chapter 10 section 2 rates of weathering rate of weathering. ... • describe how differences in...
TRANSCRIPT
5/19/2014
1
Chapter 10 Section 2
Rates of Weathering
Objectives
• Explain how the composition of rock affects
the rate of weathering.
• Describe how a rock’s total surface area
affects the rate at which the rock weathers.
• Describe how differences in elevation and
climate affect the rate of weathering.
Ledges exist in nature because
the rock that the ledge is
made of weathers more slowly than the
surrounding rock.
5/19/2014
2
Differential Weathering“Hard rocks, such as granite, weather more slowly than softerrocks, such as limestone.”
Differential Weathering – softer rocks weather away leaving harder rocks behind.
• Harder rocks = more weather resistant
(p284)
5/19/2014
3
The Shape of Rocks
Where does weathering take place?
On the outer surface of rocks
“The more surface area that is exposed to weathering, the faster the rock will be worn down.”
“Smaller rocks have more surface area… and is more exposed to the weathering process.”
Remember the rock weathering lab we did? Which experiment demonstrated how surface area affects the rate of weathering?
(p285)
5/19/2014
4
Weathering and Climate
Who do you think has fewer worries about the
condition of their car: Someone living in
Georgia or someone living in Arizona? Explain
your answer.
(p286)
Weathering and Climate
Three reasons why weathering happens more in warm humid climates:
1. Oxidation happens faster when temps are warmer
2. Water increases the rate of mechanical weathering
3. Climates of freezing and thawing have more ice wedging
(p286)
5/19/2014
5
Weathering and Elevation
Rocks of high elevation exposed to more:
• Wind
• Rain
• Ice
(p287)
Weathering and
Elevation
Gravity & weathering
• Steep slopes = quick rainwater run off
• Rainwater carries sediments
• Removing sediment = exposes rock
• Exposed rock = weathering, falling down sides
• Increased surface area = faster weathering
(p287)