Chapter 2: Weathering and soil formation

Rocks and weathering - Weathering – a process that breaks down rocks and other materials on Earth’s surface. - Erosion – the action or movement of the weathered particles from one place to another by wind, water, ice or gravity. See page 39 for examples!

Mechanical Weathering When rock is PHYSICALLY broken down into smaller pieces – it is called mechanical weathering. See pages 40-41 for examples Chalk demonstration

Chemical weathering When a substance is broken down into smaller pieces through chemical changes – it is called chemical weathering. Water – H2O Oxygen – O2 Carbon Dioxide – CO2 Organisms Acid Rain (H2SO4)

Rates of weathering How fast or slow a rock weathers depends on the type of rock AND the climate. See pages 44-45

How soil forms Soil is loose, weathered material that helps plants grow. Bedrock – solid layer of rock beneath the soil. Page 49 – describes soil composition. Write the definition of soil composition in your notes using this page!!!

How soil forms Soil formation is constantly occurring when bedrock is exposed to the weathering agents of nature and man. See diagram on page 50 for details to help you with the GRP 2-2.

Living organisms in soil Look at page 52-53…. See how all things can affect the soil and its composition. What is humus? Humus is the material in soil that makes it fertile and usable for living things.