The stone age in Scotland / [Armand Donald Lacaille].

  • Lacaille, A. D. (Armand Donald)
Date:
1954
Catalogue details

Licence: In copyright

Credit: The stone age in Scotland / [Armand Donald Lacaille]. Source: Wellcome Collection.

    62/404 (page 32)
    During the Second Period of Retreat the Scottish ice withdrew from the far-flung limits of the readvance. It left the north of England for good, thinned back towards the centres of accumulation, shrank from the shores of Northern Ireland, and melted out into the coastal area. All but the highest grounds in the Orkneys and Hebrides were deglaciated, and meanwhile sea-level was rising round Scotland. Renewed glacial intensity and oscillations along the ice-fronts interrupted the Second Period of Retreat, initiating movements which involved the mainland almost as extensively as the Scottish Readvance. Confluent Highland glaciers again filled the Midland Valley. Local ice, fed in the hills of Fife and the neighbourhood, was stirred into activity, but this time it did not join the Highland streams. The Southern Uplands once more supported an ice-sheet and their glaciers flowed north and south down the main valleys, in the upper reaches of the Tweed and its Cheviot tributaries. The ice extended into the Solway, bulged over Carrick and the Rhinns, fanned out into the sea, and just broached the coast of Antrim.1 That it could spread so far is explained by the southerly extent of the western mountains where the greatest precipitation lay in Late-Glacial times.2 On land the Lammermuir-Stranraer Moraine denotes the edge of the ice at the peak of these readvances. The absence of this moraine between eastern Ayrshire and the south-western coast (see map, Fig. 9 b) indicates that even at this time the Highland ice was confluent with glaciers nourished in the western Southern Uplands.3 The various movements were probably contemporaneous but their maxima were not. Among them, the Perth Readvance, which involved the valley of the Teith, Strathallan, and Strathearn, was a constituent of the concomitant and long-persisting District, Valley, or Moraine Glaciation. It has to be singled out for its association with the marine invasion of the lower reaches of the Tay.4 In the east of Scotland, however, the readvancing ice did not everywhere gain the sea. It was otherwise in the north-west and west, where the snowfall, like the present rainfall, was greatest, the glaciers were largest, and came down to the lowest level. Especially noteworthy are the deposits which make plain the connexion of these Highland ice-streams with the sea of the time. With the subsequent withdrawal of the ice from the line of the Lam- 1 McCallien, 1937(a), pp. 186, 191. 1 Ibid., p. 50. 2 Charlesworth, 1926(a), p. 47. 4 Simpson, 1933, pp. 633-41.