Lesson 5 - Glaciation

What is a glacier

A huge mass of ice that slowly moves over land. They can be classified into 2 general groups; Alpine glaciers and Ice Sheets.

Alpine Glaciers

Alpine glaciers form on mountainsides and move downward through valleys. Sometimes they van even create valleys, pushing dirt, soil and other materials out of their way. These glaciers can ne found on every continent except Australia.

Ice sheets

Ice sheets aren’t limited to mountainous areas. The form broad domes and spread out from their centers in all directions. As ice sheets spread, they cover everything around them in a thick blanket of ice, including valleys, plains and even entire mountain. The largest Ice sheets are called continental glaciers; they cover vast areas, including most of Antartica and Greenland. Continental glaciers are glaciers which cover over 50,000km²

How glaciers form

Glaciers can form over years when more snow piles up and melts. Soon after falling, the snow begins to become denser and more tightly packed. When new snow falls and buries the previous years’ snow, the bottom layer becomes evn more compressed. The dense grainy, ice that has survived 1 years melt cycle is called firn. When the ice grows thick enough, the firn grains fuse into a large mass called glacial ice.

Glaciers shaping lands

The glacier may begin to move under its own weight, through a process called compression melting. As they move, glaciers erode or wear away land underneath and around them. When glaciers began their latest retreat, less than 20,000 years ago, they left behind many landscape features such as lakes, valleys, and mountains.

Glaciers providing resources

Glaciers provide people with many useful resources. Glacial till provides fertile soil for growing crops. And deposits of sand and gravel are used to make convrete and asphalt. Manyrivers are fed by the melting ice of glaciers. The most important resource provides by glaciers is freshwater.

Glaciers reflect climate change

Earth’s average temperature has been increasing drastically for more than a century. Glaciers can act as indidicators of global warming and climate change in several ways. Melting Ice sheets contribute to rising sea levels. As ice sheets in Antartica and Greenland melt, they raise sea levels adding freshwater to the Ocean every day. The loss of glacial ice also mean less freshwater is available for land plants and animals. Large additions of Freshwater change the ocean ecosystem and currents. Additionally, less salt in the Ocean could disturb the gulf stream, drastically changing weather on land as well. Since glaciers are so senstitive to climate change, their melting is like an early warning system.

Where do glaciers form?

Glaciers can form in places where the climate is cold enough to accumalate snow over time without it melting. E.g. mountain ranges or polar regions

Who are glaciologists and what have they discovered?

Glaciologists are people whi study glaciers, ice sheets and other types of layers of ice in the environment. They have discovered that glaciers are key indicators of climate change and the fact that retreating glaciers coukd mean a rise in temperature.