Three Sisters (Oregon)

Three Sisters (Oregon)

The Three Sisters are three volcanic peaks of the Cascade Volcanic Arc and the Cascade Range in Oregon, each of which exceeds 10,000 ft (3,048 m) in elevation. They are the third, fourth, and fifth highest peaks in the state of Oregon and are located in the Three Sisters Wilderness, about 15 mi (24 km) southwest from the nearest town of Sisters, Oregon. The three peaks have 15 named glaciers among them, nearly half of all the 35 named glaciers in Oregon. The Sisters were named Faith, Hope, and Charity by early settlers, but "these names have not prevailed", and instead they are named North Sister, Middle Sister, and South Sister.

The Three Sisters are the centerpiece of a region of closely grouped volcanic peaks which form an exception to the typical 40-mile (64 km) to 60-mile (97 km) spacing between volcanoes elsewhere in the Cascades. Nearby peaks include Belknap Crater, Broken Top and Mount Bachelor, with Three Fingered Jack and Mount Washington somewhat to the north. The region was a volcanic center in the Pleistocene epoch, with eruptions from 600,000 - 700,000 to 170,000 years ago, an explosively active complex known as the Tumalo volcanic center. Basaltic lava flows from North Sister overlay the newest Tumalo pyroclastic deposits, making the age of North Sister, the oldest of the three, less than 170,000 years.