Soil & Weathering

 The breakdown of materials of Earth’s crust into smaller pieces. Weathering

Mechanical Weathering  Process by which rocks are broken down into smaller pieces by external conditions.  Types of Physical weathering  Frost wedging  Plant roots  Friction and impact  Burrowing of animals  Temperature changes

Frost Wedging

Plant Roots

Friction and Repeated Impact

Burrowing of Animals

Temperature Changes

Questions

Chemical Weathering  The process that breaks down rock through chemical changes.  The agents of chemical weathering  Water  Oxygen  Carbon dioxide  Living organisms  Acid rain

Water  Water weathers rock by dissolving it

Oxygen  Iron combines with oxygen in the presence of water in a processes called oxidation  The product of oxidation is rust

Carbon Dioxide  CO 2 dissolves in rain water and creates carbonic acid  Carbonic acid easily weathers limestone and marble

Living Organisms  Lichens that grow on rocks produce weak acids that chemically weather rock

Acid Rain  Compounds from burning coal, oil and gas react chemically with water forming acids.  Acid rain causes very rapid chemical weathering  Acid rain has the same ph level as tomato juice

Soil  What is soil?  Loose mixture of weathered rock, organic matter, water, and air  Is chemically and physically different from parent material

Soil Horizon  Soils have distinct zones that roughly parallel land surface

Horizon Layers  Typical soil profile  O horizon -- dark organic matter  A horizon -- contains some organic matter but many minerals are removed from this layer; Lighter-colored than O  B horizon -- contains decomposed rock such as clay, iron oxides, calcite; may be red, yellow, or tan  C horizon -- slightly altered parent material

Soil Horizons in Archaeology

Ashland, home of Henry Clay Soil Horizon 

Can you see the layers? Monticello, VA

Can you figure out the layers? Which is horizon O, A, B, & C?

Erosion  The process by which water, ice, wind or gravity moves fragments of rock and soil.

Water Erosion  Rivers, streams, and runoff

Ice Erosion  Glaciers

Wind Erosion

Mass Movements  Landslides, mudslides, slump and creep landslide clip.mpeg

POP QUIZ TIME!!  You may use your notes

POP QUIZ TIME!!  What is mechanical weathering?

POP QUIZ TIME!! 1 What are the two types of weathering?

POP QUIZ TIME!! 1 What are the two types of weathering? 2 Acid rain is which type of weathering?

POP QUIZ TIME!! 1 What are the two types of weathering? 2 Acid rain is which type of weathering? 3 Iron combines with what 2 things to form rust?

POP QUIZ TIME!! 1 What are the two types of weathering? 2 Acid rain is which type of weathering? 3 Iron combines with what 2 things to form rust? 4 Frost wedging & animal burrowing are which type of weathering?

POP QUIZ TIME!! 1. What are the two types of weathering? 2. Acid rain is which type of weathering? 3. Iron combines with what 2 things to form rust? 4. Frost wedging & animal burrowing are which type of weathering? 5. Which horizon has dark, organic matter?

POP QUIZ TIME!! 1. What are the two types of weathering? 1. mechanical & chemical 2. Acid rain is which type of weathering? 1. chemical weathering 3. Iron combines with what 2 things to form rust? 1. oxygen & water 4. Frost wedging & animal burrowing are which type of weathering? 1. mechanical 5. Which horizon has dark, organic matter? 1. Horizon O