1. Weathering

2. Weathering The breaking of rock into smaller & smaller pieces
Mechanical – wind, freezing, abrasion, release of pressure, plant & animal actions
Chemical – water dissolves, oxidation (rusting), plants secrete acid, pollution (acid rain)
Affected by the surface area of the rock exposed to the weathering process

3. Mechanical Weathering

4. AGENTS OF PHYSICAL/Mechanical WEATHERING
Freezing Action -The freezing and thawing causes alternate
expansion and contraction of rocks eventually breaking them
apart.
Dominate in mountain or polar regions.
More likely to occur in winter

5. Plant Action “Biological Action” - With plant growth the root system will increase in volume and cause cracks in the rock to expand.
Lichens are primary soil producers
creating conditions for larger plant growth.

7. Abrasion- When ice, water, or wind causes sediments
to have collisions physical weathering results.
Wind abrasion is similar to
sandblasting and slowly
weathers the rock down.

8. Chemical Weathering Alters the chemical makeup of the rock
Oxidation – “rusting”; oxygen reacts
Hydrolysis – dissolving minerals
Carbonic acid –”acid rain – extra CO2 in atmosphere mixes w/ H2O to form a weak acid.
Plants – secrete weak acids to break down rock.

9. Soil Formation
Soil is the loose, weathered material on Earth's surface in which plants can grow. It is a mixture of rock particles, minerals, decayed organics (humus) , air & water.
Bedrock is the solid layer of rock beneath the soil.
Soil forms as bedrock is weathered & mixes w/ organics & materials.
As soils form, it develops “layers” called horizons. Each horizon is named w/ letters (O, A, B & C) down to the bedrock.
Soil texture determined by the size of the particles making up the soil.