The document provides information about glacial landforms formed by glacial erosion and deposition. It describes how glaciers erode the underlying landscape to form characteristic U-shaped valleys with steep sides and flat floors. It also explains how glacial erosion forms other landforms like corries (cirques), arêtes (sharp ridges), and pyramidal peaks. Glacial deposition leaves behind landforms like moraines, drumlins, and outwash plains formed from sediments.

1. Revise Glaciation GCSE Geography: The Physical World

9. Active corrie formation Active corrie with snow and ice deepest in the centre, and steep back and side walls

10. Aretes and Pyramidal Peaks In highland areas the most obvious glaciers features are usually those created by erosion, not deposition. Features such as corries, ribbon lakes, U shaped valleys and hanging valleys are typical of upland areas such as the Alps in Europe, the English Lake District and the Southern Alps in New Zealand. Aretes When a corrie is formed, its back and side walls tend to be steep and jagged, perhaps almost vertical. When two corries form next to each other, and their adjacent walls are eroded backwards until they meet, a narrow and pointed rock ridge is formed. This is often likened to a knife edge, with near vertical sides and a sharp top edge. This feature is called an arete.

11. Pyramidal Peaks When three or more corries erode backwards and meet they cannot form an arete; it has steep sides but doesn't have the length to make a ridge. Imagine three corries at the corners of a triangle, eventually all eroding back and meeting in the middle. A sharp pointed pyramid shape is created. This is called a Pyramidal Peak, or Horn, and is a common shape for mountain tops in well glaciated areas Pyramidal Peak

12. A pyramidal peak (far right), two aretes (middle) and a valley glacier (left) in the Chamonix valley, France. (The peak is Mont Blanc)

13. Ribbon Lakes When a glacier moves along its valley, changes in the rate of flow caused by extension or compression may lead to increased deepening of sections of the valley floor. Areas of softer rock may also experience increased deepening. When the glacier retreats, the deepened sections fill with melt water and become lakes. These lakes remain long after glaciation has ended, supplied by rainfall and subsequent streams and rivers. The English Lake district owes its character to these narrow ribbon lakes along its valley floors.

14. U shaped Valley 1 U Shaped Valley When a glacier erodes its valley , a classic U shape is formed, the side walls tending to be steep and possibly curving inwards at the base, and the valley floor almost flat. U shaped valleys often start life as river valleys that existed before glaciation occurred. The glaciers then followed the existing V shaped valleys, eroding and deepening them as the ice moved. Over time the valleys became straightened, widened and deepened, keeping the steep sides and acquiring a flat base. U shaped valleys are also known as glacial troughs. The flat floor is roughly shaped by the ice which tends to cut down more evenly than flowing water. A thick layer of glacial debris (ground moraine) is deposited as the ice retreats, smothering any minor irregularities, and creating a well drained and fertile soil

15. U shaped Valley 2 Glacial U shaped valley with steep sides, flat floor, and truncated spurs (middle left)