Download Earth Materials and Processes

Ch. 2 Earth Materials &
Processes
Earth Materials & Processes
Focus:
Geologic materials and processes most important to the study of the
environment
Objectives:
– Acquire a basic understanding of the geologic cycle and its
subcycles (tectonic, rock, hydrologic, biogeochemical)
– Review of some of the important mineral and rock types and
their environmental significance
– Appreciation/significance of geologic structures
– Appreciation of the landforms, deposits, and environmental
problems resulting from wind and glacial processes
Earth Materials & Processes
1. Geologic cycles & processes (espec. Tectonics)
2. Rocks & Rock Materials
–
General properties
–
Types/classification (general)
–
Geologic structures
3. Surficial Processes: Ice & Wind
Earth (Geologic) Processes
Combinations of Internal and Surficial Processes affect and
shape the environment:
– Mountain Building Processes (Internal processes)
• Volcanism
• Faulting
• Folding
– Erosional/Depositional Processes (Surficial: driven by solar energy):
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Water/Rivers
Glaciers
Wind
Landslides
Geologic (Earth) Cycles
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Tectonic (plate tectonics)
Rock Cycle
Hydrologic Cycle
Biogeochemical Cycles
– Carbon, Nitrogen,
Phosphorous, etc.
Tectonic Cycle
• Tectonic = Large-scale internally driven
dynamic earth processes
• Shape and deform the earth’s crust (landforms)
– Mountain building
– Continents
– Basins
The earth is a differentiated planet with
dynamic internally-driven processes
Essentially all parts are in motion, producing:
“Plate” motions in the lithosphere: Plate Tectonics
Continuous cycling of “lithospheric” material through:
• Formation of new “oceanic” crust at “spreading centers”
• Destruction of older “oceanic” crust at “subduction” zones
• “Islands” of thick, relatively stable, “continental” crust
• These “zones” define plate boundaries
Surface/Crustal Manifestation of
Plate Tectonics
Observations/Correlations:
• Types and spatial distribution of plate boundaries
• Correlation between plate boundaries and volcanoes (+ earthquakes)
Two Types of Crust/Lithosphere:
r = 2.8
r = 2.9
• Oceanic
Crust (O)
• Continental
Crust (C)
r = 4.5
Core
r = 10.7
Two Types of Crust/Lithosphere:
• Oceanic (O):
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forms 70% of earth’s crust
constitutes sea-floor bedrock; ~30 km thick
made of primary volcanic “basalt”; density=2.7-3.0
Young; No old oceanic crust
• Continental (C):
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Thicker (~100 km)
Composition: Less dense sediment/granite
“floats” on denser mantle material
Older
• Mantle
– Primary material (from which basalts are derived)
– Underlies crust
Plate Boundaries
Most major tectonic activity (volcanoes,
earthquakes, etc.), and major topographic
features occur (or were formed) at plate
boundaries
Main Types of Plate Boundaries
• Divergent (splitting apart)
• Convergent (colliding)
• Third Type = Transform
(e.g., lateral offset)
Types Plate Motion, Plate Boundaries, and
Examples of Associated Landforms/Features
• Divergent (separating):
O-O
C-C
sea-floor spreading/mid-ocean ridges
Continental “rifts”: Red Sea, Rio Grande & Mississippi
river valleys, E. African (Kenyan) Rift Valley
• Convergent (colliding):
O-O Island arc Subduction; Japan, Aleutians
O-C Continental margin Subduction; Cascades, Andes
C-C Continental collision; Himalayas, Alps, Appalachians
Others: Obduction; Accreted terrain
Divergent Plate Boundaries (splitting)
Oceanic Rifts/Ridges
Continental Rifts:
– Red Sea; E. Africa
– Flood lavas (basalts)
Convergent Plate Boundaries (Colliding)
Continent-Contintent
Convergence
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Himalayas
Alps
Urals
Appalacians
Other Types of Convergence &
Convergent Features
Oman
Accreted Terrain:
•Olympic Mtns.
•Etc.
Obduction
•Coast Ranges
•Klammath Mtns
•Oman
•Newfoundland
Transform Boundaries
Lateral offset of
divergent boundaries
– Offsets of mid-ocean ridges
– San Andreas fault
Other Important Types/Features
• Hot Spots:
– Hawaiian Islands
– Yellowstone, Snake River Plain, Columbia River
Plateau
• Flood Basalt Provinces (within continents)
– Columbia River Basalts
– India, S. Africa, Greenland, Brazil, Germany, etc.
Hawaiian
Hot Spot
Also correlated with distribution of volcanoes and earthquakes (see book)
Plate Tectonics of the Western US
Major tectonic activity (volcanoes, earthquakes, etc.), and geographical features
occur at plate boundaries and/or hot spots.
Hydrologic Cycle
Carbon
Cycle
Rock Cycle
• Stay Tuned
Summary
• Earth is differentiated and dynamic
• Manifestation of dynamic earth processes in lithosphere =
plate tectonics
• Two types of crust: oceanic & continental
• Centers/Zones where crust is formed (spreading) or
destroyed (subducted) or accreted define plate boundaries
• Two types of plate boundaries:
– Divergent (splitting/spreading)
– Convergent
Summary con’t
• Major “tectonic”/topographic features/events are
localized at plate boundaries (volcanoes, earthquakes,
mountains, trenches, hydrothermal vents)
• Other related features:
– Transform boundaries (faults)
– Hot Spots (oceanic & continental)
• Hydrologic Cycle: Water transport & storage system
• Biogeochemical Cycles: Counterpart for chemicals ±
biologic systems/storage