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| Former lakes of North America | |
|---|---|
| Name | Former lakes of North America |
| Caption | Reconstructed paleolake extents and spillways |
| Location | North America |
| Type | Paleolakes, proglacial lakes, pluvial lakes |
| Inflow | Glacial meltwater, precipitation, river rerouting |
| Outflow | Spillways, drainage capture, evaporation |
Former lakes of North America
Former lakes of North America were extensive paleolakes, proglacial basins, and pluvial systems that formed during the Pleistocene and Holocene in regions now comprising Canada, the United States, and Mexico. These basins, including transient bodies linked to glaciers, rivers, and climate oscillations, left geomorphic, sedimentary, and archaeological traces that inform reconstructions of glaciation, hydrology, and prehistoric human migrations. Many named basins are associated with ice sheets, spillways, and river captures that reshaped continental drainage and influenced modern watersheds.
The classification of paleolakes relies on terminology used in studies by J Harlen Bretz, Arthur Holmes, and institutions such as the United States Geological Survey and Geological Survey of Canada, with distinctions among proglacial lakes like those associated with the Cordilleran Ice Sheet and Laurentide Ice Sheet, and pluvial systems in the Great Basin and Mexican Plateau. Key named basins include Lake Agassiz, Lake Bonneville, Lake Lahontan, Glacial Lake Missoula, Lake Winnipegosis, and Lake Chicago; researchers from universities such as Harvard University, University of Minnesota, University of Washington, and University of Toronto contribute to schematic frameworks. Definitions draw on stratigraphic work from researchers at the Smithsonian Institution, Canadian Geological Survey, and field studies near landmarks like the Missouri River, Mississippi River, Great Salt Lake, Lake Superior, and Hudson Bay.
Proglacial lakes formed where ice lobes of the Laurentide Ice Sheet or Cordilleran Ice Sheet blocked drainage, producing bodies such as Lake Agassiz and Glacial Lake Iroquois; tectonic basins like those of the Basin and Range Province hosted pluvial lakes including Lake Bonneville and Lake Lahontan. Ice-margin readvances and catastrophic jökulhlaups from ice-dammed reservoirs such as Glacial Lake Missoula scoured coulees like the Channeled Scablands and altered courses of rivers including the Columbia River, Missouri River, and St. Lawrence River. Volcanism in regions influenced basinal hydrology—events related to Mount Mazama and Yellowstone Caldera affected drainage—while glacioisostatic adjustment around centers like Hudson Bay and Great Lakes modified spillways and shorelines.
Prominent proglacial systems include Lake Agassiz in the Red River basin, Glacial Lake Algonquin and its successor Lake Nipissing linked to the Great Lakes, Glacial Lake Iroquois adjacent to the Saint Lawrence River, and Glacial Lake Missoula on the Upper Columbia River. Pluvial systems encompassed Lake Bonneville in the Bonneville Basin (source of the Bonneville Flood), Lake Lahontan with subbasins around Walker Lake and Pyramid Lake, and Lake Corcoran on the Central Valley (California). Smaller basins include Lake Hitchcock in New England, Lake Pleistocene Mono near Mono Lake, Lake Owasco and Lake Iroquois-related basins around New York (state), and former floodplain lakes such as Manitoba's Lake Agassiz remnants. International research programs involving National Oceanic and Atmospheric Administration, Natural Resources Canada, and academic centers have cataloged shorelines, deltas, and lacustrine deposits across these basins.
Postglacial drainage reorganizations rerouted major rivers—outbursts from Lake Agassiz influenced the St. Lawrence River and may have affected thermohaline circulation and events noted at paleoclimate sites like Greenland Ice Sheet cores; releases from Glacial Lake Missoula carved the Channeled Scablands and forced the Columbia River through new canyons. Capture events shifted tributaries among the Missouri River, Mississippi River, and Hudson Bay catchments; spillway incision at locales such as the St. Clair River, Niagara River, and St. Lawrence River reshaped lake basins like Lake Erie and Lake Ontario. Human-engineered changes by entities like the US Army Corps of Engineers later modified residual drainage, but many major reorganizations predate historic interventions.
Paleobotanical, faunal, and archaeological records connect former lakes to corridors of migration and resource use by prehistoric peoples including Paleoindians, with sites near Gulf of Mexico coasts, Prairie provinces, and Beringia supporting models of dispersal. Pollen sequences, diatom assemblages, and megafaunal remains (e.g., proboscideans) recovered near Lake Bonneville and Lake Agassiz inform reconstructions used by researchers at Yale University, University of Arizona, and Smithsonian Institution Paleobiology programs. Radiocarbon-dated hearths, lithic scatters, and submerged sites in former basins intersect work by Lewis Binford-influenced archaeologists and regional surveys under National Park Service stewardship.
Modern reconstructions employ remote sensing (e.g., Landsat, ASTER, LiDAR), geophysical surveys by institutions like USGS and Geological Survey of Canada, and geochronology using radiocarbon dating, optically stimulated luminescence, and cosmogenic nuclide dating developed at labs including Lawrence Livermore National Laboratory and Lamont–Doherty Earth Observatory. Paleoenvironmental proxies analyzed in universities such as University of California, Berkeley, University of Minnesota, and McGill University integrate sediment cores, shoreline mapping, and numerical modeling to resolve chronologies for events like the Younger Dryas and meltwater pulses affecting North Atlantic circulation.
Remnant shorelines, terraces, playas, and salars—evident at Great Salt Lake, Salt Lake City, Fresno County, and Reno, Nevada vicinities—support distinctive soils, wetlands, and ecological niches managed by agencies such as US Fish and Wildlife Service and Environment and Climate Change Canada. Urban centers including Chicago, Minneapolis, Toronto, and Winnipeg sit on or near former lake deposits that influence infrastructure and agriculture; canal and dam projects by the Panama Canal Authority analogue actors notwithstanding, legacy impacts include groundwater recharge patterns, mineral deposits, and paleoindian archaeology curated by institutions like the Royal Ontario Museum and Field Museum.
Category:Paleogeography of North America