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The Champlain Sea () was a prehistoric
inlet An inlet is a typically long and narrow indentation of a shoreline such as a small arm, cove, bay, sound, fjord, lagoon or marsh, that leads to an enclosed larger body of water such as a lake, estuary, gulf or marginal sea. Overview In ...
of the
Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
into the North American continent, created by the retreating
ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacier, glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice s ...
s during the closure of the last glacial period. The inlet once included lands in what are now the Canadian provinces of
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
and
Ontario Ontario is the southernmost Provinces and territories of Canada, province of Canada. Located in Central Canada, Ontario is the Population of Canada by province and territory, country's most populous province. As of the 2021 Canadian census, it ...
, as well as parts of the American states of New York and
Vermont Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...
. Today, the remains of the sea include the St. Lawrence Seaway,
Lake Champlain Lake Champlain ( ; , ) is a natural freshwater lake in North America. It mostly lies between the U.S. states of New York (state), New York and Vermont, but also extends north into the Canadian province of Quebec. The cities of Burlington, Ve ...
, Lake of Two Mountains on the lower
Ottawa River The Ottawa River (, ) is a river in the Canadian provinces of Ontario and Quebec. It is named after the Algonquin word "to trade", as it was the major trade route of Eastern Canada at the time. For most of its length, it defines the border betw ...
, and the lower Saguenay River, as well as other lakes, islands and shores.


Origins

The mass of ice from the continental ice sheets had depressed the rock beneath it over millennia. At the end of the last glacial period, while the rock was still depressed, the
Saint Lawrence Saint Lawrence or Laurence (; 31 December 225 – 10 August 258) was one of the seven deacons of the city of Rome under Pope Sixtus II who were martyred in the Persecution of Christians, persecution of the Christians that the Roman Empire, Rom ...
and
Ottawa River The Ottawa River (, ) is a river in the Canadian provinces of Ontario and Quebec. It is named after the Algonquin word "to trade", as it was the major trade route of Eastern Canada at the time. For most of its length, it defines the border betw ...
valleys, as well as modern
Lake Champlain Lake Champlain ( ; , ) is a natural freshwater lake in North America. It mostly lies between the U.S. states of New York (state), New York and Vermont, but also extends north into the Canadian province of Quebec. The cities of Burlington, Ve ...
, at that time Lake Vermont, were below sea level and flooded with rising worldwide sea levels, once the ice no longer prevented the ocean from flowing into the region. As the land gradually rose again, in the process known as
isostatic rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound ...
, the sea coast gradually retreated to its current location. The sea lasted from about 13,000 years ago to about 10,000 years ago and was continuously shrinking during that time, since the rebounding continent was slowly rising above sea level. At its peak, the sea extended inland as far south as
Lake Champlain Lake Champlain ( ; , ) is a natural freshwater lake in North America. It mostly lies between the U.S. states of New York (state), New York and Vermont, but also extends north into the Canadian province of Quebec. The cities of Burlington, Ve ...
and somewhat farther west than the city of
Ottawa Ottawa is the capital city of Canada. It is located in the southern Ontario, southern portion of the province of Ontario, at the confluence of the Ottawa River and the Rideau River. Ottawa borders Gatineau, Gatineau, Quebec, and forms the cor ...
, Ontario, and farther up the Ottawa River past Pembroke. At one time Glacial Lake Iroquois became an arm of the Champlain Sea called Gilbert Gulf. The remaining glaciers fed the sea during that time, making it more
brackish Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
than typical seawater. It is estimated that the sea was as much as above the level of today's Saint Lawrence and Ottawa Rivers.Barnett, P. J. 1988. "History of the northwestern arm of the Champlain Sea". pp. 25–36 in Gadd, N.R. (ed.) ''The Late Quaternary Development of the Champlain Sea Basin''. Geological Association of Canada, Special Paper 36. Map 5.


Geological evidence

The best evidence of this former sea is the vast clay plain deposited along the Ottawa and St. Lawrence Rivers. This resulted in distinctive forest types, and large wetlands. Other modern evidence of the sea can be seen in the form of fossils of whales ( belugas, fin whales, and
bowhead whale The bowhead whale (''Balaena mysticetus''), sometimes called the Greenland right whale, Arctic whale, and polar whale, is a species of baleen whale belonging to the family Balaenidae and is the only living representative of the genus '' Balaena' ...
s),
walrus The walrus (''Odobenus rosmarus'') is a large pinniped marine mammal with discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. It is the only extant species in the family Odobeni ...
es and other pinnipeds, and marine shells that have been found near the cities of Ottawa, Ontario, and
Montreal Montreal is the List of towns in Quebec, largest city in the Provinces and territories of Canada, province of Quebec, the List of the largest municipalities in Canada by population, second-largest in Canada, and the List of North American cit ...
, Quebec. There are also fossils of oceanic fish such as capelin. The Sea also left ancient raised shorelines in the former coastal regions, and the Leda clay deposits in areas of deeper water. The northern shore of the lake was in southern Quebec where outcrops of the
Canadian Shield The Canadian Shield ( ), also called the Laurentian Shield or the Laurentian Plateau, is a geologic shield, a large area of exposed Precambrian igneous and high-grade metamorphic rocks. It forms the North American Craton (or Laurentia), th ...
form Eardley Escarpment. This escarpment still has distinctive plants that may date back to the era when the sea existed.Brunton, D. and J.D. Lafontaine. 1974. An unusual escarpment flora in Western Quebec. The Canadian Field-Naturalist 88(3):337–344. The Eardley Escarpment is known locally as the Gatineau Hills. It is part of the Mattawa fault at the southeastern edge of the Ottawa-Bonnechere Graben, in Eastern Ontario and the
Outaouais Outaouais (, ; also commonly called The Outaouais) is a region of western Quebec, Canada. It includes the city of Gatineau, the municipality of Val-des-Monts, the municipality of Cantley, Quebec, Cantley and the Papineau Regional County Municipal ...
region of
Quebec Quebec is Canada's List of Canadian provinces and territories by area, largest province by area. Located in Central Canada, the province shares borders with the provinces of Ontario to the west, Newfoundland and Labrador to the northeast, ...
, more commonly known as the Ottawa Valley.


See also

* Lake Hitchcock * Lake Albany *
Wisconsin glaciation The Wisconsin glaciation, also called the Wisconsin glacial episode, was the most recent glacial period of the North American ice sheet complex, peaking more than 20,000 years ago. This advance included the Cordilleran Ice Sheet, which nucleated ...
* Saint Lawrence Rift System


References


Further reading

Gadd, N.R. (ed.) 1988. ''The Late Quaternary Development of the Champlain Sea Basin''. Geological Association of Canada, Special Paper 36.


External links


History of the Champlain Sea

Charlotte, The Vermont Whale


*

{{Authority control Natural history of Ontario Natural history of Quebec Natural history of New York (state) Natural history of Vermont Pleistocene Seas of the Atlantic Ocean Last Glacial Period Glacial lakes of the United States Lake Champlain Seas of Canada Seas of North America Seas of the United States