Download Geology and Soil

Geology: Processes, Hazards, and
Soils
Brian Kaestner
Saint Mary’s Hall
Thanks to Miller and Clements
Geologic Processes
35 km (21 mi.) avg., 1,200˚C
Crust
100 km (60 mi.)
200 km (120 mi.)
Crust
Low-velocity zone
 Structure of
the Earth
Mantle
Lithosphere
Solid
10 to 65km
2,900km
100 km
(1,800 mi.)
3,700˚C
Outer core
(liquid)
Core
Asthenosphere
(depth unknown)
200 km
5,200 km (3,100 mi.), 4,300˚C
Inner
core
(solid)
Fig. 10.2, p. 212
Composition of Earth’s Crust
Earth’s Crust
Oxygen 46.6%
All others 1.5%
Magnesium 2.1%
Silicon 27.7%
Potassium 2.6%
Sodium 2.8%
Calcium 3.6%
Iron 5.0%
Fig. 10.4, p. 213
Aluminum 8.1%
Features of the Crust
Oceanic crust
(lithosphere)
Abyssal Oceanic
floor
ridge
Abyssal
floor
Abyssal plain
Abyssal
hills
Trench
Folded mountain belt
Craton
Volcanoes
Continental
shelf
Continental
slope
Continental
rise
Abyssal plain
Continental crust
(lithosphere)
Mantle (lithosphere)
Mantle
(lithosphere)
Mantle (asthenosphere)
Fig. 10.3, p. 213
Reykjanes
Ridge
EURASIAN PLATE
JUAN DE
FUCA PLATE
CHINA
SUBPLATE
Transform
fault
PHILIPINE
PLATE
PACIFIC
PLATE
MidIndian
Ocean
Ridge
Transform
fault
INDIAN-AUSTRLIAN PLATE
Southeast Indian
Ocean Ridge
NORTH
AMERICAN
PLATE
COCOS
PLATE
East Pacific
Rise
MidAtlantic
Ocean
Ridge
EURASIAN
PLATE
ANATOLIAN
PLATE
CARIBBEAN
PLATE
ARABIAN
PLATE
AFRICAN
PLATE
SOUTH
AMERICAN
PLATE
Carlsberg
Ridge
AFRICAN
PLATE
Transform
fault
Southwest Indian
Ocean Ridge
ANTARCTIC PLATE
Convergent
plate boundaries
Plate motion
at convergent
plate boundaries
Divergent ( ) and
transform fault (
boundaries
)
Plate motion
at divergent
plate boundaries
Fig. 10.5b, p. 214
Internal Earth
Processes
Lithosphere
Plate tectonics
Asthenosphere
Oceanic ridge at a divergent
plate boundary
Trench Volcanic island arc
Divergent boundary
Convergent boundary
Subduction zone
Lithosphere
Rising
magma
Subduction
zone
Asthenosphere
Trench and volcanic island arc at
a convergent plate boundary
Fracture zone
Transform fault
Transform
fault
Ring of Fire
Lithosphere
Fig. 10.6, p. 215
Refer to Fig. 10-5 p. 214
Asthenosphere
Transform fault connecting two
divergent plate boundaries
Lithosphere
Asthenosphere
Oceanic ridge at a divergent plate boundary
Fig. 10.6a, p. 215
Trench
Volcanic island arc
Rising
magma
Subduction
zone
Lithosphere
Asthenosphere
Trench and volcanic island arc at a convergent
plate boundary
Fig. 10.6b, p. 215
Fracture zone
Transform
fault
Lithosphere
Asthenosphere
Transform fault connecting two divergent plate boundaries
Fig. 10.6c, p. 215
Lake
Tidal
flat
Glacier
Spits
Stream
Lagoon
Dunes
Shallow marine
environment
Barrier
islands
Delta
Dunes
Beach
Shallow marine
environment
Volcanic
island
Coral reef
Continental shelf
Continental slope
Continental rise
Abyssal plain
Deep-sea fan
Fig. 10.7, p. 216
External Earth Processes
Erosion
Mechanical weathering
Frost wedging
Chemical weathering
Refer to Fig. 10-7 p. 216
Minerals and Rocks
Mineral (diamond, bauxite)
Rock Types
Igneous (granite, lava)
Sedimentary (limestone, sandstone)
Metamorphic (marble, slate)
The Rock Cycle
Transport
Deposition
Erosion
Sedimentary Rock
Shale, Sandstone,
Limestone
Heat,
Pressure
Weathering
External Processes
Internal Processes
Metamorphic Rock
Igneous Rock
Heat,
Slate, Quartzite,
Granite, Pumice,
Pressure
Marble
Basalt
Magma
(Molten Rock)
Fig. 10.8, p. 217
Natural Hazards: Earthquakes
 Features
 Magnitude
Liquefaction of
recent sediments
causes buildings
of sink
Two adjoining plates
move laterally along
the fault line
Earth movements
Cause flooding in
Low-lying areas
Landslides may
occur on
hilly ground
 Aftershocks
 Primary effects
Shock
waves
Epicenter
 Secondary effects
Focus
Fig. 10.9, p. 217
Expected Earthquake Damage
No damage expected
Minimal damage
Canada
Moderate damage
Severe damage
United States
Fig. 10.10, p. 218
Natural Hazards: Volcanic Eruptions
extinct
volcanoes
central
vent
magma
conduit
magma
reservoir
Solid
lithosphere
Upwelling
magma
Partially molten
asthenosphere
Fig. 10.11, p. 218
See Spotlight p. 219
Volcanoes
Earthquakes
Fig. 10.5a, p. 214
Soils: Formation
Soil horizons Soil profile
Humus
Immature soil
O horizon
Leaf litter
A horizon
Topsoil
Regolith
Bedrock
B horizon
Subsoil
C horizon
Young soil
Parent
material
Fig. 10.12, p. 220
Mature soil
Rove beetle
Pseudoscorpion
Flatworm
Centipede
Ant
Ground
beetle
Mite
Adult
fly
Roundworms
Fly
larvae
Beetle
Protozoa
Mites
Springtail
Millipede
Sowbug
Bacteria
Slug
Fungi
Actinomycetes
Snail
Mite
Earthworms
Organic debris
Fig. 10.13, p. 221
Soil Properties
Fig. 10.17, p. 224
Water
Water
 Infiltration
 Leaching
High permeability
Low permeability
 Porosity/permeability
100%clay
 Texture
 Structure
 pH
0
80
Increasing
percentage clay 60
40
20
20
Increasing
percentage silt
40
60
80
Fig. 10.16, p. 224
0
100%sand 80 60 40 20 100%silt
Increasing percentage sand
Water
High permeability
Water
Low permeability
Fig. 10.17, p. 224
100%clay
0
80
clay
20
60
Increasing
percentage clay
40
silty
clay
sandy
clay
40
60
clay
loam
sandy clay
loam
20
silty clay
loam
loam
0
100%sand
loamy
sand
80
80
silty
loam
sandy
loam
sand
Increasing
percentage silt
silt
60
40
Increasing percentage sand
20
100%silt
Fig. 10.16, p. 224
Table 10-1 p. 225
Texture
Nutrient
Capacity
Infiltration
Water-Holding Aeration
Capacity
Tilth
Clay
Good
Poor
Good
Poor
Poor
Silt
Medium
Medium
Medium
Medium
Medium
Sand
Poor
Good
Poor
Good
Good
Loam
Medium
Medium
Medium
Medium
Medium
Fig. 10.15b, p. 223
Mosaic
of closely
packed
pebbles,
boulders
Alkaline,
dark,
and rich
in humus
Weak humusmineral mixture
Dry, brown to
reddish-brown
with variable
accumulations
of clay, calcium
carbonate, and
soluble salts
Desert Soil
(hot, dry climate)
Clay,
calcium
compounds
Grassland Soil
(semiarid climate)
Fig. 10.15a, p. 223
Forest litter
leaf mold
Acidic
lightcolored
humus
Humus-mineral
mixture
Light-colored
and acidic
Light, grayishbrown, silt loam
Iron and
aluminum
compounds
mixed with
clay
Tropical Rain Forest Soil
(humid, tropical climate)
Acid litter
and humus
Humus and
iron and
aluminum
compounds
Dark brown
Firm clay
Deciduous Forest Soil
(humid, mild climate)
Coniferous Forest Soil
(humid, cold climate)
Fig. 10.15b, p. 223
Global Soil Erosion
Areas of serious concern
Areas of some concern
Fig. 10.19, p. 226
Stable or nonvegetative areas
Kansas
Colorado
Dust
Bowl
Oklahoma
New Mexico
Texas
MEXICO
Fig. 10.20, p. 227
Soils: Degradation
Desertification
Evaporation
Evaporation
Transpiration
Salinization
Waterlogging
Waterlogging
Less permeable
clay layer
Fig. 10.22, p. 229
desertification
Moderate
Severe
Very Severe
Fig. 10.21, p. 228
Fig. 10.23, p. 229
Solutions: Soil Conservation
Conventional-tillage
Conservation tillage
Cropping methods
Windbreaks
Land Classification
Refer to Fig. 10-24 p. 230
Windbreaks
Fig. 10.24d, p. 230
Alley cropping
Fig. 10.24c, p. 230
Control planting and strip cropping
Fig. 10.24b, p. 230
Soil Restoration
Organic fertilizer
Animal manure
Green manure
Compost
Crop rotation
Commercial inorganic fertilizer