Image Description from historic lecture booklet: "Many of the boulders and pebbles of the till are found to be glaciated, or marked with parallel scratches. Often they look as if engraved with a sharp need. Sometimes the scratches are deep and rough. A marked polish is seen on some stones. If we dig through the subsoil to the bed-rock, we shall often find the latter scratched in the same way, or even deeply grooved and carved into fluting's and the folding. The glacier, shod with stones at its base, drags these over the bed-rock, and thus both the moving fragments and the floor over which they move are polished and graven. The direction of the scratches corresponds to that in which the erratic boulders have been moved, and so, putting these other facts together, we have full proof that glaciers have done the work."