Discussion

Abstract

Dr A. T. J. D ollar said that the tentative correlation of the Leannan fault with the Great Glen fault raised certain problems. Assuming that these dislocations were parts of the same fault, how did the authors reconcile a horizontal displacement across it of ‘perhaps as much as 25 miles’ in Donegal with that of the 65 miles suggested by Kennedy (1946) in Inverness-shire, and little more than 100 miles between the two localities? On the basis of the same assumption did the authors consider that the part of the fault between Ireland and Scotland passed from Donegal (i) north-west of Colonsay to Loch Buie, in Mull, or the north-west coast of Loch Linnhe, or (ii) across Islay and then past the south-east coast of Colonsay to Loch Buie or the north-west coast of Loch Linnhe? Further, in view of the present activity of faults of Caledonian trend in Scotland (Dollar 1951), had the authors been able to gather any seismic evidence for movement across the Leannan fault during the last 40 years from local inhabitants or otherwise ? From a geophysical examination of the Great Glen fault, now in progress, the speaker and Mr M. U. Ahmad inclined to the view that the submarine trace of what appeared to be a major dislocation, for which there was seismic (Davidson 1924, pp. 38, 58–61) and morphological evidence, swung to the west-south-west from Loch Buie; passed some 8 miles south-east of the island of Dubh Artach, and continued westwards from there