As we know, glaciers They are large, thick and solid masses of ice that form along the earth's surface as a result of the accumulation, compaction and crystallization of snow after years of having precipitated. Today we are going to talk about an interesting part of the glaciers. Its about glacier circus. The importance of glaciers is becoming more and more relevant in the context of climate change in which we find ourselves.
In this article we are going to explain what a glacial circus is and how important it is.
Dynamics of a glacier
To understand what a cirque glacier is, we must first understand how a glacier forms. When the amount of water that evaporates in summer exceeds the annual snowfall, the glacier begins to melt. For a glacier to form, there must be a positive balance between the amount of snow deposited on the Earth's surface and the amount of snow that melts or evaporates.
There are a great variety of glaciers throughout the world. Different shapes can be differentiated between each type of glacier. For example, There are glaciers with valley shapes, niche, ice fields, etc. The climatic conditions that we find are also determining factors when it comes to seeing the shape of a glacier. These conditions can be tropical, temperate, or polar. Thermal conditions influence the amount of snow that accumulates or melts. Depending on the average temperatures that we find in a glacial area, we may have more snow accumulation and greater compaction than if the temperatures fluctuate more.
Today, 10% of the surface of our planet is covered by glaciersIn ancient geological eras, it was once covered by up to 30%. It's arguably the geographical feature with the largest amount of freshwater in the world. Hence the danger of imminent melting, and consequently, rising sea levels.
84% of the total glacier area is located in Antarctica, while the remainder is divided between Greenland and other frozen areas of the planet. If you are interested in learning more about the melting of glaciers, this article may be helpful. You can also check out the article on the Totten Glacier and its accelerated rate of melting, which is relevant in this context.
What is a glacial circus
Now that we have remembered how the dynamics of a glacier work, we can fully enter the glacial cirque. A glacial circus a circus glacier is a kind of rocky basin with a semicircular shape This is caused by the constant sliding or friction of compact ice in its accumulation or feeding zone. The accumulation zone of a glacier is the part where the amount of snow deposited is much greater than the amount of snow melted. On the other hand, we have the abrasion zone, where the melting rate is greater than the accumulation rate.
The glacial cirque is usually in the shape of an amphitheater or chair with more pronounced sides or with vertical ridges that surround it. The glacial cirque usually has two parts that can be easily distinguished. We have the part that is divided by a crack called a rimaya that is transverse or horizontal: here we find the lower part, which is where more snow and ice accumulates. The upper part, on the other hand, has much larger slopes and the ice is much more compressed due to a lower temperature.
We can also find an ablation zone in a glacial cirque. This zone is where the melting, production, and calving of ice masses occurs as they enter the sea. To understand more about this process, you can consult our article on the ablation zone. climate change and its relationship with glaciers.
Characteristics of the glacier cirque
Although there is a wide variety of glacial cirques, they all share certain morphological features that distinguish them from mountain stream catchment basins. Among their main characteristics are their upper walls. They are located above the crevasse of the former glacier. These walls were not limited or destroyed by glacial abrasion. Its slopes are very steep and its surface is irregular due to the fall of the ice blocks that are going to adhere to the rock.
On the other hand, we have the floor of the glacial cirque. It has a much shallower slope than the walls. We can find various sheep-like rocks at this floor that have been eroded by the dynamics of the ice. Sometimes, we can also find morainic ridges that are parallel to the slope. The floor of the cirque can be basin-shaped or horizontal. Furthermore, Depending on their shape, they can have one or more glacial lagoons. You can also consult the article on Arctic glaciers and their impact on the landscape in relation to these phenomena.
In amphitheater-shaped cirques, the cross section has a U-shaped shape. Below the lower edge of the cirque, we can see how the slope steepens, marking the beginning of the glacial valley. For more information on the parts of a glacier, you can visit our article on the parts of a glacier.
Athough it does not seems, the berry is of great importance in the glacial cirque. It is a horizontal crack that forms in the ice on the flanks of the cirque glacier. This crack separates the fixed ice attached to the mountain rocks from the moving ice of the glacier itself.
The berry is opening and exposing the rock that is at its height in early summer. This is due to the high temperatures and the beginning of the melting of the ice. The rock is exposed to daytime and nighttime changes in temperature. These repeated cycles of freezing and thawing, under the action of frost, cause the rock to gradually disintegrate and cause the upper rocks to fall. This is how the rocks take irregular and almost vertical cut-out shapes.
These freeze-thaw cycles are being disrupted by climate change. The melting rate is increasing much more than the amount of precipitation in the form of snow that allows it to accumulate to form the glacier.
I hope that with this information you can learn more about the glacial circus.