Nicholson Impact crater
Friday, 28. March 2008, 10:29:37
Wikipedia has a list of 29 impact craters in Canada. Many of them are relatively easy to spot by satellite, which may of course be one of the reasons for the large number. Here is a nice image of one of the lesser known Canadian impact craters.
NASA image created by Jesse Allen, using Landsat data provided by the University of Maryland’s Global Land Cover Facility. Caption by Michon Scott.
Some 400 million years ago, a meteor struck Earth in what is now Canada’s Northwest Territories. Plate tectonics have rearranged Earth’s continents considerably since then, and the 12.5 kilometre wide crater is now Nicholson Lake, one of many small lakes that dot the sub-arctic, glacier-scoured landscape.
In NASA’s Landsat 7 satellite image of Nicholson Lake on 6 July 2000 the lake sports a partial, silver-blue icy coating even in the Northern Hemisphere summer, as does the smaller water body to the east. Ice-free parts of the lake appear navy blue.
A 2002 review paper examined the evolution of ecosystems created by impact events. The authors concluded that, given enough time, the small-scale ecosystem created by a meteor impact can come to resemble the surrounding ecosystem. Nicholson Lake provides a good example. While many crater lakes are isolated from other water bodies by steep crater rims (see especially the Pingualuit Meteorite Crater), Nicholson Lake has been infiltrated numerous times by nearby waterways, enabling the movement of plant and animal species between them.
• http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17972
References
* Cockell, C., Lee, P. (2002). The biology of impact craters—a review. Biol. Rev. 77, 279-310.
• http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=120935
NASA image created by Jesse Allen, using Landsat data provided by the University of Maryland’s Global Land Cover Facility. Caption by Michon Scott.
Some 400 million years ago, a meteor struck Earth in what is now Canada’s Northwest Territories. Plate tectonics have rearranged Earth’s continents considerably since then, and the 12.5 kilometre wide crater is now Nicholson Lake, one of many small lakes that dot the sub-arctic, glacier-scoured landscape.
In NASA’s Landsat 7 satellite image of Nicholson Lake on 6 July 2000 the lake sports a partial, silver-blue icy coating even in the Northern Hemisphere summer, as does the smaller water body to the east. Ice-free parts of the lake appear navy blue.
A 2002 review paper examined the evolution of ecosystems created by impact events. The authors concluded that, given enough time, the small-scale ecosystem created by a meteor impact can come to resemble the surrounding ecosystem. Nicholson Lake provides a good example. While many crater lakes are isolated from other water bodies by steep crater rims (see especially the Pingualuit Meteorite Crater), Nicholson Lake has been infiltrated numerous times by nearby waterways, enabling the movement of plant and animal species between them.
• http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17972
References
* Cockell, C., Lee, P. (2002). The biology of impact craters—a review. Biol. Rev. 77, 279-310.
• http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=120935
