Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation
Regional‐scale, high‐resolution terrain data permit the study of landforms across south‐central Ontario, where the bed of the former Laurentide Ice Sheet is well exposed and passes downflow from irregular topography on Precambrian Shield highlands to flat‐lying Palaeozoic carbonate bedrock, and thic...
Published in: | Boreas |
---|---|
Main Authors: | , , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2019
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1111/bor.12372 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12372 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/bor.12372 |
id |
crwiley:10.1111/bor.12372 |
---|---|
record_format |
openpolar |
spelling |
crwiley:10.1111/bor.12372 2024-10-13T14:08:06+00:00 Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation Mulligan, Riley P. M. Eyles, Carolyn H. Marich, Andrea S. Natural Sciences and Engineering Research Council of Canada 2019 http://dx.doi.org/10.1111/bor.12372 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12372 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/bor.12372 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Boreas volume 48, issue 3, page 635-657 ISSN 0300-9483 1502-3885 journal-article 2019 crwiley https://doi.org/10.1111/bor.12372 2024-09-19T04:19:52Z Regional‐scale, high‐resolution terrain data permit the study of landforms across south‐central Ontario, where the bed of the former Laurentide Ice Sheet is well exposed and passes downflow from irregular topography on Precambrian Shield highlands to flat‐lying Palaeozoic carbonate bedrock, and thick (50 to >200 m) unconsolidated sediment substrates. Rock drumlins and megagrooves are eroded into bedrock and mega‐scale glacial lineations ( MSGL ) occur on patchy streamlined till residuals in the Algonquin Highlands. Downflow, MSGL pass into juxtaposed rock and drift drumlins on Palaeozoic bedrock and predominantly till‐cored drumlins in areas of thick drift. The Lake Simcoe Moraines, now traceable for more than 80 km across the Peterborough drumlin field ( PDF ), form a distinct morphological boundary: downflow of the moraine system, drumlins are larger, broader and show no indication of subsequent reworking by the ice, whereas upflow of the moraines, a higher degree of complexity in bedform pattern and morphology is distinguished. Discrete radial and/or cross‐cutting flowset terminate at subtle till‐cored moraine ridges downflow of local topographic lows, indicating multiple phases of late‐stage ice flow with strong local topographic steering. More regional‐scale flow switching is evident as NW ‐orientated bedforms modify drumlins south of the Oak Ridges Moraine, and radial flowset emanate from areas within the St. Lawrence and Ottawa River valleys. Most of the drumlins in the PDF formed during an early, regional drumlinization phase of NE – SW flow that followed the deposition of a thick regional till sheet. These were subsequently modified by local‐scale, topographically controlled flows that terminate at till‐cored moraines, providing evidence that the superimposed bedforms record dynamic ice (re)advances throughout the deglaciation of south‐central Ontario. The patterns and relationships of glacial landform distribution and characteristics in south‐central Ontario hold significance for many modern and ... Article in Journal/Newspaper Ice Sheet Wiley Online Library Boreas 48 3 635 657 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
Regional‐scale, high‐resolution terrain data permit the study of landforms across south‐central Ontario, where the bed of the former Laurentide Ice Sheet is well exposed and passes downflow from irregular topography on Precambrian Shield highlands to flat‐lying Palaeozoic carbonate bedrock, and thick (50 to >200 m) unconsolidated sediment substrates. Rock drumlins and megagrooves are eroded into bedrock and mega‐scale glacial lineations ( MSGL ) occur on patchy streamlined till residuals in the Algonquin Highlands. Downflow, MSGL pass into juxtaposed rock and drift drumlins on Palaeozoic bedrock and predominantly till‐cored drumlins in areas of thick drift. The Lake Simcoe Moraines, now traceable for more than 80 km across the Peterborough drumlin field ( PDF ), form a distinct morphological boundary: downflow of the moraine system, drumlins are larger, broader and show no indication of subsequent reworking by the ice, whereas upflow of the moraines, a higher degree of complexity in bedform pattern and morphology is distinguished. Discrete radial and/or cross‐cutting flowset terminate at subtle till‐cored moraine ridges downflow of local topographic lows, indicating multiple phases of late‐stage ice flow with strong local topographic steering. More regional‐scale flow switching is evident as NW ‐orientated bedforms modify drumlins south of the Oak Ridges Moraine, and radial flowset emanate from areas within the St. Lawrence and Ottawa River valleys. Most of the drumlins in the PDF formed during an early, regional drumlinization phase of NE – SW flow that followed the deposition of a thick regional till sheet. These were subsequently modified by local‐scale, topographically controlled flows that terminate at till‐cored moraines, providing evidence that the superimposed bedforms record dynamic ice (re)advances throughout the deglaciation of south‐central Ontario. The patterns and relationships of glacial landform distribution and characteristics in south‐central Ontario hold significance for many modern and ... |
author2 |
Natural Sciences and Engineering Research Council of Canada |
format |
Article in Journal/Newspaper |
author |
Mulligan, Riley P. M. Eyles, Carolyn H. Marich, Andrea S. |
spellingShingle |
Mulligan, Riley P. M. Eyles, Carolyn H. Marich, Andrea S. Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation |
author_facet |
Mulligan, Riley P. M. Eyles, Carolyn H. Marich, Andrea S. |
author_sort |
Mulligan, Riley P. M. |
title |
Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation |
title_short |
Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation |
title_full |
Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation |
title_fullStr |
Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation |
title_full_unstemmed |
Subglacial and ice‐marginal landforms in south‐central Ontario: implications for ice‐sheet reconfiguration during deglaciation |
title_sort |
subglacial and ice‐marginal landforms in south‐central ontario: implications for ice‐sheet reconfiguration during deglaciation |
publisher |
Wiley |
publishDate |
2019 |
url |
http://dx.doi.org/10.1111/bor.12372 https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12372 https://onlinelibrary.wiley.com/doi/full-xml/10.1111/bor.12372 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Boreas volume 48, issue 3, page 635-657 ISSN 0300-9483 1502-3885 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/bor.12372 |
container_title |
Boreas |
container_volume |
48 |
container_issue |
3 |
container_start_page |
635 |
op_container_end_page |
657 |
_version_ |
1812814706457444352 |