weathering. what is weathering? the process that breaks down rock into smaller pieces, called...
Post on 26-Dec-2015
227 Views
Preview:
TRANSCRIPT
Weathering
What is weathering?
The process that breaks down rock into smaller
pieces, called sediments.
Not to be confused with WEATHER!
There are two types of weathering:
Rocks are physically broken into smaller
pieces.
Rocks are broken down through chemical
changes.
The rate of weathering is affected by climate.
Mechanical happens faster in the cold weather.Chemical is faster in warm weather.
Mechanical Weathering
(physical)
Chemical Weathering
Forms of Mechanical Weathering
Ice Wedging
Exfoliation
Abrasion
Plants and animals
Ice Wedging (a.k.a. Frost wedging)
The cycle of water freezing and thawing in the cracks of rocks, causing the rock to break.
Click the picture for ice wedging animation!
ExfoliationPressure causes rocks to crack and “peel’ away in slabs.
Abrasion
Sediments carried by wind or water rub against other rock and wear it down. Like sandpaper!
Plant Wedging
Plant roots grow large and break apart rock.
Animals
Animals burrow into the ground and loosen sediment and soil.
Surface Area of Rock
As rock is broken apart by mechanical
weathering, the amount of rock
surface area exposed to air and water increases.
These smaller pieces will be
weathered faster than a larger piece.
EXIT SLIP1. What is weathering?
2. How do mechanical weathering and chemical weathering differ?
3. What type of weather conditions would increase the rate of chemical weathering?
4. The diagram shows the process of ice wedging. Explain how this process physically weathers rocks.
5. How can plants and animals contribute to the mechanical weathering process?
Forms of Chemical Weathering
Oxidation
Dissolution
Hydrolysis
Organic Acids
OxidationWhen materials that
contain iron are exposed to oxygen and water, they become a reddish color.
Ayer’s Rock, Australia
Dissolution Carbonic acid in rain dissolves rock. This can form caves and cause sinkholes.
Hydrolysis
Water combines with the minerals in rock and cause a chemical change.
If water combines with the mineral feldspar, clay is formed.
Organic Acids
Plant roots give off acids that dissolve rock.
EXIT SLIP6. Oxidation occurs when materials that contain iron are
exposed to what two compounds?
7. Dissolution can form sinkholes. Explain the process of dissolution.
8. How do plants and animals chemically weather rocks?
Can you tell which mountain is older?
What is soil?
A mixture of weathered rock, decayed organic matters, mineral fragments, water, and air.
Factors Affecting Soil Formation
top related