Unit 4: Weathering, Erosion, Deposition and Landscapes

• Weathering is the breaking of rocks by changing their chemical composition. It occurs when rocks are exposed at the Earth’s surface. Agents of erosion transport these weathered materials

• Physical weathering results primarily from temperature changes, such as intense heat; the action of water freezing in rock crevices; and living organisms, such as tree roots and burrowing animals. Temperature changes alternately expand and contract rocks, causing granulation, flaking, and massive sheeting of the outer layers. Frost action and organisms widen cracks, exposing deeper layers to chemical weathering.
  
• Chemical weathering alters the original mineral composition of rock in a number of ways, such as by dissolving minerals by water and weak soil acids; by oxidation by producing a reaction with carbon dioxide; and by hydration, which is a process in which water chemically combines and reacts with minerals. Plants, such as lichens, also decompose certain rocks by extracting soluble nutrients and iron from the original minerals.
  
   The major factor in soil formation is the climate in which it forms in. Some types of climate are tropical, forest, grassland, desert, and arctic soils.

 WEATHERING POWERPOINT FROM CLASS

Here are some links for this unit

Surf your watershed http://www.epa.gov/surf2/hucs/04140203/

General weathering and erosion info http://www.rgs.edu.sg/events/geotrip/process.html

Encarta Encyclopedia Article  http://encarta.msn.com/index/conciseindex/0E/00E05000.htm

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Review Sheet- Weathering, Erosion, Deposition and Landscapes

Define-

Weathering-                                                                                             Surface Area: Volume—

Erosion-

Deposition-

PHYSICAL WEATHERING: types and description-                                                               

1.

2.

3.

CHEMICAL WEATHERING: (first to form = first to weather)   Requires:

1.

2.

Define SOIL:             Residual            Transported

A-horizon  

B-horizon

C-horizon

**It take from 100-400 yrs to form 1 cm of topsoil=a RESOURCE!!**

EROSION of sediments:  caused by—

1.

2.

3.

4.

DEPOSITION (sedimentation) of sediments:  affected by—                                                               

1. 

2.

3.

4.

EROSIONAL/DEPOSITIONAL SYSTEMS:

1.       Meandering Streams

    2.       Karst Topography (caves and caverns)

3. Glaciers (see GLACIERS review sheet)

SORTING of SEDIMENTS: (diagram, graph)

Vertical; Horizontal

Deposition in:

1)      In STREAMS

2)    By GRAVITY

3)      By GLACIERS

Define LANDSCAPE: (diagrams)

MOUNTAIN:                                     PLATEAU:                            PLAIN:

Describe the climate’s influence on landscape:

COMPETENT (tougher) rocks: form on higher lanscapes- plateaus, mountains, escarpments

SOFT rocks: erode faster

STREAMS: follow zones of weakness downslope- faults, etc.

GLACIAL LANDFORMS:  particular features, see GLACIERS section of review…

Drainage Patterns:

     DENDRITIC       ANNULAR        TRELLIS            RADIAL      RECTANGULAR