Earth Science
Objectives:
• Seismic Activity Map Assignment
• Identify, compare, and model earth’s layers.
• Identify and examine historical evidence of
plate tectonics.
• Identify, compare, and model plate
boundaries.
Plate Tectonics
Plate Tectonic Vocabulary
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Continental drift
Continental Crust
Convection
Convection Current
Convergent
Boundary
• Divergent Boundary
• Mid-Ocean Ridge
• Ocean Trench
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Pangaea
Plate Tectonics
Seafloor Spreading
Subduction Zone
Mid-Atlantic Ridge
Crust
a. What are the two types of crust?
b. Each type of crust is composed of what
kind of rock?
c. Which type of crust is denser?
Shorelines are not true boundaries:
1. Continental margin –
where the ocean water
covers the continental
crust
2. Deep ocean basinwhere the ocean water
covers oceanic crust
water
Continental
margin
Oceanic basin
Oceanic crust
Continental crust
•The ocean water may cover miles of the continental
crust
Earth’s Tectonic Plates
dpc.ucar.edu
Crust
• The crust is broken into separate
plates.
• How many plates are there?
• T or F
Plates are stationary.
Plate Movement
• What causes plates to move?
• As the plates move, everything on them
moves along with them.
• Examples:
*The North American plate moves west at a
rate of 4 cm per year (1.6 in./yr)
*The Pacific Ocean plate moves northward at
the same rate.
Plate Movement
• Convection currents produced in the mantle
cause the plates to move.
• As the plates move, everything on them
moves along with them.
• Examples:
*The North American plate moves west at a
rate of 4 cm per year (1.6 in./yr)
*The Pacific Ocean plate moves northward at
the same rate.
• PLATE TECTONICS
• The continental & oceanic plates on the
earth’s surface are constantly moving.
• Many geologists believe that at one time all
landmasses were together: supercontinent.
Also called?
Pangaea
uni-graz.at
Alfred Wegener:
•He was a leading scientist in providing
evidence that continents were moving.
• CONTINENTAL DRIFT THEORY:
*Continents are drifting or moving.
*Break-up of Pangaea occurred around 240 million yrs ago
* Over time continents broke up into smaller pieces and have
drifted to their current location
*The continents are currently still moving
Alfred Wegener: Continental Drift Evidence
Evidence:
1. Similarities in coastlines
2. Similarities in fossil records
3. Similarities in rock
Continental Drift: Evidence
• 180 million years ago, Pangaea began to
break up into separate continents.
• Provided evidence of ancient animal and
plant remains from South America, Africa,
India, and Australia that were very similar.
Wegener’s Continental Drift Theory
• What problem or concern do you think other
geologist had with Wegner’s theory?
Could not provide direct evidence that the
continents were moving.
Continental Drift Theory: Conclusive Evidence
• Where?: Under the Atlantic Ocean
• What? Mountain Range
– Mid Atlantic Ridge
the ridge looks like a mountain with a valley
running down the center
velikovsky.info
Who? Harry Hess
Aerial picture of the Mid-Atlantic Ridge
Harry Hess’ Important Observations
– Studied rock data from the Mid Atlantic
Ridge
– Found in the center of the ridge is a crack
or rift.
– Magma would flow up through this rift
Harry Hess Conclusion:
– The ocean floor was moving away from the ridge on
both sides.
– As it moved away, it was replaced by rising magma
that cooled and solidified into new rock.
– He called this process: Sea Floor Spreading
Sea Floor Spreading
Thingvellir, the spreading zone in Iceland
between the North American (left side) and
Eurasian (right side) tectonic plates. January
Hess’ Later Observations and Conclusions
– Continued to support sea floor spreading.
– Evidence by further studying the structure,
properties, and age of the rock around the MidAtlantic ridge.
Scientific Evidence is Dynamic
Scientific evidence presented to the public is only
established after years of sound research in the
hands of many scientists. Despite this truth,
scientists continue to test these facts as
technology advances.
Homework: Read and annotate the article “ UCLA
scientist discovers plate tectonics on Mars”. Explain with
three supporting facts from this article why the
statement above is necessary for science to
remain beneficial to humanity.
Bell Ringer: Plate Tectonics
1. Identify the 4 layers of the earth and what state of
matter (solid or liquid) they are in.
2. Which layer(s) is/are responsible for the magnetic
field around the earth. Explain your answer.
3. What is plate tectonics?
4. What indirect evidence did Wegener have to
hypothesize his continental drift theory?
5.What direct evidence did Hess have to conclude
from his research seafloor spreading?
6. What causes plates to move?
Plate Boundaries
• Plate boundaries are where two plates meet.
• What type of plates can meet?
• There are 3 types of plate boundaries:
1. divergent boundaries
2. convergent boundaries
3. transform boundaries
Earth’s Tectonic Plates
dpc.ucar.edu
Divergent Boundaries
What are divergent boundaries?
Divergent Boundaries
• Iceland is along a divergent boundary.
• The North American Plate & the Eurasian Plate
Thingvellier,Iceland
Divergent Boundaries
Mid-Atlantic Ridge: Extends from the Arctic
Ocean to beyond the southern tip of Africa &
moves 2.5cm per year.
Divergent Boundaries:
African Rift Valley – east African Plate is spreading &
has torn Saudi Arabia away from the rest of the
African continent forming the Red Sea
Convergent Boundaries
What is a convergent boundary?
Convergent Boundaries
There are three types of convergent boundaries?
1. Oceanic-oceanic
2. oceanic-continental 3. continental-continental
nature.nps.gov
Convergent Boundaries
Continental Convergence:
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Continental convergence form mountain ranges
Example: Himalayan Mountains formed by the
convergence of the Indian and Eurasian Plates.
nature.nps.gov
nature.nps.gov
Himalayan Mountain Range
destination360.com
geography.howstuffworks.com
Convergence Boundaries:
Continental and Oceanic Convergence:
• Create trenches and volcanic mountains
• One crust subducts under another.
Aleutian Islands
•
Pacific Plate & North American Plate form
the Aleutian Islands in the Pacific Ocean
off the northeast coast of Siberia
Andes Mountains
Nazca Plate & South American Plate form the
Andes Mountains on the western border of the
South American continent
geo1202peru.blogspot.com
Convergent Boundaries:
Oceanic Convergence
• Creates trenches, volcanic islands, and
volcanic island arcs
• Subduction zone
Mariana Trench
• Located in the Pacific Ocean near Japan.
• Created by ocean-to-ocean subduction.
-Phillipine Plate is subducting under the Pacific Plate
Transform Boundaries
What is a transform boundary?
Transform Boundaries
Create Earthquakes
•
San Andreas Fault
By Robert E. Wallace, USGS
The Pacific Plate and the North
American Plate slide past each
other.
Plate Tectonics
Homework due Wednesday:
• Complete sea floor spreading questions.
• Complete questions from plate tectonic
worksheet.
• Continue to record seismic activity.
Heads-Up:
• Quiz tomorrow over Earth’s Layers/Plate
Tectonics
• Test on Monday: Earth’s Layers and Plate
Tectonics
Sea Floor Spreading Model
Use the picture below to help understand the sea floor
spreading model you made last week.
a. What kind of boundary is represented at #1? (slit?)
b. What kind of boundary is represented at #2? (slit?)
1.
2.
Plate Tectonics
Objectives:
• Sea Floor Spreading Model qts. due
• Plate Tectonic Map qts.
• Impacts of Plate Tectonics (video/text)
• Plate Tectonic Gallery Walk
• Plate Tectonics on Mars article
• Study Guide
What does Plate Tectonics Impact?
• Read pg. 257 and record in your notes the
following:
* What is effected by plate tectonics?
*How is it effected by plate tectonics?
* Why is it effected by plate tectonics?
Plate Tectonics
• How does it affect climate?
* Changed the climate over the last 250 million years
by constantly creating geological processes
(volcanoes;earthquakes) that produced heat and
chemicals in the atmosphere that would promote
and support life. Climate keeps most water from
freezing.
• How does it affect life?
• Plate tectonics promotes diversity among animals
by causing isolation due to geographical formations
(mountains).
Plate Tectonics on Mars
• Annotate and write a descriptive summary
about the article, “UCLA scientist discovers
plate tectonics on Mars.”
• Due:
Earth Science
Homework:
• Plate Tectonic Map article summary. Due Monday
• Work on study guide. Due Tuesday.
• Seismic Activity Map- if not recorded data daily.
• Test:
• Tuesday, Feb. 5th
Plate Tectonic Map Qts.
dpc.ucar.edu
Earth’s Tectonic Plates
dpc.ucar.edu
After Test
• Turn in the following:
*Plate Tectonics Map Activity w/map.
*Study Guide (optional)
*Sea Floor Spreading for partial credit
*Plate Tectonic articles for partial credit
Pick-up:
*Earthquake Worksheet. Due Monday
*Seismic Activity Map is also due Monday