to the National Atlas Home page
About | Fact Sheets | Contact Us | Partners | Products | Site Map | FAQ | Help | Follow us on Twitter 
Part of Project LogoAgricultureBiologyBoundariesClimateEnvironmentGeologyGovernmentHistoryMappingPeopleTransportationWater
to the Interactive Map MakerMap LayersPrintable MapsWall MapsDynamic MapsArticlesMapping Professionals





 
Geology
Map Maker
Geologic Map
Shaded Relief
Map Layer
Generalized Geologic Map of the Conterminous United States
North America Shaded Relief
 

Article

  The North American Tapestry of Time and Terrain

Introduction
The Two Maps
Zoom In
Features
Legend and Rock Ages
Rock Types
Political Boundaries
Credits

  Features
 

Manicouagan Crater

  Close-up of Manicouagan Crater from Tapestry image

Landsat image of Manicouagan Crater Image source: USGS/EROS Landsat 7 Site

 

In the northern part of Quebec, among some of the oldest rocks on the continent, a curious ring of water surrounds a remarkably circular island. This is the site of Manicouagan crater; with a diameter of more than 70 km across its prominent rim (the outer shore of the lake), it is one of the largest and best exposed craters on the planet. Manicouagan was formed by a meteor’s collision with Earth more than 200 million years ago. Many of the local rocks were melted by the heat and pressure of the impact, and their ages were "reset" to reflect the time of impact. As can be seen in the image, most of the region is made of Precambrian rocks (the reds, yellows and oranges), but much of the island is made up of Triassic rock (green).

As a result of underground fluid pressure pushing the rock in the crater upward during a bout of post-impact equilibration, Manicouagan has a plateau in the center, rather than the characteristic depression associated with craters. The remaining, ring-shaped depression filled with water, creating the lakes Manicouagan and Mouchalagane. These lakes have since been dammed to create the annular Manicouagan Reservoir around that central plateau, now an island, the Ile René-Levasseur.