Conway granite near where it is mined. The Old Man of the Mountain, a famous geologic feature in New Hampshire (which collapsed in 2003) was made of Conway granite. The formation is found throughout the lower areas of the central White Mountains, such as Franconia Notch, Crawford Notch, the center of the Pemigewasset Wilderness, and the Saco River valley. Other exposures of the formation include the Belknap Mountains south of Lake Winnipesaukee. Conway granite Conway granite is a typically pink mineral-rich igneous (or mesoperthitic) biotite granite. It is amphibole-free and of coarse particle size (with portions of the rock fine-grained or porphyritic).
Granite Dells old Prescott & Eastern Railroad through the eastern Granite Dells. Both are rail trail conversions. The precambrian Dells' granite has been dated at 1.4 billion years old. Its pluton was intruded at a depth of around one or two miles (1.6 to 3.2 km). These cover rocks have since been eroded away. Weathering along joints produced the rounded boulders and other unusual rock formations that characterize the Granite Dells. This process is called spheroidal weathering, and is common in granitic terrains. The Dells' granite has an unusually high uranium content, and thus homes built over the granite should be checked