What is a Glacier?
A glacier is a thick mass of ice that covers a large area of land. About ten percent of the world’s land area is covered by glaciers. Most glaciers are located near the North Pole or Antarctica, but glaciers also exist in mountain ranges such as the Himalayas and the Andes.
How do Glaciers Form?
Glaciers form from snow that doesn’t melt even during the summer. When enough snow builds up the weight of the snow will compress and turn into solid ice. It can take hundreds of years for a large glacier to form.
How do Glaciers Move?
Although glaciers are made of ice and appear to be stationary, they are actually moving. The weight of the glacier will cause it to descend slowly, like a very slow moving river. The speed of glaciers varies considerably, with some moving as slowly as several feet per year while others can move several feet per day.
Types of Glaciers
Scientists have named different types of glaciers. Here are some of the main categories:
Calving – A calving glacier is a glacier that ends up in a body of water such as a lake or ocean. The term calving comes from icebergs that either break off from a glacier or “lay” in the water. If the body of water is tidal (such as an ocean), the glacier may also be called a tidal glacier.
Cirque – The Cirque Glacier forms on the mountainside. They are also known as alpine or mountain glaciers.
Hanging – Hanging glaciers form on the ridge above the frozen valley. They are said to be suspended for not reaching the valley where the main glacier is located.
Ice Cap – An ice cap that forms when ice completely covers an area of land such that no part of the land, including the top of a mountain, crosses the top of the ice cap.
Ice field – An ice rink is when the ice completely covers a flat surface.
Piedmont – A piedmont glacier that forms when a glacier flows through a plain at the edge of a mountain range.
Polar – A polar glacier is a glacier that forms in an area where temperatures are consistently below freezing.
Temperate – Temperate glaciers are glaciers that coexist with liquid water.
Valley – A valley glacier is a glacier that fills the valley between two mountains.
Features of Glacier:
Ablation zone – The ablation zone is the area below the accumulation zone where the glaciation is located. In this region there is loss of ice mass due to ablation processes such as melting and evaporation.
Accumulation zone – This is the area of the glacier where snow falls and accumulates. It is located above the resection area. It is separated from the resection area by the balance line.
Crevasses – Crevasses are huge cracks that occur in the surface of a glacier, usually where the glacier flows fastest.
Firn – Firm is a type of compressed snow located between new snow and glacial ice.
Head – The glacier head is where the glacier begins.
Terminus – The terminus is the end of the glacier. It is also known as the foot of the glacier.
Glaciers Change the Land
As glaciers move, they can change the terrain creating many interesting geological features. Here are some geological features created by glaciers.
Arete – A ridge is a steep ridge formed by two glaciers eroding on opposite sides of a ridge.
Cirque – A cirque is a mountainside bowl-shaped landform formed by the head of a glacier. Drumlin – Drumlin is a long oval hill created by the movement of glacial ice.
Drumlin – A drumlin is a long oval-shaped hill produce by glacial ice movement.
Fjord – A fjord is a U-shaped valley between steep cliffs created by glaciers.
Horn – A horn is a pointy-shaped mountain peak created when many glaciers erode the same mountain top.
Moraine – A moraine is the accumulation of matter (called arrival) left by a glacier. Examples include rocks, sand, gravel, and clay.
Tarn – Tarns are lakes that fill in circles as glaciers melt.
Interesting Facts about Glaciers
Most of Greenland is covered by a huge ice cap nearly two miles thick in places.
Due to friction, the upper part of the glacier moves faster than the lower part.
A receding glacier is not actually receding, but is melting faster than it creates new ice.
Sometimes glaciers move much faster than usual. This is called an icy “climb”.
At more than 125 miles long, Alaska’s Bering Glacier is the longest glacier in the United States.
A scientist who studies glaciers is called an glaciologist.