File:Geological sketches, at home and abroad (1882) (14595935328).jpg

Identifier: geologicalsketch00geik (find matches)
Title: Geological sketches, at home and abroad
Year: 1882 (1880s)
Authors: Geikie, Archibald, Sir, 1835-1924
Subjects: Geology
Publisher: New York : Macmillan and Co.
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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orth-west alone. To realise what the appearance of the old gneiss at thepresent surface involves we must bear in mind that it wasfirst buried under several thousand feet of red sandstone,that the area was then further submerged until the vast pileof sediment was deposited out of which the Highlands havebeen formed, that these sedimentary accumulations—howmany thousand feet thick we cannot yet tell—were subse-quently over the Highland area crumpled and metamor-phosed into crystalline schists, and that finally towards thewest the ancient platform of gneiss was once more ridgedup and gradually bared of its superincumbent load of rock,until now at length some portions of it have been oncemore laid open to the air. There is thus a special historical interest in this frag-ment of the old gneiss country. It is a portion of theearliest European surface of which as yet we know any-thing—a surface in chronological comparison with whichthe Alps are of quite modern date. For many years past
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152 GEOLOGICAL SKETCHES. (vn I have at intervals wandered over it, finding in its undula-tions of bare rock a fascination which a fairer landscapemight fail to exert. Each visit suggests some fresh problem,if it does not cast light on earlier difficulties. One of thequestions which must particularly engage the attention ofevery observant traveller in Western Sutherland and Rossis the origin of that extraordinary contour presented by thegneiss. A very slight examination shows that every domeand boss of rock is ice-worn. The smoothed, polished,and striated surface left by the ice of the glacial period iseverywhere to be recognised. Each hummock of gneiss isa more or less perfect roche moutonnee. Perched blocksare strewn over the ground by thousands. In short, therecan hardly be anywhere else in Britain a more thoroughlytypical piece of glaciation. An obvious answer to the question of the origin of thepeculiar configuration of this gneiss country is to refer itto the action of the last i

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