May 3, 1906] 



NA TURE 



AT rilE IIKAD OF LOCH FYNE.' 



A I MU.V.R minilxr of contributors even than 

 those mentioned on the title-pape have con- 

 spired to make this memoir authoritative and com- 

 plete. It is descriptive of Sheet 37 of the i-meh 

 eeolo'Mcal map of Scotland, an attractive work pub- 

 hshed in 1903, in which the north-east and south- 

 west lines of the Caledonian earth-foldmjj pre- 

 dominate, and are followed out in the trend of the 

 intrusive masses. The meinoir is illustrated by excel- 

 lent plates, one of which is here reproduced ; and the 

 fact that part of the ground is familiar to the tourist 

 gives it an additional interest. 



The retjion described is cut. from corner to corner, 

 bv the noble inlet of Loch l-"yne. Tlie parallel reach 



landscape. The fundamental rocks of the district 

 are metamorphic, and formed a part of the Caledonian 

 continent, on which the Old Red Sandstone gathered; 

 and Mr. Hill points out how denudation is removing 

 the Devonian lavas and lake-deposits in the north- 

 west and is revealing, in the sculpture of the old 

 continent, a highland much like that of modern 

 days. The ice-llows of the Glacial epoch, however, 

 have moulded the present surface in many of its 

 details, have left erratic blocks in quaint positions on 

 the hills, and have deposited moraines and banks of 

 gravel across the edges of the ancient schists. 



The metamorphosed series is mainly of sedimentary 

 origin, with manv bands of limestone. The albite- 

 schists (p. 15), which are " highly micaceous or 

 chlorilic rocks with grains or crystals of clear 



of Glencroe, with Lech Restil. The rugged hill 

 From "The Geology of Mid Argyll." 



s formed by Ihe Ben Bheula 



of Loch Awe lies in the north-west, and Loch Eck, 

 banked out bv gravel terraces from the sea, comes in 

 near Loch Long in the south-east. The traveller by 

 land usually enters the region by the steep and rugged 

 fastnesses of Glencroe, and leaves it by Glen Aray, if 

 he is willing to face the rain-swept moorland above 

 which Cruachan towers in the north. The geological 

 surveyors, however, have become familiar with a 

 wide area practically untrodden by any visitor. 

 Mr. Hill's appreciative introduction should be read 

 witli the aid of the hill-shaded Ordnance map. 

 Sheet 37, one of the most beautiful products of a 

 draughtsman who surely possessed a sentiment for 



1 " The Geilogy cf Mid-Argyll." Bv J. K. Hill, with the collaboration 

 of r. N. Peach, C. T. Clough. and H. Kynaston, with petioeraphical 

 notes bv J.IJ. H. Teall and J. S. Flett. Pp. vi + i66. Memoir..; of the 

 Oeoloaical Survey, Scotl-ind. (Glasgow, for H.M. Stationery Office : 

 J. Hedderwick and Sons, Ltd., 1505.) Price Sj. 



NO. 1905, VOL. 74] 



secondary albite," are of special interest. Dr. Tealf 

 supplies an analvsis, showing 3-2 per cent, of soda 

 and an equal aniount of potash. This allows 28 per 

 cent, of the rock to be formed of albite. " Green 

 beds," which are hornblendic, and yet are not the 

 intrusive epidiorites so familiar in Dalradian areas, 

 occur in a band south-east of Loch Fyne, and rnay 

 have been derived clasticallv from some preexisting 

 basic igneous series (p. 18)' True iills of epidiorite 

 occur, however, plentifully among the metamorphic 

 rocks between Loch Awe and Loch Fyne. In the 

 same region there are numerous later intrusions of 

 quartz-porphvrv and other igneous rocks, probably 

 post-Silurian' in age. " Kentallenite," described in 

 detail by Mr. Hill in 1900 (Quart. Journ. Geol. Soc., 

 vol. Ivil, p. 531), and first known from the Appin 

 promontory, occurs here and there, as a link between 



