April 26, 19 17] 



NATURE 



173 



BEH NEVIS AND GLEN COE.' 



SHEET 53 of the map of Scotland comprises the 

 especially interesting area around Ben Nevis, 

 Glen Coe, and Loch Linnhe. This district includes 

 the highest summit in the British Isles ; it presents 

 ideological problems, both tectonic and petrologic, of 

 unusual variety, and it has a most instructive and 

 diversified physiography. It is described in a memoir 

 which is a most valuable contribution to Scottish 

 geology. This work has been mainly written by Mr. 

 k. B. Bailey, and is characterised by its high literary 

 quality, its originality of view, its happy expressions 

 and apt comparisons, and its sympathetic summarj' 

 of previous work on the district, beginning with 



being pre-glacial, cannot be due to the glacial en- 

 largement of the main valleys. 



Mr. Bailey adopts the view that the main north- 

 west to south-east valleys are due to a pre-glacial 

 river systeq^, and that they were broken by cross 

 valleys into segments separated by secondary water- 

 sheds. In the development of these river valleys he 

 admits that earth movements played an important 

 part, though he considers that the fractures which 

 determined the vallfeys remained latent until opened 

 by river action. He compares the valleys to the 

 Zambezi gorge, which, though admittedly guided by 

 fractures in the rocks, lacks the features indica- 

 tive of the structural origin of these Highland valleys. 

 Mr. Bailev attributes manv of the valleys to erosion 



F:g. I.— Ben Nevis and Glen Nevis Gorge. By permission of the Controller of H.M. Stationery Office. 



Macknight and MaccuUoch at the beginning of the 

 last century. The oroblems in the Ben Nevis district 

 of most general interest are those connected with the 

 physiography of the Scottish Highlands. The High- 

 land glens have been often attributed to glacial 

 erosion, and some of their most conspicuous features 

 to the glacial deepening of the valleys. Mr. Bailey, 

 however, submits ample evidence that the valleys 

 were pre-glacial, that Glen Nevis, for example, has 

 not been glacially deepened, that some of the gorges 

 have escaped any serious glacial modification, and 

 that the much-quoted hanging valleys of the district, 



' Memoir Geol. Surv. Scot'and. '-The Geology of Ben Nevis and Glen 

 Coe, and the Surrounding I ountry." (Explanation of Sheet 53.) By E. B. 

 Bailey and H. B. MaufTe. Pp. x-f-247-i-plates xi. 



along shatter-belts, which were attributed by Dr. 

 Marr, the author of the term, to the crushing of a 

 band of rocks along an oscillatory fault that may 

 produce no final displacement of the rocks beside it. 

 The description of shatter-belts in the memoir (pp. 

 215-16) gives no clear evidence as to their origin. 

 Some are bands of broken rock along ordinary faults ; 

 some are later than the last of the Cainozoic dykes, and 

 are therefore geologically modern. So far as can be 

 judged from the scanty evidence given in the memoir, 

 these formations may be bands of rocks shattered be- 

 tween parallel ruptures due to tension during the eleva- 

 tion of the country into broad, low upfolds. Mr. Bailev 

 remarks that if many of the Highland valleys had 

 been originated along tension clefts some of them 



NO. 2478, VOL. 99] 



