My Science School

The sheer weight and size of glaciers give them an enormous power to carve out the landscape. Much like mega bulldozers, they crush and grind everything that comes in their way, pushing the debris along until it is deposited in distinctive piles called moraine.

Glaciers are huge masses of ice that move across the land. ?Glaciers? are often called rivers of ice for the way they move down mountainsides and carve valleys. Though climate change is threatening glaciers today, there are still many glaciers changing landscapes around the world through erosion and material deposition. Glacial landforms left behind by glaciers include moraines, drumlins, troughs, aretes, horns and cirques.

There are three distinct ways that glaciers shape the land: 1) erosion 2) transportation and 3) deposition. Erosion picks up material through weathering through plucking and abrasion. That material is then transported as it moves downhill. Sometimes the material is hidden inside or at the base of the glacier, or sometimes it is on top of the glacier, accounting for the dirty color of some glaciers. Those rocks and other transported materials eventually get deposited to a new place as the glacier melts; this leftover material is called glacial till, and it's what forms many of our landscapes today from the last ice age!

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When they form in the high mountains, these rivers of ice are called alpine glaciers. They flow down through the mountains, cutting and breaking up the rocks, creating sharp peaks, ridges and gouging out unique, U-shaped valleys.

A glacier that is surrounded by mountains is called an alpine or mountain glacier. They are a persistent body of snow that moves under its weight at a slow pace. Alpine glaciers are a sheet of snow that forms over a cirque or high rock basin. The iceberg’s uppermost layer is brittle, but the ice beneath behaves like a plastic substance flowing gently.

The glacier usually forms in a cirque or high rock basin where snow accumulates throughout the year. The most amazing fact about this glacier is that the rate of accumulation at the upper surface balances the rate of evaporation and melting at the lower end.

The glacier begins to occupy a sloping valley situated in between the creeks or steep rock walls. Following that, the accumulation of snow occurs at the upper part of the bowl-shaped depression called a cirque.

The glacial ice starts flowing downwards, slowly abrading and plucking the bedrock. The accumulation of snow that is compacting and recrystallizing is called firn.

The flow then accelerates across the steep rock where the deep crevasses or gaping fractures mark the icefall. The lower part of the glacier denotes ablation. As the ice thins, it evaporates and melts, thereby losing its plasticity. There are chances of developing fissures, as the glacier tries depositing debris at the terminus when it melts.

Credit: EARTHECLIPSE

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Glaciers are a very important source of fresh water. Melting glacier ice keeps many of Earth's rivers flowing. Glaciers create fertile valleys for farming and their deposits are also rich in resources.

Glaciers are keystones of Life on Earth. As giant freshwater reservoirs, they support the planet’s life systems and influence our day-to-day lives, even for communities who live far away from them. However, glaciers are disappearing.

The disappearance of glaciers makes visible the invisible. It makes tangible the current climate change that can be hard to perceive in other ecosystems. The recent evolution of glaciers found in World Heritage sites paints a true picture of their decline in a warming planet.

A study led by Jean-Baptiste Bosson in 2019 shows that most World Heritage glaciers have lost a significant portion of their mass since 1900; some even completely disappeared, as in Africa or the Alps. The study predicts that glaciers could disappear from almost half of World Heritage sites by 2100 if business-as-usual emissions continue.

Credit: International Union for Conservation of Nature

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Fjords are very deep, long and narrow inlets with steep sides or sheer cliffs, seen along the coasts of Norway, New Zealand and Canada. A fjord is formed when the sea comes in to fill the U-shaped valley left by a glacier after it has retreated.

A fjord is a long, deep, narrow body of water that reaches far inland. Fjords are often set in a U-shaped valley with steep walls of rock on either side.

Fjords are found mainly in Norway, Chile, New Zealand, Canada, Greenland, and the U.S. state of Alaska. Sognefjorden, a fjord in Norway, is more than 160 kilometers (nearly 100 miles) long.

Fjords were created by glaciers. In the Earth's last ice age, glaciers covered just about everything. Glaciers move very slowly over time, and can greatly alter the landscape once they have moved through an area. This process is called glaciation.

Glaciation carves deep valleys. This is why fjords can be thousands of meters deep. Fjords are usually deepest farther inland, where the glacial force was strongest.

Some features of fjords include coral reefs and rocky islands called skerries.

Some of the largest coral reefs are found at the bottom of fjords in Norway. They are home to several types of fish, plankton and sea anemones. Some coral reefs are also found in New Zealand. Scientists know much less about these deep, cold-water reefs than they do about tropical coral reefs. But they have learned that the living things in cold-water reefs prefer total darkness. Organisms in cold-water reefs have also adapted to life under high pressure. At the bottom of a fjord, the water pressure can be hundreds or even thousands of kilograms per square meter. Few organisms can survive in this cold, dark habitat.

Skerries are also found around fjords. A skerry is a small, rocky island created through glaciation. Most of the Scandinavian coastline is cut into thousands of little blocks of land. These jagged bits of coastline are skerries. The U.S. states of Washington and Alaska also have skerries.

Even though skerries can be hard to get around in a boat, fjords are generally calm and protected. This makes them popular harbors for ships.

Credit:  National Geographic Society

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Glaciology is the study of natural forms of ice, particularly glaciers, and phenomena related to ice. It includes the study of how glaciers are formed and depleted, how they move, and how they affect the physical landscape, the climate, and living organisms. It is one of the key areas of polar research. It also involves research into glacial history and the reconstruction of past glaciation, thus providing insights into the ice ages. The apparent presence of ice on Mars and Jupiter's moon Europa brings in an extraterrestrial component to the field.

Thus, glaciology is an interdisciplinary earth science, integrating geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on humans adds the fields of human geography and anthropology. A person who studies glaciers is called a glaciologist.

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Glacial ice is a different color from regular ice. It is so blue because the dense ice of the glacier absorbs every other color of the spectrum except blue — so blue is what we see!

It’s Not Just Frozen Water!

Sometimes the glacial ice appears almost turquoise. Its crystalline structure strongly scatters blue light. The ice on a glacier has been there for a really long time and has been compacted down so that its structure is pretty different from the ice you normally see. Glacial ice is a lot different from the frozen water you get out of the freezer.

It’s Not Just Frozen Snow!

Glacial ice is not just frozen compacted snow. There are other things in the ice that make it much different from the ice in your home. Glaciers move through rock and soil as they carve their way down a slope. This means the ice is going to have a lot more ingredients than just water.

Credit: Alaska Satellite Facility

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