The quaternary history of the British Channel
Résumé
Several lines of evidence for former glaciation of the English Channel are considered. These include the following major geomorphical features: (1) extensive areas of flat featureless sea bed bounded by cliffs with residual steep-sided rock masses rising about 60-150 m above them, (2) terrace forms bounded by breaks in slope or low cliffs, (3) palaeovalley systems related to the present land drainage, (4) enclosed deeps (fosses); all except (3) may be attributed to a glacial origin. The distribution of erratics on the Channel floor and in the modern and raised beaches of its coasts are attributed to widespread Saalian glaciation. This glaciation was responsible for the deposition of morainic material at Selsey and the damming-up of glacial Lake Solent. The so-called ‘100 foot raised beach’ of west Sussex is now re-interpreted as a fluvioglacial deposit laid down at the northern margin of the English Channel ice. It is thought that at the height of the Saalian glaciation mean sea-level fell to between 90 and 180 m below o.d. and that for a time the ice was grounded near the western margin of the continental shelf. Possible reconstructions of the limits and main movements of the Weichselian and Saalian ice sheets covering the British Isles and English Channel are included.