Come and see the magical sights you have never seen before!

Glaciers are masterpieces of nature in cold regions, and such places also have summers. Whenever the temperature rises in summer and the glaciers melt, many unique landscapes will be created.

Glacier melting can be divided into three types: subglacial melting , intraglacial melting and ice surface melting .

Subglacial melting: The earth's crust often transfers heat to the bottom of the glacier, causing subglacial melting. However, subglacial melting is insignificant for huge glaciers;

Intraglacial melting: When the meltwater from the ice surface flows into the interior of the glacier along the cracks in the glacier, intraglacial melting will occur. Intraglacial melting can give rise to many unique glacial karst phenomena, such as ice caves and cirques;

Ice melting: The ice surface will produce "differential melting" due to different degrees of melting. Differential melting often produces many magnificent natural scenes, such as ice lakes, ice towers, etc.

Today, let us take a look at those strange phenomena of glacier melting!

Glacier, copyrighted image, unauthorized reproduction

01

Ice Cave

A different world

As the meltwater on the glacier flows, it often forms a network of small river branches, sometimes winding and sometimes diving into the ice. On some glaciers with large areas and abundant meltwater, the intraglacial rivers are particularly well developed.

When the river in the ice flows out from the end of the ice tongue, it often erodes into a deep ice cave . The entrance of the cave is like an archway of an ancient city. The water flowing out of the ice cave is turbid and white like milk because it contains suspended debris. In glaciology, it is called glacial milk. When the glacier stops flowing, walking into the ice cave is like entering a crystal palace.

Ice cave, copyrighted image, unauthorized reproduction

In some glaciers, you can walk to the bottom of the glacier through the tunnel in the ice cave. There are single ice caves, tree-shaped ice caves, and caves within caves. There are icicles and stalactites hanging in the caves, and the patterns on the cave walls are very beautiful. Some ice caves have exits hanging high on ice cliffs, forming very spectacular ice water waterfalls.

02

The glacier's funnel

In the upper part of the river valley, near the top of the mountain and the watershed, there is always a water collection funnel. When the climate gets colder and glaciers begin to develop, the water collection funnel near the top of the mountain will first be occupied by ice and snow. When the ice and snow accumulate in the water collection funnel to a certain extent, they will flow and become glaciers .

The glacier has a huge erosion effect on the valley bottom and its edge. It works continuously like a carpenter's plane and file. The original water collection funnel is gradually eroded into a basin shape surrounded by mountains on three sides, like a rattan chair. This kind of terrain is a cirque. Most cirques are developed at elevations near the snow line .

For ordinary valley glaciers, you often have to climb up the ice ridge to see the vast snow basin. When the glacier disappears, the bottom of the basin becomes a cirque lake. Cirque lakes are often seen on high mountains. They are regularly distributed at a certain height, representing the height of the snow line in the ancient glacial era.

Cirque, Image source: Wikipedia

03

Lake on a glacier

It is hard for people who have never been to a glacier to imagine that there are lakes of various sizes on the surface of a glacier. In fact, on some larger glaciers, lakes on the surface of the ice are common.

The five Great Lakes of North America are the largest group of glacial lakes in the world. Image source: Wikipedia

Why do lakes appear on glaciers?

There are three main forms of the formation of glacial lakes.

One is that the subglacial river channel on the glacier melts the glacier , forming a huge cave or tunnel. The top of the cave collapses, forming a deeper and larger long lake.

One is formed by water accumulation in the depression of glaciers , which produces intense dissolution in summer.

In addition, the rugged peaks around the glacier often drop rock debris.

If larger rocks cover the glacier, it will cause differential melting - the ice around the large rocks exposed to the sun will all melt, while the ice in the shade under the rocks will not melt yet, resulting in the "growth" of ice mushrooms of varying sizes.

Ice mushrooms, copyrighted image, unauthorized reproduction

If the collapsed rock is small, it will melt faster when heated by the sun, and the rock will sink into the ice, forming a cylindrical ice cup. The ice cup forms large and small water pits on the ice surface. During the summer melting period, the water temperature on the ice surface is high, sometimes reaching 5°C. Therefore , the melting effect of the accumulated water is strong, which can gradually fuse the honeycomb-shaped ice cup together to form a wide and shallow ice lake .

The frozen lake adds a more colorful scenery to the glacier. In summer, when the sun rises or sets, the lake is covered with a myriad of rays of light, which is brilliant and dazzling.

Ice lake, image source: Wikipedia

04

Ice Tower

The tower-shaped ice columns that stand on the surface of a glacier are seracs.

Many large glaciers in the Everest and Shishapangma regions have developed forests of seracs that are rare in the world. Tens of meters high seracs, one after another, seem to be sculptured out of white marble. They stand on the glaciers in various shapes and forms. Some look like the spire of the Big Wild Goose Pagoda in Xi'an, some look like the pyramids on the banks of the Nile in Egypt, some look like stiff camels, and some look like sharp swords reaching toward the sky.

Ice tower, Image source: Wikipedia

05

Glacier "annual rings"

The granular snow and ice layers in the granular snow basin remain roughly flat and stacked one on top of the other. The ice layers accumulated each year are called annual layers in glaciology. How are annual layers divided?

It turns out that after the winter snow melts in the summer, an ablation surface will be formed. There is a lot of pollution on the ablation surface, so it is also called the pollution surface. The pollution surface is a natural symbol for dividing annual layers .

With annual layers, the age of ice can be measured like tree rings. Since glaciers trap some air and dust when they form, glaciologists can extract air bubbles and dust from them and analyze the climate when the glacier formed .

Year layer, image source: Wikipedia

06

Conclusion

Although the natural melting of glaciers will create many strange scenes, global warming has made many beauties disappear. The large-scale melting of glaciers has had many impacts on the earth. For humans, low-carbon life is urgent.

Produced by | Science Popularization China

Author: Earth Story

Producer｜China Science Expo

Submitted by: Computer Information Network Center, Chinese Academy of Sciences

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