WEATHERING TAKE TWOMr. Lewis

Vocab from last day (and an organizer!)

Weathering – the breakdown of rock due to exposure to the atmosphere and elements

Mechanical Weathering – When rock is broken down into smaller pieces (physical change)

Chemical Weathering – When rock is dissolved or it’s chemical composition changed

Ice Wedging – Water in small cracks freezes, expands and forces rocks apart breaking it

Erosion – the transport of broken down rock and soil

Chemical Weathering Caused by rainwater, oxygen, carbon dioxide, and

acids of plant decay Hydrolysis – the chemical reaction of water and

other substances Oxidation – the chemical reaction of oxygen and

other substances

Hydrolysis of carbon dioxide makes Carbonic Acid-This is why rain is normally acidic

Carbonic acid affects calcite the most causing it to dissolve completely (commonly makes underground caves)

Rocks and Weathering

Quarts does not react with water, oxygen or acids.

Quarts also doesn’t have cleavage so resists mechanical weathering

Feldspar Hornblende Augite Calcite Gypsum

Rocks which resist weathering

Rocks which easily weather

Climate and Weathering Chemical weathering happens faster

when the climate is warm and wet Mechanical weathering happens faster

when the climate is cold and dry Surface area is also an important factor:

More surface area = faster weathering

Weathering When rocks of different weathering

resistance are in the same place, neat landscapes can be made