The glacier ice never actually moved backward or toward the north. As the face of the glacier melts, unsorted sediments called glacial drift are deposited along a curved front forming a moraine. The deposition representing the farthest advance of the glacier is the terminal moraine. When the glacier pauses in its retreat long enough to deposit substantial sediment along another front, it is called a recessional moraine. As a glacier moves sliding on its bed, geothermal gradients and friction cause basal ice to melt.
Water is released at the base of the face of the glacier.
In addition, large quantities of melt water released during warmer summer seasons travels down cracks in the surface ice, runs through channels within the glacier and is released at the glacial face as well. In temperate glaciers most water reaches the bed well before the snout. Melting is due primarily to air temperature, although even in sub-zero temperatures melting occurs due to intense radiation. Areas covered with darker material will melt faster as this material absorbs radiation more efficiently. This depends on the rate of melting and the interconnectedness of englacial channels.