302 



E. B. Bailey — The Sgitrr of Eigg. 



Geikie Las taken the more obvious course of regarding this fragmental 

 deposit as a river-gravel underlying a pitchstone lava. Harker, 

 assured from tlie other evidence that the pitchstone is intrusive, 

 holds that the fragmental deposit is an agglomerate enclosed in 

 a funnel-shaped neck which, does not pierce the lower lavas of the 

 cliff-face because it passes behind them. Tor Harker the association of 

 the pitchstone and this fragmental deposit is nothing more than 

 a coincidence. So far as the material of the deposit goes, I know of 

 nothing to decide between the two interpretations. The deposit 

 consists in large measure of subangular blocks of vesicular basalt, 

 with a fair proportion of well-rounded boulders derived from the 

 sounder portions of the basaltic flows ; small pieces of Torridon 

 Sandstone also occur, but are comparatively rare ; fragments of pitch- 

 stone are altogether absent. 



Fig. 3. — Bidein Boidlieach, showing the sea-cliff in which the ridge of the 

 Sgurr terminates north-westward. After Harker [3, p. 53]. 



The cliff is made of alternations of basalt, B, anddolerite, D, terminating 

 against pitchstone, P, and also against a fragmental rock, A, which Harker 

 regards as agglomerate in a neck, and Geikie as gravel in a river-channel. 

 A particularly massive band of dolerite along the cliff-top, south of the 

 pitchstone and fragmental rock, is lettered D. A basalt dylie, B, cuts the 

 basalt-dolerite succession of the cliff, but not the fragmental rock, A. 



A point very greatly in favour of Geikie's reading is the fact that, 

 as seen in the cliff, the pitchstone exactly fits into the upper part of 

 the hollow, in the bottom of which, apparently at any rate, the frag- 

 mental material lies (Fig. 3, A). If we accept Harker's hypothesis 

 it is surely remarkable that such a delicate adjustment should occur 

 at any place at all, and doubly strange that the modern cliff should 

 be cut to the precise position requisite to reveal it. 



I am very reluctant indeed under such circumstances to relinquish 

 Geikie's interpretation, which accounts so simply for one sweeping 

 curve furnishing the boundary of pitchstone and fragmental deposit 

 alike. 



Dr. Harker has gone further than mere suggestion of a possible 

 accidental companionship between the pitchstone and the fragmental 

 material. He believes that he can actually prove that the two belong 

 to widely separate epochs. It is necessary to examine very thoroughly 



