weathering:

56

Upload: gafna

Post on 07-Jan-2016

77 views

Category:

Documents


1 download

DESCRIPTION

WEATHERING: Is the breakup of rock due to exposure to processes that occur at or near Earth’s surface. Types of Weathering. Chemical Weathering. Mechanical Weathering. Chemical Weathering. Biomechanical Weathering. Biochemical Weathering. Biomechanical Weathering. Biochemical Weathering. - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: WEATHERING:
Page 2: WEATHERING:

WEATHERING:

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

Page 3: WEATHERING:

Types of Weathering

Mechanical Weathering

Chemical Weathering

Biomechanical Weathering

BiochemicalWeathering

Chemical Weathering

Biomechanical Weathering

BiochemicalWeathering

Page 4: WEATHERING:

Ice Wedging

Page 5: WEATHERING:

Abrasion:•The wearing away of rock material by grindingaction

Exfoliation: •The peeling of surface layers from exposed bedrock

Hydrolysis:•The chemical reaction of water with other substances

Page 6: WEATHERING:

Abrasion

Page 7: WEATHERING:

Exfoliation

Page 8: WEATHERING:
Page 9: WEATHERING:

Hydrolysis

Page 10: WEATHERING:

Limestone Karst

Page 11: WEATHERING:
Page 12: WEATHERING:

Oxidation Oxidation of Desert Landscape

Page 13: WEATHERING:

Weathering by Living Things (Biomechanical/Physical)

Page 14: WEATHERING:

Weathering by Living Things (Biochemical)

Page 15: WEATHERING:

EROSION:

•The removal and transport of materials by natural agents.

Page 16: WEATHERING:

Transport Agents

WindWater

GlaciersGravity

Volcanic Eruption

Page 17: WEATHERING:

Wind

Page 18: WEATHERING:

Water

Page 19: WEATHERING:

Ice

Page 20: WEATHERING:

Gravity

Page 21: WEATHERING:

Volcanic Eruption

Page 22: WEATHERING:

MASS WASTING

Page 23: WEATHERING:

Types Mass Movement Erosion: (Mass Movement )

• Talus – rock fragments that have been weathered from a cliff and pulled down by gravity.

Page 24: WEATHERING:

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 betweenthe soil and bedrock which makes the soil easier for gravity to pull down)

Page 25: WEATHERING:
Page 26: WEATHERING:

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.

Page 27: WEATHERING:

Creep

Page 28: WEATHERING:

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 istoo steep and the bottom can’t support it.

Slump Animation

Page 29: WEATHERING:

Slump

Page 30: WEATHERING:

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

Page 31: WEATHERING:

Mudflow

Page 32: WEATHERING:

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

Page 33: WEATHERING:

Earthflow

Page 34: WEATHERING:

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.

Page 35: WEATHERING:

Lahar

Page 36: WEATHERING:

Soils

Page 37: WEATHERING:

Soil is a combination of highly weathered clastic sediments (mostly sand, silt and clay),

chemical sediments and organic material in which plants can

grow.

Page 38: WEATHERING:

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

Page 39: WEATHERING:

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

Page 40: WEATHERING:

Soils formed from sediments that were produced elsewhere are called

Transported Soils (Example: Glacial and Alluvial Soils)

Page 41: WEATHERING:

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

Residual Soil

Page 42: WEATHERING:

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)

Page 43: WEATHERING:

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)

Page 44: WEATHERING:

Organic remains (Humus)

Fine particles of weathered parent material mixed with Humus- Topsoil

Clays, Iron Oxides and dissolved minerals that have leachedFrom above- Subsoil, usually brown or red

Partially weathered parent material- Rock Fragments

Parent Rock- “Bedrock”

Page 45: WEATHERING:

Soil Formation Sequence

Page 46: WEATHERING:

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.

Page 47: WEATHERING:

Examples of Soil Profiles from around the World (Different types

of soils)

Page 48: WEATHERING:
Page 49: WEATHERING:
Page 50: WEATHERING:
Page 51: WEATHERING:
Page 52: WEATHERING:
Page 53: WEATHERING:
Page 54: WEATHERING:

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.

Page 55: WEATHERING:

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).

Page 56: WEATHERING:

Salinization- The build-up of dissolved minerals that are concentrated in lower soil

horizons, and are brought to the surface through irrigation.