185/.] NICOL LOCH GREINORD. 169 



seen rising through thick masses of drift containing large angular 

 boulders of gneiss. This covering of detritus and the frequent breaks 

 in the sections render it difficult to estimate the thickness of the 

 newer sandstone, but it probably does not exceed 100 to 150 feet. 



Age of Beds. Lias Boulders. — The absence of fossils renders it 

 impossible to determine the exact age of this curious deposit, and its 

 mineral character throws no light on the question. The position of 

 the beds and the fragments contained in the upper formation, prove 

 that it belongs to a far more recent period than the underlying red 

 sandstones. The wide interval that separates it from the newer 

 secondary rocks of Skye will also scarcely permit us to trace out even 

 a probable connexion. The only indication of these newer forma- 

 tions which I could discover in the vicinity was on the other side of 

 the peninsula, on the shore near Tinafuline, opposite to Island Ewe. 

 The coast there is strewed with great numbers of fragments (from 

 one or two inches to a foot or more in diameter) of a compact white 

 limestone, and so numerous that the farmers in the neighbourhood 

 have collected them to burn for lime. This rock is clearly distinct 

 from the older limestones, or that imbedded in the newer breccia. 

 Though the fragments are apparently little worn by transport, and 

 so abundant, I could not find any rock from which they were derived. 

 The limestone contains pieces of black carbonized wood, and a con- 

 siderable number of fossil shells. The latter almost all belong to 

 one or two species of Ostrcea. Some of them resemble the Ostrcea 

 irregularis, Goldfuss, of the lias, and others the O. Hebridica, de- 

 scribed by Professor Edward Forbes in his paper on Loch Staffin*. 

 Another shell is perhaps a fragment of the Potamomya 1 Sedgwickii 

 of that paper. There can be little doubt, therefore, that these frag- 

 ments belong to the same formation as the oolite of the north of 

 Skye ; and, as they have evidently not been transported from a great 

 distance, their occurrence indicates that these rocks must formerly 

 have had a much w T ider extension than they now possess, the di- 

 stance from Loch Staffin being about thirty miles in a direct linef . 

 They also render it probable that the red sandstones are of the age 

 of the Trias, or perhaps of the Lower Lias. These fragments of the 

 oolite are, I believe, the most northern traces of its existence on the 

 western shore of the mainland yet observed. 



Deductions. — Assuming this, therefore, as the more probable age 

 of the newer red sandstone, it follows that the older red sandstone 

 had been raised up on edge and undergone considerable denudation 

 previous to the deposition of the lias-beds of the Western Islands. 

 The softer and less metamorphic condition of the enclosed fragments 

 of the quartzite and limestone, than of the same rocks now seen in 

 situ, might lead to some curious speculations. It would, however, be 

 wrong at once to infer that these changes in the older rocks have 



* Journ. Geol. Soc. vol. vii. p. 110, plate 5. fig. 4. 



f Besides the shells and carbonized wood, this limestone contains curious grey- 

 coloured patches with white spots, like little masses of volcanic ashes. These 

 seem to me to show that volcanic action was going on in the neighbourhood at 

 the time these beds were being formed. 



