Elephant Rocks State Park

Geologically, Elephant Rocks State Park consists of a tor, which is a high, isolated rocky peak, usually of jointed and weathered granite. The alkaline granite here was formed in the Proterozoic 1.5 billion years ago from a dome of molten magma. Nearly vertical fractures formed in the stone as it cooled, and uplift of the formation enhanced the fracturing. Eventually the overlying strata were removed through erosion, exposing the granite dome. With exposure, water and ice worked to weather and erode the surface of the granite along fracture joints. Spheroidal weathering of the granite and later erosion of the resulting saprolite that once surrounded these corestones left the elephant rocks as boulders perched on the ground surface.

• http://en.wikipedia.org/wiki/Elephant Rocks State Park
• Page 100 - Dicka, A. B., 2012, 101 American Geo-sites you've gotta see: Mountain Press Publishing Co., 250p.