Brent crater
Encyclopedia
The Brent crater is an impact
Impact event
An impact event is the collision of a large meteorite, asteroid, comet, or other celestial object with the Earth or another planet. Throughout recorded history, hundreds of minor impact events have been reported, with some occurrences causing deaths, injuries, property damage or other significant...

 crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 in both the geographic township of Deacon, Unorganized South Nipissing District and the municipal township of Papineau-Cameron
Papineau-Cameron, Ontario
Papineau-Cameron is a municipal township in northeastern Ontario, Canada, in Nipissing District. The township is located on the south side of the Mattawa and Ottawa Rivers along Highway 17....

 in Nipissing District, northeastern
Northeastern Ontario
Northeastern Ontario is the region within the Canadian province of Ontario which lies north and east of Lakes Superior and Huron.Northeastern Ontario consists of the districts of Algoma, Sudbury, Cochrane, Timiskaming, Nipissing and Manitoulin; and the single-tier municipality of Greater...

 Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, located north of Cedar Lake in northern Algonquin Provincial Park
Algonquin Provincial Park
Algonquin Provincial Park is a provincial park located between Georgian Bay and the Ottawa River in Central Ontario, Canada, mostly within the Unorganized South Part of Nipissing District. Established in 1893, it is the oldest provincial park in Canada. Additions since its creation have increased...

. It is 3.8 kilometres (2.4 mi) in diameter and the age is estimated to be 396 ± 20 million years (Middle Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...

). The crater can be accessed using Brent Road, 32 kilometres (20 mi) south of Ontario Highway 17.

A sign, erected at the site by the Archeological and Historic Sites Board, Archives of Ontario, reads:

The Brent Crater: First recognized in 1951 from aerial photographs, the crater is a circular depression about two miles in diameter formed in Precambrian
Precambrian
The Precambrian is the name which describes the large span of time in Earth's history before the current Phanerozoic Eon, and is a Supereon divided into several eons of the geologic time scale...

 crystalline rocks. Geophysical and diamond drilling
Exploration diamond drilling
Exploration diamond drilling is used in the mining industry to probe the contents of known ore deposits and potential sites. By withdrawing a small diameter core of rock from the orebody, geologists can analyze the core by chemical assay and conduct petrologic, structural and mineralogic studies...

 investigations show that the crater has a present depth of about 1,400 feet but is partly filled with sedimentary rock
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....

s with a thickness of 900 feet. The rocks beneath the crater floor are thoroughly fragmented over a depth of 2,000 feet. Like the similar New Quebec (Chubb) crater
New Quebec crater
The Pingualuit Crater , formerly called Chubb Crater and later New Quebec Crater , is a young impact crater, by geological standards, located in the Ungava Peninsula of Quebec, Canada...

, the Brent crater is attributed to the high speed impact of a giant meteorite
Meteorite
A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

. It is calculated that the impact released energy equaling 250 megatons of TNT and occurred about 450 million years ago when this area was probably covered by a shallow sea.


There is an observation tower on the rim of the crater. The old wooden tower was demolished in July 2007, because it was not safe to use due to its age. A new tower has been built on a hill directly across the Brent Road from the demolished tower. The new tower on the hill offers a much better panorama of the entire crater. Parking will also be increased as part of the new tower improvements. There is a hiking trail leading to the crater floor. There are two small lakes, Gilmour and Tecumseh, located in the crater. Unlike most Algonquin Park lakes, which are usually acid
Acid
An acid is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger, and turn blue litmus paper red...

ic, the water in these lakes contains bicarbonate
Bicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...

; this is thought to be a result of some sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....

ary deposits of limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

 escaping removal by glaciers in the lower parts of the crater.

The crater lies in the Ottawa-Bonnechere Graben
Ottawa-Bonnechere Graben
The Ottawa-Bonnechere Graben , with its branch the Timiskaming Graben, is an ancient rift valley in the Canadian Shield of Northeastern Ontario and Quebec, Canada. This rift valley was formed when the Earth's crust moved downward about a kilometre between two major fault zones known as the Mattawa...

, a 452 million year old rift valley
Rift valley
A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. This action is manifest as crustal extension, a spreading apart of the surface which is subsequently further deepened by the forces of erosion...

.

The crater was named after the nearby village of Brent
Brent, Ontario
Brent is a community on Cedar Lake on the Petawawa River in northern Algonquin Provincial Park, and is located in geographic Deacon Township in the Unorganized south part of Nipissing District in northeastern Ontario, Canada....

.

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