Forests That have been Around For a Long Time.
All that stands in their path is effectively destroyed as the glaciers move forward. Then, too, they collect rocks and other debris as they go about their business. Moraine is the scientific term for this sediment. Some of the things that the glacier would otherwise crush can be protected by this moraine.
And it’s true of some old forests, too. To avoid uprooting and destroying the forest, the moraine provides sand or other non-abrasive material to cushion the glacier’s movement. What’s left beneath is still there. Glacier retreat reveals entire forests in some locations. It is quite fascinating how natural landscape is preserved as the glacier retreats.