Is glacier ice a kind of rock

Glaciers shape the landscape

Wherever glaciers move, they shape the landscape. Stones enclosed in the ice act like coarse sandpaper: They grind rock from the subsurface at the edges of the glacier. The ice masses carry away the rubbed off rubble. The glacier scrapes out the rock. This creates valleys that look round like a U in cross-section and are therefore called U valleys.

Sand and boulders that are dragged along by the glacier ice remain at the edges and at the bottom of the glacier on the way down and form small and large hills. Such boulders on the edge of the glacier are called moraines.

When it is very cold for a long time, the glaciers grow and advance further and further into the landscape. If it gets warmer, however, the ice masses melt and the glaciers retreat. The moraines of rubble remain, however. Centuries later you can still tell from them how far the glacier had penetrated. The place that the glacier once excavated and covered with its ice is shaped like a tongue. One therefore speaks of a tongue pelvis.

What is a glacier?

Glaciers flow down from the mountains like white tongues. Others cover huge land masses as mighty ice sheets. Glaciers are primarily made up of ice and can be hundreds of meters thick and several kilometers long. Most of the fresh water on earth is frozen into ice! But how do such ice masses come about?

Glacier ice forms where it is very cold all year round. Such low temperatures prevail high up in mountains, for example in the Alps. The snow that falls there doesn't completely thaw, even in summer. The snow cover is therefore getting thicker and heavier. Under this load, the loose snowflakes are first pressed into granular firn and then into thick ice.

In the areas around the North Pole or South Pole, too, more snow falls throughout the year than can thaw again. Then, even in flat landscapes, glaciers form. The glaciers of the polar regions are thousands of meters thick. They are shaped like huge shields and are therefore called ice sheets.

Glaciers flow very slowly down the slope under the weight of their own weight. Melt water at their bottom makes it easier for them to slide across the ground. With their ice mass, they also drag sand and rocks with them that have been blown off the ground by frost.

If a glacier finally penetrates into warmer regions, its ice melts. The meltwater flows off in a trickle; a river forms when there is a large amount of water. If the meltwater collects in a basin, a glacial lake is created in it.

constant dripping wears away the stone

Deep gorges in the mountains, wide sandy beaches by the sea and wide rivers that meander through meadows and fields - all of these are landscapes that we know well. Because they are so varied, we find them impressive and beautiful.

The sculptor of all these landscapes is the water cycle. Sooner or later, water shapes the surface of the earth more strongly than any other force. It washes away soil after a downpour. It digs into the ground and loosens parts of the rock. It carries earth and weathered rock debris with it down into the valley. Where the water drains off more slowly, it lets go of its burden of silt, sand and rubble. When there is high water it floods the flat areas of a valley, the river floodplains. Here, too, it deposits fine mud. When the water finally flows into the sea, it works the coasts and forms very different landscapes, for example cliffs or long sandy beaches.

Water also shapes the landscape in the form of ice. If water freezes in cracks in the stone, it bursts the stone. As a glacier, it planes out notch-shaped river valleys to form round trough valleys. And the moraine landscape in the foothills of the Alps with its boulders and boulders is the result of glaciers that formed the subsoil a long time ago.

Ice Age glaciers

On earth, warm and cold times have alternated over the past million years. During the warm periods, the ice melted and the glaciers shrank. During the ice ages, however, the temperature dropped so much that large amounts of new ice were formed. As a result, glaciers were able to spread over large areas.

At that time, large parts of northern Germany and the Alpine foothills were covered by huge glaciers. How far the glaciers reached can still be read today from the rubble hills that the glaciers left behind. The rubble made up of larger and smaller rock particles was removed in the glacier ice and deposited at the point where the ice melted again. When whole mounds of debris pile up, it is called moraines.

When the great glaciers melted during the Ice Ages, rivers and streams of meltwater formed at their lower ends. These rivers dug valleys into the ground that are now known as glacial valleys. Hollows or depressions in the landscape filled with water and turned into lakes.

How are valleys formed?

River and valley are inseparable. But why? How do these elongated hollows, which are called valleys, even come about? Wherever water runs off in small streams or large rivers, a valley forms. This is because flowing water digs deeper and deeper into the subsoil. The soil on the sides slides down towards the river bed. A slope forms to the right and left of the watercourse; this creates a valley along the river.

Valleys can look very different: steep walls or gentle slopes, wide valley floors or just enough space for the river. The shape depends on how strongly the water attacks the bottom and the side walls and how stable the rock is.

It's steep in the mountains, at the headwaters of a river. The water shoots down the mountain with force. Because of its high speed, it transports a lot of sand and debris there. With this rubble, it grinds the ground heavily and can dig itself deep. This creates rather narrow, deep valleys.

Towards the mouth, the river widens and carries more and more water. As the terrain becomes flatter, the water flows more and more slowly. For this reason, the lower reaches of the river gradually deposit the cargo it has carried along with it on the ground again. Erosion takes place here more on the side walls, so that broad, flat valleys are created.

The rock through which the river flows is also responsible for the different valley shapes: water and rubble dig into solid rock without a lot of rock sliding down the sides. This creates valleys with steep or even almost vertical walls. Soft rock layers, on the other hand, slide quickly and lead to flat slopes.

Valleys are divided into different types based on their shape: Narrow valleys with steep walls are called canyon, with vertical walls one speaks of one Klamm. Narrow valleys with gentler slopes are called Kerbtal or V valley designated. If, on the other hand, the valley floor is significantly wider than the river, it is a Sohlental, or - with steep walls - by one Kastental.

A special form of valleys are Canyons. Here the water has dug its way through different layers of rock that lie on top of each other like several layers of cake. Some layers could easily be removed by the river, they were washed out wide and round, the more resistant layers broke off steeply and angularly. The result is a valley, the side walls of which slope down like steps towards the river. A famous example of such a valley is the Grand Canyon in the US state of Arizona.

Shaped by the ice, flooded by the sea

It is a breathtaking sight: the rock walls on Norway's fjord coast rise up to a thousand meters. Even large cruise ships can easily drive into this fantastic mountain backdrop. Not only was the surf of the sea at work here, but one thing above all: ice!

During the Ice Ages, Northern Europe was under a huge ice sheet. Huge glaciers flowed towards the Atlantic and scraped deep valleys with steep walls into the subsoil. After the end of the ice ages, the sea level rose and the water flooded the trough valleys of the glaciers. The result is the famous fjords. In Greenland, Alaska and on the west coast of Canada, fjords were also formed which, because of their depth and their protected location, are well suited as locations for harbors.

The glaciers of the Ice Age did not only create fjord coasts. The small islands in the Baltic Sea between Sweden and Finland also bear witness to the Ice Age. As the huge glaciers rolled over the land, they grinded angular rocks and mountains into smooth, round cusps. After the ice masses melted, the rounded hump landscape was washed over by the sea. The humps that did not sink into the water now jut out of the sea as small islands: the skerries. The many small islands form their very own coast, called the archipelago.

Gullies and basins that were excavated by meltwater during the Ice Ages flooded the sea after the climate warmed up. Today they have become valley-shaped bays that extend far into the country. The result is a fjord coast, as we know it from the Kiel fjord, for example. The gently undulating landscape of ground and terminal moraines also partially sank into the water on the coasts. The hills of the terminal moraines formed the coast with its typical flat and wide bays, inland there are often flat lakes. Such a coast is called the Bodden coast, as it is found, for example, in Western Pomerania between the L├╝beck and Oder bays.