This glacial material acted like a giant piece of sandpaper being dragged across the land surface. The last of the ice melted away some 10,000 years ago. As you walk this trail you will see the effects and results of glaciers. The scoured and scratched granite was probably covered by soil before the grinding ice dragged the surface material away and exposed the ancient bedrock. The things that look like dead leaves growing on the rocks are lichens.
Lichens are pioneers.
They are the first plants to cover bare earth and rock. A lichen is a combination of two plants, an algae, and a fungus. The fungus absorbs and stores water, which the algae combines with sunlight to make food for other plants. The fungus produces an acid which eats in the rock on which it grows. This acid helps to crumble the rock into fine particles.