Glaciers
Masses of ice that move like sheets on land (continental snow or piedmont glacier where heavy snow is distributed in low-lying plains) or flow down mountain slopes linearly in broad valleys such as rivers (mountain and snow in the valley) are called glaciers.
- Its movement is slow and is due to gravity.
- Their erosion is severe due to friction caused by the weight of the ice.
- Items snatched from the ground by ice (usually large angular blocks and fragments) are pulled down or to the sides of valleys and cause extensive damage by scratches and snatches.
- Glaciers can cause extensive damage even to climatic rocks and can reduce high mountains into low hills and plains.
Erosional landforms formed by glaciers:
Cirque:
- Cirques are found on the heads of glacial valleys. They are deep, long, and wide vessels or sloping jars that drop high walls on a glacier’s head and sides.
- A lake of water can often be seen among the cirques after the disappearance of ice. Such pools are called cirque or tarn pools.
Horns and Serrated Ridges:
- Horns are sharp-pointed and high-sided peaks that form when three or more glaciers cut forward until the cirques meet.
- The gap between the sidewalls of the cirque or the walls of the head becomes narrower due to continuous erosion and turns into chains with saws sometimes called serrated or saw-toothed ridges with a very sharp crest and a curved structure.
Glacial Valleys / Troughs:
- Shiny valleys: These are shaped like an ark and have a U-shaped base with a flat bottom and a steep slope.
- The valleys may contain dirty debris or debris shaped like moraines that look like swamps.
- There may be valleys hanging over a high point on one or both sides of a large ice valley.
- The dividing surfaces or spurs of these hanging valleys that open up in the icy valleys are usually trimmed to make them look like triangular sides.
- Deep ice vessels that fill with seawater and form coastal areas (plateaus) are called fjords/fiords.
Depositional Landforms developed by Glaciers:
Glacial Till:
These are inseparable and beautiful debris dropped by melting glaciers. Most pieces of stone in the till are angular to angular in shape.
Outwash Deposit:
These glacio-fluvial deposits are rock debris small enough to be carried by a stream of melting water. The pieces of rock are round at the edges. Unlike deposits, external deposits are slightly different and varied.
Moraines: They are the long layers of glacial till.
- Terminal Moraines: These are long piles of rubble and are attached to the ends (toes) of glaciers.
- Lateral Moraines: They may join the last moraine that makes horse-shoe shaped ridges. These moraines partially or completely from the glacio-fluvial fluid push objects alongside the glaciers.
- Ground Moraines: Many glaciers in the receding valleys leave an unusual sheet of tar over their valleys. Such deposits vary greatly in thickness and location, called ground moraines.
- Middle Moraine: These are moraines in the centre of the ice valley surrounded by lateral moraines. They are imperfectly formed in comparison with lateral moraines. Sometimes, these are indistinguishable from ground moraines.
Eskers:
- When glaciers melt in the summer, water cascades over the ice or flows to the edges or even across glaciers.
- This water accumulates beneath the ice and flows like streams below the ice.
- Such streams flow on the ground (not in a valley cut off from the ground) and ice forms its shores.
- Rough objects such as rocks and blocks and small particles of rock debris carried by the stream are found in an ice valley below the ice and after melting the snow it can be found as a rough valley called esker.
Outwash Plains:
- The glacio-fluvial deposits are dominated by glacio-fluvial deposits.
- It is in the form of broad alluvial followers who may come together to form plains without rocks, mud, sand, and clay.
Drumlins:
- Drumlins: It has smooth, oval-shaped ridge-shaped features composed mainly of a layer of ice with a large amount of rock and sand.
- Long drumlin axes go along with the ice route.
- They may be about 1 km long and 30 m or more in height.
- One part of the ice-shaped drum called the stoss end is thicker and thicker than the other called the tail.
- Drumlin is formed as a result of the dumping of rock debris under heavy ice loads in ice crevices.
- The end of the stoss is dull due to the pushing of the ice.
- Drumlin indicates the movement of the ice.