The Geological Story of Glacial Grooves
What Is A Glacial Groove?
A glacial groove is a long, linear trough that was scoured into solid bedrock by the great ice sheet which covered almost all of Canada during the last ice age. Often the grooves occur in sets of parallel furrows, or troughs (Figure 1).
How Are Glacial Grooves Made?
Glacial grooves were created beneath a glacier. The grooves were created by the slow movement of the massive glacier that once covered almost all of Canada. As glaciers slowly move, or flow, across the rock land, they pick up pieces of rock from the size of tiny clay to large boulders. The boulders, sand and clay materials were trapped under the glacial ice. As the glacier moved, some the trapped material was dragged along the surface of the rocks beneath the ice. The rock fragments acted like sandpaper and they abraded the rock as the glacier pushed and pulled them along. That abrasion gouged out softer rock beneath the glacier to form the grooves. The grooves are exposed when the glacier melts.
What Is The Shape Of A Glacial Groove?
Most glacial grooves are straight. They can be several meters in length. They can be several centimeters to several meters in width and several centimeters in depth (Figure 2).
How Do Geologists Use Glacial Grooves?
Glacial grooves give geologists information about the direction the ancient glacier moved. The path of the glacier’s movement is parallel to the long direction of the glacial groove.
Additional photos of glacial grooves
Andy Fyon, Oct 27/18.