Weathering Erosion and Soil Notes Weathering Notes Weathering

Weathering, Erosion, and Soil Notes

Weathering Notes

Weathering - The surface processes that break down rock into small pieces called sediment.

Two Types of Weathering 1. MECHANICAL WEATHERING – Physical processes that break rock into fragments with the same makeup and characteristics as the original rock. Examples: 1. Plant Roots 2. Burrowing Animals 3. Ice Wedging - occurs when water enters cracks of rocks, freezes and expands, and breaks rock apart.

Mechanical - Plant Roots

Mechanical – Burrowing Animals

Mechanical – Ice Wedging

Two Types of Weathering • 2. CHEMICAL WEATHERING – Chemical reactions dissolve minerals in rocks or change them into different minerals. • Example: Oxidation - chemical process that occurs when iron is exposed to oxygen in the air causing the rock to break down.

Chemical - Oxidation

Chemical – Dissolving

Factors that Affect Rate of Weathering Factor Effects Climate Chemical Weathering - is rapid in warm, wet climates. Heat or high temperatures speed up chemical reactions that occur in water. Mechanical Weathering – is often rapid in colder climates that have frequent freezing and thawing. Some types, such as granite, weather slowly in warm wet climates than others, such as marble. Rock Type

Erosion Notes

Erosion - The wearing away and moving of surface materials by gravity, water, wind, or glaciers. 4 Agents of Erosion: 1. Wind 2. Water 3. Gravity 4. Glaciers

Types of Erosion Transportation- the carrying of sediments from one place to another. Mass Movement- occurs as gravity moves materials down a slope as one large mass. Deposition- when erosion agents drop sediments as they lose energy.

Types of Mass Movement Description Slump A mass of sediment slips along a curved surface. Mudflow A mixture of sediment and water flows down a slope. Creep Sediment moves downhill slowly. Rock Fall or Rock Slide Layers or blocks of rock break loose and move downhill suddenly.

MUDFLOW SLUMP

CREEP

ROCK SLIDE

Erosion Causes Consequences • Agricultural Cultivation • Forest Harvesting • Overgrazing • Urban Construction • Weather • Building Problems • Poor Soil • Damage to buildings and land Prevention • • Contour Farming Terracing Slopes Manage Crops

Soil Notes

SOIL- A mixture of weathered rock, decayed organic matter, mineral fragments, water, and air. A. It may take soil up to 1000’s of years to form.

The formation of soil is influenced by: Time affects soil formation because rocks are being weathered constantly and new soil is being added on top of old soil. This takes 1000’s of years but the layers of soil help determine how much water and nutrients a soil Length of sample TIME rock contains. weathered Biota means, “all the living organisms in an area”. This includes plants, animals even bacteria and decomposers. Biota helps speed up soil formation. Climate Formation of Soil Biota Hot climates can speed up chemical weathering, while cold weather can lead to ice wedging. Topography is the shape and steepness Slope – (Topography) or slope of the land. If the land is flat, water enters the soil and can speed up weathering. If the area is on a hill or slope the soil can be washed away or eroded. Types of Rock – Parent material (Parent Material) is the rock or sediment that forms soil when it is weathered. Bedrock is parent material that forms in the same place where the soil forms.

C. Soil may be made up of: • Particles of sediment such as clay, silt, and sand. • Humus - decaying, dark-colored plant and animal matter. • Water and air, which fill in the space between soil particles. • A soil profile consists of several horizons, or layers

HORIZON A Topsoil CHARACTERISTICS Top layer Fertile More humus, less rock C Bedrock B Subsoil Middle Layer Less Humus Lighter in Color Minerals through leaching Bottom layer Rocky Little organic matter Affected by glaciers

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