Three distinctive, snowcapped stratovolcanoes are easily identified in this near-vertical photograph of Unimak Island, one of many volcanic islands in the Aleutian archipelago. The Aleutian archipelago, formed by the collision of the Pacific Plate with the western extension of the North American Plate, forms a northern part of the Ring of Fire that encircles the Pacific Ocean. Unimak Island, the large island nearest the Alaskan Peninsula, is separated from the peninsula by Bechevin Bay, shown at the bottom of the photograph. Shishaldin Volcano, the westernmost and tallest of the three featured volcanoes, reaches a maximum elevation of 9387 feet (2860 meters) above sea level and has been very active during the last two centuries, especially during the mid-1900s. Isanolski Volcano, the middle volcano, climbs to 8088 feet (2465 meters) above sea level. Each of these volcanoes exhibits a classic erosional drainage pattern that radiates in all directions from the central peak.