You know ice feels quite smooth, but that is not the case with glacial ice, which is relevant when answering, “How does ice cause erosion?”
The truth is that numerous glacial ice contains boulders and other elements that grind against the mountainside, leaving distinctive scars on the landscape.
It means when anything (like ice) scrapes away at a surface, it carries the shattered bits of rock and dirt along with it as it goes.
This process is called erosion. But, how do glaciers cause erosion?
Glacial ice causes erosion in different ways, but mostly glaciers slide down mountain sides because of their mass and the force of gravity, causing erosion.
How Does Ice Cause Erosion?
So, does ice cause erosion? Yes, it surely can. But, it can do it through a number of processes.
For instance:
Abrasion
Have you ever used sandpaper on wood? It is a perfect example of abrasion.
This sort of erosion happens when a glacier contains rocks of varying sizes.
When you look at the ice near the base of a glacier, you will probably see particles of rock, dirt, and other detritus.
These rocks scrape against the bedrock beneath the glacier, wearing them down as the glacier flows downhill.
Over time, this wears away (or “abrades”) the surface of the rock, leaving visible ridges and valleys.
Plucking
When a glacier melts, it typically reveals fissures in the bedrock.
There is a chance that these fissures will widen and eventually connect to one another under the ice sheet.
Similarly, when glaciers move over a mountain range, they can loosen some rocks more than others, allowing meltwater to seep in between the cracks.
Meltwater is the water released from frozen surfaces, such as snow or ice.
With enough time and the right conditions, this meltwater can seep through the glacier’s massive crevasses and reach its icy bed at the glacier’s base.
The freezing of this meltwater causes the weak rock to separate from the mountainside, and the ice then continues its downward journey, eventually removing the rock.
The Power of Glaciers and Erosion
Glaciers are massive ice sheets typically as thick as twice their width.
Meaning they are exceptionally dense slabs of ice made for compacting snow.
Because of this load, they are also in motion.
Erosion occurs when a glacier’s immense weight presses down on the ground.
This triggers processes such as internal slippage, basal sliding, and the formation of crevasses that are subsequently filled with new snow.
Fact: Glaciers are vast stores of freshwater crucial to the functioning of the biosphere and impact people’s daily lives all over the world.
Understanding How Ice Causes Erosion
To understand how ice causes erosion, you must consider the example of making a snowball.
You grab handfuls of snow and compact it in your hands.
Some of the snow will melt as a result of the warmth and compression from your palms.
Once you remove your hand from the liquid water, it returns to its frozen state.
It means the snow was fluffy before, but now it is compacted like a snowball.
That is also how glaciers form, only on a far greater scale.
The Formation of Glaciers
It begins with the sun playing a major role and gradually melting the snow.
The water eventually freezes during the night or as the temperature dips.
Still more snow keeps falling to the ground.
Layer upon layer of snow, along with melting and freezing, will eventually compress to the point where it becomes a solid block of ice.
If this ice accumulates at a high altitude, it will gradually flow downwards like a river of ice.
A glacier is the proper name for this phenomenon. On level ground, this mass of ice is known as an ice cap.
Ice Erosion Changing the Land
Something you need to know about ice erosion is that it can significantly change the land’s surface.
The landscape can shift as ice moves across it. But it takes time.
You might see snow or ice in your area, but obviously, it does not stay that way all year long.
It gets out of hand if there is snow in the winter and not as much heat in the summer to melt that ice. And eventually, it will change to glaciers.
Glaciers have the potential to alter the landscape as they expand throughout the globe.
They erode the land’s surface, transporting the resulting rock and sediment to new locations before dumping it.
So, glaciers produce both eroding and depositing landforms.
Fact: Some of Antarctica's glacial ice may be over a million years old, whereas Greenland's glacial ice is over 100,000 years old.
The Time It Takes for Glacial Erosion
The time period on earth when glaciers cause erosion may vary greatly.
The estimates put it anywhere from the hundreds to millions of years.
Some glaciers respond to short-term variations (10-100 years), but some take significantly longer, even up to 10 million years.
It usually depends on how glaciers respond to any change in climate pressure.
However, it is worth mentioning that erosion caused by flowing water is the quickest type.
The Grand Canyon in Arizona is an impressive testament to the strength of flowing water.
Over millions of years, the Colorado River eroded away rock, creating the canyon we see today.
Is Ice Erosion the Same as Weathering?
When learning the concept of ice erosion, it is important to understand how it differs from the weathering process.
You already know that erosion refers to a process that involves wearing away rocks and moving them elsewhere.
On the other hand, weathering is the process by which rock is broken down or changed at its original location on or near the Earth’s surface.
Weathering usually happens due to chemical, physical, and biological processes.
In other words, it refers to the fracturing or shattering of rocks, and water, wind, and climate can all initiate or accelerate the weathering process.
Examples of Erosion and Weathering
The distinctions between erosion and weathering become clear when you compare the two processes side by side.
For instance: If you notice the river’s rocks being broken down, this is weathering. But if they turn into pebbles and begin moving along a river bed, it is erosion.
Similarly, the process of small particles of a rock tearing away from the original source is weathering.
But, if strong winds take those grains of sand somewhere else, it is the perfect example of erosion.
And if you notice rock salt deposits breaking apart into smaller pieces, it is weathering.
But if they land in ocean water and currents take them to a new place, it refers to erosion.
Fact: Norway's fjords were formed out of a flatter region of Earth by the action of glaciers, which eroded away rock to create enormous streams.
What are Some Real-Life Examples of Ice Erosion?
There are several examples of ice erosion on both Earth and Mars. Here is a bit more about several instances of ice erosion.
The British Isles
The group of islands we now call the British Isles was covered by glaciers for a good portion of the last 10,000 years.
The hills and cliffs they carved into the landscape are still visible today as a result of their work.
The Wonder of Greenland
Many of Greenland’s distinctive features were sculpted by the relentless erosion of ice.
Most notably, a glacier’s gradual progress across the land formed a massive depression in the center of the country, a great example of ice erosion.
The Incredible Lake Louise
The erosion of glaciers creates a unique type of lake known as a glacial lake.
When a glacier melts, it leaves behind a trench dug into the ground.
Lake Louise, Canada, is a good example of a glacial lake.
Similarly, ice erosion had a significant role in the formation of the Great Lakes.
The glacier steadily carved out these massive bowls from the ground, and when it retreated, it left behind enough meltwater to fill the lakes.
The Expansive Mt. Baker-Snoqualmie National Forest
To get better examples of erosion, you may have to check some in Mt. Baker Snoqualmie National Forest in Washington.
In Washington state’s national forest, numerous glacier valleys are easily recognized by their U-shaped gorges.
There are more glaciers here than in any other part of the continental United States (except for perhaps Canada).
Fact: The Yosemite Valley in California's Sierra Nevada mountains was formed by glacial erosion, after being home to glaciers for well over 30 million years.
Takeaway
How does ice cause erosion?
To understand the process of erosion, you will have to develop a better understanding of how glaciers form and change the landscape in the long run.
Gravity has a role to play, so does the sun. Erosion can also work in different ways.
But, it takes thousands of years for glaciers to cause erosion and eventually change the landscape.
