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Loess is a geologically recent deposit of silt or material which is
usually yellowish or brown in color and consists of tiny mineral
particles brought by wind to the places where they now lie. It is a
product of past glacial activity in an area. It is a sedimentary deposit

of mineral particles which are finer than sand but coarser than dust or
clay, deposited by the wind. Loess is a type of silt which forms fertile
topsoil in some parts of the world. Loess was formed during the time

after the Ice Age when glaciers covered a great portion of the earth.
When the climate warmed up, the warm temperatures melted the
glaciers creating tremendous flows of water down into a valley or
river, and exposing vast plains of mud. When these plains dried,

strong winds blew the exposed sediments and swept the finer
materials from the flood plains into huge clouds of dust, which were
deposited into the bluffs, that is, bold steep banks. As silt

accumulated, higher bluffs were formed.

Figure 4.7. Ice sheets

Ice sheets and glaciers form the largest component of perennial

ice on this planet. Over 75% of the world's fresh water is presently
locked up in these frozen reservoirs. A glacier is a huge mass of ice,
that flows slowly over land. They form in the cold polar regions and in
high mountains. The low temperatures in these places enable large

amounts of snow to build up and turn into ice.

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