Abstract

A dome in Palaeozoic limestone at Kingston is 7.5 m in diameter as revealed in a roadcut and about 11 m at its maximum as indicated by ground-penetrating radar. The centre has been displaced 1.5 m upward in the exposure and up to 2.5 m internally in a circular arch. The dome appears to be roughly circular in plan and up-arching of the limestone extends to about 17 m depth. The dome has been eroded to a nearly plane surface by glaciation as indicated by striations on limestone blocks at the surface. Based on similarity of form to features in modern periglacial environments, the dome is proposed to have originated by frost heaving of bedrock before the late Wisconsinan glaciation of southern Ontario. This is the first report of such a feature, and recognition of their occurrence in formerly periglacial regimes should provide a useful tool in palaeoenvironmental reconstruction. Copyright © 2000 John Wiley & Sons, Ltd. Un dome developpe dans des calcaires plaeozoiques a ete observe lors de l'excavation d'une tranchee a Kingston. Le diametre de la forme telle qu'elle est apparue dans la tranchee, est de 7.5 m; a son maximum, il atteindrait 11 m selon une prospection radar. Le soulevement visible dans la tranchee est de 1.5 m, mais le soulevement maximum serait de plus de 2.5 m formerait ainsi une arche. Le dome est approximativement circulaire en plan et le soulevement s'etend jusqu'a une profondeur d'environ 17 m. Le dome a ete rabote par un glacier jusqu'a une surface presque plane en laissant des stries en surface sur les blocs de calcaire. Etant donne la similitude de forme avec des phenomenes connus actuellement dans les environnements periglaciaires actuels, ce dome est interprete comme resultant d'un soulevement par le gel du bedrock, soulevement anterieur a la derniere phase glaciaire qui a recouvert l'Ontario meridional. Le present article est la premiere description d'un phenomene periglaciaire fossile de ce type. La reconnaissance de phenomenes semblables pourrait fournir un outil utile pour des reconstructions paleoenvironnementales. Copyright © 2000 John Wiley & Sons, Ltd.

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