Hetherington Erratics Field

The heritage value of the Hetherington Erratics Field lies in the insights it provides into prehistoric glacial flows and the migrations of the early inhabitants of North America.

The Hetherington Erratics Field is one of several major sites located within the Foothills Erratics Train, a long, narrow chain of erratics (glacially-transported rocks) stretching from Jasper south to Montana. Geologists believe that a rockslide in the mountains of the Jasper area dropped large quartzite boulders onto the surface of the passing Athabasca valley glacier during the last ice age. The glacier initially moved eastward before being deflected to the south by the massive Laurentide Ice Sheet. As the glacier flowed south, it deposited a wealth of boulders along its path, including the mammoth "Big Rock" Erratic at Okotoks. The Hetherington Erratics Field is situated at a point in the Foothills Erratics Train where the belt of glacially transported rocks bottlenecks, narrowing from several kilometres to a single kilometre wide. It appears that a steep hillside prevented the boulders from being distributed further west. The site contains roughly twelve large erratics plus dozens of smaller glacially-transported rocks. The larger erratics feature polished corners and substantial surrounding depressions, evidence of their use as rubbing stones by buffalo and, more recently, by cattle. The site offers vital insights into the direction of the glacial flows of the Cordilleran and Laurentide Ice Sheets. It also provides compelling evidence about the period in which an ice-free corridor appeared on the eastern slopes of the Rockies and in the Foothills. Emerging at the end of the last ice age, roughly 10,000 years ago, this corridor is believed to have been one of the primary passageways used by the earliest inhabitants of North America to penetrate the interior of the continent.