Brent crater

The Brent crater is an impact crater located north of Cedar Lake in Algonquin Provincial Park in the Nipissing District of Ontario, Canada. It is 3.8 km in diameter and the age is estimated to be 396 ± 20 million years (Middle Devonian).

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 crystalline rocks. Geophysical and diamond drilling investigations show that the crater has a present depth of about 1,400 feet but is partly filled with sedimentary rocks 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, the Brent crater is attributed to the high speed impact of a giant meteorite. 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 acidic, the water in these lakes contains bicarbonate; this is thought to be a result of some sedimentary deposits of limestone escaping removal by glaciers in the lower parts of the crater.

The crater lies in the Ottawa-Bonnechere Graben which is an ancient rift valley.

The crater was named after the nearby village of Brent.

External links

* [http://www.unb.ca/passc/ImpactDatabase/ Earth Impact Database]
* [http://maps.google.com/maps?ll=46.073656,-78.482723&spn=0.048323,0.056477&z=3&t=k&hl=en Satellite image of the region] (from Google Maps)
* [http://www.ottawa.rasc.ca/articles/odale_chuck/earth_craters/brent/index.html Aerial Exploration of the Brent Structure]