Glaciers and Other Icy Bergs
Glaciers and Other Icy Bergs
People have always wanted to explore and understand the world around them. Long ago, people knew about glaciers, but it was only in the 1800s that explorers and scientists started to find out more about them.
In the 1800s, a scientist built a hut on the Unteraar Glacier in the Swiss Alps. Between 1827 and 1840 the hut moved about 1.6 km downstream. Markers placed on the surface of the glacier also showed that the glacier was moving. The study of glaciers had begun.
Scientists have learned many facts about glaciers since the 1800s. Modern scientists use planes, radar, radios, and drills to track and measure the size and movement of glaciers.
There are two main types of glaciers- valley glaciers and ice sheets (these are also called continental glaciers). These two types of glaciers have different shapes and sizes and they are found in different places around the world.
Valley Glaciers flow down from mountain valleys. Valley glaciers are long and narrow. Valley glaciers are found high up in mountain ranges near the equator, such as the northern Andes of South America and lower down in mountain ranges in cooler parts of the world, such as the Southern Alps of New Zealand and the European Alps.
Ice Sheets are the largest glaciers and their ice is extremely thick.
Ice sheets are found near polar regions in Antarctica and Greenland.
Some glaciers flow until they reach the edge of the ocean. Often, a large chunk of the glacier will break off and float away into the ocean.
These huge floating pieces of ice are called icebergs. Icebergs are mostly hidden under the water. Only one-seventh to one-tenth of an iceberg can be seen above the waterline.
The largest icebergs come from the Antarctic. The largest iceberg ever seen was in the ocean near the Antarctic. It was about 200 miles (320 km) long and about 60 miles (97 km) wide. North Atlantic icebergs that come from Greenland are much smaller. Eventually, an iceberg will melt away into the ocean.
Icebergs can be very dangerous to ships. It was an iceberg that collided with the famous ship the Titanic, causing it to sink. This tragedy took the lives of 1,503 people.
Often, a large chunk of the glacier will break off and float away into the ocean,
How Glaciers Are Formed
Glaciers farm when snow collects in cold polar regions and high mountain valleys. As more and more snow falls, the snowflakes are squeezed together and become ice. The sun only melts a little of the ice but each year, more and more snow falls. The ice builds up until it is heavy and thick. When the ice begins to move, glaciers are formed.
How Glaciers Move
In the 1950s, scientists discovered that valley glaciers and ice sheets move in different ways.
Valley glaciers usually move by basal sliding. The ice at the bottom of the glacier starts to melt and the ice on top starts sliding downhill. Ice sheets move by a process called internal deformation. The weight of the snow on top causes the snowflakes to change shape and slide over each other.
Most glaciers move slowly - less than 1 foot (30 cm) a day. But, at times, some glaciers surge, or race ahead, up to 100 feet (30 m) a day. The fastest-moving glacier is called the Quarayaq Glacier in Greenland. This glacier is said to move at an average of 80 feet (24 m) a day.
...scientists discovered that valley glaciers and ice sheets move in different ways.
Shaping the Earth
Glaciers have been changing and shaping the surface of the Earth for many thousands of years. As the ice moves downhill, it drags rocks away from the sides and surface of the mountain. This ice is so heavy it acts like a bulldozer to carve hollows out of the mountains. Sometimes these hollow valleys are at the edge of the sea. Over time, the seawater invades the valleys and they become fiords.
Sometimes glaciers carve away part of the tops of the mountains and leave spires and peaks. One of the most famous of these glacial peaks is in the Swiss Alps, called the Matterhorn.
The action of the moving glaciers crushes and grinds the rocks into a fine powder that is rich in minerals. Farmers in many parts of the world grow food crops on soil that has been improved by glaciers.
The ice is so heavy it acts like a bulldozer to carve hollows out of the mountains.
Life on Glaciers
Valley glaciers are home to eagles and other birds, Animals with thick coats, such as marmots, mountain goats, and hares, can survive in the harsh conditions. Moss and other low-growing plants cling to rocky patches.
On the great ice sheets near the oceans, seals and polar bears live. In Greenland, the ice is home to polar bears, arctic foxes, wolves, reindeer, and small rodents.
How People Use Glaciers
In some places, people pipe the water that melts from the tip or snout of a glacier into their towns for fresh drinking water. Farmers in many countries use glacier water to irrigate their farmlands. People also use the glacier water to make electricity at power stations. Glaciers are often important tourist attractions, bringing money into the community. Exploring, hiking, climbing, and skiing are some of the sports people like to do on or near glaciers.
On the great ice sheets near the oceans seals and polar bears live.
Scientists have learned a lot about glaciers since the 1800s. Today, some scientists believe that the Earth is getting warmer. They think that the glaciers will melt away. If all the glaciers melted, the oceans would rise and large areas of land would be flooded. But other scientists have noticed that some glaciers are growing larger.
Glaciers are important because they contain most of the world’s fresh water. Scientists will continue to study glaciers to find out more about them. Glaciers may become even more important in the future.