Geology: Processes, Hazards, and Soils

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Geology Processes, Hazards,and Soils
Chapter 10 G. Tyler Millers Living in the
Environment 13th Edition
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Eight Most Common Chemical Elements ()
WHOLE EARTH WHOLE EARTH CRUST CRUST
Iron 33.3 Oxygen 45.2
Oxygen 29.8 Silicon 27.2
Silicon 15.6 Aluminum 8.2
Magnesium 13.9 Iron 5.8
Nickel 2.0 Calcium 5.1
Calcium 1.8 Magnesium 2.8
Aluminum 1.5 Sodium 2.3
Sodium 0.2 Potassium 1.7
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Features of the Crust
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Abyssal hills
Folded mountain belt
Abyssal floor
Oceanic ridge
Trench
Abyssal floor
Craton
Volcanoes
Continental rise
Oceanic crust (lithosphere)
Continental slope
Abyssal plain
Continental shelf
Abyssal plain
Continental crust (lithosphere)
Mantle (lithosphere)
Mantle (lithosphere)
Mantle (asthenosphere)
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Spreading center
Oceanic tectonic plate
Oceanic tectonic plate
Ocean trench
Collision between two continents
Plate movement
Plate movement
Tectonic plate
Oceanic crust
Oceanic crust
Subduction zone
Continental crust
Continental crust
Material cools as it reaches the outer mantle
Cold dense material falls back through mantle
Hot material rising through the mantle
Mantle convection cell
Mantle
Two plates move towards each other. One is
subducted back into the mantle on falling
convection current.
Hot outer core
Inner core
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Reykjanes Ridge
EURASIAN PLATE
EURASIAN PLATE
Mid- Atlantic Ocean Ridge
ANATOLIAN PLATE
JUAN DE FUCA PLATE
NORTH AMERICAN PLATE
CARIBBEAN PLATE
CHINA SUBPLATE
Transform fault
PHILIPPINE PLATE
ARABIAN PLATE
PACIFIC PLATE
AFRICAN PLATE
COCOS PLATE
Mid- Indian Ocean Ridge
SOUTH AMERICAN PLATE
Transform fault
Carlsberg Ridge
East Pacific Rise
SOMALIAN SUBPLATE
INDIAN-AUSTRLIAN PLATE
Southeast Indian Ocean Ridge
Transform fault
Southwest Indian Ocean Ridge
ANTARCTIC PLATE
Plate motion at convergent plate boundaries
Plate motion at divergent plate boundaries
Convergent plate boundaries
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Plate Tectonics

• Theory explaining the movement of tectonic plates
  and the processes that occur at their boundaries.
• more commonly referred to as continental drift

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Tectonic Plate Boundaries

• Divergent boundary

• Convergent boundary
• Subduction zone

• Transform fault

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Divergent Boundary
Lithosphere
Asthenosphere
Oceanic ridge at a divergent plate boundary
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Trench
Volcanic island arc
Lithosphere
Rising magma
Asthenosphere
Subduction zone
Trench and volcanic island arc at a convergent
plate boundary
Convergent Boundary
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Fracture zone
Transform fault
Lithosphere
Asthenosphere
Transform fault connecting two divergent plate
boundaries
Transform Faults
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Ring of Fire
Volcanoes
Earthquakes
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Natural Hazards Earthquakes

• Features
• Shock waves
• Focus and epicenter
• Magnitude
• Richter Scale
• 1(insignificant) to 9 (great) 10X
• Aftershocks
• Primary Effects
• shaking
• Secondary Effects
• Rockslides, fires, and flooding
• tsunamis

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Minerals and Rocks

• Minerals
• Naturally occurring
• Crystalline structure
• Inorganic
• Solid
• Rocks solid, cohesive, aggregate of one or more
  crystalline minerals
• Igneous (granite, lava)
• Sedimentary (limestone, sandstone)
• Metamorphic (marble, slate)

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Rock Cycle

• Cycle of creation, destruction, and
  metamorphosis.
• Three major rock classifications
• Igneous
• Sedimentary
• Metamorphic

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External Processes
Heat, Pressure
Internal Processes
Heat, Pressure
Igneous Rock Granite, Pumice, Basalt
Magma (Molten Rock)
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Soil

• Complex mixture of
• eroded rock
• mineral nutrients
• decaying organic matter
• water
• air
• micro-organisms
• Renewable resource
• Weathering of rocks
• Sedimentation
• Decomposition of organic matter

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Soils Formation

• Soil horizons

• Soil profile

O horizon Leaf litter
A horizon Topsoil
Humus
B horizon Subsoil
C horizon Parent material
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Soil Properties

• Infiltration

• Leaching

• Porosity

• Permeability

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Soil Properties

• Texture

• Structure

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Gravel 2-64 mm
Sand 0.05-2 mm
Silt 0.002-0.05 mm
Clay less than 0.002 mm
Soil Texture Triangle
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Chemical Properties of Soil

• pH
• Fertility
• 20 minerals needed for plant growth
• Major Nutrients (N-P-K)
• Nitrogen
• Phosphorus
• Potassium
• Minor Nutrients
• Soil Tests

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Desertification
Conversion of rangeland, rain-fed cropland, or
irrigated cropland to desert-like land, with a
drop in agricultural productivity of 10 or more.

• Causes
• Overgrazing
• Deforestation
• Surface mining
• Erosion
• Salinization
• Soil compaction

• Consequences
• Worsening drought
• Famine
• Economic losses
• Lower living standards
• Environmental refugees

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Soil Degradation

• Salinization -
• the accumulation of salt

• Waterlogging
• saturation of soil with irrigation water or
  excess precipitation so the water table rises
  close to the surface.

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Solutions Soil Conservation

• Conventional-tillage

• Conservation tillage

• Cropping methods

• Windbreaks

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Conventional tillage

• Crop cultivation method in which a planting
  surface is made by plowing land, breaking up the
  exposed soil, and then smoothing the surface.

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Conservation tillage

• Crop cultivation in which soil is disturbed
  little (mini-mum tillage farming) or not at all
  (no-till farming) to reduce soil erosion, lower
  labor costs, and save energy.

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Terracing
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Contour planting and strip cropping
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Alley cropping
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Windbreaks
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Soil Restoration

• Crop Rotation
• planting a field with different crops from year
  to year to reduce soil nutrient depletion.

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Soil Restoration

• Organic Fertilizers
• Animal manure
• Improves soil structure
• Adds organic nitrogen
• Stimulates beneficial soil bacteria and fungi
• Green manure
• Fresh and growing green vegetation
• Compost
• Microorganisms break down organic matter in the
  presence of oxygen

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Soil Restoration

• Commercial Inorganic Fertilizers
• Nitrogen, Phosphorus and Potassium
• N, P, K
• Advantages
• Easily transported, stored, and applied
• Disadvantages
• Not adding humus
• Reducing organic matter content
• Lowering oxygen content
• Supply only 2 or 3 of the more than 20 nutrients
  needed
• Require large amounts
• Release nitrous oxides