Glossary

 

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Geomorphology

Science of landforms that studies the evolution of the Earth's surface and interprets landforms as records of geological history.


Gibbsite

Al(OH)3. Mineral with a platy structure, that occurs in highly weathered soils and in laterite.


Glacial drift

Unstratified deposits laid down directly beneath the ice or dropped from the surface as the ice melted.


Glaciers

Large masses of ice that form by the compaction and recrystallization of snow under freezing conditions; glaciers often move downslope or outward in all directions because of the stress of their own weight; they may be stagnant or retreating under warming conditions.


Glaciofluvial deposits

Material moved by glaciers and subsequently sorted and deposited by streams flowing from the melting ice. The deposits are stratified and may occur in the form of outwash plains, deltas, kames, eskers, and kame terraces. See also Glacial drift and till.


Glaciolacustrine deposits

Material ranging from fine clay to sand derived from glaciers and deposited in glacial lakes by water originating mainly from the melting of glacial ice; many such deposits are bedded or laminated with varves.


Gley soil

Soil formed under naturally wet or waterlogged conditions as evidenced by grey colours stemming from the reduction, under anaerobic conditions, of ferric iron to the ferrous state.


Ground water

That portion of the water below the surface of the ground at a pressure equal to, or greater than, that of the atmosphere. See also water table.


Gully

Channel resulting from erosion and caused by the concentrated but intermittent flow of water during and immediately following heavy rainfall; gullies are deep enough (usually >0.5 m) to interfere with, but not obliterated by, normal tillage operations.



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