Chapter 12-Glaciers

           Physical Geology Illustrated Vocabulary     
Cochise College                                                     
Geology Home Page  
Roger Weller, geology instructor
copyright 2018-Roger Weller    3/21/18  

glacial grooves, Yosemite Park, California

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 All About Glaciers *


alpine glacier

-is a valley glacier.



-are a prominent mountain range in southern Europe.



-is a skinny mountain ridge shaped on opposite sides by a series of glacial cirques.
-arete diagram



-is a large mass of snow that rapidly slides down a slope.



-is the large crack at the top of a valley glacier where it is pulling away from the mountain.
-bergschrund diagram



-is a scoop-like depression on the side of a mountain formed by a valley glacier eroding the
-cirques, Kebler Pass, Colorado

-Rocky Mountains Park-cirque-1 

-Rocky Mountains Park-cirque-2 


continental glaciation

-occurs when glaciers cover a large portion of a continent.  Modern examples are Greenland and
the Antarctic.



-is a very large crack on top of a glacier


crustal rebound

-During an ice age the weight of a thick continental glacier presses the crust of the earth down. 
After the glacier melts, the crust slowly rises up to its previous elevation.



-is a long, skinny, cigar-shaped hill that has be sculpted by a glacier flowing over it.
-drumlin diagram



-is a boulder far removed from its original source and deposited by a glacier.

-Yosemite-glacial grooves and erratics-1           

-Yosemite-glacial grooves and erratics-3 



-is a snakelike ridge of water lain gravel deposited by a steam flowing beneath a melting glacier.
-esker diagram


-is a U-shaped glacial valley that is partially flooded by seawater.
-fiord diagram
-fiord-Opal's Pals



-is glacial ice, a granular form of ice similar to the material in a "slush ball".
-glacial ice-firn-Opal's Pals


frost wedging

-Water gets into a crack, freezes, and expands.  The tremendous pressures exerted by the
expansion of water into ice can cause the rock to split further.


glacial grooves

-As a glacier moves across bedrock, the large rocks that the glacier is dragging along gouge long

-Yosemite-glacial grooves-1       

-Yosemite-glacial grooves-2     


glacial plucking

-is the process where glacial ice is frozen in cracks and as the glacier moves the ice pulls rock
fragments out of the bedrock.
-glacial plucking-Mt.Whitney


glacial polish

-A glacier moving across a bedrock surface can polish the bedrock by abrasion with the fine rock
material embedded in the ice.

-Yosemite-glacial polish 

-Mt. Whitney-glacial polish 
-Mt. Whitney-glacial polish-B
-Mt.Whitney-glacial polish-D


glacial striations

-are scratches left on boulders and cobbles and bedrock as rocks are dragged along by a glacier and rubbed
against each other during the movement.  Also includes large, long, linear features
-glacial striations-Mt. Whitney
-Montana- glacial striations*


glacial till

-is the unsorted rock debris, ranging from boulders to silt, that are left behind when a glacier melts.



-is a moving mass of ice on land that is at least 150 feet thick


hanging valley

-is a small U-shaped glacial valley exposed on the upper side of a larger U-shaped glacial valley. 
The smaller valley was formed in colder times by a tributary valley glacier meeting up with a
larger valley glacier.
-hanging valley diagram



-is a mountain with very steep slopes which was carved with cirques on three or more by valley
glaciers.  The most famous glacial horn is the Matterhorn in Switzerland.

-Rocky Mountains Park-horn and cirques       


Ice Ages

-are distinct times in the history of the Earth when major portions of the continents were covered
by glaciers.



-is a small lake surrounded by glacial till.  A kettle is formed by a depression created by the
melting of a large piece of glacial ice covered over with till.
-kettle lake diagram


lateral moraines

-are the piles of glacial till deposited along the sides of a glacier.
-moraine diagram



-is a very fine, silty material that started out as rock flour (rocks ground up by glacial action to a
fine powder), but is now a wind-deposited soil.


medial moraine

-When two valley glaciers merge to form a larger valley glacier, their area of contact is often
marked by a line of glacial debris accumulated from lateral moraines of the two glaciers.


outwash plains

-are flat land areas covered by the silty material carried by streams flowing away from a melting


permafrost ground

-is semi permanent frozen ground.


rock flour

-is rock that has been crushed and ground to a fine powder by glacial action.


terminal moraine

-is the pile of glacial till at the base (snout) of a glacier.
-moraine diagram


U-shaped valley

-is created when a valley glacier scrapes out the bottom and sides of the valley that it is moving
-U-shaped glacial valleys, Kebler Pass, Colorado

-Rocky Mountains Park-U shaped valley-1 

-Rocky Mountains Park-U shaped valley-2 


valley glacier

-is a glacier in a mountain valley.  A valley glacier is also known as an alpine glacier.


Wisconsin Ice Age

-is the most recent of the Pleistocene advances of glaciers moving across North America.  The
Wisconsin Ice Age ended about 15,000 years ago.


zone of ablation

-is the portion of a glacier below the snowline where the glacier is melting.


zone of accumulation

-is the region of a glacier above the snow line where ice in the form of snow is being added to the