Notices of Memoirs — A. Harker — Ice-Erosion in Skye. 35 



across. The veiy irregular grains of quartz are frequently cracked 

 and show crush shadows. Plagioclase is not uncommon, zircon 

 as before, and some quartz vermicule. Possibly the rock contains 

 cordierite. 



Conclusions. 



One characteristic feature of the rock, the irregular outline of 

 the grains and the inclusion, or partial inclusion, of one mineral 

 by another, may, in my opioion, be best explained as the result of 

 movement in a somewhat viscous mass. The cracked quartzes 

 and garnets, the lines of fracture in which are now healed, together 

 with a confused grouping often found among the smaller particles 

 of quartz and felspar, indicate that, at one time, the rock has 

 suffered from the effects of crush, from which it subsequently, 

 more or less completely, recovered. The outlines of the quartz 

 and felspar, which, as just remarked, may be accounted for by 

 fluxional movement, at the same time suggest that pressure has 

 been at work forcing them, as it were, into the minimum space. 



The presence of sillimanite and probably of cordierite, which 

 render the alumina percentage unusually high,' may possibly be 

 due to an incorporation of argillaceous material, although no obvious 

 reason exists why the magma may not have been exceptionally rich 

 in this constituent from the beginning. However this may be, the 

 Darjiling gneiss is certainly not a result of the metamorphosis of 

 Gondwana beds. 



Another point requiring elucidation is the presence of the hard 

 siliceous 'eyes.' Conceivably during the movement preceding its 

 solidification, the magma picked up small fragments of a foreign 

 rock, which, being softened and permeated by their liquid 

 surroundings, have resulted in the mineral assemblage seen. The 

 graphite must have formed, if not from igneous fusion, then from 

 a state closely approaching it. The structure as a whole is 

 indicative of crystallization where freedom of molecular movement 

 was restricted.* 



To Canon T. G. Bonney I am indebted for many yaluable 

 suggestions which are embodied in the preceding notes. 



IsTOTICES OIF nvniEIMIOIS-S- 



I. — Ice-Erosion in the Cuillin Hills, Skye. By Alfred 

 Barker, M.A., F.G.S. Trans. Koyal Soc. Edinburgh, 1901, 

 vol. xl, pt. 2, pp. 221-252. 



rpHOSE who are interested in hill-climbing will know that 

 \_ " Sligachan, in Skye, is the rock-climbing centre par excellence 

 of the British Isles " ; and as Mr. Charles Pilkington further remarks 

 in the fascinating Badminton volume on Mountaineering, " The 

 Alpine climber will find an additional interest in the district from 



1 See Mr. J. J. H. Teall'sPres. Address to Gaol. Assoc, Proc. Gaol. Assoc, 1899, 

 vol. xvi, pp. 72, 73. 

 * See paper by Canon T. G. Bonney, Quart. Journ.Geol. Soc., 1891, vol. xlvii,p. 105. 



