Mound or layer of moraine in the ablation zone of a glacier the rock has been plucked from the mountainside by the moving glacier and is melting out on the ice surface.
An irregular-shaped layer or pile of glacier sediment formed by the melting of a block of stagnant ice. Ultimately, ablationa moraine is deposited on the former bed of the glacier. Also called Ablatio
n Till.
A time span extending from a seasonal maximum of glacier mass to a seasonal minimum. The ablation season is the same as the summer season on most glaciers, which are of winter-accumulation type. Speci
al cases include glaciers of summer-accumulation type and year-round ablation type, and glaciers that have more than one ablation season during the year.
The part of the glacier where ablation exceeds accumulation in magnitude, that is, where the cumulative mass balance relative to the start of the mass-balance year is negative. Unless qualified, for e
xample by giving a date within the year, references to the ablation zone refer to its extent at the end of the mass-balance year. The extent of the ablation zone can vary strongly from year to year.
A device installed at the glacier surface for the measurement, during the ablation season, of changes in elevation of the glacier surface relative to a fixed elevation, such as that of the top of a ma
ss-balance stake embedded in the ice beneath the surface. A star ablatometer is an array of rigid metal arms that can be attached to a stake and levelled. A graduated rod is lowered through holes in the arms to measure changes in the surface elevation, yielding a considerably larger sample than that obtained from readings of the stake alone. Sometimes an ablatometer is actually a sonic ranger.