Transcript Earth*s Geologic Processes

Earth’s Geologic Processes
Earth is a dynamic planet
The Earth Is a Dynamic Planet
1. Three major concentric zones of the earth
a. core
• inner most zone; solid inner mass surrounded by molten
material
b. mantle
• Including the asthenosphere
c. crust
• outermost and thinnest
• Continental crust – underlies continents including
continental shelf
• Oceanic crust: 71% of crust
2. Lithosphere - crust & outermost part of the
mantle (above asthenosphere)
Major Features of the Earth’s Crust
and Upper Mantle
Fig. 14-2, p. 348
Tectonic Plate Boundaries
Three types of boundaries between
plates:
a. Divergent boundaries
• Move apart
• Magma
• Oceanic ridge
b. Convergent boundaries
• Collide together
• Subduction zone
• Trench
c. Transform boundaries:
• Slide past each other
• San Andreas fault
Oceanic and Continental Plates
Be able to locate these areas on a world map!
1. When oceanic plate collides with continental plate
• continental plates rides on top of oceanic plate & oceanic plate is
pulled into mantle (subduction)
2. When oceanic plates move apart:
• Magma flows up through cracks and creates trenches
• EX: Mid-Atlantic Ridge)
3. When oceanic plates collide:
• Trenches form at the boundary between the plates
4. When continental plates collide:
• Mountains form
• EX: Himalayans are a result of Indian plate being pushed into Tibet
Earth’s Major Tectonic Plates
Fig. 14-4, p. 349
Himalayan Mountains
Results of Indian plate colliding
with Tibet plate
Volcanoes
1. Occur where magma reaches earth’s surface
through a central vent
2. Many occur along plate boundaries
3. Ring of Fire
4. Intraplate volcanism
a. volcanism within the plate interiors
b. Called hotspots
c. Most hotspots are thought to be underlain by a large
plume of anomalously hot mantle
d. The Big Island of Hawaii is one example located within
the Pacific Plate
1.
2.
3.
4.
Nazca plate is colliding with the South American plate – creating Andes
Mtns
Cocos plate is crashing into the North American – creating volcanoes
Pacific, Juan de Fuca, and Gorda plates have built the Cascades (Mt. St.
Helens)
Subduction of the Pacific plate under the Eurasian plate is responsible for
Japanese islands and volcanoes (Mt. Fugi)
Volcanisms and Intraplate Hotspots
Big Island of Hawaii and
Yellowstone volcanoes formed
as intraplate hotspots
Vocabulary of Earthquakes
2 Earthquakes
September 25, 2013
September 24, 2013
Magnitude 7.0 Peru
Magnitude 7.7 Pakistan
– Centered off Peru's sparsely
populated southwestern
coast
– minor damage and light
injuries were reported.
– Pakistan's remote south-west
province.
– Killed at least 208 people
– Many houses were flattened
and thousands of people have
spent the night in the open.
Richter Scale
An earthquake with a magnitude of 7 is 1000 times stronger than one with a
magnitude of 4
Earthquake Risk in the United States
Figure 16, Supplement 8
World Earthquake Risk
Figure 17, Supplement 8
Earthquakes on the Ocean Floor Can
Cause Huge Waves Called Tsunamis
• Tsunami, tidal wave
– Travels several hundred miles per hour
• Detection of tsunamis
– Buoys in open ocean
• December 2004: Indian Ocean tsunami
– Magnitude 9.15 and 31-meter waves at shore
– Role of coral reefs and mangrove forests in reducing
death toll
Formation of a Tsunami and Map of Affected
Area of Dec 2004 Tsunami
Fig. 14-8, p. 352
Rock Cycle
• Change of rocks from
one type to another type
• Slowest of all of Earth’s
cycles
Rocks verses
Minerals
Rock: composed of 1 or
more minerals
Minerals: solid chemical
substances with uniform
structures that forms
under specific
temperatures & pressures
Formation of Rocks
• Rock: forms when
magma from Earth’s
interior reaches the
surface, cools, and
hardens
• At surface, rock masses
are broken up, moved,
and deposited elsewhere
• New rock can be formed
from deposited material
• Magma is the original
source of all rock
Igneous Rocks
Both form directly from magma
• Basaltic:
 Dark colored
 Dominant rock type of oceanic plates
• Granitic
 Lighter colored
 Dominant rock type of continental
plates
 Forms sand when it breaks down
 Soils are permeable (helps move
water through)
Basaltic Rock
• Form bulk of earth’s crust but
covered with sedimentary rock
Granitic Rock
Sedimentary Rock
• Forms when sediments
(mud, sands, & gravel) are
compressed by over-lying
sediments
• Occurs over long periods of
time when environments
are buried (creates
pressure on material below)
• Rock may be very uniform
in composition or very
heterogeneous
Metamorphic
• Sedimentary, igneous, or
metamorphic rock are subjected
to high temperatures &
pressures
 May cause partial melting
• Pressure causes great physical
and chemical changes in rock
limestone
 May reshape internal crystalline
structure
• Pressure caused by overlying
rock layers or by plate tectonics
• EX: slate, marble, anthracite
marble
Physical Weathering
• Mechanical breakdown of rocks and minerals
• Caused by wind, water, or temperature changes
• Coarse grained or metamorphic rock tends to weather more
quickly over time
• Plant roots (trees) break apart rock
• Increases the surface area for chemical weathering
Chemical Weathering
• Lichen slowly release acid
onto rock
• A plant’s roots or animal cells
undergo cell respiration and
the CO2 produced diffuses
into soil, reacts with H2O &
forms carbonic acid (H2CO3).
• Acid rain also reacts with
rock and breaks it down
Lichen growing on rock
Erosion
• Physical removal of rock
fragments such as sediment,
soil, and other particles from
the ecosystem
• Caused by:
 Non-living things: wind,
water, and ice transport
soil & minerals down
slope
 Living things such as
animals that burrow
under soil
• Erosion is a natural process
(carves canyons)
Erosion by stream flow