Types of Glaciers – UPSC

Continental Glaciers

• Continental glaciers, also known as ice caps or continental ice sheets, are the largest glaciers on the planet. About 99% of the glacial ice on earth is contained within ice sheets. The Antarctic ice sheet and Greenland ice caps alone cover more than 50,000 square kilometers.
• These glaciers are not bounded by mountains or similar landforms. Thus, they tend to spread out in all directions and cover everything in their path. When ice sheets fan out from the center, entire valleys, plains, and even mountains ranges get perched in snow.

Ice caps & ice fields

• By contrast, an ice cap or ice field covers an area of less than 50,000 square kilometers. However, an ice cap or ice field can also completely cover peaks in mountainous areas, such as the ice fields found in Patagonia.
• These enormous glacial formations can feed many other types of glacier, which spread out from their center.

Outlet glaciers

• Glaciers that flow out of ice sheets, icefields, or ice caps are called outlet glaciers. The flow of outlet glaciers is affected by the landscape, traveling through valleys and exposed rock.
• An outlet glacier often continues through these rocky channels to become a valley glacier. An example of an outlet glacier is the Lambert Glacier in Antarctica.
• Outlet glaciers can further include different types of glaciers such as valley glaciers and piedmont glaciers.
• Similar to the case with valley glaciers, outlet glaciers also flow in a direction determined by the underlying landscape.
• Given the rise in global temperatures due to global warming, it is believed that a significant proportion of the rise in sea level is due to the melting of outlet glaciers in Greenland.

Valley glaciers

• Valley glaciers are flowing ice streams confined within steep valley walls. These types of glaciers are often easy to identify due to their long and narrow, ribbon-like appearance.
• Valley glaciers can form when an outlet glacier slides away from an icefield. However, most valley glaciers typically originate from mountain glaciers and stretch out towards gorges, basins, and of course, valleys.

Hanging glaciers

• A hanging glacier will generally begin high in the mountains, feeding into a valley glacier. However, unlike the smooth meeting of a river with its tributaries, hanging glaciers tower over the edge of cliff-faces like enormous frozen waterfalls.
• They originate high up in the mountains and flow down its sides but the defining characteristic of hanging glaciers is that they end abruptly.
• For example, the mighty Tronador or ‘thunder’ glacier in northern Patagonia earned its name from the sound of the ice crashing into the bowl-shaped valley below.
• The Eiger Glacier in Switzerland is an example of hanging glaciers.

Cirque glaciers

• Cirque glaciers are perhaps the smallest types of glaciers. They are found in the bowl-shaped hollows called cirques, hence, the name cirque glaciers.
• Cirques are formed in mountain ranges where the fallen snow settles quite quickly into the surrounding topography.
• The Lower Curtis Glacier and the Eel Glacier are some examples of cirque glaciers found in the US.

Piedmont glaciers

• These types of glaciers are a subtype of valley glaciers found in areas where a relatively narrow mountain valley spreads out into a wide-open plain or a deeper and larger valley.
• Piedmont glaciers refer to a mass of ice that has flowed downslope towards low-lying plains. It fans out in the area and creates broad lobes of solid ice.
• The largest piedmont glacier in the world is located in southeastern Alaska.

Rock Glaciers

• All glaciers have a significant amount of rock and other debris that gather when ice flows over the bedrock. However, rock glaciers, as the name suggests, are unlike any other type of glacier. With the mass of ice predominantly hidden beneath rock debris, you might not initially think a rock glacier is a glacier at all. It looks more like a muddy landslide instead.
• Rock glaciers are probably the most slow-moving glaciers amongst all other varieties discussed so far.

Tidewater Glaciers

• A Tidewater glacier is a river of ice that forms when a glacier flows to the coast. The edge of tidewater glaciers that leads the glacial flow slightly lifts upwards and floats in the ocean. This creates towering ice cliffs that can rise as high as 200 feet in the air.
• Tidewater glaciers are notorious for a violent phenomenon known as calving. Calving occurs when bits and pieces of ice break away from the sides of a tidewater glacier and collapse into the surrounding waters with a loud crashing sound. This creates strong waves.