The rounded contours of the Alabamas form a sharp contrast between the glacially chiseled ridges of the Sierra peaks to the west. Both geologic features were shaped by the same uplifting occurring 100 million years ago. The hills have been subject to a type of erosion known as chemical weathering. When the hills were still covered with soil, percolating water rounded the granite blocks and sculpted the interesting formations you see today. Hundreds of natural arches and windows can be found throughout the area.