Chemical and/or Physical breakdown of rock Physical Weathering (mechanical) breakdown of rock into...

• Chemical and/or Physical breakdown of rock

Physical Weathering

• (mechanical)

• breakdown of rock into smaller pieces– Does not involve a

chemical change in the rock

Frost Action/Wedging

• alternate freezing and thawing due to the expansion of water when freezes = potholes

b. Abrasion

– Rounding of rocks due to the rocks hitting each other

c. Root Action

• Roots wedge and grow in rocks

d. Exfoliation

• Large sheets of loosened rock peel away

Chemical Weathering

• Breakdown of rock due to a chemical change in the rock

• Often requires water

• The higher the temperature, the faster the chemical weathering

a. Oxidation

Iron + Oxygen iron oxide, (commonly called rust)

b. Carbonation

• Carbon dioxide + water = carbonic acid (in rain) – a weak acid

• Slowly dissolves Limestone and Marble

Karst Topography

CavesandSinkholes

• http://www.youtube.com/watch?v=tQvv8YFCGsY

• Karst and corvettes

• http://blog.hemmings.com/index.php/2014/02/12/breaking-news-eight-cars-damaged-by-sinkhole-at-the-national-corvette-museum/?refer=news

c. Hydration

• Water plus other minerals

• Ex. Feldspar + water will slowly change into clay

1. Particle Size/Surface Area exposed at Surface

• The more surface area exposed, the ________ the weatheringquicker

Why will smaller particles weather faster?

Which will weather faster and why?

Pebbles Sand Silt Clay

2. Mineral Composition

a. The harder the rock, the longer it takes to break down

b. Calcite/Limestone >> dissolves in acidic water

Which layer, X or Y is more resistantto weathering?

Y, is hasn’t weathered as much

3. Climate

• A. Warm, moist climate >>>

• B. Moist with temperature variations of freezing and thawing >>>