not be surprised were it to come out at Loch 

 Sligachan, since the limestone which immediately follows it in 

 regular order is to be seen there. These beds, the limestone on 

 the one hand and the quartz with schist on the other, will be guides 

 to those who wish to search for this rock in other parts of the 

 island. 



The mineral character of this sandstone is very uniform ; it is 

 most commonly of a red colour, but it becomes brown or grayish, 

 when in the neighbourhood of the schist, and sometimes even 

 partakes of the blue colour of this substance. It is of a moderately 

 fine grain and very tractable as a building stone, sometimes possess-f 

 ing the softness of an ordinary sandstone and at others acquiring a 

 flinty kind of hardness, more particularly when it approaches the 

 schist. It is generally mixed with clay, or is of an argillaceous 

 nature, and in some places moreover it is found to contain particles 

 of calcareous matter : in some few places coarser portions are to be 



