REVIEW OF EROSION AND WEATHERING - HOW THE EARTH
WEARS AWAY MOUNTAINS
Vocabulary: Erosion –The removing of rocks and rock materials by
_______________, _____________, ________________ water, and
_______________ . When the load of removed rock is dropped to a new
place it is called deposition.
Weathering - the break up of rocks at or near the surface. This process can
occur by chemicals or physical or mechanical means.
Both the processes of weathering and erosion often operate together to
change the Earth’s surface.
As rock material is weathered and eroded it can produce ______________.
This material then can accumulate in layers and by pressure and natural
cements form _______________________ rocks.
Examples of physical or mechanical weathering: Physical weathering is
when rocks are broken in to smaller pieces without changing the chemical
composition of the rock
1. Plant _______________ breaking up rock.
2. Animals walking on rock and digging into the ground.
3. When the _________________ of over laying rock is eroded away this
releases pressure and the new exposed rock expands and cracks. This is
called exfoliation because the exposed rock looks like it is peeled away.
4. When rocks heat up in the day they will _________________ (get larger
in volume) and in the night the rocks will cool and _________________
(get smaller in volume). This process of expanding and contracting
causes the rocks to peel and break apart. This usually occurs in
______________________ environments.
5. Moving water and air (wind) can carry sand and other particles. When
these particles strike rocks, they chip away the surface, much as you
would if you rubbed a rock with sandpaper. This process is called
abrasion.
Running water smoothing the rocks
6. When water collects in cracks of rock and the temperature goes down the
water will change to a ___________ called _________. Because ice takes
up more space then liquid water the ice expands and breaks up the rock.
This process is called ice wedging.
Examples of chemical weathering: Chemical weathering is when a rock is
broken down by chemical action resulting in a change in the composition of
a rock.
1. Chemicals in the atmosphere combine with water to form weak
____________ (such as carbonic acid) that eat away rocks. Example –
Water combines with carbon dioxide to form a weak acid that can eat
away and ________________ rock. Especially the rock in South
Florida called _______________________. This type of weathering is
a very slow process. It takes about 60,000,000 years to dissolve a
1000 foot layer of ____________________ rock. This process forms
caverns, sink holes, and sinkhole ponds. A sinkhole is a natural hole
or depression formed by acids dissolving the rock or by caves
collapsing. If the sinkhole fills up with water it is called a sinkhole
pond.
Sink hole Florida inside must show - http://www.youtube.com/watch?v=6RC9LP9lq5Y
2. When oxygen forms with other substances such as iron. In iron it
forms a new substance called iron oxide or rust which is red-brown in
color. This can weaken and crumble rocks as well as metals. This
process is called oxidation
FORCES THAT CAUSE EROSION
1. _______________ are large sheets of ice and snow on land made by
pressure and the melting and refreezing of water. As glaciers move under
the pull of gravity they cause ____________ by cutting U shaped valleys
and breaking and moving _____________.
http://www.bbc.co.uk/scotland/learning/bitesize/standard/geography/images/
g95_3.gif
http://www.personal.kent.edu/~sclement/dynamics/glaciers/glacie13.jpg
http://farm6.staticflickr.com/5065/5624644929_107305e3e2_z.jpg
http://www.pbs.org/wgbh/nova/vinson/ice-05.html
http://www.pbs.org/wgbh/nova/vinson/ice.html
2. _______________ - The winds cause the removal of loose rock material.
Sand grains driven by the wind will polish and grind away rock that the
loose particles of sand hit.
3. Ocean _________ will carry away and break up sand and rock material
on beaches. On our local beaches, in order to slow down wave erosion on
the back of the beach we have built sand hills called _______________.
On these dunes in order to slow down wave and wind erosion we have
planted plants. The plant _______________ hold down the sand and soil
and keep it from being eroded away.
4. Underground water - Acids in water will dissolve rock and carry away
the dissolved rock like limestone. This process helps form caverns and
the formations found inside caves stalagmites, stalactites, and columns as
the water evaporates and leaves behind the dissolved solid material.
Stages of the Formation of a Cave or Cavern
5. ________________ _________ - like rivers and streams break up rock
material, smooth and polish rock, and dissolve some minerals like
____________. Running water is the most common form of erosion and
forms V shaped valleys. Flooding of rivers or excessive rain will cause
major erosion in a short period of _____________________.
http://www.igeography.ie/mature-stage.html aging of a river video
6. The force of ____________ is the underlying force of erosion and
deposition. It causes water and glaciers to move down hill. Gravity can
also directly cause erosion in the form of landslides, mudslides, and the
slow movement of material down a hill. This process is called masswasting.