1. Glaciers

2. Formation of glaciers Glaciers – a large mass of moving ice. At high elevations and in polar regions, snow can remain on the ground year-round. This permanent snow is called a snowfield. When the snow partially melts and refreezes it creates a grainy ice called firn. The weight of the accumulated snow and firn eventually compresses the air out from between the grains. The result is a glacier that moves downslope or outward under its own weight. Glaciers hold an unimaginable amount of freshwater. How could we use this as an alternative water source? What are some problems you could foresee with harvesting glacial ice?

3. Type of Glaciers Alpine glaciers – a narrow, wedge-shaped mass of ice that forms in a mountainous region. It is confined by its topography. Continental glaciers – a massive sheet of ice that may cover millions of square kilometers, that may be thousands of meters thick, and is not confined by any topography. How do glaciers move?

4. Movement of glaciers Basal slip – the process that causes the ice at the base of glacier to melt and the glacier to slide. Internal plastic flow – the process by which the glaciers flow slowly as the grains of ice deform under pressure and slide over each other. How could we demonstrate these processes in an experiment?

5. Glacial Erosion and Deposition Like so many other forces on earth, glaciers are both constructive and destructive forces. Can you think of some landscapes sculpted by glacial activity?

6. Ice Ages Today, continental glaciers are located mainly in latitudes near the North and South Poles. However, thousands of years ago, ice sheets covered much more of Earth’s surface. Ice age – a long period of climatic cooling during which the continents are glaciated repeatedly.

7. Glacial and Interglacial Periods Continental glaciers advance and retreat several times during an ice age. Glacial Period – a period of cooler climate that is characterized by the advancement of glaciers. Interglacial Period – A period of warmer climate characterized by the retreat of glaciers.

8. Glaciation Glaciation in North America Glaciers covered about one-third of Earth’s surface during the last glacial period. Most glaciation took place in North America and Eurasia. So much water was locked in ice during the last glacial period that sea level was as much as 140 m lower than it is today. As a result, the coastlines of the continents extended farther than they do today. How did glaciation affect human migration?

9. Are we currently in a glacial or interglacial period?

10. Causes of glaciation Milankovitch theory – the theory that cyclical changes in Earth’s orbit and in the tilt of Earth’s axis occur over thousands of years and cause climatic changes.

11. Milankovitch Theory

12. Biological evidence of glaciation Evidence of past glaciation has been discovered in the shells of dead marine animals found on the ocean floor. Foraminifera is a type of shelled organism that is greatly affected by changes in ocean water. When the temperature of ocean water changes, these creatures change the way they make their shells. The remains of the creatures act as a proxy record by which we can “see” changes in climate. What are some other causes