WEATHERING: Is the breakup of rock due to exposure to processes that occur at or near Earth’s surface

Mechanical Weathering Chemical Weathering Types of Weathering Chemical Weathering Mechanical Weathering Chemical Weathering Biomechanical Weathering Biochemical Weathering Biomechanical Weathering Biochemical Weathering

Ice Wedging

Abrasion: The wearing away of rock material by grinding action Exfoliation: The peeling of surface layers from exposed bedrock Hydrolysis: The chemical reaction of water with other substances

Abrasion

Exfoliation

Hydrolysis

Limestone Karst

Oxidation Oxidation of Desert Landscape

Weathering by Living Things (Biomechanical/Physical)

Weathering by Living Things (Biochemical)

EROSION: The removal and transport of materials by natural agents.

Transport Agents Wind Water Glaciers Gravity Volcanic Eruption

Wind

Water

Ice

Gravity

Volcanic Eruption

MASS WASTING

Types Mass Movement Erosion: (Mass Movement ) Talus – rock fragments that have been weathered from a cliff and pulled down by gravity.

Types Mass Movement Erosion: (Mass Movement ) Landslide – movement of a mass of bedrock or loose soil and rock down a slope of a hill, mountain, or cliff. usually occurs on steep slopes after heavy rains or when large amounts of snow melt. (makes soil heavier and can make a layer of water between the soil and bedrock which makes the soil easier for gravity to pull down)

Types of Landslides: (Mass Movement Erosion) Creep – slow, gradual movement of soil down a slope. Objects fixed in the soil (fence) will also lean downhill. The presence of water in soil contributes to creep.

Creep

Types of Landslides: (Mass Movement Erosion) Slump - blocks of land tilt and move downhill along a surface that curves into the slope. Usually occurs because the top of the slope is too steep and the bottom can’t support it. Slump Animation

Slump

Types of Landslides: (Mass Movement Erosion) Mudflow - rapid movement of water that contains large amounts of suspended clay and silts. Can travel up to 100km/Hr can move rock, boulders, trees, and houses occurs in drier regions that get infrequent, but heavy rainfall

Mudflow

Types of Landslides: (Mass Movement Erosion) Earthflow - mass of weathered material saturated with water flows downhill Slower and less fluid than a mudflow. speed depends on the amount of water in soil, composition of soil, and steepness of slope can last a couple of days to years

Earthflow

Types of Landslides: (Mass Movement Erosion) Lahar - mudflow that accompanies a volcanic eruption. heat from the erupted material melts the snow on top of a volcano which and it moves down the side of the volcano.

Lahar

Soils

Soil is a combination of highly weathered clastic sediments (mostly sand, silt and clay), chemical sediments and organic material in which plants can grow.

The material from which soil is formed is called Parent Material.

A soil can either be a Transported Soil or a Residual Soil.

Soils formed from sediments that were produced elsewhere are called Transported Soils (Example: Glacial and Alluvial Soils)

A soil whose parent material is the bedrock beneath it is a Residual Soil

Residual Soils form as their parent material is weathered away Residual Soils form as their parent material is weathered away. How fast this happens depends on four things: 1. The rock type of the parent material (ex. some rocks are more chemically stable than others) 2. Climate (high rainfall, hot temps. Increase rate of soil formation) 3. Plant and Animal Activity (Biochemical and Biomechanical Weathering) 4. Slope (A deep soil can’t form on a slope)

A cross-section of a soil, from the surface (A) to the un-weathered parent material (R) is called a Soil Profile. (A) (B) (C) (R)

Organic remains (Humus) Fine particles of weathered parent material mixed with Humus- Topsoil Clays, Iron Oxides and dissolved minerals that have leached From above- Subsoil, usually brown or red Partially weathered parent material- Rock Fragments Parent Rock- “Bedrock”

Soil Formation Sequence

Conditions in which soils develop in different locations cause the profiles of soils to vary in appearance. What causes this variation is the composition, appearance and thickness of the 4 major layers or Horizons of a soil profile.

Examples of Soil Profiles from around the World (Different types of soils)

Soil Fertility-The ability of a soil to grow plants Soil Fertility-The ability of a soil to grow plants. Since different types of plants have different nutrient requirements, different soil types have different plant populations.

Harvesting crops that have used nutrients from the soil, removes those nutrients from the ground. This can cause soil to become depleted of nutrients. Several things can prevent this: 1. Allowing fields to remain “fallow” for a period. 2. Crop rotation. 3. Fertilizing (downsides-nutrients in runoff).

Salinization- The build-up of dissolved minerals that are concentrated in lower soil horizons, and are brought to the surface through irrigation.