Chapter 5 Weathering, Soils, & Mass Movements

What do you know? What process breaks down rock into smaller pieces? A.) cementation B.) compaction C.) weathering D.) deposition Answer – C.) weathering

What do you know? Which of the following are types of weathering? Mechanical? Chemical? Answer: Both are forms of weathering

Mechanical Weathering Mechanical weathering occurs when physical forces break rock into smaller and smaller pieces without changing the rock’s mineral composition Each piece has the same characteristics as the original rock

Mechanical Weathering Mechanical Weathering Animation Mechanical Weathering Surface area increases as breakup a rock

Mechanical Weathering of Rocks 3 types 1 2 Uploading Frost wedging 3 Root wedging

1. Uploading Large masses of igneous rock are exposed through uplifting and erosion of overlying rocks

2. Frost Wedging The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices Sections of rock that are wedged loose and fall apart Frost Wedging Animation Can of coke explodes when it is frozen!

Frost Wedging

3. Biological Activity Plant roots can grow into cracks in rock and wedge the rock apart as they grow Burrowing animals move rocks to the surface, where weathering is more rapid

Chemical Weathering Chemical weathering is the transformation of rock into one or more new compounds If I gave you a piece of paper, how would you show me mechanical weathering? How would you then show me chemical weathering?

Chemical Weathering Water Most important agent in chemical weathering i.e. Oxygen dissolved in water reacts easily with certain minerals

Chemical Weathering Iron on barrels coverts to rust Iron + oxygen (from air) coverts to iron oxide (rust)

Chemical Weathering Rain water mixes sulfur & nitrogen produced from the burning fossil fuels- coal & gasoline Forming acid rain

Chemical Weathering “Acid Rain” Acid rain accelerates the chemical weathering of stone monuments and structures

Chemical Weathering Exposure to moisture and oxygen turns the copper into copper sulfate which is green in color.