Abstract

J. L. Roberts and J. E. Treagus write:Anderton (1988) has recently proposed in this Journal a radical revision of Dalradian structure and tectonics. This is based on his view that many of the slide-zones previously identified as structural features are in fact listric growth-faults and disconformities, dating back to when the Dalradian sequence was itself deposited. There can be little doubt that some formation contacts can be interpreted in this way, particularly where they affect the little-deformed Dalradian rocks lying to the northwest of the Loch Awe Syncline. However, Anderton (1988) extends this model so that it also applies to the whole of the Dalradian outcrop from Ballachulish to Schiehallion. This has resulted in a highly simplistic model of the structural complexity shown by these intensely deformed rocks, as Anderton himself admits may well be the case (1988, p. 677). In attempting this revision, Anderton has ignored virtually all the published evidence concerning the structural relationships seen in these rocks, while he has produced no new evidence to support his own views.

The main elements in Anderton's (1988) reinterpretation are twofold, as far as they relate to the Dalradian rocks lying immediately above what we have termed the Boundary Slide (Roberts & Treagus 1979). First, Anderton (1988, p. 676) considers all these rocks to be autochthonous; and second, the synformal plunge-depressions of Ballachulish and Schiehallion areas correspond to half-graben basins, generated by syn-depositional movements on listric growth-faults, which are now represented by the Fort William and Dalradian Boundary Slides,

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