The Caledon-Guelph outwash, Ontario, Canada: its origin, deposits, and economics

• Main Author: Hymers, Lesley Anne
• Other Authors: Martini, I.P.
• Format: Thesis
• Language: English
• Published: 2001
• Subjects: Late Pleistocene Caledon-Guelph outwash; Paris Moraine; Caledon; Guelph; formation; sediment distribution; aggregate deposit; Canada; Ice Sheet
• Online Access: https://hdl.handle.net/10214/22075

The Late Pleistocene Caledon-Guelph outwash has developed in front of the Paris Moraine from Caledon to Guelph and to Paris in southwestern Ontario. Its sediments were transported and deposited by braided meltwater streams that flowed quasi-parallel to the front of the Ontario lobe of the Laurentide Ice Sheet. These streams received input of sediment and water from various points along their path, and never developed a graded profile. They were also affected by strongly variable discharge related to variation in thaw in different seasons and from day and night. Occasional bursts of ice-dammed supra- and/or sub-glacial lakes may have triggered short-lived but powerful mega-floods. These events led to a complex distribution of variable deposits of sand and gravel. As a result, these deposits maintain the record of events and processes active in these glacial marginal environments. These sand and gravel deposits were studied in four representative pits: Caledon, Erin, Martini (within the outwash), and the Leslie pit (within an ice-contact zone). Stagnant water conditions are revealed by few local occurrences of silt and fine sand layers. Braided stream conditions, with continuous cutting and filling of channels, is revealed by the alternation of massive sandy gravels and cross-bedded deposits. Evidence of extremely large magnitude floods is recorded by the presence of imbricated coarse boulders, large foresetted deposits, and large channel fills, particularly in the Caledon region. The Caledon-Guelph outwash is an economically important aggregate deposit. The deposits are valuable because of their quantity and quality. They are thick, lack deleterious lithologies, usually require limited processing, are located near transportation routes, and major market areas.