Protalus ramparts and related features along the niagara escarpment, niagara peninsula, ontario
Abstract Talus foot ridges interpreted as protalus ramparts have been identified along 17 out of 42 km of the Niagara Escarpment within the Niagara Peninsula. They are distinguished from various types of slope form (rotational slumps, debris slides, quarries, dumps, moraines, raised shorelines and b...
| Published in: | Permafrost and Periglacial Processes |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
1994
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1002/ppp.3430050306 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.3430050306 https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.3430050306 |
| Summary: | Abstract Talus foot ridges interpreted as protalus ramparts have been identified along 17 out of 42 km of the Niagara Escarpment within the Niagara Peninsula. They are distinguished from various types of slope form (rotational slumps, debris slides, quarries, dumps, moraines, raised shorelines and bedrock ledges) by their regular linear nature and their restriction to slopes facing between north‐east and north‐west. Morphologies range from a simple terrace with a flat top and a steep rocky outer slope, to compound ridges with closed depressions between. Maximum widths from rampart crest to main talus foot average 25 metres. Ramparts are characteristically extremely bouldery and include angular blocks of Thorold and Grimsby Sandstones weathered from the Escarpment slope, Ironde‐quoit Limestone and Lockport Dolomite blocks with metre dimensions transported to the outer slopes of the ramparts from the upper edge of the Escarpment, and clay from the weathering of Escarpment shales and from Wisconsinan diamictons. Associated firn field dimensions probably fluctuated dramatically in size during the year, and the palaeoclimatic implication is that there existed substantial late‐lying to perennial firn fields following local deglaciation at 12.5 ka BP. Independent confirmation of an early postglacial tundra climate is provided by the basal portions of pollen stratigraphies obtained nearby. The latest period when the firn fields might have existed is during the Younger Dryas chronozone (11 ka to 10.0 ka BP) when regional climatic cooling may have allowed the re‐establishment of a tundra‐like climate, especially in areas with severe microclimates. |
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