Proglacial lakeIn geology, a proglacial lake is a lake formed either by the damming action of a moraine during the retreat of a melting glacier, a glacial ice dam, or by meltwater trapped against an ice sheet due to isostatic depression of the crust around the ice. At the end of the last ice age about 10,000 years ago, large proglacial lakes were a widespread feature in the northern hemisphere. The receding glaciers of the tropical Andes have formed a number of proglacial lakes, especially in the Cordillera Blanca of Peru, where 70% of all tropical glaciers are.
Abrasion (geology)Abrasion is a process of erosion which occurs when material being transported wears away at a surface over time. It is the process of friction caused by scuffing, scratching, wearing down, marring, and rubbing away of materials. The intensity of abrasion depends on the hardness, concentration, velocity and mass of the moving particles. Abrasion generally occurs in four ways: glaciation slowly grinds rocks picked up by ice against rock surfaces; solid objects transported in river channels make abrasive surface contact with the bed and walls; objects transported in waves breaking on coastlines; and by wind transporting sand or small stones against surface rocks.
Glacial motionGlacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes. Most lakes in the world occupy basins scoured out by glaciers. Glacial motion can be fast (up to , observed on Jakobshavn Isbræ in Greenland) or slow ( on small glaciers or in the center of ice sheets), but is typically around . Glacier motion occurs from four processes, all driven by gravity: basal sliding, glacial quakes generating fractional movements of large sections of ice, bed deformation, and internal deformation.
EskerAn esker, eskar, eschar, or os, sometimes called an asar, osar, or serpent kame, is a long, winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions of Europe and North America. Eskers are frequently several kilometres long and, because of their uniform shape, look like railway embankments. The term esker is derived from the Irish word eiscir (Old Irish: escir), which means "ridge or elevation, especially one separating two plains or depressed surfaces".
