Glacial limits, sea-level changes and vegetational development in part of Wester Ross
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The area studied is part of Wester Ross, north-west Scotland, and includes the Applecross Peninsula and the land to the east between Strathcarron and Glen Torridon. Mapping of glacial landforms involved study of aerial photographs and subsequent field work. Evidence was found for the existence of two ice caps and five separate coire glaciers during the Loch Lomond Readvance, their various termini being represented today by clear lateral and end moraines at fourteen out of twenty-five locations. In nine cases, multiple lateral and/or end moraines suggest fluctuation of these ice margins during the Stadial maximum. An earlier stage of glaciation not related to the Late-Devensian ice-sheet maximum is represented by a single moraine and glacial striae. It is believed that this substage probably occurred between 18,000 and 14,000 years ago. Former sea-level changes were investigated by accurate mapping and instrumental levelling of raised coastal features. Three major periods of formation were identified :- 1. A pre-glacial or interglacial stage, evidenced by a highlevel rock platform at 32 to 37 m O.D.; 2. Raised beaches and deltas lying between 21 and 28 m O.D. relating to a period of very early Lateglacial deglaciation; 3. Postglacial features lying below about 10 m O.D. Pollen analysis of core sequences from two sites helped confirm the Loch Lomond Readvance age of the end moraines in Strath a' Bhathaich and to elucidate the history of vegetational development in the area between ca. 13,000 and 9,000 B.P. The Lateglacial pollen diagram indicates early development of a treeless Empetrum- dominated landscape that reverted during the Stadial to tundra-like conditions with a floristically-poor, open vegetation. Both Postglacial diagrams indicate a rapid recovery in early Postglacial times, with the return of pioneer species shortly superceded by a closed vegetation, and then by immigration of birch trees, and the establishment of a mixed birch-hazel woodland.