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Roger Weller, geology instructor

by Joseph Renegar
Physical Geology
Fall 2017

How Glaciers Are Formed

Huge masses of ice move their way across many regions while spreading their large mass of thousands of years of ice and compacted snow with nothing except land standing in their way.  Glaciers are year-round masses of ice that originate on land. They are usually larger than 100 square feet.  Glaciers are on every continent except for Australia.  There are some glaciers that can look dusty or rocky.  While other glaciers may radiate a light bluish color making it look as if they are lit from inside the glacier.  Glaciers are comprised of snow that has fallen over hundreds or thousands of years.  That snow slowly over time compresses into an extremely large ice mass.  When snow remains in a certain location for an extended period of time it will begin to turn into ice and this is how a glacier is formed.  Glaciers have their own unique ability to move on their own because of their huge masses.  When a glacier moves, it will move like a slow river.  The size of a glacier can vary between hundreds or dozens of kilometers in length.

Glaciers may be massive and really powerful, but they begin with just a very small snowflake.  Even the largest glacier started with only a snowflake.  Each crystal flake contained inside a glacier is not like another.  It takes tons of thousands of snowflakes to eventually create glacier ice.  Glaciers are huge masses of ice mixed with snow, rock, water, and sediment.  Glaciers are one of nature’s most beautiful substances because they can form in the atmosphere just as snow alone.  Every glacier is different in its own way.  Each glacier also has different surroundings depending on where it is located and what type of glacier it is.

Glaciers are seen by many as a significant piece from the last Ice Age.  They occupy a huge area of the world’s total land mass.  If someone had to guess one area where glaciers might be, they would probably guess Antarctica.  This is because many glaciers are found in colder regions of the world. Endre Før Gjermundsen, who has a PhD in mountain glaciology at The University Centre in Svalbard, Norway, said, “We expect glaciers to erode landscapes and make the mountain slopes steeper and the ridges sharper…” .  Most glaciers sit between mountain ranges that were much larger before the ice age that happened two million years ago.  While it is true that many European mountains are not the same as they were years ago specifically because of glaciers, scientists just recently discovered that mountains are not always going to be eroded.  Lead author and glacier scientist Gjermundsen found that “The Svalbard peaks have been covered by a type of ice known as cold-based ice, which acts as a protective layer and protects the mountains from erosion.  It’s totally different to how other European mountains have been eroded and shaped over the same period.” It is interesting that some mountains can be affected by glaciers while other mountains are unchanged due to if the glacier is hot or cold on the inside.

            Cooler temperatures can endure for long periods of time.  When this happens, it leads to an Ice Age and polar ice begins to move into lower latitudes.  During the last Ice Age, huge ice sheets moved from the poles.  The glacial ice sheets covered many places in the world.  Scientists know that there have been at least eight Ice Age cycles within the last 750,000 years.  These Ice Ages were separated by periods of warmer climates which are called interglacial periods.  The Earth is actually currently near the end of an interglacial.  This means that another Ice Age could be due very soon.  We could experience the next Ice Age in the next few thousand years.  This is a part of the cycle known as the normal climate variation cycle.  Climate change is not fully understood yet though.  Scientists still many questions that need answering when it comes to climate change.  Glaciers might change slowly over longer periods of time, but they can provide very important global climate change signals that we need to know about.

            There are many different types of glaciers. Ice sheets, shelves, and caps are examples of types of glaciers by where they are.  Ice sheets can be found in Antarctica and Greenland.  Ice sheets are massive in size as they can cover more than 50,000 square kilometers.  Ice sheets can flow into a sea and become an ice stream.  Ice shelves are pieces of glacier ice that floats on the sea.  Ice caps are basically just a smaller version of ice sheets.  The different types of mountain glaciers are cirque, valley, tidewater, piedmont, and ice aprons.  Cirque glaciers are bowls or basins that are carved into a mountain. They are very short when compared to their width.  Valley glaciers are found at high altitudes and can flow downward from cirques, ice caps, high ice fields, or ice sheets. Valley glaciers are usually tongue shaped.  The Bering and Hubbard are the longest valley glaciers in the Americas.  A tidewater glacier is basically just a valley glacier that has entered the sea.  Piedmont glaciers form where mountain valleys have opened into other valleys or plains.  Ice aprons are formed at steep mountain slopes that look as if they cannot hold snow.  Avalanches can be caused by ice aprons. Ice aprons are also known as hanging glaciers.

Glaciers can be identified by the temperature of an area as well.  Warm or temperate glaciers are made up of ice that is at its melting point throughout.  Melt water is more abundant in the summer, but still continues flowing throughout winter. Warm glaciers are known to form in most mountain regions outside Antarctica.  Warm glaciers are also normally eroded.  A cold glacier is the complete opposite of a warm glacier.  Most of the ice in a cold glacier is at temperatures that are below freezing.  Cold glaciers are frozen and not eroded very much.  Cold glaciers are found in the sub-polar and polar regions of the world.





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