Earth Science Regents Review
Unit 3
What are the layers of the earth?



Crust: thin,
rocky outer
layer (oceanic
and continental)
Lithosphere:
crust and upper
part of the
mantle.
Asthenosphere:
top part of the
mantle,
convection
occurs within
Facts About the Layers



Mantle: thickest
middle layer, mafic,
crust dives into the
mantle to melt
Outer Core: made of
iron and nickel,
solid
Inner Core: made of
iron and nickel,
liquid
2) What are the different types of
crust and how do they differ?


Continental
crust: land
crust, lighter,
less dense,
granite, thicker
Oceanic crust:
under the
ocean, darker,
more dense,
basalt, thinner
4) Is the outer core solid or
liquid? How can you tell?
Liquid; The
interior
temperature
is above the
melting
point.
Summary:




A) At what depth is the temperature
4,200oC ____________
Layer? ______________
B) What is the pressure at a depth of
5,000 km ____________
Layer? ______________
What are the three types of plate
boundaries?
• A) convergent
• B) divergent
• C) transform
2) What are divergent boundaries?
• Type: Divergent
•
•
(plates move
apart)
Geologic Feature:
Mid-ocean ridges
Example: MidAtlantic Ridge
Convergent Boundaries
• Type: Continent-Continent convergence
(plates move together)
• Geologic Feature: Mountains
• Example: Himalayas
Convergent Boundaries
• Type: Continent-Oceanic convergence
Oceanic crusts sinks into the mantle and
melts (subduction)
• Geologic Feature: Volcanic Mountains and
Trenches
• Example: Andes Mountains & Peru-Chile
Trench
Convergent Boundaries
• Type: Oceanic-Oceanic convergence (two
•
•
oceanic plates come together)
Geologic Feature: Volcanic Islands and deep
trenches
Example: Aleutian Islands, Aleutian Trench
Transform Boundaries
• Type: Transform
•
•
(plates slide past
each other)
Geologic Feature:
Faults
Example: San
Andreas Fault
How do you use p. 5 of the ESRT’s?
2) What evidence is there for past
crustal movement?
Who was Alfred L. Wegener?

He proposed that
the earth was a
single
supercontinent
(Pangaea) that
separated over
time.
What evidence did he have for his
theory?




N. and S. America fit
together with Africa
and Europe
The structure of the
rocks matched
perfectly with the coast
of Africa and Europe
Tropical fossils were
found in cold climates
along the coast
Evidence of glaciation
in S. America, S. Africa,
India & S. Australia
3) What do we know about the age
of the ocean floor?
• New crust is
created at
ridges so the
oldest crust is
near the
continents.
5) What happened to the earth’s
magnetic field?
• Periodically,
the poles
switch
positions
and the
north pole
becomes the
south pole
(reverse
polarity).
6) How do we know this
happened?
• The rocks of the ocean floor contain iron and
their magnetic orientation keeps switching.
2) What are the two types of
waves?

Primary waves
(P-waves):
compressional
waves, faster,
go through
anything
 Secondary
waves (Swaves): shear
waves, slower,
can only go
through solids
3) What is a shadow zone?

This is an
area of the
earth where
earthquake
waves
cannot be
detected.
4) How is it created?

(a) S-waves can only go through solids so
they get absorbed when they reach the outer
core.
 (b) P-waves get refracted when they reach
the outer core.
How do we find the epicenter distance
of one wave?
(a)
(b)
(c)
Locate the travel time along the yaxis
Go across until you hit the curve
Look down to see where they meet
5) How do we find the
epicenter?

Using p. 11 of
the ESRT’s find
the travel time,
go across to
the P or S
curve then look
straight down.
1) What does information from
seismograph stations tell us?
One station?
Distance to the epicenter.

1) What does information from
seismograph stations tell us?


Two stations= two possible locations
Three stations= the exact geographic
location
2) What happens as the two waves
travel farther away from the
epicenter?

The two
waves get
farther
apart
because
the P-wave
is much
faster.
Finding the epicenter distance using two
waves?



Draw two dots on a paper the
number of minutes apart.
Slide the paper until the dots match
the curves.
Look down to see the distance.
Can we answer these?




If the travel time of an S-wave is 9 minutes 40
seconds, what is the epicenter
distance?______________
If the difference in arrival times of the P- and Swaves is 6 minutes 20 seconds, how far is the
distance to the epicenter? ________________
A P-wave arrived at 3:32:00 p.m. and the S-wave
arrived at 3:36:30 p.m. How far away is the
epicenter?_____________
If a P-wave arrived at 12:02:50 p.m. and the Swave arrived at 12:12:10 p.m., what is the
distance to the epicenter?
________________
Exit Card
-Match each
lettered location
with the correct
seismogram
-If the difference
in arrival times of
the P- and Swaves is 5
minutes 00
seconds, how far
is the station from
the epicenter?