Stony Man: A Billion Years in the Making

Mountains wear away in small steps or large events like a seed sprouting into a tree!

Stony Man Mountain is both old and new. Notice the many curiosities as you hike through the young forest, alive with newness and change, to the ancient rocks on Stony Man's 4,011' summit.

How exactly did a yellow birch tree grow out of a boulder? This story can help us understand the geologic history of Stony Man. While granite from an ancient mountain range is the oldest rock in the park at one billion years old, the Appalachian Mountains (and the greenstone boulders along this hike) were formed much more recently. As tectonic plates collided and new rocks were pushed to the surface, these mountains reached their greatest height about 350 million years ago. Since that time, the mountains have been breaking down, shaped by weathering and erosion into the peaks you see today.

Weathering can take many forms. Imagine water freezing and expanding to widen cracks in this rock, living things breaking down to form soil in those cracks, and a yellow birch seed falling into place. Notice how much pressure from the tree's roots has broken down this boulder in less than a century. It can be hard to visualize geologic time relative to our own short lifetimes, but here we can observe the gradual processes that are happening all around us.

Returning to this mountain in a year, a decade, or a century, how much further will this boulder have split as the birch tree continues its search for moisture and nutrition?