Lower Curtis Glacier, in a cirque on the western slopes of Mount Shuksan in North Cascades National Park, is named for photographer Asahel Curtis and is a clear example of recent glacier change in the North Cascades. It has a negative mass balance, losing more snow and ice each year than it gains. Between 1908 and 1984 it thinned by 45 meters, then lost another 6 meters from 1984 to 2002, and its surface area shrank 28 percent between about 1850 and 1950. Although it advanced from 1951 to 1979, it has retreated since 1985, with its steep terminus contributing to ice loss.