Sunset at Red Rock Coulee
Spherical sandstone concretions glow red in the last light of the day at Red Rock Coulee in southeast Alberta.
In the upper parts of Red Rock Coulee, erosion has exposed a number of large, spherical sandstone concretions, which give the area its name.
These round boulders, some more than two meters in diameter and tinted red with iron oxide, stand out in stark contrast to the light gray clays and shales that make up the surrounding bedrock.
Some of the boulders have completely emerged and appear ready to roll away, while others remain only partly exposed.