Laurentian River System

An 1890 map of the ancient Laurentian River

The Laurentian River System is an ancient river in southern Ontario, Canada.^[1][2][3][4] The river predates the recent ice ages.^[5] The river valley was filled with glacial debris. Water still flows down this old valley—underground. The source of the aquifer is the Georgian Bay,^[6] approximately 200 kilometres (120 mi) away.

In 2003 it was discovered that the southern section of the Laurentian aquifer reaches under High Park in Toronto, Canada.^[6] This is believed to be where the Laurentian River System drains into Lake Ontario.

The bedrock under Toronto has several dips believed to be carved by the Laurentian River.^[7]

See also

• List of rivers of Ontario

References

1. "CAMC/YPDT - High Park". 2006. Retrieved 2011-11-29. Based on this, as well as on previous gravity work completed by the University of Waterloo (Gill and Karrow, 1996) it was suspected that one of the main outlets of the Laurentian River, a significant pre-glacial bedrock valley, was located in the vicinity of High Park.
2. "Ancient River Found Flowing Beneath Toronto". Reuters. 2003-09-19. Retrieved 2011-11-29. There's an ice-age river flowing deep under Canada's largest city. There has been for at least a million years but it wasn't until last month that anyone saw any real evidence of it.
3. "Before the Ice Age". Lost Rivers. 2003. Retrieved 2011-11-29. The river that drained this area, the Laurentian River, flowed through the Toronto area. It had started from Lake Superior and flowed though the Lake Huron Basin, the Georgian Bay Basin and, through a valley in bedrock, now hidden by the Oak Ridges Moraine, to the Lake Ontario Basin and thence by the St. Lawrence Valley to the Ocean.
4. "Discover the natural wonders of Toronto's High Park". High Park Nature. 2011-04-26. Retrieved 2011-11-29. The drilling had gone down about 40 metres when a mixture of shale, gravel, sand and water exploded 15 metres up into the air. The drill had tapped into an ancient underground river! Called the Laurentian River, it is an artesian aquifer thought to be flowing very slowly from Georgian Bay through a layer of sand and gravel just above bedrock level.
5. "Oak Ridges Moraine". York, Peel, Durham, Toronto and The Conservation Authorities Moraine Coalition. 2014-08-04. Retrieved 2016-02-04. Since first proposed by Spencer in 1881, the Laurentian River system has been noted and delineated by different Ontario geoscientists (e.g. White and Karrow, 1971, Brennand et al, 1998). In this part of south-central Ontario, the Laurentian River - believed to have been a main drainage pathway for a significant portion of the Great Lakes Basin - flowed from the Wasaga Beach area at Georgian Bay southwards through Simcoe County and York Region to Toronto where it has been traced into the Lake Ontario basin.
6. Reeves, Wayne and Palassio, Christina (2007). HTO: Toronto's Water from Lake Iroquois to Lost Rivers to Low-flow Toilets. Toronto: Coach House Books. pp. 284–285.
7. "Quaternary Geology: Toronto and Surrounding Area" (PDF). Ontario Geological Survey. 1980.

External links

• Reuters article, about the recent discovery of the aquifer, archived at a water conservation site.