464 Notices of Memoirs — Dr. Hicks — the " Grampian Series." 



N.E. to S.W. where there are indications of newer rocks in liroken 

 fohls, but the majority of those which he claimed as being of 

 pre-Cambrian age are now generally admitted to be older than any 

 of the PalEeozoic rocks of that area. The further descriptions of 

 these rocks now given have been prepared with the kind assistance 

 of Professor T, G. Bonney, D.Sc, F.R.S., to whom the author 

 some time since submitted specimens, collected at various points in 

 the year 1880. 



From near Ballachulish, etc., a finely -banded, fine-grained 

 micaceous schist, containing apparently a considerable amount of 

 felspathic matter. 



From Glen Spean, etc. Fine-grained gneisses, not rich in quartz, 

 but with a considerable amount of black mica, not markedly foliated 

 except as the result of subsequent pressure. All are characterized, 

 by a peculiar speckled aspect, the spots being about the size of pins' 

 heads. The felspar varies from a warm to a reddish gray. 



From Tyndrum, etc. A somewhat varying series of schists, but 

 with a common facies. Some have but little mica, consisting mainly 

 of quartz and felspar, and pale-gray or reddish in colour ; others ai'e 

 very micaceous schists of a lead colour, with sheen surfaces and 

 indications of mineral banding. There are also very quartzose 

 gneisses of a white or pinkish-white colour. 



Crianlarich and Killin, etc. Calc mica-schists, with sheen surfaces, 

 due to subsequent pressure, but showing mineral banding. Also 

 fine-grained gneisses like some of those near Tyndrum, but as they 

 have a very marked cleavage foliation they may originally have 

 been somewhat coarser grained. A garnetiferous mica-schist from 

 several places. 



Blair Athol, etc. Dark mica-schists, with rather a carbonaceous 

 aspect, and a very marked cleavage foliation. Some show on close 

 examination along the edges a speckled aspect, recalling some of the 

 gneisses mentioned above. There is also a fairly coarsely crystalline 

 limestone, with specks and streaks of green serpentinous material 

 and some scattered pyrite ; also a calc mica-schist, modified by 

 pressure, and an important series of quartzose schists similar to those 

 found at Tyndrum, etc. 



To the south of this line, as mentioned by the author in another 

 paper (Proceedings of the Geologists' Association, vol. vii. p. 84), 

 •' schistose and slaty chloritic rocks become more abundant in associa- 

 tion with micaceous rocks," and "everywhere strongly recall to mind, 

 the pre-Cambrian rocks of Wales, especially those in Anglesea, and 

 in the Lleyn Promontory." The author insisted that the term 

 " Grampian " was the only suitable name for this group of pre- 

 Cambrian rocks. It was suggested and adopted by him at a time 

 when all these rocks were claimed by the Geological Survey as of 

 Silurian age, and these rocks are nowhere in Britain so well exposed 

 as in the Grampian mountains of Scotland. 



