J. W. JTJDD ON THE SECONDARY ROCKS OF SCOTLAND, 717 



the Pabba Shales well-exposed in the flats uncovered at low water ; 

 and the sandy and littoral facies of the Scarpa Series is exhibited in 

 the cliffs, especially at the fine waterfall behind Carsaig House and in 

 the quarries which have recently been opened for the new buildings. 

 The latter beds have also been quarried at some places to the west- 

 ward, and make their appearance at many points in the cliffs, espe- 

 cially about the Nun's Cave, which has been hollowed out in them. 



The fossils of the Pabba Shales of Carsaig were collected with 

 much perseverance by the late Captain Bedford, while engaged in 

 preparing the Admiralty Charts of these inaccessible shores. A list 

 of species drawn up from his collections by Messrs. Davidson and 

 Etheridge will be found in the Geologist, vol. v. p. 443. 



The sandy representative of the Scalpa beds is, as at Duart, rather 

 poor in fossils — Pecten sublcevis, Phill., and Oryphcea cymbium^ Lam., 

 being, indeed, the only common forms. The rock here seems to be 

 capable of furnishing a useful freestone. It was quarried for the 

 famous edifices of Iona ; and fresh supplies have recently been ob- 

 tained for the repairs of those buildings. But for the inaccessibility 

 of the rocky shores on which they are exposed, it is probable, indeed, 

 that the beds would be extensively worked for building-purposes. 



The exposures of the Middle Lias near Carsaig are of much interest, 

 furnishing us, as they do, with the most southern exposure of the 

 beds of that age in the Hebrides. Their equivalents next make their 

 appearance as we pass southwards in the north of Ireland and in the 

 outlier on the borders of Cheshire and Shropshire, though it is im- 

 possible to doubt that beds of this age have originally existed, and 

 have been removed, by denudation, over a great part of the inter- 

 vening area. 



d. The Upper Lias. 



As the beds of this age (owing to the faults by which the series 

 of strata is there broken up) are nowhere exhibited in the Eastern 

 Highlands, it is of particular interest to find them so clearly dis- 

 played, and presenting such an unmistakable and characteristic 

 fauna, in the Hebrides. Lying, as they do, between the hard masses 

 of the Scalpa Series below, and the Inferior Oolite above, the Upper 

 Lias beds are almost everywhere covered by heavy taluses of fallen 

 blocks ; and it is not to be wondered at that Murchison, failing to 

 recognize their existence, massed the strata of Middle Lias with 

 those of the Inferior Oolite. To Messrs. Bryce and Tate we are 

 indebted for first pointing out the existence of the Upper Lias 

 formation in Skye — though even they appear to have failed to 

 detect proof of its existence in the neighbouring island of Eaasay. 

 During my study of the district, I have found many evidences 

 of the presence of this part of the Lias series, and have examined 

 some interesting sections of its beds in both these islands, suc- 

 ceeding also in tracing deposits belonging to this geological horizon as 

 far southwards as Ardnamurchan. In this last-mentioned district, 

 however, the strata in question have suffered greatly from meta- 

 morphic action. 



