Erosion

Years ago, magma cooled beneath the surface to form granite. In more recent geological times, massive glaciers covered the area, carving U-shaped valleys and leaving striations and gouges as they moved. 

When the glaciers retreated, the sea flooded inland, raising and lowering the land and creating rivers and lakes. Today, the coast of Acadia continues to be worn down by crashing waves, storms—especially nor'easters with their strong winds, high seas, and rising tides—and seasonal freeze-thaw cycles that expand cracks in the bedrock and gradually weaken mountainsides. While these natural climate changes shaped Acadia over millennia, human-driven shifts have also played a role.