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Spring 2025 > Chapter 8 - ESC1000 > Flashcards

Chapter 8 - ESC1000 Flashcards

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1
Q

List the three types of external processes?

A

Weathering, mass wasting, and erosion.

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2
Q

What are external processes?

A

Processes such as weathering, mass wasting, and erosion that is powered by gravity and the Sun, and transforms solid rock into sediment.

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3
Q

What are internal processes?

A

A process such as mountain building or volcanism that derives its energy from Earth’s interior and elevates Earth’s surface.

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4
Q

What is weathering?

A

The disintegration and decomposition of rock at or near Earth’s surface.

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5
Q

What is mass movement?

A

The downslope movement of rock, regolith, and soil under the direct influence of gravity.

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6
Q

What is erosion?

A

The incorporation and transportation of material by a mobile agent, such as water, wind, or ice.

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7
Q

What are the 2 types of weathering?

A

Mechanical weathering and chemical weathering.

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8
Q

What is mechanical weathering?

A

The physical disintegration of rock, resulting in smaller fragments.

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9
Q

What is chemical weathering?

A

The processes by which internal structure of a mineral is altered by the removal or addition of elements.

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10
Q

Explain how mechanical weathering aids chemical weathering?

A

Mechanical weathering breaks rocks apart into smaller rocks thus increasing the surface area available for chemical weathering.

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11
Q

What 4 processes lead to mechanical weathering?

A

Frost wedging, salt crystal growth, sheeting, and biological activity.

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12
Q

What is frost wedging?

A

The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices.

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13
Q

Explain how salt crystal growth works?

A

Sea spray or salty groundwater penetrates crevices and pore spaces in rocks, and as the water evaporates, salt crystals form. As the crystals grow, they weaken the rock and expanding the cracks.

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14
Q

What is sheeting?

A

A mechanical weathering process characterized by the splitting off of slab like sheets of rock.

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15
Q

What causes sheeting?

A

A plutonic mass exposed to confining pressure is uplifted and exposed to the surface where all that pressure is released and expands outwards causing the rock to increase in volume. The increase in volume is stronger than the rock and it tends to break in a series of fractures - sheets.

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16
Q

What is an exfoliation dome?

A

A large, dome-shaped structure, usually composed of granite, formed by sheeting.

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17
Q

How much does water increase in volume when it freezes?

A

It increases in 9% of volume.

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18
Q

What is biological activity weathering?

A

When the activities of organisms such as plants, animals and humans can cause weathering.

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19
Q

What is the most important agent of weathering?

A

Water.

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20
Q

What is carbonic acid?

A

A weak acid formed when carbon dioxide is dissolved in water. It plays an important role in chemical weathering.

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21
Q

How does granite weathers?

A

The carbonic acid attacks and replaces the potassium ions in the feldspar structure, thereby disrupting the crystalline network.

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22
Q

What is the most abundant product of chemical breakdown of feldspar?

A

Residual clay minerals.

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23
Q

What are other 2 residuals of chemical breakdown of feldspar and what happens to them?

A

Silica which is removed from the structure and carried away by groundwater. The silica eventually precipitates and fills pore spaces or is carried away to the ocean where animals use it to build shells. Quartz remain intact but are released from the rock where it can remail in the soil or carried away to the sea or other sites of deposition where it becomes the main constituent of sand. In time it can become lithified to form sandstone.

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24
Q

What is spheroidal weathering?

A

Any weathering process that tends to produce a spherical shape from an initially blocky shape.

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25
What is differential weathering?
The variation in the rate and degree of weathering caused by factors such as mineral makeup, degree of jointing, and climate.
25
How does carbonic acid form in nature?
Rain acquires some dissolved carbon dioxide as it falls through the atmosphere and it picks up more from decaying matter in the surface.
25
Why is soil referred as an interface?
Soil forms where the geosphere, atmosphere, hydrosphere, and biosphere meet.
26
What is soil?
A combination of mineral and organic matter, water, and air; the portion of the regolith that supports plant growth.
27
What is regolith?
The layer of rock and mineral fragments that nearly everywhere covers Earth's surface.
28
What is humus?
The organic decomposed matter made up of plants and dead organisms.
29
Why is humus important?
It provides an important source of plant nutrients and enhances the ability of soil to retain water.
30
Why is water and air important in soild?
Water provides contains many soluble nutrients and the necessary moisture for the chemical reactions that sustain life. Air is the source of oxygen and carbon dioxide needed by most microorganisms and plants need.
31
What is soil texture?
The relative proportions of clay, silt, and sand in a soil. A soil's texture strongly influences its ability to retain and transmit water and air.
32
What are peds?
Clumps of soils.
33
Why is soil structure important?
It influences how easily a soil can be cultivated and how susceptible it can be to erosion.
34
List the 5 controls of soil.
1. Parent Material 2. Time 3. Climate 4. Plants and Animals 5. Topography
35
What is parent material?
The source of the weathered mineral matter from which soil develops.
36
What are residual soils?
Soils whose parent material is bedrock.
37
What are transported soils?
Soils that develop on loose sediment.
38
How does parent material influences soils in 2 ways?
1. Influences the rate of weathering thus the rate of soil formation. 2. The chemical makeup of the parent material affects the soil's fertility.
39
What 2 factors of climate are the most influential factor in soil formation?
Temperature and precipitation.
40
How does temperature and precipitation affect soil formation?
They determine whether chemical weathering or mechanical weathering predominates and also greatly influence the rate and depth of weathering.
41
What is leaching?
The degree to which various materials are removed from soil by percolating water.
42
How does time affect soil formation?
The nature of soil is strongly influenced by the length of time processes have been operating. In a short period of time, the parent material greatly influences the characteristics of the soil. As time passes by, climate influences the characteristics of the soil even greater.
43
How does plants and animals influence soil?
The types and abundance of organisms influence the physical and chemical properties in soil.
44
What is the primary source for organic matter in soils?
Plants.
45
What does soil fertility depends in part on?
In the amount of organic matter present.
46
Why are microorganisms important in soil?
They play an important role in decaying plant and animal matter.
47
How does topography influence soil?
The length and steepness of slopes can significantly affect the amount of erosion and water content of soil.
48
How does slope orientation affect soil?
The direction a slopes is facing can cause a slope to receive more or less sunlight and that can cause differences in temperature and moisture.
49
What are soil horizons?
A layer of soil that has identifiable characteristics produced by chemical weathering and other soil-forming processes.
50
What is soil profile?
A vertical section through a soil, showing its succession of horizons and the underlying parent material.
51
What are the 5 soil horizons?
O, A, E, B, and C
52
What is the O soil horizon?
Thin, loose, and partly decayed organic matter.
53
What is the A soil horizon?
Largely mineral matter mixed with about 30% humus.
54
What is topsoil?
It's the combination of soil horizon O and A.
55
What is the E soil horizon?
Zone of eluviation and leaching which contains little organic matter.
56
What is eluviation?
The washing out of fine soil components from the horizon by downward-percolating water.
57
What is leaching?
The depletion of soluble material from the upper soil by downward-percolating water.
58
What is the B soil horizon?
Accumulation of clay transported from above. Referred to as the zone of accumulation or subsoil.
59
What is solum?
The O, A, E, and B horizons in a soil profile. Living roots and other plant and animal life are largely confined to this zone. Also referred to it as "true soil".
60
What is the C soil horizon?
It's partially altered parent material. It will eventually transform into soil, but it has not crossed the threshold that separates regolith from soil.
61
What is a mature soil?
A well developed soil profile that indicates stable environmental conditions over an extended time span.
62
What is an immature soil?
Soils that lack horizons because soil building has going on only for a short time.
62
What is soil taxonomy?
A soil classification system based consisting of six hierarchical categories based on observable soil characteristics. The system recognizes 12 soil orders.
63
What is soil erosion?
It's a natural process of soil moving from one place to another by erosional forces such as water and wind.
64
What is sheet erosion?
When water flows across the surface carrying dislodged particles of soil.
65
What are rills?
Tiny channels formed by sheet flows.
66
What are gullies?
Deeper channels formed as rills enlarge.
67
How does wind affect erosion?
When dry conditions prevail, strong winds can remove large quantities of soil from unprotected fields.
68
What affects the rate of soil erosion?
Depends on soil characteristics and factors such as climate, slope and type of vegetation.
69
List 3 methods of controlling soil erosion.
1. Constructing terraces in steep slopes. 2. Creating grassed waterways. 3. Plant rows of trees and shrubs that act as windbreaks.
70
What is the main force of mass movements?
Gravity.
71
What is a trigger?
An event, such as an earthquake or heavy rainfall, that initiates a mass movement process.
72
What are the 4 triggers of mass movement?
Water, over-steepened slopes, removal of vegetation, and earthquakes.
73
What is the angle of repose?
The steepest angle at which loose material remains stationary, without sliding downslope.
74
What are the 3 types of motion in mass movements?
Fall, slides, and flow.
75
What is fall?
A type of movement common to mass-wasting processes that refers to the free falling of detached individual pieces of any size.
76
What is slide?
A movement common to mass-wasting processes in which material moving downslope remains fairly coherent and moves along a well defined surface.
77
What is flow?
A type of movement common to mass-wasting processes in which water-saturated material moves downslope as a viscous fluid.
78
What are the 4 rapid forms of mass movement?
Slump, rockslide, debris flow, and earthflow.
79
What is a slump?
The downward slipping of a mass of rock or unconsolidated material moving as a unit along a curved surface.
80
What is a rockslide?
The rapid slide of a mass of rock downslope along planes of weakness.
81
What is a debris flow?
A relatively rapid type of mass wasting that involves a flow of soil and regolith containing a large amount of water.
82
What is a lahar?
A mudflow on the slope of a volcano that results when unstable layers of ash and debris become saturated and flow downslope, usually following stream channels. A type of debris flow.
83
What is earthflow?
The downslope movement of water-saturated, clay-rich sediment. Most characteristic of humid regions.
84
What are the 2 slow forms of mass movement?
Creep and solifluction.
85
What is creep?
The slow downhill movement of soil and regolith.
86
What is solifluction?
A slow, downslope flow of water-saturated materials common to permafrost areas.
87
What is permafrost?
Any permanent frozen subsoil.

Spring 2025 (16 decks)

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