Water, temperature changes, and chemical reactions are key factors in weathering and erosion. Water is particularly powerful in mechanically and chemically breaking down rock. Moving water, glaciers, wind, and gravity transport eroded materials and deposit them elsewhere. Over time, this leads to soil formation and changes in landforms, as seen with caves and karst topography. Different soil types such as loess are suitable for certain agricultural uses. Plant roots and acids like acid rain also contribute to chemical weathering of rocks.

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

2. Can you hypothesize how the circle shapes were made ?
ann c cloutier 2011 copyright

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
ann c cloutier 2011 copyright

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
ann c cloutier 2011 copyright

5. Caves and Karst topography are examples of
chemical erosion and the new formation of other
rock types
ann c cloutier 2011 copyright

6. Soil Horizons soil is made up of weathered rocks and
humus, which is decayed organic matter in soil
ann c cloutier 2011 copyright

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
ann c cloutier 2011 copyright

8. Plant acids, roots, acid rain = chemical
weathering
ann c cloutier 2011 copyright

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
ann c cloutier 2011 copyright

10. The end of acid rain ?
ann c cloutier 2011 copyright