The Lac Wiyâshâkimî (the official name, in French, formerly Lac à l'Eau Claire, a

calque In linguistics, a calque () or loan translation is a word or phrase borrowed from another language by literal word-for-word or root-for-root translation. When used as a verb, "to calque" means to borrow a word or phrase from another language w ...

of the lake's name, Wiyâšâkamî, in Northern East Cree, changed form of ''wâšâkamî'' or ''wâšekamî'' in more southerly Cree dialects), also called the Clearwater Lakes in English and Allait Qasigialingat by the

Inuit Inuit (; iu, ᐃᓄᐃᑦ 'the people', singular: Inuk, , dual: Inuuk, ) are a group of culturally similar indigenous peoples inhabiting the Arctic and subarctic regions of Greenland, Labrador, Quebec, Nunavut, the Northwest Territories ...

, are a pair of

annular lake An impact crater lake is a lake inside a depression caused by the impact of a meteor. It is also known as an annular lake in cases where the water body is shaped like a ring, as many impact crater lakes are. Examples One of the largest impac ...

s on the Canadian Shield in

Quebec Quebec ( ; )According to the 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 one of the thirtee ...

, Canada, near Hudson Bay. The lakes are actually a single body of water with a sprinkling of islands forming a "dotted line" between the eastern and western parts. Its name in Cree is due to the clear water it holds. There are actually 25 lakes with names that mean "Clearwater Lake" in the province (26 if the ''Petit lac à l'Eau Claire'' — the Small Clearwater Lake — is included). Collectively, this body of water is the largest, northernmost and the second-largest natural lake in Quebec after

Lake Mistassini Lake Mistassini () is the largest natural lake by surface area in the province of Quebec, Canada, with a total surface area of approximately and a net area (water surface area only) of . It is located in the Jamésie region of the province, appro ...

. In 1896, the explorer and geologist

Albert Peter Low Albert Peter Low (May 24, 1861 – October 9, 1942) was a Canadian geologist, explorer and athlete. His explorations of 1893–1895 were important in declaring Canada's sovereignty over the Arctic, and eventually defining the border between Quebec ...

, a member of the Geological Survey of Canada, provided a probable explanation for the lakes' descriptive Cree name by highlighting the extraordinary clarity and depth of their icy waters.

Impact craters

The Clearwater Lakes occupy the near-circular depressions of two eroded

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

s (

astrobleme An impact structure is a generally circular or craterlike geologic structure of deformed bedrock or sediment produced by impact on a planetary surface, whatever the stage of erosion of the structure. In contrast, an impact crater is the sur ...

s).Robertson, P.B. & Grieve, R.A.F. 1975 Impact structures in Canada: Their recognition and characteristics. Journal of the Royal Astronomical Society of Canada, v. 69, pp. 1-21. The eastern and western craters are and in diameter, respectively. Both craters were previously believed to have the same age, 290 ± 20 million years (

Permian period The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

), promoting the long-held idea that they formed simultaneously. According to this doublet impact crater theory initially proposed by Michael R. Dence and colleagues in 1965, the impactors may have been gravitationally bound as a

binary asteroid A binary asteroid is a system of two asteroids orbiting their common barycenter. The binary nature of 243 Ida was discovered when the Galileo spacecraft flew by the asteroid in 1993. Since then numerous binary asteroids and several triple a ...

, a suggestion also made by Thomas Wm. Hamilton in a 1978 letter to ''

Sky & Telescope ''Sky & Telescope'' (''S&T'') is a monthly American magazine covering all aspects of amateur astronomy, including the following: *current events in astronomy and space exploration; *events in the amateur astronomy community; *reviews of astronomic ...

'' magazine in support of the then-controversial theory that asteroids may possess moons (such as, for example, asteroid

243 Ida Ida, minor planet designation 243 Ida, is an asteroid in the Koronis family of the asteroid belt. It was discovered on 29 September 1884 by Austrian astronomer Johann Palisa at Vienna Observatory and named after a nymph from Greek mythology. ...

with its satellite Dactyl). Clearwater East and Clearwater West are both

complex crater Complex craters are a type of large impact crater morphology. Above a certain threshold size, which varies with planetary gravity, the collapse and modification of the transient cavity is much more extensive, and the resulting structure is cal ...

s with distinct central peaks. These peaks are caused by the gravitational collapse of crater walls and subsequent rebound of the compressed crater floor. Lake water and sediments cover the central peak of Clearwater East, but bathymetric surveys of the lake floor and core drilling confirm the presence of a peak in its center.

Ordovician

However, repeated ⁴⁰Ar/³⁹Ar dating of impact melt rocks from both impact craters suggests that Clearwater East has an age of approximately 460–470 million years, corresponding to the

Middle Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. Th ...

time period.

Permian

Clearwater West was formed 286.2 ± 2.6 million years ago, in the Early Permian.Bottomley, R.J., York, D., and Grieve, R.A.F. 1990. ⁴⁰Argon-³⁹Argon dating of impact craters. Proc. 20th Lunar Planet. Sci. Conf., LPI, Houston, pp. 421–431.Schmieder, M., Schwarz, W. H., Trieloff, M., Tohver, E., Buchner, E., Hopp, J. & Osinski, G. R. 2014
New ⁴⁰Ar/³⁹Ar dating of the Clearwater Lake impact structures (Québec, Canada) – Not the binary asteroid impact it seems?
Geochim. Cosmochim. Acta (in press). Both Clearwater impact structures also carry different geophysical (

natural remanent magnetization Natural remanent magnetization (NRM) is the permanent magnetism of a rock or sediment. This preserves a record of the Earth's magnetic field at the time the mineral was laid down as sediment or crystallized in magma and also the tectonic movement o ...

) signatures and different geochemical fingerprints of the impacting meteorite in the

impact melt Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impac ...

of each crater.Palme, H., Janssens, M.-J., Takahashi, H., Anders, E. and Hertogen, J. 1978. Meteoritic material at five large impact craters. Geochim. Cosmochim. Acta 42, 313–323.

Micro climate

Because of its size, Lac à l'Eau Claire can affect the local climate, as attested to by the distribution of plant species. Although the lake's shorelines are populated mainly by boreal species, the flora of the central islands in the western basin of the lake is characteristically

arctic The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenland), Finland, Iceland, N ...

, making the islands an arctic enclave.

National park

A vast area surrounding the lakes,

Richmond Gulf Lake Tasiujaq (french: lac Tasiujaq; iu, Tasiujaq, script=Latn (which resembles a lake)) is a large triangular-shaped inland bay located on east side of Hudson Bay just above 56th parallel north in Quebec, Canada. It was formerly known as Richmo ...

(''Lac Guillaume-Delisle''), and Iberville Lake (''Lac D'Iberville'') are part of the Tursujuq National Park, Quebec's largest national park, opened in 2012.Ministère du Développement durable, de l'Environnement et des Parcs, ''Provisional Master Plan Parc national des Lacs-Guillaume-Delisle-et-à-l'Eau-Claire'', Quebec, 2008,
Online version
)

Notes

References

External links

Aerial Exploration of the Clearwater West StructureAerial Exploration of the Clearwater East Structure
{{Impact cratering on Earth Impact craters of Quebec Lakes of Nord-du-Québec Ordovician impact craters Permian impact craters Impact crater lakes