Chapter 6: Weathering and Soil Formation

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Chapter 6 Weathering and Soil Formation
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• The breaking down of rock and other substances at
  Earths surface is ___.

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• weathering

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• The principle stating that the same processes
  that operate today also operated in the past is
  ____.

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• Uniformitarianism

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• Which type of weathering causes the mineral
  composition of rocks to change?

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• Chemical Weathering

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• What are the most important factors in
  determining the rate of weathering?

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• Type of rock Climate

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What can geologists infer from the rounded,
eroded shapes of the Appalachian Mountains?
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• The mountains have been eroding for millions of
  years.

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• How does ice wedging cause mechanical weathering
  of rock?

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• Freezing thawing of water

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• Does weathering occur rapidly or slowly in a hot
  and wet climate?

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• Rapidly

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• Which agent of mechanical weathering occurs when
  rock is worn away by the grinding action of other
  rock particles?

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• Abrasion

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• A rock containing iron becomes soft and crumbly
  and reddish-brown in color. Which cause of
  chemical weathering has taken place?

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• Oxygen

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• Why does permeable rock weather easily?

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• Permeable rock contains many small, connected
  airspaces which allows water to pass through
  easily.

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• Why are areas of limestone easily eroded by
  groundwater?

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• Water combines with carbon dioxide as it sinks
  into the ground, creating carbonic acid, which
  slowly dissolves the limestone.

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• What begins the process of soil formation?

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• Weathering of bedrock

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• Soil that is rich in humus has high___________.

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• Fertility

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Soil formation would take place most rapidly with
the weathering of ______.

1. granite on a mountain top.
2. limestone in a desert.
3. granite in a cold, dry climate.
4. limestone in a warm, wet climate.

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• D. limestone in a warm, wet climate.

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• Why is soil a valuable natural resource?

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• Soil is important to all living things on land.

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• What are the two jobs of living organisms in
  soil?

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• mix the soil make humus

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• Earthworms add their wastes to the soil, then
  they die and decay in the soil. They are
  contributing to the formation of __________.

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• Humus

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Which of the following would be found in the B
horizon?

• clay, minerals, and little humus.
• humus only.
• partly weathered rock.
• topsoil.

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• A. clay, minerals, and little humus.

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• Plant growth and animal activity result in which
  type of weathering?

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• Mechanical weathering

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• Define contour plowing.

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• The practice of plowing fields along curves of a
  slope.

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• A marble statue is left exposed to the weather.
  Within a few years, the details on the statue
  have begun to weather away. What is the cause?

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• Carbonic acid in rainwater

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• In conservation plowing, why do farmers leave
  dead weeds and stalks of the previous years crop
  in the ground?

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• To retain moisture and hold soil in place