Chemical or Physical weathering, agents, and process 9th grade

1. Weathering, Soil Formation &
Erosion Processes
by Ann C Cloutier 2011 Earth & Space

2. Can you hypothesize how the circle shapes were made ?
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3. Water is a powerful force
in chemical and physical (mechanical) weathering
• Temperature and pressure
are major factors in the
process of mechanical
weathering
• Changes in temperature can
cause a rock to split
• Chemical weathering is a
reaction between the rocks
and water
• It can result in the formation
of new rocks and minerals
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4. Agents of erosion
erosion is the process that moves weathered pieces of rocks to
new locations
(transport and deposition)
• Moving water in streams
and oceans
• Glaciers*
• Wind
• Gravity
• Gravity is the force
behind most agents of
erosion
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5. Caves and Karst topography are examples of
chemical erosion and the new formation of other
rock types
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6. Soil Horizons soil is made up of weathered rocks and
humus, which is decayed organic matter in soil
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7. Loess soil is great for the “Bread Basket”
USA agricultural crops
• Soil is residual or
transported
• Residual soil remains on
top of its parent rock
• Transported soil is
moved to a location
away from its parent
bedrock by water, wind
and glaciers
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8. Plant acids, roots, acid rain = chemical
weathering
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9. Who are the agents of erosion ?
• Wind • Particles and sediments must be very
tiny <2mm for the wind to pick up
• Water is fluid and flows downward;
• Water depending on the volume of water,
the slope it is descending and its
velocity, will determine how and
what it can move
• Gravity • Gravity makes rocks and sediments
roll downward; usually unsorted and
mixed particle sizes
• Glaciers are the BIG movers and
• Glaciers shakers of land formation; Sheets of
glacial ice can sandpaper bedrocks,
make grooves, pluck mountain tops
off and mix everything up
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10. The end of acid rain ?
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