The Tyrrell Sea, named after

Canadian Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, alt ...

Joseph Tyrrell, is another name for prehistoric

Hudson Bay Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...

, namely as it existed during the retreat of the

Laurentide Ice Sheet The Laurentide Ice Sheet was a massive sheet of ice that covered millions of square miles, including most of Canada and a large portion of the Northern United States, multiple times during the Quaternary glacial epochs, from 2.58 million year ...

. Roughly 8,000 years BP, the Laurentide Ice Sheet thinned and split into two lobes, one centred over

Quebec Quebec ( ; )According to the Government of Canada, Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is ...

Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province , subdivision_name1 ...

, the other over Keewatin. This drained Glacial Lake Ojibway, a massive proglacial lake south of the ice sheet, leading to the formation of the early Tyrrell Sea. The weight of the ice had isostatically depressed the surface as much as 270-280 m below its current level, making the Tyrrell Sea much larger than modern Hudson Bay. Indeed, in some places the shoreline was 100 to 250 km farther inland than at present."Geomorphology From Space, Plate C-24: Hudson Bay Shorelines."
(Accessed 3/7/06) It was at its largest at roughly 7,000 years BP.

Isostatic uplift 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 a ...

proceeded rapidly after the retreat of the ice, as much as .09 m per year, causing the margins of the sea to regress quickly towards its present margins. The rate of uplift decreased with time however, and in any event was nearly matched by

sea level rise Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...

from the melting ice sheets. When the Tyrrell Sea "became" Hudson Bay is difficult to define, as Hudson Bay is still shrinking from isostatic rebound.

References

Historical geology Geology of Ontario Geology of Canada Holocene Hudson Bay {{palaeo-geo-stub