If so, then it is evident that at that time the three glaciers described ran far out into the Lake, until reaching deep water, where they formed icebergs.

Under these conditions, it is plain that the pressure on this, the subaqueous portion of the glacial bed, would be small, and become less and less until it becomes nothing at the point where the icebergs float away.

The pressure on the bed being small, not enough to overcome the cohesion of ice, there would be no spreading.

_A glacier running down a steep narrow canyon and out into the deep water, and forming icebergs at its point, would maintain its slender, tongue-like form, and drop its debris on each side, forming parallel ridges, and would not form a terminal moraine because the materials not dropped previously would be carried off by icebergs_.

In the subsequent retreat of such a glacier, imperfect terminal moraines might be formed higher up, where the water is not deep enough to form icebergs.