DEFINITION OF A GLACIER
A glacier may be roughly defined as an accumulation, on land, of perennial ice that slowly flows by creep because of its own weight. An exact definition, however, is more complicated because (1) even thick accumulations of winter or seasonal snow, as well as tiny ice bodies on cliffs, exhibit flow properties, (2) perennial ice that shows no clear evidence of flow may cover large areas, (3) formerly active glaciers may stagnate and cease to show evidence of flow, and (4) perennial ice accumulations fed by avalanches from active hanging glaciers often exhibit little motion. Recognition of active-glacier ice is sometimes difficult when it is concealed by seasonal snow. Even where some moving ice is evident, defining the boundaries of individual glaciers presents problems for several of the reasons listed above.
For this study, a glacier is defined as any perennial ice that has an area of at least 0.10 km2. Included are (1) active glaciers, (2) ice patches derived from direct snow accumulation, wind drift, or snow avalanches, without regard for evidence of glacier flow, and (3) relict ice from former active glaciers. Ice patches derived from avalanching of ice from hanging glaciers are considered to be part of the parent glacier.
There are mountain glaciers of many diverse forms in the North Cascades (pls. 2 and 3). The most common are small ice patches scattered widely throughout the range. Next most common are glaciers on steep, irregular slopes (pl. 3A, B, C, D, F, G). Many cirque glaciers (pl. 3E, H, I) are present; Boston Glacier (pl. 3E) covers 7 km2 and is the largest single glacier of this type. McAllister, Honeycomb, and South Cascade Glaciers are small valley glaciers. Seven slope glaciers that diverge from a common ice cap on Mount Baker cover an area of 35 km2. Small ice fields consisting of contiguous glaciers of various forms are around Eldorado and Dome Peaks and south of Glacier Peak. The longest glaciers in the North Cascades are the Deming (4.7 km) and Park (4.7 km) on Mount Baker and Honeycomb (4.8 km) near Glacier Peak.
Last Updated: 28-Mar-2006