Weathering and Erosion

1
(No Transcript)
2

• WEATHERING
• Is the breakup of rock due to exposure to
  processes that occur at or near Earths surface

3
Types of Weathering
Chemical Weathering
Mechanical Weathering
Chemical Weathering
Biomechanical Weathering
BiochemicalWeathering
Biomechanical Weathering
BiochemicalWeathering
4
Ice Wedging
5

• 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

6
Abrasion
7
Exfoliation
8
(No Transcript)
9
Hydrolysis
10
Limestone Karst
11
(No Transcript)
12
Oxidation
Oxidation of Desert Landscape
13
Weathering by Living Things (Biomechanical/Physica
l)
14
Weathering by Living Things (Biochemical)
15

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

16
Transport Agents
Wind Water Glaciers Gravity Volcanic Eruption
17
Wind
18
Water
19
Ice
20
Gravity
21
Volcanic Eruption
22
MASS WASTING
23
Types Mass Movement Erosion (Mass Movement )

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

24
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)

25
(No Transcript)
26
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.

27
Creep
28
Types of Landslides (Mass Movement Erosion)

• Slump - blocks of land tilt and move downhill
  along a surface that curves into the slope.
• Usually occurs becausethe top of the slope
  istoo steep and the bottom cant support it.

Slump Animation
29
Slump
30
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

31
Mudflow
32
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

33
Earthflow
34
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.

35
Lahar
36
Soils
37
Soil is a combination of highly weathered clastic
sediments (mostly sand, silt and clay), chemical
sediments and organic material in which plants
can grow.
38
The material from which soil is formed is called
Parent Material.
39
A soil can either be a Transported Soil or a
Residual Soil.
40
Soils formed from sediments that were produced
elsewhere are called Transported Soils (Example
Glacial and Alluvial Soils)
41
A soil whose parent material is the bedrock
beneath it is a Residual Soil
42
Residual Soils form as their parent material is
weathered away. How fast this happens depends on
four things1. 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
cant form on a slope)
43
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)
44
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
45
Soil Formation Sequence
46
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.
47
Examples of Soil Profiles from around the World
(Different types of soils)
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
(No Transcript)
53
(No Transcript)
54
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.
55
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 this1.
Allowing fields to remain fallow for a
period.2. Crop rotation.3. Fertilizing
(downsides-nutrients in runoff).
56
Salinization- The build-up of dissolved minerals
that are concentrated in lower soil horizons, and
are brought to the surface through irrigation.