Mineralogy of Sky. 35 



point it out so distinctl5^ The certainty of a transition between 

 these two rocks is equally well marked by another circumstance, 

 although that indication does not appear at Loch Eishort; namely, 

 by the alternation of the beds of schist with the red sandstone, 

 a phenomenon to be observed at Loch Scavig, as I shall presently 

 show. Following this sandstone it is to be seen forming a con- 

 siderable part of the hills which rise on the northern side of Loch 

 Eishort, and extending along that shore as far as the farm of 

 Borrereg where it ceases. The beds succeed each other with 

 great regularity, and are of considerable thickness ; as far aS 

 I should judge from a rude estimate formed by comparing the 

 measures of their edges with the space which they occupy, I should 

 imagine that the collective mass does not here fall much short of a 

 thousand feet in thickness, tallying in this respect very nearly with 

 the dimensions which it seems to maintain in Rum as well as in 

 Soa, both of which I have no doubt are different portions of th,e 

 same rock. 



This red sandstone is also found skirting the southern shore of 

 Loch Eishort in different places, and is particularly conspicuous at 

 the castle of Dunscaich, a building of no high antiquity, but 

 situated on a rock, the traditional residence of Cuchullin " King 

 of the Isle of Mist." This position is readily explained by observ- 

 ing that the line of Loch Eishort crosses that of the direction of the 

 sandstone in an oblique manner, leaving thus a portion of it on the 

 southern shore ; it is here often in contact with the white quartz 

 rock, the intermediate blue rock having disappeared. From this 

 I should be inclined to suspect that there is a real chasm between 

 the conjoined rocks consisting of mica slate and quartz rock, and the 

 stratified ones now under review, how much soever some of their 

 portions may appear consecutive. I have pointed out at some 



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