Stop #4, Drumlin
The drumlin is created from debris trapped between the glacier and the ground, and then dragged along until a bump in the ground triggers the sudden release of the debris into a mound. As the glacier continues to move, it reshapes the round mound into a whaleback- shaped mound with the gently sloped side pointing in the direction of the retreating ice.
If you look carefully ahead of you, you will see the steep face to the left (south) and the gently sloping side to the right (north). Drumlins can be created by advancing ice, but often are re-eroded and re-shaped when the glacier retreats.
A region containing numerous drumlins can provide the glaciologist with a clue of the direction the ice took when it retreated. Though the overall direction of retreat is from south to north, the direction can be quite different in a localized area
Visit Dexter Drumlin on George Hill Rd. in Lancaster, Mass., or Drumlin Farm in Lincoln Mass., for outstanding examples of drumlins. See a drumlin in Canada that is free of trees displaying the whaleback shape.
Let’s divert our attention from the glacier to a brief description of the Gray family and their use of the land at stop #5 110 yds. ahead.