Red sandstone concretions at Red Rock Coulee Natural Area, Alberta.
Red Rock Coulee is a patch of dry mixed grassland at the head of a coulee system cut by retreating glaciers. The site is fenced and surrounded by agricultural land on all sides. The coulee system drains the west slope of Bull Head Butte, the highest topographic feature in the area.
In the upper parts of the coulee, erosion has exposed a number of large, spherical sandstone concretions, which...more »