Weathering and Soil Formation

1
Weathering and Soil Formation

• Chapter 10
• Standard S6E5.d
• Describe process that change rocks and the
  surface of the earth.

2
What you will review

• Describe how ice, water, wind, gravity, plants,
  and animals cause mechanical weathering.
• Describe how water, acids, and air cause chemical
  weathering of rocks.

3
The Big Idea????

• Weathering is a continuous process that results
  in the formation of soil and the development of
  landforms.

4

• 1. Weathering
• 2. Mechanical weathering

• The process by which rock materials are broken
  down by the action of physical or chemical
  processes.
• The breakdown of rock into smaller pieces by
  physical means.
• Examples ice, wind, water, gravity, plants,
  and animals.

5
Abrasion Wind, Water, and Gravity

• Abrasion is the grinding away of rock surfaces
  through mechanical action.
• Wind sand/silt blown against exposed rock.
• Water rocks/pebbles roll bump/scrape each
  other.
• Gravity Rocks fall on each other from a
  mountainside.

6
Ice

• The alternate freezing thawing of soil /rock is
  called frost action.
• Ice wedging is when water seeps into cracks
  during warm weather, freezes during cold,
  expands, and pushes against the sides of the rock
  causing cracks.

7
Check point

• Name three things that can cause abrasion.
• Wind
• Water
• Gravity

8
More Mechanical Weathering

• Plants strong roots grow slowly over time
  forcing the rocks to expand crack.

9

• Animals- burrowing in the ground breaks loosen
  rocks to be exposed to weathering.
• Ex Moles, prairie dogs, insects, worms, and
  gophers

10

• Chemical weathering

• The process by which rocks break down as a result
  of chemical reactions.

11

• Acid precipitation - Rain, sleet, or snow, that
  contains a high concentration of acids.
• Examples sulfuric and nitric acids from
  volcanoes, burning of fossil fuels.

12

• Acids in Groundwater - Carbonic or sulfuric acids
  in groundwater dissolve rocks form caverns.
• Mammoth Cave, Kentucky

13

• Living things Lichens produce acids that can
  slowly break down rock.
• Air oxidation Iron combines with Oxygen to
  produce a chemical reaction called rust.

14
ReviewWhich one is which?

• A rock fall on a mountainside
• mechanical
• A rusty bridge
• chemical
• Lichens and mosses growing on a boulder
• chemical
• An alpine glacier advancing down a valley
• mechanical