SOLID EARTH
FINAL REVIEW
Layers
crust, mantle, outer core, inner core
Inner core- solid iron & nickel
Outer core- liquid iron & nickel, where
magnetic field is generated
Mantle makes up most of Earth’s mass
Lithosphereis the solid crust & upper mantle
(the tectonic plates)
Asthenosphere- soft layer of upper
mantle (convection currents)
Pressure and temperature increase
with depth
Magma is formed when rock melts
Primary (p waves ) are compression waves
• Secondary waves (s waves) are shear waves
P waves can travel through
BOTH solids and liquid
• S waves can only travel through solids
Seismic waves arrive in this order- P, S,
then surface
Indirect evidence of the interior is
obtained by studying seismic waves
Ocean crust gets denser as it gets cooler
LESS DENSE
MORE DENSE
Oceanic crust is denser and younger
than continental
• Continental crust is older than oceanic
Oceanic crust is mostly basalt
Continental crust is mostly granite
• Oceanic
Continental
Sediments get thicker and older away
from the mid-ocean ridge
Convection currents in the mantle
move tectonic plates
Seismographs record ground movements
Earthquakes can cause; building collapse,
soil liquefaction, and a tsunami
E3.4B
• Richter scale measures ground movement
• Moment magnitude scale measures energy
released
• Mercalli scale measures earthquake damage
Earthquakes with a shallow focus are
more likely to cause severe damage
A bulge in the surface of a volcano is a
warning sign
• A "bulge" developed on the north side of Mount St. Helens as magma
pushed up within the peak. Angle and slope-distance measurements to
the bulge indicated it was growing at a rate of up to five feet (1.5 meters)
per day. By May 17, part of the volcano's north side had been pushed
upwards and outwards over 450 feet (135 meters). The view is from the
northeast.
Movements along a fault are measured
with; tilt meters, laser ranging devices, and
GPS satellites
E3.4C
• A Tsunami is a giant wave caused by an
underwater earthquake
Aftershocks can cause more damage and
injuries so people should NOT go back inside
Actual ground movement is least likely
to cause deaths during earthquakes
Deaths occur from collapsing dams flooding,
falling debris, and fires from broken electric
and gas lines
E3.4C
• Types of rock and soil under buildings affect
how it responds to an earthquake
Seismic gaps, foreshocks and changes
in rock help forecast earthquakes
Japan’s March 11, 2011 Earthquake
Earthquake risk is high on the Pacific coast
because the Pacific and North American plates
meet at the San Andreas Fault
Most EQ and Volcanoes occur at plate
boundaries and where stress on the rock is
greatest
Transform boundary forms when
plates slip past each other
A fault is a break in the Earth’s crust
Heat transfer by direct contact is conduction, by
flowing in a fluid is convection and through open
space is radiation.
Wegener’s hypothesis stated the continents were
once joined as Pangaea and then broke apart.
Wegener’s
hypothesis
stated the
continents
were once
joined as
Pangaea and
then broke
apart.
Convection currents occur because heated
material becomes less dense and rises
The density of each plate determines
what occurs when plates collide
Plate tectonic theory explains why and
how continents move
A rift valley forms when two
continental plates diverge
Sea-floor spreading causes new ocean
floor to constantly be produced
When oceanic and continental plates collide
the oceanic plate subducts under the
continental
An underwater mountain chain formed by
sea-floor spreading is called a mid-ocean
ridge
Along mid-ocean ridges molten
material rises from the mantle
Uplifting brings rocks to Earth’s surface
where they then can erode
The Himalayas formed by the process
of convergence.
Divergence forms rift valleys and the
mid-ocean ridges
Deep-ocean trenches form in a
subduction zone
• In plate movement speed = distance / time
so a plate that moved 550 cm in 50 years
moved at a rate of 550/50= 11 cm/year
Carbon¹⁴ dating works because of carbon in
living things, it doesn’t work on the moon
The half-life of a radioactive element is the
time it takes for ½ of the atoms to decay
Radioactive decay is when atoms of an
unstable element break down to form
another element
• Fossils provide evidence for; changes in the
Earth’s surface, how environments have
changed over time, how groups of organisms
have changed over time.
Fossils are most common in
sedimentary rocks
Index fossils were; common while alive, existed
for a short distinct time, geographically
widespread, and easily recognizable
Index fossils tell the relative age of rocks. Rocks with
identical index fossils are about the same age
Index fossils
tell the
relative age
of rocks.
Rocks with
identical
index fossils
are about the
same age
USGS
Earth is about 4.6 billion years old
Most of the atmosphere now is
Nitrogen
The atmosphere formed during the
precambrian time
The impact hypothesis states an asteroid or
meteorite from space caused the extinction of
dinosaurs.
The gradual
development
of new
organisms
from
preexisting
ones is called
evolution
Geologic time scale is a record of life forms
and geologic events in Earth’s history
The longest geologic time is the precambrian
Fossils are rare in precambrian rocks because
most precambrian organisms had soft body
parts that did not form fossils
E5.3C cont.
• Blue green bacteria used photosynthesis to
make food and produced more oxygen in the
atmosphere. Photosynthesis produces oxygen
During the rise of life a great number
of different organisms evolved
Ozone layer formation allowed plants and
animals to move out of the water onto
land during the Paleozoic Era
• The Permian mass extinction probably
occurred because organisms could not live in
the new climate created by Pangaea
Earth’s ‘second atmosphere’ was made of
mostly carbon dioxide, nitrogen and water vapor
The Cenozoic mass extinction of large
mammals probably occurred because of
the ice ages
• Volcanic out gassing helped form the
Earth’s atmosphere
Done E5.3C
The
geologic
time
scale is
divided
into eras
and
periods
Some Sedimentary rocks form from
fragments of other rocks
• Steps to form sedimentary rocks from igneous
rock are erosion, deposition, compaction and
cementation- erosion removes and transports
rock materials
Lynn S. Fichter © 2000
Rocks change to metamorphic rock by
heat and pressure
Rock cycle is the process rocks follow to change
to other rocks; igneous, sedimentary, &
metamorphic
Large crystals form in granite when
it cools slowly
• Plate collisions affect the rock cycle when one
plate is forced down to the heat of the mantle
and produces metamorphic rock
During an Earthquake stand in a
doorway or crouch under a desk
Fossils of tropical plants are found in Antarctica
giving evidence plates moved
Sonar is used to map the ocean floor
The Pacific Ring of Fire is a zone of
volcanoes and earthquakes
USGS
The Pacific Ring of Fire is a zone of
volcanoes and earthquakes
• The mantle is heated by earth’s core energy
and radioactivity
Past earthquakes are studied to predict
where future earthquakes may occur
The composition of the interior affects the
speed and direction of seismic waves
Subduction is one plate going under
another
Volcanic mountains form at a
convergent boundary of two plates
Following are the slides #73-end
combined
• The Permian mass extinction probably
occurred because organisms could not live in
the new climate created by Pangaea
• Earth’s ‘second atmosphere’ was made of
mostly carbon dioxide, nitrogen and water
vapor
•
• The Cenozoic mass extinction of large
mammals probably occurred because of the
ice ages
• Volcanic out gassing helped form the
Earth’s atmosphere
• The geologic time scale is divided into eras
and periods
• Some Sedimentary rocks form from fragments
of other rocks
• Steps to form sedimentary rocks from igneous
rock are erosion, deposition, compaction and
cementation- erosion removes and transports
rock materials
• Rocks change to metamorphic rock by heat
and pressure
• Rock cycle is the process rocks follow to
change to other rocks; igneous, sedimentary,
& metamorphic
• latals form in granite when it cools slowly form
in granite when it cools slowly
• Plate collisions affect the rock cycle when one
plate is forced down to the heat of the mantle
and produces metamorphic rock
• During an Earthquake stand in a doorway or
crouch under a desk
Fossils of tropical plants are found in
Antarctica giving evidence plates moved
• The mantle is heated by earth’s core energy
and radioactivity