APES 9/30 Today’s Warm Up:
Solve the following:
(3 x 105)(4 x 105)
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Unit #2: What
does the Earth
have to offer?
Chapter 14
Geology & Earth
Resources
William P. Cunningham
University of Minnesota
Mary Ann Cunningham
Vassar College
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Outline
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Geologic Time—NOT in Textbook
Tectonic Processes—14.1
Rocks and Minerals—14.2
 Rock Cycle
Economic Geology and Mineralogy—14.3
Environmental Effects of Resource Extraction—Stay
tuned
 Mining
- Reclamation
Conserving Geological Resources—Stay tuned
Geological Hazards—Stay tuned
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Geology and Earth Resources
Haiti, 2010----Magnitude 7.0
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Case Study
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How strong were the two earthquakes?
Why was there more damage in Haiti, then in
Chile?
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Our Earth is a Dynamic Planet
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Earth’s Layers:
 Core - dense, intensely
hot metal, mostly iron.
Generates magnetic field
enveloping the earth.
 Mantle - hot, pliable layer
surrounding the core.
Less dense than core.
 Crust - cool, lightweight,
brittle outermost layer.
Floats on top of mantle.
The MOHO is the
boundary bet. crust &
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mantle
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Understanding Geologic Time Scale
Key Principles:
Each layer of rock= a “slice” of time
Principle of Superposition = any one layer is
older than the layers above it and younger
than the layers below it
Factors that Complicate the Time Scale:
Layers can be eroded, distorted, tilted, or
inverted—leads to misleading conclusions
Strata from same time in different locations is
not always the same
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Shows only part of Earth’s history
Strata
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Rock Strata are
not always
perfectly flat
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Timeline of Development
Earth is believed to be approx. 4.6 billion years old
First organisms are Prokaryotes
Eukaryotes came
much later
Multicellular Life forms, first in
sea, then on land
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Figure 14.6
p299
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The Continental Drift Theory
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Alfred Wegener 1915 suggested that Continents
were once one land mass (Pangaea) that broke up
approx 200mya:
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His Evidence:
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Fossilized tropical plants beneath Greenland’s icecaps
Tropics of Africa & South America have glaciated
landscapes
Evidence of previous polar climates in tropical regions
Continents form puzzle
Similarities in rocks & fossils along coasts of N & S
America and coasts of Africa & Europe
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Seafloor Spreading Theory:
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Study of rocks along mid-oceanic ridges
showed that the rocks are older in both
directions as move farther away from ridge
Suggested
that new crust
is created at
these rift
zones—the
seafloor is
spreading in
that area
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Tectonic Processes
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Tectonic Plates = large blocks of the Earth’s crust
 Slide slowly across earth’s surface, floating on
asthenosphere (upper mantle)
- Ocean basins form where continents crack
and pull apart.
- Magma (molten rock) forced up through the
cracks forms new oceanic crust that piles up
underwater in mid-ocean ridges.
Plates move slowly and form 3 different
boundary types—Transform, Divergent, and
Convergent
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Tectonic Plates
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APES 10/5 Today’s Warm Up:
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Solve the following:
(1.5 x 105) (2x10-3)
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Plate Boundary
Types:
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Image from: http://www.regentsearthscience.com/tsunami/plates.gif
Plate Boundaries:
1.Transform Boundary—
• Common--earthquakes
• Example: San Andreas Fault line in
N.America
2.Divergent Boundary—
• Common—oceanic earthquakes (milder),
form rifts & ridges—new crust forms
• Example: Mid-Atlantic Ridge, African Great
Rift Valley
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Plate Boundaries:
3. Convergent Boundary—
• Most often—Subduction—one plate moves below
the other—happens when oceanic plate is
involved—volcanoes common & severe
earthquakes
• Example: formation of Cascade Mtns—oceanic &
continental collide
• When 2 oceanic plates converge get Island Arc
• Example: Japan, Aleutian Islands in Alaska
• Sometimes two continental plates collide &
compress
• Example: Himalayan Mountains
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Tectonic Plate Movement
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Earthquakes:
caused by grinding and jerking as plates slide past
each other
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Massive amt. of stored energy is released very quickly
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Focus = some point, below Earth’s surface, where the
energy is released
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Seismic waves travel out from focus in all directions—
1st P Waves (horizontal movement, minimal damage—
all materials)& 2nd S Waves (vertical-through solids
only--more damaging)
Severity Depends on :
1. amt of stored (potential) energy that’s released
2. Distance the rock mass moved
3. How deep the movement occurred
4. Type of rock material
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Earthquakes
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Earthquakes - sudden movements of the Earth’s
crust that occur along faults where one rock mass
slides past another
 Gradual movement - called creep or seismic slip
- When friction prevents creep, stress builds up
until eventually released with a sudden jerk.
- Point at which first movement occurs is called
the epicenter—directly above the focus at the
surface
Most seismically active region in U.S. is the west
coast. Because??
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Earthquakes:
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Severity measured by Richter Scale—represents
ten-fold increases in wave amplitude, and 32 times
increase in energy released
Primary Effects on Environment:
Damage to buildings, infrastructure, knock down
trees
Secondary Effects:
Rock slides, flooding (due to land sinking), fires,
tsunamis
Worst death tolls from earthquake occur when
construction is poor. So where will damage be the
greatest?
Now buildings in US earthquake zones are
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reinforced.
Seismic Map of Earthquake Risk in the US
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Volcanoes
95% occur at subduction zones & midoceanic ridges
May produce/release:
Ejecta—lava rock &/or ash
Molten Lava
Toxic Gases—steam, CO2, SO2, and HCl
Can Affect Climate:
SO2 forms SO42- in stratosphere—serves as
condensation nuclei for clouds (makes acid
rain) and reflects shorter wavelength solar
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rays (cools temps—affects plant growth)
Volcanoes
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Volcanoes and undersea magma vents are the
sources of most of the Earth’s crust.
 Many of world’s fertile soils are weathered
volcanic material.
 500 million people live in danger zones.
 Pyroclastic Flow--deadly clouds of hot gas and
ash like those that destroyed Pompeii,
temperatures exceed 1000oC,they move at 60
mph and can kill in minutes.
 Mudslides often accompany eruptions.
 Volcanic dust and sulfur emissions reduce
sunlight and temperature around the globe.
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Volcanic eruption
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Other Geologic Hazards
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Asteroid impact led to extinction of
dinosaurs.
Floods take the greatest number of
lives, while
Wind causes the most property
damage.
Hurricanes bring both of these, don’t
they?
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Landslides
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Landslides are examples of mass wasting, in which
geologic materials are moved downslope from one
place to another.
 Can be slow and subtle or swift as in rockslides
and avalanches
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Road construction, forest clearing, cultivation, and
building on steep, unstable slopes increase the
frequency and damage done by landslides.
When road construction is over on a sloped piece
of land, what do they do? Why?
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Landslide in Pacific Palisades, California
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14.2 Rocks and Minerals
A mineral is a naturally occurring, inorganic, solid
element or compound with a definite chemical
composition and regular internal crystal structure.
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Rock Types
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A rock is a solid, cohesive, aggregate of one or
more minerals.
 Each rock has a characteristic mixture of
minerals, grain sizes, and ways in which the
grains are mixed and held together.
Rock Cycle - cycle of creation, destruction, and
metamorphosis—
Three major rock classifications:
 Igneous—cooling & crystalization of magma
 Sedimentary—compaction of sediments carried
from place to place (wind, water, ice, gravity)
 Metamorphic—modifies rocks using heat,
pressure, & chemical agents into new forms
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Rock Cycle
Mechanical /Physical
Weathering—physical
breakup without
changing chemical
composition—
scraping, rubbing
Chemical
Weathering—removal
or alteration of portions
of rock due to
reactions—oxidation,
hydrolysis
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Sedimentary Rock
The sedimentary rock of Bryce Canyon National Park
has been carved by erosion into tall spires.
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Geomorphology
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Geomorphology is the study of the processes
that shape the earth’s surface and the structures
they create.
Humans shape the Earth’s surface more than any
other single geomorphic process except plate
tectonics.
Estimates are that humans move 30-35 gigatons
(billion tons) of Earth materials
We also add approx 10 Gt each year to river
sediment through erosion from our activities
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End of 14.2—Stop Here
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Economic Geology & Mineralogy
Economic mineralogy is the study of minerals that are
valuable for manufacturing.
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Economic Geology and Mineralogy
Metals
Metals consumed in greatest quantity by world
industry (metric tons annually):
- Iron
(740 million)
- Aluminum
(40 million)
- Manganese
(22.4 million)
- Copper and Chromium
(8 million ea)
- Nickel
(0.7 million)
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Non-Metal Mineral Resources
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Gemstones and Precious Metals
 Their monetary value bankrolls despots, criminal
gangs, terrorism, inhumane labor conditions.
 Ex: Conflict Diamonds
Sand and Gravel - greatest volume and dollar value
 Brick and concrete construction, paving,
sandblasting
 Glass production
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The Rest of Chapter 14 will be covered in
another unit
Stay Tuned
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