Alaska from space

Leveling Forces: Glaciers

Glaciers: Huge masses of ice that form when more snow accumulates in the winter than melts in the summer.

Valley or alpine glaciers form up in the mountains, when snow accumulates in river valleys.

Ice sheets, or continental glaciers are landmasses at high latitudes that are covered in ice. Today, there are ice sheets covering Greenland and Antarctica.

Evidence of Ice Ages Ice Ages have occurred repeatedly throughout earth’s history, during periods of global cooling. We are presently in a period of global warming (and have been for a long time). The last four ice ages occurred over the last 2 million years. The last bit of ice left our area 10,000 years ago. http://serc.carleton.edu/eslabs/cryosphere/5b.html gak and flow activity (http://www2.pvc.maricopa.edu/ssd/geog/outlines/GPH111/18_glacie rs.html )

ice in last glaciation

Axis and ice ages

Ocean currents

Temperature changes in time

Carbon dioxide levels

As the snow accumulates and becomes packed, it becomes ‘locked’ around objects, hills, boulders, etc. The lower parts of the glacier begin to move when the weight of snow is great enough. Any objects and sediments in the glacier’s path are ripped out and moved.

Glacial movement

The valley becomes ‘u-shaped’ due to this erosion. Continental glaciers cause hills to become rounded and scoured. They can completely reshape the landscapes.

Yosemite shape

Tom McGuire’s glacial images: Describe other evidence of glacial erosion including: striations, cirques, horns, kettles, hanging valleys and waterfalls. http://hmxearthscience.com/Warehouse/geology/surface_processes/animations/Glacial%20Advance.swf

Edge of glacier

Valley glacier and flow

Ribbons of ice http://hmxearthscience.com/Warehouse/geology/surface_processes/animations/glaciers.swf

Latitude and glaciers

Valley glacier diagrams http://hmxearthscience.com/Warehouse/geology/surface_processes/animations/valley%20glacier.swf

Glacial deposition (handout) Glaciers deposit sediments either as: unsorted glacial till, abruptly at the edges and sides of the glacier; or as sorted glacial outwash as the glacial meltwaters move out from the glacier.

Drumlins from space

Glacial Striations

erratic

Glacial plain

U-shaped

Describe these depositional features from your text: Outwash plains, kames, eskers, drumlins, erratics and moraines. http://hmxearthscience.com/Warehouse/geology/surface_processes/animat ions/continental%20glacier.swf

Regents glacial picture

( Glacial sediments and erratics.) Sediments carved or carried by glaciers tend to be: polished by the ‘rock-tumbler effect’, rounded, scratched and unlike the underlying bedrock ( Glacial sediments and erratics.) http://hmxearthscience.com/Warehouse/geology/surface_processes/animations/ch20_glaciers.swf

til and moraine

Glacial sediments

Glacial striations and polish

Old sea terraces

From Glacial till: sediments are unsorted and dumped by glaciers at the sides or end. Sediments are unsorted, and dumped in huge piles, ridges or hills

Glacial outwash: Meltwater from the glacier carries sediments onto plains, valleys, etc. Sediments are sorted by the running water, but show signs of having been scratched and polished in a glacier.

Transported soils are found where a glacier has moved through an area Transported soils are found where a glacier has moved through an area. New York’s soils are transported soils.

Glacial streams

NYS glacial remains: Long Island, http://www.lisrc.uconn.edu/lisrc/geology_simple.asp?p2=6 http://soundbook.soundkeeper.org/chapter.asp?SectionID=5 Quarternary Geology of NYC area: http://3dparks.wr.usgs.gov/nyc/moraines/quaternary.htm ‘fields’ of drumlins that look like flocks of sheep from the air, http://www.geo.cornell.edu/geology/classes/Geo101/graphics/drumlin.jpg the Finger Lakes, http://www.gly.uga.edu/railsback/FieldImages/FingerLakes.jpeg the gravel/sand/rock deposits that are important as resource, http://docs.unh.edu/NY/newb03sw.jpg hanging troughs and waterfalls, http://pubs.usgs.gov/sim/2007/2960/sheet3.pdf bashakill map huge glacial erratics, http://geology.about.com/od/glaciers_ice/ig/glacier-pictures/erratic.htm striated bedrock, unsorted transported soils. http://www.dec.ny.gov/permits/53826.html

17-35 and 51 http://media. pearsoncmg

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