1. What happened to the Appalachian
Mountains?
Weathering and Erosion!
Appalachian mountains today What scientists think the
Appalachian mountains
looked like 300 mya.

3. Weathering
•Weathering – The breaking down of rocks
on Earth’s surface into sediments.
•There are two types of weathering:

4. Mechanical Weathering
1. Mechanical Weathering- Rocks will
sometimes break down into smaller
pieces but is still the same material.

6. Mechanical Weathering
a. Ice Wedging (Freeze-Thaw cycles) -
Water has a unique property: it expands
when it freezes! When water enters a
crack in a rock and freezes, then
expands and thaws over and over again
it eventually breaks the rock up!

7. Mechanical Weathering
b. Abrasion - Wind, water, ice, and
gravity carry rock and sand particles
that grind away and break down rocks
like sandpaper (or sandblasting).

8. Mechanical Weathering
c. Plants and Animals-
Plant roots can grow into
cracks and break open rocks.
Burrowing animals move rock
material to the surface making it
easier to break down.

9. Chemical Weathering
2. Chemical weathering- breaking down of
rock by chemical reactions or changes.
Examples of Chemical Weathering:
a. Water - can dissolve and change rocks
and minerals. (Feldspar can change to
clay)

10. Chemical Weathering
b. Rust - Oxygen can
combine with Iron in
rocks which can
make them appear
red.
c. Lichens - Organisms
that live on rocks
called Lichens can
produce acids which
wear away at rocks.

11. Chemical Weathering
d. Acid Rain-Pollution reacts with the water vapor
in the clouds, producing acid rain.