Crow Peak is a dominant landmark because of its geological makeup. Billions of years ago, this area was covered by an ocean. Layers of sediment were deposited on the ocean floor, eventually hardening to form limestone and other sedimentary rock layers. Underground molten rock called magma pushed the sedimentary layers upward forming hills. During the uplifting, crevasses within the limestone hills filled with magma. These flows of magma, called intrusions, cooled to form igneous rock. The limestone and other sedimentary rock erodes at a faster rate than the harder igneous rock. As the oceans eceded, the overlying sedimentary rock eroded, exposing the igneous intrusions. Crow Peak and other peaks you can see from the Crow Peak summit, such as Bear Butte, Spearfish Mtn., and Terry Peak, were formed in this manner. Erosion of this igneous rock and the sedimentary rock surrounding these peaks continues to shape the landscape of the Northern Black Hills.