Ermine Glacier lies on the north slopes of Glacier Peak in Washington State and, like the mountain’s other glaciers, has generally retreated in the modern era. During the Little Ice Age, it extended down to about 4,400 feet and joined neighboring Vista Glacier to the west. It then withdrew upslope until the mid-1950s, before advancing again during a cooler, wetter period that lasted into the mid-1970s. Afterward its retreat resumed, and between 1992 and 2005 it shrank by 308 meters, or about 1,010 feet.