Geophysical Science Chapter 5

Mechanical Weathering

Physical forces break rock into smaller and smaller pieces without changing the rock’s mineral composition

Frost Wedging

When water works its way into cracks in rocks, water freezes and expands eventually breaking the rock

Chemical Weathering

The transformation of rock into one or more new compounds

Spherodial weathering

When water enters the joints of rock and weathers the corners, the corners and edges become more rounded

Laterite

Forms in hot, wet tropical areas, a type of soil that’s made of iron oxide and is a reddish color

Pedalfer

Forms in temperate areas that receive more than 63cm of rain each year, common in the eastern united states, rich in iron oxide and aluminum, red-brown color

Pedocal

Form in the drier western United states in grasses and bush vegetation, rich in calcite, light gray brown

Mass Movement

The transfer of rock and soil downslope due to gravity

Rockfall

Occurs when rock or rock fragments fall freely through the air

Rockslide

occurs when a slide of bedrock moves along a flat surface

Slump

The downward movement of a block of material along a curved surface

Mudflow

A mass movement of material containing water moving down quickly

Earthflow

Flows that move relatively slow about a few mm per day

Creep

The slowest mass movement, travels a few mm or cm per year

3 examples of mechanical weathering

1. 1. frost wedging

2. 2. unloading

3. 3. Biological activity

3 examples of chemical weathering

1. 1. dissolution

2. 2. reactions with water

3. 3. reactions with oxygen

Which mechanical weathering process forms exofliation domes?

Unloading

3 factors that affect the rate of chemical weathering

1. 1. The amount of surface area exposed

2. 2. rock characteristics

3. 3. climate

Chemical weathering has the greatest effect in what type of climate?

A climate with high temperature and abundant moisture

Rocks that are most to least susceptible to chemical weathering

limestone, marble, granite

What gas forms a mild acid when dissolved in water?

Carbon dioxide

In a flat, warm wet climate soil formation would be the

greatest

Particle size determines the plants..

texture

What is the main source of organic material in soil

plants

Horizon B is also called

subsoil

What is the main force behind mass movements

gravity

3 common causes of mass movements

1. 1. Saturation of surface materials with water

2. 2. oversteepening of slopes

3. 3. earthquakes

3 human activities that have increased soil erosion

1. 1. Farming

2. 2. logging

3. 3. construction

Soil erosion depends on..

climate, slope, and type of vegetation

These are structures formed when water erodes the soil (in order)

1. 1. Sheet erosion

2. 2. rills

3. 3. gullies

3 natural events that could increase the rate of soil erosion

1. 1. earthquakes

2. 2. floods

3. 3. rainfall