Late Quaternary Subaqueous Outwash Deposits Near Ottawa, Canada
Brian R. Rust, Richard Romanelli, 1975. "Late Quaternary Subaqueous Outwash Deposits Near Ottawa, Canada", Glaciofluvial and Glaciolacustrine Sedimentation, Alan V. Jopling, Barrie C. McDonald
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Stratified sands and gravels lying above Wisconsinan till and below fossiliferous marine deposits near Ottawa have markedly fluvial characteristics. Textures, paleocurrents, and sedimentary structures including channels, cross-beds, and ripple cross-lamination all indicate deposition by unidirectional flows of water. Many deformation structures can be ascribed to movement of water or water-saturated sediment, but some are regarded as collapse features related to the melting of buried ice.
The succession in which the stratified sediments occur indicates that they were deposited by glacial melt-water issuing below nearly a hundred meters of standing water. They are therefore termed subaqueous out-wash and are made up of proximal boulder gravel with a sharp change to distal sand. Features which are thought to be characteristic are an association with flow till, ice-contact deformation, and (for the sand only) graded units of ripple-dri ft cross-lamination, and large scale channels with apparently massive fill.
Conditions suitable for the formation of subaqueous outwash were probably widespread during Pleistocene deglaciation because large-scale isostatic depression of the land tended to pond marine or fresh water against ice fronts.
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Glaciofluvial and Glaciolacustrine Sedimentation
This publication is the outgrowth of a symposium on Glacial Sedimentology that was held in Buffalo, New York, March 1972. The great interest generated in glacial phenomena during the nineteenth century had important implications and repercussions for the infant field of sedimentology. It provided its fair share of the background stimulus necessary to establish sedimentology as a separate branch of the earth sciences in the twentieth century. The time for reciprocity is now at hand; feedback from the expertise gained in the burgeoning field of sedimentology can greatly help the Quaternary specialist solve particular field problems. The last decade has witnessed a growing interest in the sedimentology of the Quaternary, and it seems appropriate now to summarize progress in the study of stratified drift, to present results of some recent studies, and to focus attention on avenues of research that should be explored in the near future.