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Earth’s Interior and
Plate Tectonics
17.1
Earth’s Interior
Earth
is made up of 4 main
layers.
Crust
Mantle
Outer Core
Core
Crust
The
outermost and thinnest
layer of Earth.
Oceanic Crust – thinner more
dense crust (4 to 7 km)
Continental Crust – thicker less
dense (20-40 km, 25 miles)
Mantle
The
layer of rock between the
Earth’s crust and its core.
Denser than the crust.
2900 km thick
80% Earth’s volume
Core
The
center of a planetary
body.
Outer Core- liquid metal
Inner Core- solid metal
Earth’s Interior
As
you travel inside the Earth,
the temperature will increase.
The higher temperatures are a
result of radioactive isotopes
found in the rocks and layers
naturally decaying
Plate Tectonics
 The
theory made by Dr. Alfred
Wegner that Earth’s surface is made
up of large moving plates.
 Pangaea - super continent when
continents were one. (200 million
years ago)
Plate Tectonics

1.
2.
3.
4.
Evidence supporting the theory:
location of animal remains
the Earth’s appearance
(continental drift)
Magnetic alignment of oceanic
rocks show older rocks moving away
from oceanic ridges
Geological formations
250 million years in the future
Moving Plates
Lithosphere-
the thin outer
shell of the Earth, consisting of
the crust and the rigid upper
mantle. (over 30 large
pieces)
These pieces are called the
tectonic plates
Move 1 to 16 cm per year
How plates Move
Asthenosphere-
the zone of
the mantle beneath the
lithosphere that consists of
slowly flowing solid rock.
The lithosphere “floats” on
top of the asthenosphere.
How Plates Move
Convection
heat currents
from the Asthenosphere
causes the lithosphere to
move.
Asthenosphere
Plate
tectonics
Plate Boundaries
Three
Types:
Diverging Faults
Converging Faults
Transforms Faults
Plate Boundaries
Diverging Boundaries
When
two plates move
apart.
Caused by the rising of hot
molten rock called magma.
Forms mid-ocean ridges, new
oceanic crust (rift valley), and
volcanoes
Converging Boundaries
(Subduction Zones)
 Areas
where the lithosphere is diving
under each other. (subduction)
 Trenches form between two oceanic
plates (Mariana Trench off of Asia)
 Volcanoes, and mountains form when
an oceanic plate and continental plate
meet.
 Huge continental mountains form when
continental plates collide (Mt. Everest)
Convergence of the Nazca and South
American Continental Plates in Peru.
Transform Faults
When
rocks vibrate horizontally
past each other at faults.
Faults
a crack in the Earth created
when rocks on either side of a
break move.
Cause earthquakes
San Andrea Fault
Earthquakes
and Volcanoes
17.2
Earthquakes
The
movement of the Earth’s
lithosphere (tectonic plates)
along transform faults.
Japan, California, and
western coast of South
America experience the
most.


https://www.youtube.com/watch?v=7PfTh1Pix8E (science of Nepal)
What Causes
Earthquakes?
 Pressure
builds up between
moving plates causing
rocks to break
 This releases energy as
seismic waves.
 These waves cause the
Earth to shake.
Parts of an Earthquake
 Focus
is the exact area along the
lithosphere where the
earthquake originates.
Causing waves to travel in all
directions.
 Epicenter
is the area right above the
focus on the Earth’s surface.
Fault
Seismic Waves
Measured
as shock
waves
These seismic waves
help scientist
understand the interior
of the Earth.
3 types
Seismic Waves
1. Primary
Waves ( P-
Waves)
 Originate at focus
 Longitudinal vibration
st
 1 wave to reach
recording station
Seismic Waves
2. Secondary
waves)
 Originate
waves (S
at focus
 Move slower
 Transverse vibrations
Seismic Waves
3.
Surface Waves
Are the last waves to
register with seismographs.
 Only move across the
Earth’s surface.
 Circular motion vibrations
 Cause the most destruction

Seismology
The
science of detecting
and measuring earthquakes
Seismographs instruments
used to measure data from
an earthquake.
There is over 1000 stations
around the world
Modern Seismograph
How it works
See in action
Seismology
Scientist
use the difference
in time between P and S
waves to calculate the
distance to the epicenter.
They need information from
at least three stations to
pinpoint the focus and
epicenter of an
earthquake.
The Richter Scale
a scale that represents
the relative magnitude
of an earthquake.
Does not predict
damage it will cause

30
HTTP://WWW.CNN.COM/2010/WORLD/AMERICAS/01/12/HAITI.EARTHQ
UAKE/INDEX.HTML
http://earthquake.usgs.gov/earthquakes/
Haiti
San Francisco 1918
Alaska 1964
Indonesia 2004
http://news.bbc.co.uk/2/hi/asia-pacific/4136289.stm
Indonesia

Google Maps Earthquakes
Volcanoes
Vent
Any opening in Earth’s crust
where magma reached
Earth’s surface. (lava)
Release molten rock, lava,
ash, and poisonous gas.
Types of Volcanoes
1. Shield volcano
 Largest volcanoes
 very fluid lava that
flows great distances.
 Eruptions are usually
mild.
 Gentle slopes.
Shield Volcano
Types of Volcanoes
2.
Composite
 Lava is much thicker
 traps gases in the magma
 causes the eruptions to be
very violent (most
destructive)
 Steeper slopes
 (Mt. Fuji, Mt St. Helens)
Mt. Vesuvius- Pompei
Types of Volcanoes
3.
Cinder cones
 smallest and most
abundant
 gases are trapped
 they erupt violently with
lots of ash.
Types of Volcanoes
4.
Seamounts
 Underwater volcanoes
Seamount erupting
Virtual Volcano

virtual volcano review
Where do volcanoes
occur
75% occur in the Pacific
Ocean (Ring of Fire)
Along divergent and
convergent plate
boundaries
Minerals and
Rocks
17.3
Structure and Origins of Rocks
All rocks are made and composed
of mixtures of different minerals.
-Minerals: are natural, inorganic solid
compounds with a definite chemical
composition and internal structure.
 3500 known minerals in Earth’s crust
 Rocks and minerals classified by
texture, hardness, color, and density.

Feldspar
Pyroxene
Mica
Olivine/ “peridot”
Dolomite
Quartz
Clay
Calcite
Three Main Rock
Types
Igneous
Sedimentary
Metamorphic
Igneous Rock
Rock
formed physically from
cooled and hardened
magma or lava.
As a rock cools minerals
crystallize and grow.
Size of crystals depend on
how long the rock cools
Types of Igneous Rocks
1. Extrusive
igneous rock
 cools on surface of
Earth.
 Small mineral crystals
 Basalt, Obsidian
Extrusive Igneous Rock
Igneous Rocks
2. Intrusive
 Form
igneous rock
by cooling below
the Earth’s surface.
 Larger mineral crystals
 granite
Intrusive Igneous Rock
Sedimentary Rocks
Rock
formed physically
from the compressed or
cemented deposits of
weathered sediment.
Recycled rocks
Sometimes contain
fossils
Fossils
Sedimentary Rocks
They
are named
according to the size of
the fragments they
contain.
Sedimentary Rock Examples
 Conglomerate
 Rock
with
pebble sized
fragments
Sedimentary Rock Examples
 Sandstone
 Rock
with sand
sized fragments
Sedimentary Rock Examples
 Mudstone
 Rock
with fine
mud sized
fragments
Sedimentary Rock Examples
 Shale
 Rock
with flaky
mud sized
fragments
Sedimentary Rock Examples
 Limestone
 Rock
with fossils
of organisms that
lived in water
Metamorphic Rocks
Rock
chemically formed
from other rocks as a result
of being under
tremendous heat and
pressure for a period of
time.
New minerals form as a
result
Metamorphic Rock Examples
Marble
Formed
from
limestone
under heat
and pressure
Metamorphic Rock Examples
Slate
Formed
from
mudstone or
shale under
heat and
pressure
Rock Cycle- old rocks
will form into new
rocks p 580
How old are rocks?
Principle
of Superposition
Oldest will be on the bottom,
and the newest on top.
Useful with sedimentary rock
and dating fossils
Only gives a relative estimate
age
Principle of Superposition
How old are rocks?
Radioactive Dating
most minerals contain
material
with radioactive isotopes.
Scientists measure the amount
of radioactive material left in
rock sample and compare to
the rate at which the materials
decay.
Gives a more exact age of the
rocks.
Radioactive Half Life
Dating
Radioactive
Dating
Weathering and
Erosion
17.4
Weathering
Two
Types:
Physical
Chemical
Physical Weathering
Process
in which rocks are
broken down into smaller
pieces without altering the
rock’s composition.
Ice and plants are two
types of physical
weathering
Physical Weathering
When
water seeps into
rocks and then expands as
it freezes, breaking the rock.
Roots of plants can grow in
between the wedges, and
break the rocks.
Chemical Weathering
Breaking
down of rock
by changing its
chemical composition.
(chemical reaction)
Example #1
Badlands
(SD) are the
result of chemical
weathering
Iron reacting with oxygen
(oxidation) breaking
down rock leaving new
red hematite (Fe2O3)
minerals on the surface.
Example #2
When
CO2 dissolves in
water, Carbonic acid is
released
This acid then breaks
down the calcite forming
underground caverns
Example #3
Acid
rain
Precipitation that has an unusually
high concentration of acid in it.
Formed as a result of excess
burning of fossil fuels.
Acid rain is strong enough to
chemically break down rock
leaving behind the remains of
rocks.
Erosion
The
physical process by
which rock and the
products of weathering are
removed.
Weathered material may
be removed by running
water, wind, ice, or gravity.
Water Erosion
Glacier Erosion
Beach Erosion
Wind Erosion
Deposition
 Physical
process of relocating
sediment by laying eroded material in
a different space.