﻿1861.] 



MCRCHISON AND GEIKIE HIGHLANDS. 



199 



flaggy beds of the Bealloch of Kintail, which, with a south-easterly- 

 dip, range northwards to the deep gorge of the Glomach, where, in a 

 scene of singular wildness and grandeur, the stream, in falling over 

 the cliffs, gives rise to the highest cascade in Scotland. 



Skye. — Following the line of outcrop of the Lower Silurian quartz- 

 rock and limestone, we have arrived at the shores of the Atlantic. 

 But these rocks are prolonged into the Island of Skye ; and before 

 tracing the structure of the interior of the mainland, we will sketch 

 in outline that of Sleat — the southern peninsula of Skye. 



In a former memoir*, it was shown that the Lias of Strath, in 

 Skye, rested unconformably upon red (Cambrian) sandstone, and 

 that the sandstone stretched across the island from sea to sea, with 

 a north-westerly dip. It was also pointed out, that some powerful 

 faults existed in the district, whereby the secondary shales and lime- 

 stones were thrown down in wedge-form among the older strata. We 

 have now ascertained that the same faulted character extends across 

 Loch Eishort into Sleat, rendering the geology of that peninsula in- 

 tricate and difficult. With the limited time at our disposal, and the 

 want of a map having any approach to accuracy, we did not attempt 

 to work out the detailed structure of this region. 



Sleat appears to have formed originally, previous to the occurrence 

 of the faults, an anticlinal ridge consisting fundamentally of Cam- 

 brian sandstone with the quartz-rock, limestone, and upper gneissose 

 beds folded over it. Traces of this simple structure are sufficiently 

 abundant ; but it has been greatly modified and deranged by the 

 influence of certain longitudinal dislocations, by which the north- 

 western side of the arch has fallen in ; and considerable confusion 

 has been introduced into the southern end of the peninsula. 



The Cambrian, rising from under the Lias, forms the north side of 

 Loch Eishort and runs across to the Bay of Lussay. Erom the head 

 of Loch Eishort a fault extends to the shore near Kyleakin, the effect 

 of which is to throw down the quartzose flaggy beds against the 

 Cambrian sandstones, both of which have a north-westerly dip. 

 Another fault runs probably from about Kyleakin, along the north- 

 west flank of Ben Cailleaich, towards the Point of Sleat, with the 

 same effect as the other ; so that the arch becomes still further frac- 

 tured towards the south-west end of the island. 



At Ord the red sandstones are also considerably faulted. On the 

 hills above the House they are surmounted by quartz-rock in thick 

 beds of snowy whiteness. These dip north-west, at a steep angle, 

 forming the side of a steep hill, at the bottom of which they are 

 covered by limestone, evidently on the same horizon with that of 

 Assynt and Loch Broom. 



This limestone appears to be surmounted by quartz -rock ; but this 

 part of the island is dislocated to no common extent, and would 

 require much care and time in the unravelling of its details f . 



* Geikie, Quart. Journ. Geol. Soc. vol. xiv. p. 1 et seq. 



t I am now convinced that the white quartz-rock noticed in my former paper 

 as wedged in at the side of a fault on the shore of Loch Eishort really belongs 

 to this Lower Silurian series, and is therefore the product of a much older meta- 



p 2 



