Do Now: Read the Short story from John Muir, then answer the following questions: 1. Why is soil an important part of our environment? T and T 2. What are ways soil can be weathered?

Aim: Why is soil an important resource?

I. Soil is more than just dirt. Complex, ancient material teeming with living organisms Categorized by physical & chemical features color & texture How does soil form?

A. Soil Origin Weathering process that breaks rock into smaller pieces first step in soil formation

1. Physical weathering Aka mechanical Doesn’t change the chemistry of the rock Forces= wind and water

2. Chemical weathering Result of chemical interactions between water, minerals in the rock and other atmospheric gases.

3. Biological weathering result of the activities of living organisms

Severe erosion following tropical forest removal, Madagascar. What role does vegetation play?

Evacuated ocean front homes from cliffside erosion & heavy rains due to "El Nino" in What type of erosion is this?

B. Soil Texture Categories by U.S. Dept. of Agriculture (USDA) Clay- particles < 0.002mm in diameter Easily sticks together, really compacted Little pores so it can hold little water

Soil Textures Continued: Silt- particles mm in d Sand- particles mm in d Too large to easily stick, loose Large pores so it can hold more water

C. Soil Acidity & Alkalinity pH range= #0-14 Tells you the [] of hydrogen ions Soils pH is usually between 4-8 Neutral/slightly acidic Acidity: How acidic the soil is. pH = 0-6 Alkalinity: How basic the soil is pH = 8-14

1. pH affect on soil pH affects solubility of nutrients Determines the nutrients available for absorption by plant roots If too acidic/basic, certain soil nutrients will not be able to be used by regional plants

2. When soil becomes too acidic… ions of heavy metals like mercury (Hg) or aluminum (Al) can leach onto the ground water which can travel to streams & rivers harming plant & aquatic life Ex: aluminum ions can damage the gills of a fish and cause them to suffocate