CGRG Bibliography of Canadian Geomorphology
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Author : Dreimanis, A.; Winder, C.G.; and Aaltonen, R.A.
Date : 1998
Title : London, Ontario; geology, geomorphology, geodata.
Publication : Urban Geology of Canadian Cities. Edited by: P.F. Karrow. Geological Association of Canada, Special Paper
Issue : 42:
Page(s) : 237-260.
Abstract
London is in the broad valley of the Thames River, with the Arva Moraine to the northwest and the Ingersoll Moraine to the south. The landscape is mainly glacial in origin, formed by the Huron and Erie lobes. Both lobes alternately advanced and retreated over the interlobate area, now occupied by the center of London. When they retreated, the area was repeatedly scoured by meltwater streams or flooded by ice-marginal lakes when the stream outlets were blocked. The latest. Late Glacial to Recent, sequence was: (1) oscillating glacial meltback and erosion of a wide valley; (2) damming of Lake London by both lobes meeting southwest of the city and deposition of deltaic and glaciolacustrine sediments; (3) final glacial retreat, meltwater stream erosion and deposition of fluvial gravel and sand; and (4) continuation of stream activity in the London Basin. The Pleistocene cover ranges from 20 m in the northeast to 100 m in the southwest, and it is underlain by Devonian limestone and shale. Where buried valleys in the bedrock and Pleistocene tills were filled by gravel and/or sand, artesian water was formerly obtained to supply London. The main sources of constructional material are deltaic gravels. Generally, building excavations in clayey and silty till, sand, lacustrine silt and clay and gravel are stable. Problems occur with saturated sand, particularly in the downtown area, organic deposits in old meanders of Holocene age on flood plains and occasional slumping adjacent to steep slopes. A geotechnical data file was compiled in the early 1970s; local consulting engineers have their own files.
Bibliography of Canadian Geomorphology