I. Earth's external processes include: occur at or near the earth’s surface.

            a) weathering  b) mass wasting  c) erosion

 

II. Weathering the disintegration and decomposition of material at or near the earth’s surface

A. Two kinds of weathering

1. Mechanical weathering-physically breaking down the rock

            a) frost wedging-expansion of water when it freezes

            b) unloading-releasing the pressure causes layers to exfoliate

            c) Biological activity- plant roots or burrowing animals

2. Chemical weathering-alters the chemical make-up or rock containing minerals

            a) oxidation by oxygen and corrosion due to acids

B. Rates of weathering

1. Advanced mechanical weathering aids chemical weathering by   increasing the surface area

2. Important factors are

a. Rock characteristics-opposite Bowen’s reaction series

b. Climate-mechanical good in polar regions, chemical good in tropics (warm and moist)

 

III. Soil- A combination of mineral matter, water, and air – that portion of the regolith (rock and mineral fragments) that supports the growth of plants

A. Controls of soil formation

1. Parent material  2. Time  3. Climate  4. Plants and animals  5. Slope

B. Soil Erosion- poorly protected soil is more prone to erosion

 

IV. Mass Wasting - The downslope movement of rock, regolith, and soil under the direct influence of gravity

1. Important triggering factors are:

            a)water b)oversteepend slopes c)removal of vegetation d)earthquakes

A. Types of mass wasting processes is defined by

1. The material involved

2. The movement of the material

3. The rate of the movement

 

B. Forms of mass wasting

a. Slump

b. Rockslide

c. Debris flow (mudflow)

d. Earthflow

e. Creep

f. Solifluction