| Term |
 |
|
| Definition |
|
|
| glacier |
a large mass of moving ice |
| snowline |
elevation above which ice and snow remain throughout the year |
| snowfield |
an almost motionless, permanent mass of ice and snow on the ground |
| firn |
grainy ice formed through cycles of melting and re-freezing |
| alpine glacier |
a narrow, wedge-shaped glacier that forms in muntainous regions |
| continental glacier |
a massive sheet of ice that may cover millions of square kilometers |
| ice sheet |
another name for a continental glacier |
| crevasse |
a large crack or fissure that results from ice movement |
| ice shelf |
an ice sheet that hangs over an ocean |
| iceberg |
large blocks of ice which have broken away from a glacier or ice shelf, onto the ocean |
| ice age |
a long period of climactic cooling during which the continents are glaciated repeatedly |
| glacial period |
a period of cooler climate during which glaciers advance |
| interglacial period |
a period of warmer climate during which glaciers retreat |
| Milankovitch Theory |
theory that cyclical changes in Earth's orbig and the tilt of Earth's axis over thousands of years cause climactic changes |
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