1. Mass Movements and Erosion
Soil as a resource
Debbie Suzaña
Michelle German
Science 9th
February 22nd, 2013
Miss Chalas
2. Mass Movements
Mass movements refer to the downward transportation of
weathered materials by gravity. Landslides and rock falls are
examples of very sudden movements of this type. Of course
geological agents such as water, wind and ice all work with gravity
to cause a leveling of land.
3. Types of mass movement are distinguished based on how the soil,
regolith or rock moves down slope as a whole.
• Soil creep: is a long term process. The combination of small
movements of soil or rock in different directions over time are
directed by gravity gradually down slope. The creep makes
trees curve to maintain their perpendicularity even if they lose
their root footing.
4. A slump: is a form of mass wasting that occurs when a
coherent mass of loosely consolidated materials or rock
layers moves a short distance down a slope.
5. Earthflows • Mudflows
An earthflow is a down slope
viscous flow of fine-grained A mudflow is the most rapid and
materials that have been fluid type of downhill mass wasting.
saturated with water, and It is a rapid movement of a large
moves under the pull
of gravity. They are an mass of mud formed from
intermediate type of mass loose soil and water.
wasting that is
between downhill
creep and mudflow.
6. Erosion and landforms
• Erosion is the removal and transport of materials and it can be caused
naturally or through artificial means.
• One of the most powerful causes of erosion is water. Water is sometimes
called the universal solvent, because it is so effective at dissolving and
changing things.
• Rain and runoff contribute to erosion, as do glaciers, snow, and ice. Ice
can be particularly insidious, because it will literally rip rock and soil apart
as it expands and contracts. Many seashores distribute spectacular
examples of water erosion, in the form of huge terraces of rocks slowly
worn away by the ocean.
7. A resource is a source or supply
Soil as a Resource from which benefit is produced.
Soil is an important resource that can
be conserved and protected.
Because soil support plant life, which in
turn support animal and human life, it
is an important renewable resource.
8. Areas with the most fertile soil are often the same
places where people want to build houses. Thus, it is
important to conserve and protect the soil that is
available as a resource.
Soil fertility
Soil fertility is the ability of soil to grow plants. The
proportions of mineral matter, water, and organic
matter in soil determine the types of plants that will
grow in the soil. A number of problems, which include
soil depletion and salinization, threaten soil fertility.
9. Soil depletion
Crop plants and natural vegetation use up nutrients in soil.
When the plants die, they decompose in the ground, and
the nutrients are returned to the soil. When the crops are
harvested, however, the nutrients are removed from the
soil.
Soil depletion occurs when the soil
gradually becomes so lacking or depleted
in nutrients that it can no longer grow a
usable crop.
10. • Irrigation can make desert soils very Salinization
fertile. The problem, however, is that
the water brought in to irrigate a
desert contains dissolved minerals.
In time, the soil contains so much mineral
matter from the evaporated irrigation water
that the soil can no longer sustain crop
growth a process called salinization.
11. Erosion and soil conservation
For farms to remain productive, soil erosion must be controlled using soil conservation
methods:
Windbreaks, also known as shelterbelts, are
belts of trees planted along the edges of fields.
These trees slow and reduce wind erosion.
CONTINUE…
12. Contour farming is a method that inhibits water
from flowing rapidly downhill and carrying soil
with it. Is utilized in irrigation-dependent
regions where slope are moderately steep.
Terrace uses steps, that are built into the side of
a mountain or hill. Flattening a slope into
terraces slows the speed of runoff.
Strip – cropping is a method of farming used
when a slope is too steep or too long, when one
does not have an alternative method of
preventing soil erosion.
