Geology Ch. 5

Front 1

External processes include (name 3)

Back 1

weathering

erosion

mass wasting

Front 2

Weathering

Back 2

the disintegration and decomposition of rock at or near Earth's surface

Front 3

Erosion

Back 3

the removal of material by a mobile agent, usually water, wind, or ice.

Front 4

Mass Wasting

Back 4

the transfer of rock material downslope under the influence of gravity; and

Front 5

Why are they called external processes? What powers them?

Back 5

They are called external processes because they occur at or near Earth's surface and are powered by energy from the Sun.

Front 6

What are internal processes?

Back 6

By contrast, internal processes, such as volcanism and mountain building, derive their energy from Earth's interior.

Front 7

Mechanical weathering:


What are the 3 processes?

Back 7

BUF

is the physical breaking up of rock into smaller pieces. Rocks can be broken into smaller fragments by


biological activity

unloading

frost wedging

Front 8

Biological Activity

Back 8

biological activity (by humans, burrowing animals, plant roots, etc.).

Front 9

Unloading

Back 9

unloading (expansion and breaking due to a great reduction in pressure when the overlying rock is eroded away), and

Front 10

Frost Wedging

Back 10

frost wedging (where water works its way into cracks or voids in rock and upon freezing, expands and en¬larges the openings),

Front 11

Chemical weathering

Back 11

alters a rock's chemistry, changing it into different substances.


Oxygen dissolved in water will oxidize iron-rich minerals, while carbon dioxide (CO2) dissolved in water forms carbonic acid, which attacks and alters rock.

Front 12

___________is by far the most impor¬tant agent of chemical weathering.

Back 12

Water

Front 13

The chemical weathering of silicate minerals frequently produces:

Back 13

(1) soluble products contain¬ing sodium, calcium, potassium, and magnesium ions, and silica in solution

2) insoluble iron oxides, including limonite and hematite

(3) clay minerals

Front 14

(4) The rate at which rock weathers depends on such factors as:

Back 14

CMP


climatic factors

mineral makeup

particle size

Front 15

Climate Factors

Back 15

temperature
moisture

Frequently, rocks exposed at Earth's surface do not weather at the same rate. This differential weathering of rocks is influenced by such factors as mineral makeup and degree of jointing.

Front 16

Mineral Makeup

Back 16

calcite readily dissolves in mildly acidic solutions, and silicate minerals that form first from magma are least resistant to chemical weathering

Front 17

Particle Size

Back 17

particle size—small pieces generally weather faster than large pieces;

Front 18

Soil is a combination of:

Back 18

WAM

organic matter

water

air

portion of the regolith (the layer of rock and mineral fragments produced by weathering) that supports the growth of plants

Front 19

About half of the total volume of a good-quality soil is a mixture of

Back 19

disintegrated and decom¬posed rock (mineral matter)

humus (the decayed re¬mains of animal and plant life);

Front 20

The other half is....

Back 20

pore spaces where air and water circulate.

Front 21

The most im¬portant factors that control soil formation are:

Back 21

PPATTC

parent material
time
climate
plants
animals
topography

Front 22

Soil-forming processes operate from the ______________ and produce zones or layers in the soil called _____________

Back 22

surface downward


horizons

Front 23

Soil erosion is a natural process that is part of the _________cycle.

Back 23

rock


Once in a stream channel, soil particles, which can now be called sediment, are transported downstream and eventually de¬posited. Rates of soil erosion vary from one place to another and depend on the soil's characteristics as well as such fac¬tors as climate, slope, and type of vegetation. Human ac¬tivities have greatly accelerated the rate of soil erosion in many areas.

Front 24

secondary enrichment

Back 24

weathering creates ore deposits

by concentrating minor amounts of metals into economically valuable deposits.


accomplished by

(1) removing undesirable materials and leaving the desired elements enriched in the upper zones of the soil

(2) removing and carrying the desirable elements to lower soil zones where they are redeposited and become more concentrated.

Front 25

What important ores are created by weathering?

Back 25

aluminum
copper
silver