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View the effects of erosion which happens around us all of the
time.
The erosion in this park is caused by water, which washes away the
sand. After a while the sand is dug away away so much that the sand
around collapses and causes the hole to get bigger and
bigger.
A general description on erosion:
Some from (Source: http://en.wikipedia.org/wiki/Erosion)
Erosion is the carrying away or displacement of solids usually by
the agents of currents such as, wind, water, or ice by downward or
down-slope movement in response to gravity or by living
organisms.
Erosion is distinguished from weathering, which is the process of
chemical or physical breakdown of the minerals in the rocks,
although the two processes may happen concurrent.
Erosion is a noticeable intrinsic natural process but in many
places it is increased by human land use. Poor land use practices
include deforestation, overgrazing, unmanaged construction activity
and road-building. Land that is used for the production of
agricultural crops generally experiences a significant greater rate
of erosion than that of land under natural vegetation. This is
particularly true if tillage is used, which reduces vegetation
cover on the surface of the soil and disturbs both soil structure
and plant roots that would otherwise hold the soil in place.
However, improved land use practices can limit erosion, using
techniques such as terrace-building, conservation tillage
practices, and tree planting.
A certain amount of erosion is natural and, in fact, healthy for
the ecosystem. For example, gravels continuously move downstream in
watercourses. Excessive erosion, however, does cause problems, such
as receiving water sedimentation, ecosystem damage and outright
loss of soil.
Great landscapes have been formed due to erosion. Two well known
examples of this would the Grand Canyon in America, and the Fish
River Canyon in Namibia.
The opposite of erosion is 'deposition'.
Local knowledge.
In South Africa, the ditches caused by erosion is also known as
"Dongas".
Dongas were used by both sides during the Boer wars, as defensive
positions.
At this park.
In some instances, as can be seen in this park, erosion is
accelerated by human intervention. The cement tablet which the
water runs over, causes excessive erosion where the cement tablet
ends, and this is where the many layers of sand becomes visible.
This accelerate erosion is due to the water loosing very little
energy flowing over the concrete, and so the run off of the water
at the end of the concrete slab, has lots of energy. This
additional energy which the water mass has, erodes the sand away
much quicker at this point,as can be seen.
In extreme cases, the impact can be high as roads can be washed
away.
To log this cache, you need to complete the following 4
tasks:
1) Take a photo of you and your GPS at the spot.
2) Explain what the erosion looks like at the park, by taking /
estimating some measurements (the width of the donga, height of the
erosion, shape of the donga walls).
3) Explain how one could stop the erosion at this site.
4) Name one instance, where you have seen the effects of erosion
other then this park (can be anywhere, including TV)
Additional Hints
(Decrypt)
Nafjre nf vs lbh ner ba n svryq gevc.