Weathering and Erosion
Soil
• One result of
weathering is the
formation of soil
–Soil: a loose mixture
of rock fragments
and organic material
• Characteristics
determined by the
parent rock
–Includes
composition, color,
texture, and moisture
level
Target #10- I can
define the term
“soil”
Target # 11- I can
describe a soil profile
Target #12- I can label
the parts of a soil
profile on a diagram
• Generally, soils will
develop distinct
layers over time
–Soil profile: a
vertical section of
soil that shows the
layers of horizons
• Horizon: a
horizontal layer of
soil
• Draw the diagram
on the board
Target #13- I can define
all the parts of a
general soil profile
• Horizon C
–Bedrock: the solid, unweathered rock
found beneath all the other layers
–Regolith: the layer of weathered rock
fragments just above the bedrock
Target #13 cont.
• Horizon B
–Subsoil: contains clay, mineral
deposits, and organic matter
–Zone of Leaching: layer made of sand
and silt, lost most of its minerals due
to movement of water through the
layer
• Horizon A
–Topsoil: a dark
colored layer made
of organic material,
living organisms,
and rock particles
–Humus: the top,
organic layer of soil
made mostly of leaf
litter and organic
matter
Target #13 cont.
• Soil provides for many
important environmental
and societal functions
Target #14- I can
summarize why soil
is important for
environmental and
societal function
– Provides ecosystem
services critical for life
• Acts as a water filter
• A medium for growing
• provides habitat for billions
of organisms,
• contributes to biodiversity
– Supplies most of the antibiotics used to
fight diseases.
– Humans use soil as:
• a holding facility for solid waste
• filter for wastewater
• foundation for our cities and towns.
– Finally, soil is the basis of our nation’s
agro-ecosystems
• provide us with feed, fiber, food and fuel.
• Losing Dirt to Natural
Disasters
– Too much rainfall can lead to
mudslides or landslides
– The stripping away of the
topsoil prevents plants from
growing right away
• Losing Dirt to Man-made
Disasters
– Pollute it by dumping
chemicals and other wastes.
– Deplete it of nutrients by over
farming
– allow livestock to over graze
it
Target #15- I can
state How Nature
and Humans Have
Affected the Earth’s
Soil
• Desertification
– If too many animals are allowed to graze
for too long, the grass can be stripped
away and the soil will lose its anchoring
roots. The area can become a desert
• Soiled Soil
– If soil is polluted due to events like waste
dumping, the soil becomes toxic and is
potentially harmful to communities