Carswell impact structure

Carswell is an impact structure within the Athabasca Basin of the Canadian Shield in northern Saskatchewan, Canada. It is 39 km in diameter and the age is estimated to be 115 ± 10 million years (Lower Cretaceous). The impact structure is exposed at the surface.

The central peak complex of faulted metamorphic rocks displays shatter cones, planar deformation features, pseudotachylyte veins, and impact melts and breccias. There is also evidence of planar deformation features in quartz grains far to the south of the outer ring of present-day hills, which suggests the ring of hills are not the rim of the original crater but a peak ring within a much larger structure. The Carswell Formation, composed of algal limestone, may have formed on seamounts elevated to near the surface as part of the peak ring.

Access
The Carswell impact structure can be reached by Saskatchewan Highway 955. The 245 km gravel road begins in the village of La Loche and ends at the old Cluff Lake mine site within the crater. The Cluff Lake uranium mine produced over 62 million pounds of yellowcake during its 22-year operating life. Since the mine is now closed and decommissioned, there are no travel services in the vicinity and no functional airstrip. Motorists driving to the structure need to carry sufficient fuel and supplies for the round trip back to La Loche.