1. WEATHERING & EROSION

2. What is Weathering?
Process by which rocks on or near Earth’s surface break down and change.

3. MECHANICAL WEATHERING
Also called physical weathering.
Changes rocks size and shape but NOT composition.
EX:
Frost Wedging: freezing water expands in rock causing cracks
Pressure:
from tree roots
removal of rock layers above. When rock layers are removed, rock can expand causing cracking.

4. CHEMICAL WEATHERING Changes rocks composition New minerals are formed
Determined by
Composition of rock
Calcite dissolves in acidic water
Temperature
As temperature increases so does rate of weathering

5. Water
Hydrolysis- reaction of water with other substances.

6. Oxygen Oxidation- reaction of oxygen with water.
Iron reacts with oxygen & creates rust
Magnetite + oxgyen = hematite

7. Acids
Carbon dioxide, nitrogen oxides, and sulfur dioxides from fossil fuels create acids in atmosphere.
Cause acid rain.
These acids dissolve minerals in rocks.
Can also tarnish metals

8. WHAT AFFECTS THE RATE OF WEATHERING?
Climate
Temperature & precipitation in an area
Chemical weathering more common where temperatures & precip are higher
Physical weathering more common where dry, and cold (freezing & thawing occur more common)

9. Rock type & composition
Hardness
Sedimentary rocks more easily weathered than hard igneous or metamorphic

10. Surface area
Mechanical weathering breaks rock up into smaller pieces… creating more surface area for chemical weathering to occur

11. Topography & other variables
Sloped areas expose fresh rock after erosion. Fresh rock can then be weathered.
Decaying organic matter releases CO2 which creates acid which weathers rock faster.

12. WHAT IS EROSION?
Transporting weathered materials from one place to another.

13. WATER Steeper slopes, faster water flows
Faster water flows, more erosion occurs
Rill erosion- creates small channels
Gully erosion- creates deep, wide channels

14. COASTAL EROSION Ocean waves & tides also cause erosion
Constant erosion of beaches leads to creation of sand bars which eventually become barrier islands.

15. ICE Glaciers Scrape out large sections of earth’s landscape
Carry large rocks & debris over many miles

16. WIND Occur in areas with limited rainfall and high temperatures
Most of these areas have very little plant-life to hold soil in place
Creates dunes

17. PLANTS, ANIMALS, HUMANS Minor impact compared to water, wind, glaciers
When humans excavate land, cause erosion, leads to water pollution
When animals burrow, shovel dirt somewhere else.

18. DAILY QUIZ #1 The breakdown of rocks is Oxidation is a form of
a. Erosion b. Weathering c. Mass wasting
Oxidation is a form of
a. Mechanical weathering b. Chemical weathering
When a rock changes in size & shape but not composition, it went through
Wind erosion can create
a. Glaciers b. Mass wasting c. dunes
Coastal erosion results from
Ocean Waves
Glacier formation
Chemical weathering