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Unit7 Day 5
2. Define
as the process by which
Earth materials carried by wind, water, or ice settle out and
are deposited.
3. Describe the agents of
: gravity,
water (running water and waves), glaciers, and wind.
7. Describe the depositional and erosional features caused
by glaciers (to include
and .
Glaciers are
for much of the
existing landscape in the
and many other places in the world
such as northern Europe and Asia.
They are a link to Earth’s environmental past as well as a
useful way for scientists to track
Glacier is a
of ice. They form
near the poles and in
areas at high
There are even glaciers at the
at high
elevations in the Andes mountains in Chile
Glaciers develop when
and the weight of the top layers exert enough pressure to
force the accumulated snow to
into ice
Valley Glaciers
Valley Glaciers form in
when the ice becomes too heavy to maintain
its rigid shape and
This usually occurs when the ice exceeds 20m in thickness
of a valley glacier
slows down
the sides and bottom
Movement down slope is usually
only a few mm per day
Valley glaciers carve V-shaped stream valleys into
Continental Glaciers
Continental glaciers cover broad,
. They form under the same climatic
conditions as valley glaciers, but move in a different way.
They once covered about 30% of the Earth’s surface, but
now cover only about
Today’s continental glaciers are confined to Greenland,
Northern Canada, and Antarctica
A continental glacier is
at its
center. The weight of the thicker central region forces the
glacier to
in all directions
causing movement
Glacial Erosion
Glaciers are the most powerful erosional agents, they can
literally “
” as they
plow across the landscape as
leaving distinct erosional features
form as the glacier carves
out the sides of existing V-shaped stream valleys
parallel scratches that form as embedded rocks in a glacier
scratches across the bedrock
are deep depressions formed in the
U-shaped valleys
are where two cirques on opposite sides of a
mountain meet and form a sharp, steep ridge
are where three or more cirques
meet and form a pyramid-shaped peak
famous example
in the Swiss Alps is a
are formed where a
tributary valley joins a U-shaped valley
Glacial Deposition
is the mixed debris that
glaciers carry embedded in their ice and on their tops and
are ridges of
is the area
at the leading edge of the glacier where the meltwater
streams flow and deposit outwash
form when glaciers move
over older moraines
are long, winding ridges of layered
sediments deposited by streams flowing under a melting
Glacial lakes form when large blocks of ice break off a
glacier and leaves behind a depression. The hole fills up with
precipitation and runoff to form a
Kettle lakes are common in New England, New York and
Unit 7 Day 5
Wind Erosion
can pick up and
Earth materials in the process of erosion. A current of
rapidly moving air can pick up and carry sediments in
the same way that other agents do. Wind is unique in
that it can also transport sediments
against the force of gravity.
When wind-blown particles tend to accumulate where
an object such as a rock or piece of vegetation blocks
Dune is a pile of
Wind generally cannot carry particles as large as those
The conditions under which a dune forms such as
transported by
availability of sand, wind
and the presence of vegetation determines the shape of
the sand dune
Hurricanes and tornadoes are the exception
Wind Transport
Types of Dunes
Winds transport materials in different methods
Barchan dunes are solitary crescent shaped dunes that
depending on the
is the method of transport by
which particles stay airborne for long periods
is transportation of particles by a
Particles also move by simply
the ground as the wind pushes them
form in flat areas where there is little sand or vegetation
Transverse dunes form where there is plenty of sand,
little or no vegetation, and strong, steady prevailing
Parabolic dunes are U-shaped and form between
clumps of vegetation
Longitudinal dunes form in areas where there is
limited sand available and strong prevailing wind
Wind Erosion
Areas that receive
amounts of .
are most susceptible to wind
Precipitation helps to hold down the sediments and
allows the
which helps curb
the effects of wind erosion
Deflation is the lowering of land surface as a result of
wind erosion
occurs when particles such as sand .
the surface of rocks and
wears them down
Since many sand particles are made of the hard
mineral quartz,
can be a
very effective agent of erosion
Ventifacts are rocks shaped by wind-blown sediments
Wind Deposition
Wind deposition occurs in areas where there is a
change in wind velocity as materials
and form a deposit on the ground
Dunes are very important to the environment. Coastal
against beach and coastal erosion
by reducing the direct
coastal dunes
Human activities such as building in coastal dune
areas have increased
and nearshore .
because of disruptions to the
dune building process
Many parts of Earth’s surface are covered with thick
layers of
. Where precipitation is
adequate loess soils are some of the
The fertile
have loess soils