Glacier Action: Erosion and Deposition

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A glacier is an ice mass that moves due to its own weight. They frequently inhabit the snow fields.

We are aware that the earth's landmass is not exactly like what we see elsewhere. Certain regions are enveloped in dense, verdant forests, while others feature arid, scorching deserts, everlasting ice sheets, etc. Snowfields are the areas of the earth's surface that are permanently covered with ice, among these many landmasses. The snowline is the lowest point on a snow-field or permanent snow cover.

A glacier originates in regions where snowfall over long periods of time—often centuries—exceeds the amount of snow that melts and sublimates.

They create features like seracs and crevasses. Unlike a crevice that originates in rock, a crevasse is a deep crack or fracture found in an ice sheet or glacier. A serac is a block or column of glacial ice that forms when a glacier's crevasses cross.

On glacier surfaces, ogives, which appear as dark and light bands of ice, are alternating wave crests and valleys (troughs). They are related to the seasonal movement of glaciers; the width of one dark band and one light band typically corresponds to the glacier's yearly movement.

Glaciers are the world's greatest freshwater reservoirs, making up around 10% of the planet's land surface.

Depending on where the glacier located, they fall into one of the following categories:

• Piedmont and continental glaciers both move outward in all directions.
• Glaciers in valleys and mountains: descend from higher altitudes

landform erosion brought on by glaciers

1. Corris or Cirque

These are long, wide, deep troughs or basins with extremely steep walls at the head and sides that descend vertically.

They are essentially a bowl-shaped depression created by glacier erosion.

These water-filled depressions are referred to as Tarn Lakes, Corrie Lakes, or Cirque Lakes.

2. Fjords/fjords, U-shaped or hanging valleys

By smoothing out the flaws in an already-existing valley, the glacier deepens and widens it rather than creating a new one like a river does.

These valleys are known as U-shaped Valleys or Hanging Valleys because they are produced by glacial erosion and take the shape of a letter "U."

A fjord is an extremely deep chasm formed by glaciers that is filled with seawater and forms coastlines.

When a glacier sculpts a U-shaped valley through ice segregation and bedrock erosion, a fjord is created, and the valley eventually fills with seawater (produced in mountains nearby sea).

3. Aretes and Horns

Horns are peaks with sharp points and steep sides.

They are the result of the cirque wall eroding headward.

Arete is the name for the saw toothed ridge that forms as the gap between two cirque walls narrows due to gradual erosion.

Landforms deposited by glaciers

Two categories exist for glacial deposits:

(i) Unsorted coarse and fine debris is known as glacial till;

 (ii) Various approximately stratified deposits are known as outwash.

1. The Moraines

• Long ridges made by glacial till deposits are called moraines.
• These deposits are known as terminal moraines when they are found at the terminus of a glacier, and lateral moraines when they are found on both sides of the glacier.
• Medial moraines are created when two glaciers' lateral moraines unite.
• A glacier takes on the shape of a horseshoe when the lateral moraines on both sides join together.
• Deposits left remain in places where glaciers once covered them are known as ground moraines.

2. Eskers

• When summertime melts the glaciers, the resulting water builds up beneath the ice and runs through channels beneath the ice like streams.
• These streams carry away very coarse material such as boulders, blocks, and small fractions of rock debris.
• Later, as the ice melts entirely, they are deposited in the valleys themselves and appear as curving ridges on the surface.
• Eskers is the name given to these ridges.

3. Drumlins

• These are mostly made of glacial till and have a smooth, oval shape resembling ridges.
• It resembles an inverted spoon, with the tail end being the narrowest part at the bottom and the stoss end being the highest.
• They were created by glaciers moving over a little impediment, such as tiny surface rocks.
• In those impediments, glacial till is formed, and the movement of the glacier forms these deposits into the shape of an inverted spoon.