Transcript Michela Griffin

Geology and Earth Resources
By: Michela Griffin
Earth as a Layered
Sphere
Core: Interior of the earth; composed of a dense,
intensely hot mass of metal that is thousands of
kilometers in diameter; contains metal
Surrounding the core is the mantle: Less dense than
the core; contains oxygen, nitrogen, magnesium
Outermost layer of earth is the crust: cool,
lightweight, outermost layer of the earth’s surface
that floats on the soft underlying layers- where the
seafloor and continents are
Tectonic Processes
The upper layer of the mantle has convection currents
that break the overlying crust in huge blocks called
Tectonic Plates: Huge blocks of the earth’s crust that
slide around slowly, pulling apart (diverge) to open
new ocean basins or crashing into each other
(converge) to create new, larger landmasses
When an oceanic plate collides with a continental
landmass, the continental plate will ride up over the
seafloor.
Continents drift together giant landmass (i.e.
Pangaea)
Techtonic Processes (cont.)
Earthquakes are caused by grinding and jerking as
plates slide past each other or as they converge or
diverge
Mountain ranges are pushed up at the margins of
colliding plates (i.e. Himalayas- Indian subcontinent
into Asia)
Speed of processes vary- 1cm a year to 18cm a year
Rocks and Minerals
Mineral: naturally occurring, inorganic, solid element
or composed with a definite chemical composition
and a regular internal crystal structure
Most fundamental characteristics: 1) Chemical
Composition and 2) Crystal Structure
No 2 Minerals are the same
Rock: solid, cohesive, aggregate of one or more
minerals
The Rock Cycle
The rock cycle includes a variety of geologic processes
that can transform any rock
The Rock Cycle (cont.)
Three major rock classifications: igneous,
sedimentary, and metamorphic
Igneous Rocks: The most common rock type; made
by cooling magma
Sedimentary rock is formed from the long-term
deposit and compaction of sediments into rock.
Metamorphic rock is rock formed when another
type of rock is changed by pressure, heat, and
tectonic processes. (i.e. limestone  marble)
IGNEOUS ROCK
SEDIMENTARY ROCK
METAMORPHIC
ROCK
Weathering
Mechanical weathering is the physical
breakup of rocks into smaller pieces without
changing the chemical composition.
Chemical weathering is the selective removal
or alteration of specific components that
leads to weakening and disintegration of the
rock
Economic Geology and
Mineralogy
Economic geology is the study of minerals that are
heavily used in manufacturing and an important part
of commerce.
Metals have been very important in human affairs (i.e.
Stone Age)
Most economically valuable resources exist everywhere
in small amounts
Metals & Nonmetals
Metals consumed in greatest quantity: iron,
aluminum, manganese, copper and chromiumproduced mainly in mountainous areas
Nonmetals (covers silicate minerals to sand, gravel,
salts, etc.): durable, highly valuable, and easily
portable
i.e. Gemstones
Sand and gravel production comprise by far the
greatest volume and dollar value of all nonmetal
mineral resources.
Environmental Effects
of Resource Extraction
Mining and purifying all of the mineral resources can
have severe environmental and social consequences
Can affect water quality: i.e. sulfuric acid is produced
when gold and other metals are mined from sulfide
ores- DANGEROUS
Chemical substances can contaminate lakes and
streams
Mining
Placer mining- washing out metals deposited in the gravel of
streambeds (i.e. gold) destroys streambeds but fills the water
with suspended solids that smother aquatic life
Other types of mining: open-pit mining, strip mining, and
underground mining
Risk of fires: inaccessibility and size of the fires make many
impossible to extinguish and control
‘Toxic Soup’ in metal mines can leak into lakes and endanger
wildlife- 12,000 miles of rivers and streams in the U.S. are
contaminated by mine drainage
1997 federal Surface Mining Control and Reclamation Act
requires better restoration of strip-mined lands; but restoration
is difficult because it is expensive
Processing Ores
Metals are extracted from ores by heating or with
chemical solvents- releases large quantities of toxic
materials
Smelting: roasting ore to release metals; major source
of air pollution
Heap-Leach Extraction: piling crushed ore in huge
heaps and spraying it with a dilute alakine-cyanide
solution; large water pollutant
Conserving Geologic Resources
Recycling
Metals are easily recyclable and require
much less energy than extracting new
metals (i.e. Aluminum)
New materials can be substituted for old
Using iron and steel replaced by polymers,
aluminum, etc.
Geologic Hazards
Earthquakes, volcanic eruptions, floods, and
landslides and other catastrophic events, though rare,
have shaped the earth significantly
Earthquakes can be very
destructive
Earthquakes are sudden movements in the earth’s crust
that occur along faults where one rock mass slides past
another one
‘Mysterious, sudden, and violent’
Worst death toll occurs in cities with poorly constructed
buildings
Most seismically active region in the U.S. is along the west
coast where tectonic plates are colliding
Tsunamis are giant seismic sea swells generated from the
center of an earthquake. They are incredibly destructive to
coastal areas.
Volcanoes
Volcanoes and undersea magma vents produce much of the
earth’s crust but release large volumes of ash and dust into the
air can block sunlight
“Ring of Fire”- seismic activity and active volcanoes around the
edge of the Pacific Ocean
More than 500 million people live in the danger zone around
volcanoes
Nuees ardentes (glowing clouds) are deadly, denser than air
mixtures of hot gases and ash like those that inundated Pompeii
Mudslides are also dangerous
Landslides
Mass wasting: geological materials are moved down
slope from one place to another
i.e. Rockslides and avalanches
Over $1 billion in property damage is done every year by
landslides in the U.S.
Many human activities such as road construction and
forest clearing increase the frequency and damage
done by landslides
Works Cited
http://martianchronicles.files.wordpress.com/2008/08/103949main_earth10.jpg
http://www.earth.northwestern.edu/people/seth/B02/nasa_plate_map.jpg
http://www.matt-willard.com/artwork/design/Rock-Cycle.jpg
Montgomery, C. W. 1997. Environmental Geology (4th ed.). Dubuque, IA: WCB/McGrawHill Co.
Plummer, C. C., et al. 1999. Physical Geology. Dubuque, IA: WCB/McGraw-Hill Co.
Ripley, E. A., et al. 1996. Environmental Effects of Mining. Delray Beach, FL: St. Lucie
Press.
http://www.mysciencebox.org/files/images/Rocks.JPG
http://www.fcgov.com/oem/oem-images/earthquake-map.gif
http://www.mhhe.com/biosci/pae/environmentalscience/cunningham6/student/olc/ref
erences_16.mhtml