Graystone Peak

Graystone Peak is situated 8.5 miles (13.7 km) south-southeast of the community of Silverton in the Weminuche Wilderness, on land managed by San Juan National Forest. It is part of the Needle Mountains which are a subrange of the San Juan Mountains.^[2] Precipitation runoff from the mountain drains into tributaries of the Animas River. Topographic relief is significant as the summit rises 4,800 feet (1,500 meters) above the river in two miles (3.2 km) and 2,890 feet (880 meters) above Tenmile Creek in 0.85 mile (1.37 km). It is set six miles west of the Continental Divide, 0.7 mile south of Electric Peak, and one mile east-southeast of Mount Garfield. These three peaks can be seen from U.S. Route 550 at Molas Lake. The mountain's toponym has been officially adopted by the United States Board on Geographic Names,^[4] and was recorded in publications as early as 1906.^[5]

According to the Köppen climate classification system, Graystone Peak is located in an alpine subarctic climate zone with very long, cold, snowy winters, and cool to warm summers.^[6] Due to its altitude, it receives precipitation all year, as snow in winter and as thunderstorms in summer, with a dry period in late spring.

Graystone Peak is part of the Uncompahgre Formation,^[7] which is a sequence of quartzite and black phyllite some 8,200 feet (2,500 meters) in thickness.^[8] The formation dates to the Statherian period and is interpreted as metamorphosed marine and fluvial sandstone, mudstone, and shale. The formation overlies plutons with an age of 1,707 million years.