Glaciers

A glacier is a large, slow-moving river of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity.

A. Confined Ice 1.) Cirque Glaciers := Cirque Glaciers are named for the bowl-like hollows they occupy, which are called cirques. Typically, they are found high on mountainsides and tend to be wide rather than long.

2.) Valley Glaciers := Commonly originating from mountain glaciers or ice fields, these glaciers spill down valleys, looking much like giant tongues. Valley glaciers may be very long, often flowing down beyond the snow line, sometimes reaching sea level.

3. ) Piedmont Glaciers :=A piedmont glacier is a valley glacier that has spilled out onto adjacent flat land.

B. Unconfined Ice 1.) Continental Ice Sheets := Found only in Antarctica and Greenland, ice sheets are enormous continental masses of glacial ice and snow expanding over 50,000 square kilometers. The ice sheet on Antarctica is over 4200 meters thick in some areas, covering nearly all of the land features except the Transantarctic Mountains, which protrude above the ice. Another example is the Greenland ice sheet.

2.) Ice Caps := Ice caps are miniature ice sheets, covering less than 50,000 square kilometers. They form primarily in polar and sub-polar regions that are relatively flat and high in elevation.

* Transitional Ice Masses := Nunatak = An area that is unglaciated, but surrounded by ice.

A.) Surface 1.) Temperate 2.) Subpolar 3.) Polar B.) Bed 1.) Cold-Based 2.) Warm-Based

The sheer weight of a thick layer of ice and the fact that it deforms as a "plastic" material, combined with gravity's influence, causes glaciers to flow very slowly. Ice may flow down mountain valleys, fan across plains, or in some locations, spread out to the sea. Movement along the underside of a glacier is slower than movement at the top due to the friction created as it slides along the ground's surface.

When the glacier moves through irregular terrain, cracks form in the fracture zone. These cracks can be up to 50 meters deep, at which point they meet the plastic like flow underneath that seals them.

Moraine refers to any glacially formed accumulation of unconsolidated debris which can occur in currently glaciated and formerly glaciated regions, such as those areas acted upon by a past ice age.

A drumlin is an elongated whaleshaped hill formed by glacial action. Its long axis is parallel with the movement of the ice, with the blunter end facing into the glacial movement.

-Julius M. Judan Envi. Sci. 1 WFR