Mount Rushmore community. Recent pine beetle infestations have threatened the forest. Mount Rushmore is largely composed of granite. The memorial is carved on the northwest margin of the Black Elk Peak granite batholith in the Black Hills of South Dakota, so the geologic formations of the heart of the Black Hills region are also evident at Mount Rushmore. The batholith magma intruded into the pre-existing mica schist rocks during the Proterozoic, 1.6 billion years ago. Coarse grained pegmatite dikes are associated with the granite intrusion of Black Elk Peak and are visibly lighter in color, thus explaining the light-colored streaks on the
Mount Blue State Park Mount Blue State Park Mount Blue State Park is a public recreation area covering in the town of Weld, Franklin County, Maine. The state park's bifurcated land includes acreage on the west shore of Webb Lake as well as Mount Blue and other peaks to the east of the lake. The park is connected by road with the Tumbledown Public Lands, the site of Little Jackson Mountain, Tumbledown Mountain, and Tumbledown Pond, an alpine lake near the top of Tumbledown and Little Jackson mountains. The park and public lands are managed by the Maine Department of Agriculture, Conservation and Forestry.