DEGLACIAL HISTORY OF NORTHERN ST. GEORGE'S BAY, WESTERN NEWFOUNDLAND
Quaternary mapping in the Stephenville area has identified a sequence of late-glacial and Holocene events, which are based upon surficial and paleo ice-flow indicator mapping, and the documenting of features and sediment related to sea-level change. The entire area was glaciated during the late Wisc...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.459.8820 http://www.nr.gov.nl.ca/nr/mines/geoscience/publications/currentresearch/2000/batterson_sheppard.pdf |
| Summary: | Quaternary mapping in the Stephenville area has identified a sequence of late-glacial and Holocene events, which are based upon surficial and paleo ice-flow indicator mapping, and the documenting of features and sediment related to sea-level change. The entire area was glaciated during the late Wisconsinan. The earliest ice-flow direction identified was from the north. This flow was identified in the Harrys River valley and over the entire Port au Port Peninsula. Later flows were gen-erally coastward from ice centres in The Topsails and the southern Long Range Mountains. The latter flow crossed the north-ern St. George's Bay impinging on the coastal platform west of Stephenville, and extending as far west as Abrahams Cove on the Port au Port Peninsula, but did not cover the north coast of the Peninsula. Deglaciation commenced about 13 500 BP. Marine limit was up to 65 m asl on the Port au Port Peninsula, decreasing eastward. This suggests eastward-retreating ice in the Stephenville area, and this retreat is suggested by the pattern of eskers observed in the area. Glaciers were calving into a raised postglacial sea, as indicated by sediment sequences exposed in coastal cliffs west of Stephenville, many of which are interpreted to have been deposited in an ice-proximal glaciomarine envi-ronment. No evidence was found to support a regional, late-glacial re-advance of ice in the area. Holocene sea levels fell until a lowstand at-25 m at about 9500 BP. At this time, a series of shallow ponds occupied mod-ern East Bay and West Bay, with the intervening lowland area being a wetland. The remnants of this wetland are found on the Shoal Point spit. The continuous sea-level rise from the lowstand to the present day has resulted in coastal erosion of uncon-solidated cliffs. |
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