Chapter 5 Flashcards

Sedimentary Rocks: Soil and Weathering

1
Q

Weathering

A

Physical/chemical breakdown of rock at or near the surface of the Earth to produce sediment.

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2
Q

Mass wasting

A

Transfer of that material downhill under influence of gravity.

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3
Q

Erosion

A

Sediment movement by water, ice or wind

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4
Q

Deposition

A

Sediment reaches a location where it accumulates

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5
Q

Lithification

A

Sediment turns into sedimentary rock

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6
Q

Mechanical weathering

A

Breaks the rock into smaller pieces by increasing surface area to allow chemical weathering to be more effective

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7
Q

Frost wedging

A

Water expands by 9% when it freezes and exerts pressure to break rock. Broken rock falls down to form talus.

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8
Q

Sheeting

A

Granite at the surface breaks into sheets/onion like layers due to pressure release. Temperature cycles create exfoliation domes.

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9
Q

Chemical weathering

A

Chemical reactions breakdown rock and ends with chemical sediment, ions dissolved in water. Hot and wet environments accelerate process.

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10
Q

Dissolution

A
  1. Electrostatic forces allow ions to be removed from solid. Pure water dissolves rock and the presence of a small amount of acid increases the effect.
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11
Q

Oxidation

A

Iron minerals that will break down when exposed to the atmosphere

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12
Q

Hydrolysis

A

Hydrogen ions react with and replace positive ions.

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13
Q

Spheroidal weathering

A

Manifestation of chemical weathering where sharp corners have more surface area per unit volume than flat surfaces. Chemical weathering is faster on corners and produces a smooth shape.

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14
Q

Regolith

A

Layer of rock and mineral fragments formed by weathering. Unconsolidated material that is mechanically weaker than the bedrock. Very thin, or non-existent in the Arctic and up to 5m thick in mountains. Thickest in sedimentary basins and along major rivers.

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15
Q

Soil

A

Interface between lithosphere, biosphere, hydrosphere and atmosphere. A combination of minerals and organic material in the upper part of the regolith.

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16
Q

Good soil

A

50% mineral matter and humus (decayed animal and plants), 25% air, 25% water.

17
Q

Parent material

A

Influences rate of soil formation (slower on bedrock, faster on unconsolidated material). Chemical makeup controls chemistry of soil and fertility. Different climates can produce different soil from the same parental material.

18
Q

Time

A

Initially, soil composition depends on the parent material. After, climate will have a greater effect.

19
Q

Climate

A

Temperature and precipitation. Most important soil influence

20
Q

Topography

A

Soil moves down a steep dry slope by erosion and does not develop. Lowlands will have higher moisture content and plenty of time to develop.

21
Q

Plants and animals

A

High organic content in a forest or bog, low organic content in a desert. Fungi, bacteria, worms etc… Influence soil composition and formation.

22
Q

Soil profiles

A

Soil formation is a top-down process and results in layers known as horizons.

23
Q

Horizon sequence

A

OAEBC

24
Q

O horizon

A

Layer of organic material

25
Q

A horizon

A

Mineral matter.

26
Q

E horizon

A

Layer of light colored minerals. Eluviation and leaching

27
Q

B horizon

A

Layer of precipitates.

28
Q

C horizon

A

Layer of altered parent material.

29
Q

True Soil (solum)

A

Horizons OAEB

30
Q

Top Soil

A

Horizons OA

31
Q

Pedalfer soil

A

Develops in a relatively humid, wet climate (forests). Calcium carbonate leached downwards by acidic conditions. B-horizon enriched in iron oxides and aluminum rich clays.
Found in SE Canada, Pacific coast and eastern United States.

32
Q

Pedocal soil

A

Found in relatively dry areas with grassland vegetation. Calcium carbonate leached upwards and precipitated.
Found in the Canadian Prairies (Edmonton).

33
Q

Laterite soil

A

Develops in hot, wet tropical climates. Intense leaching of calcium carbonate and silica. Leaves upper soil concentrated in aluminum and iron that gives red color. Minimal humus, not good for agriculture.

34
Q

Chernozemic

A

Central Alberta has drier climate than Northern Alberta. Pedocal soil

35
Q

Luvisolic

A

Northwest Alberta has wetter climate, Rocky Mountains are lower. Pedalfer soil

36
Q

Cryosolic

A

Permafrost regions, mature soil does not develop

37
Q

Soil erosion

A

Affected by rain, gullies, humans, rivers wind, etc…