720 EEroRT— 1892. 



3. The Ice- Shed in the North-West Highlands during the Maximum 



Glaciation. By B. N. Peach, F.U.S., F.G.S., and J. Horne, F.G.S. 

 [Communicated by permission of the Director-General of the Geological Survej'.] 



In the course of the geological survey of the North-west Highlands certain data 

 have been observed which seem to point to the conclusion that during the maximum 

 glaciation the ice-shed did not coincide with the existing water-shed of the region. 

 From an examination of the striae and the distribution of the boulders, it would 

 appear that the ice-parting then lay to the east of the present water-shed. In the 

 group of mountains forming the eastern chain of Assynt, Sutherlandshire, extend- 

 ing from Glasven and Ben Uidh by Coniveall to Braebag, the phenomena relatuig 

 to this remarkable dispersion of the ice may be seen to advantage. On Ben Fuaran, 

 which is composed of displaced members of the Cambrian formation (quartzites, 

 fucoid beds, and serpulite grit), boulders of Lewisian gneiss are met with, which 

 Lave been borne westwards from the deep corries on the north-east slope of the 

 Ben More range. In like manner on the long ridge of Braebag, running south- 

 wards from the Beallach of Coniveall, the average height of which is over 2,000 

 feet, splendid striated surfaces are observable, the ice-marldngs pointing in a 

 westerly direction. Numerous blocks of thrust Lewisian gneiss and granulitic 

 quartz-schist (Moine schist) occur on the crest and slopes of this ridge, derived 

 from areas lying to the east of Braebag. The average level of the plateau 

 formed by the eastern schists to the east of Kiuloch Ailsh is lower than that of the 

 water-shed south of the Beallach of Coniveall. 



Passing southwards to the mmmtainous region in Ross-shire, in the neigh- 

 bourhood of Kinlochewe, Loch Maree, there is abundant evidence of the granulitic 

 Moine schists having been carried to higher levels by the westerly movement of 

 the ice. On the elevated peaks and slopes of Sgurr Ban, Oorrie Mac Fearchar, 

 Ben Slioch, and Ben Eighe, composed of Torridon sandstone and Cambrian 

 strata, numerous blocks of various types of the eastern schists have been observed. 



It would appear that during the great extension of the ice, even these lofty 

 mountains had been overstopped by the ice-sheet, while at a later period the various 

 mountain groups formed independent centres for the dispersion of local glaciers. 



4. On a, Bone Cave in the Cambrian Limestone in Assijnt, Sutherlandshire. 



By B. N. Peach, F.B.S., F.G.S., and J. Horne, F.G.S. 



[Communicated by permission of the Director-General of the Geologieal Survey.] 



The authors called attention to a group of caves occurring en the south side of 

 the valley of Allt an Uamh (Burn of the Caves) traversing the limestone plateau 

 of Inchnadamff, Sutherlandshire. Owing to the limestones being piled together 

 by reversed faidts, the streams flowing on to the plateau from the surrounding 

 less pervious rocks plunge underground on reaching the limestone and emerge 

 at lower levels. All the tributaries of the Allt an Uamh, save during heavy floods, 

 disappear at a considerable distance above the caves, and issue as two powerful 

 springs about a mile below the bone cave. The authors are of opinion that a stream 

 may have issued from the floor of the bone cave at a time when the valley was 

 filled with glacial deposits up to the level of the caves. These materials having 

 been largely removed by denudation, the water circulates at lower levels in the 

 limestone plateau. 



In (he autumn of 1889 the authors, together -with the Rev. Mr. Short and Mr. 

 Clarence Fry, explored the most easterly cave with the following results, the 

 materials being carefully examined as they were removed : — 



(a) Peaty matter from a few inches to a foot thick. 



(6) Lenticular layer of calcareous marl about one foot thick, composed of the 

 remains of various land shells. 



(c) Red clay or cave earth from one to three feet. Indications of human occu- 

 pation occur at various levels in the form of layers of charcoal, split and calcined 

 bones, comprising reindeer, red deer, badger, fox, bones of birds— chiefly of grouse 

 — with nests of frog bones. 



