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LANDFORMS AND THEIR EVOLUTION 55 Figure 6.11 : Some glacial erosional and depositional forms (adapted and modified from Spencer, 1962) Glacial Valleys/Troughs Depositional Landforms Glaciated valleys are trough-like and U- The unassorted coarse and fine debris shaped with broad floors and relatively dropped by the melting glaciers is calledglacial smooth, and steep sides. The valleys may till. Most of the rock fragments in till are contain littered debris or debris shaped as angular to sub-angular in form. Streams form moraines with swampy appearance. There by melting ice at the bottom, sides or lower may be lakes gouged out of rocky floor or ends of glaciers. Some amount of rock debris formed by debris within the valleys. There small enough to be carried by such melt- can be hanging valleys at an elevation on one water streams is washed down and deposited. or both sides of the main glacial valley. The Such glacio-fluvial deposits are called faces of divides or spurs of such hanging outwash deposits. Unlike till deposits, the valleys opening into main glacial valleys are outwash deposits are roughly stratified and quite often truncated to give them an assorted. The rock fragments in outwash appearance like triangular facets. Very deep deposits are somewhat rounded at their edges. Figure 6.12 shows a few depositional glacial troughs filled with sea water and making up shorelines (in high latitudes) are landforms commonly found in glaciated areas. called fjords/fiords. Moraines What are the basic differences between They are long ridges of deposits of glacial till. glacial valleys and river valleys? Terminal moraines are long ridges of debris Reprint 2026-27