Plate Tectonics Unit Notes
Inside Earth- Chapter 1
Glencoe- Chapter 17 (Sec. 1-4)
Glencoe- Chapter 22 (Sec. 2)
E1.2E
Evaluate the future career and occupational prospects of science fields.
E2.1B
Analyze the interactions between the major systems (geosphere, atmosphere,
hydrosphere, biosphere) that make up the Earth.
E2.1C
Explain, using specific examples, how a change in one system affects other Earth
systems.
E2.2A
Describe the Earth’s principal sources of internal and external energy (e.g.,
radioactive decay, gravity, solar energy).
E2.2C
Describe natural processes in which heat transfer in the Earth occurs by
conduction, convection, and radiation.
E3.2A
Describe the interior of the Earth (in terms of crust, mantle, and inner and outer
cores) and where the magnetic field of the Earth is generated.
E3.2B
Explain how scientists infer that the Earth has interior layers with discernable
properties using patterns of primary (P) and secondary (S) seismic wave arrivals.
E3.2C
Describe the differences between oceanic and continental crust (including density,
age, and composition)
E3.p3A
Describe geologic, paleontologic, and paleoclimatalogic evidence that indicates
Africa and South America were once part of a single continent.
E3.p3B
Describe the three types of plate boundaries (divergent, convergent, and
transform) and geographic features associated with them (e.g., continental rifts
and mid-ocean ridges, volcanic and island arcs, deep-sea trenches, transform
faults).
E3.3A
Explain how plate tectonics accounts for the features and processes (sea floor
spreading, mid-ocean ridges, subduction zones, earthquakes and volcanoes,
mountain ranges) that occur on or near the Earth’s surface.
E3.3B
Explain why tectonic plates move using the concept of heat flowing through
mantle convection, coupled with the cooling and sinking of aging oceanic plates
that result from their increased density.
E3.3C
Describe the motion history of geologic features (e.g., plates, Hawaii) using
equations relating rate, time and distance.
Earth’s Interior
Science of Geology- began in 1700s
Geologist- scientist who studies how earth is made and shaped (E1.2E)
 study chemical and physical features of rock- hardened mass of minerals
 study the processes that create and change earth’s features and search for clues about
Earth’s history
A. Studying Surface Changes
a. 2 forces:
i. Constructive = “building” (mountains and elevated landforms)
ii. Destructive = “tear down” (erosion- wind, water, etc.)
b. 7 continents surrounded by (ocean) water
B. Finding Indirect Evidence- what’s inside the earth?
a. Deepest “hole” in the earth is approximately 12 km (7 miles)
 located in Russia
 it’s 6,000 km (3720 miles) to the center of the earth
b. Geologists use seismic waves to understand the earth’s interior- study their
speed and path (E3.2B)
c. Have discovered there are several layers to the earth’s interior- like an apple
(E3.2B)
A Journey to the Center of the Earth- temperature and pressure increase as you go deeper
A. Temperature
a. Deeper you go, the warmer it gets
b. For every 40 meters (131 feet) you descend, it gets 1° C warmer
i. Occurs for several km, then spreads out steadily
ii. 6370 km to center of Earth (3960 miles)
c. Heat from inside the Earth is generated from radioactive decay from inside the
Earth. Elements like U, Th, K, and Rb have radioactive isotopes. During
radioactive decay, sub-atomic particles are released by the decaying isotope and
move outward until they collide with other atomic particles. Upon collision, the
kinetic energy of the moving particles is converted to heat. If this heat cannot be
conducted away, then the temperature will rise. (E2.2A)
B. Pressure- force pushing on a surface
a. Deeper you go, the greater the pressure
Three Layers of Earth’s Interior- think of an apple cut in half (E3.2A)
A. The Crust- outer layer (looks like extremely thin outer skin of an apple)
a. Continental Crust- older, less dense layer of rock that makes up land- mostly
made of granite (E3.2C)
b. Oceanic Crust- younger, more dense layer of rock that makes up ocean floormade mostly of basalt (E3.2C)
B. The Mantle- mushy layer of molten metal (“hot rock”) (looks like the “middle” or
“meat” of the apple)
 2 parts to the Mantle
1. Lithosphere- rigid layer of crust and upper layer of mantle
2. Asthenosphere- soft, flexible plastic-like middle layer of mantle
* Lithosphere “floats” atop the weak asthenosphere, which allows continents to
move- kind of like an ice cream sandwich- “cookie” slides on the “cream”
* Rising hot magma from mantle can heat nearby lake (geothermal energy). This is
just one example of interacting earth systems. (E2.1B)
C. The Core- made of iron and nickel (looks like the core of an apple)
a. Two parts
i. Outer core- like a thick liquid (kinda like syrup)
1. Where earth’s magnetic field is generated (movements)
(E3.2A)
ii. Inner core- like a big ball of solid metal (due to extreme pressure)
b. Slightly smaller than the earth’s moon (but more dense)
c. Estimated temperature closely resembles temperature of sun’s surface
Earth’s Magnetic Field
 Currents in the liquid outer core create a magnetic field inside the earth (E3.2A)
 Acts like a bar magnet
Convection Currents in the Mantle (E2.2C) (E3.3B)
Convection Currents and the Mantle (Chapter 17, section 4)
Heat Transfer- movement of energy from warmer object to cooler object.
Ex: touching a HOT stove
3 Types of Heat Transfer:
1. Radiation- transfer of energy through space
 NO direct contact between objects
 Ex: Heat from the sun; Heat from open flame/fire (E2.2C)
 Light Bulb- put your hands near the bulb and they warm up
2. Conduction- transfer of energy by direct contact
 Ex: Imagine a spoon inside a pot of soup. Heat from the soup (and the pot) is transferred
to the spoon, causing it to get hot.
 Ex: Rocks that melt as they are subducted deep into the Earth. (E2.2C)
 Light Bulb- Touching the light bulb, you will feel a “burn”
3. Convection- transfer of energy by movement of liquids and gases (fluids)
 Liquids/gasses heat up, rise, cool, sink, and heat up again = convection current
 Heat transferred from one part of fluid to another
 When heat is removed, currents will eventually stop
 Ex: Currents in the mantle; Boiling Water
 Light Bulb- Gases in the bulb are heating up, rising to the top, cool and sink
It’s still not clear as to what causes these plates to move about. The leading hypothesis is that
heat from the core sets convection currents in motion and keeps it going in the MANTLE
(Asthenosphere)- been going on for billions of years. (E3.3B)
The warm, less dense magma rises as result of buoyancy. The cold, more dense magma sinks as
result of gravity. This up-and-down movement causes a convection current. These currents are
set in motion by subducting slabs of crust. (E3.3B)
Continental Drift (E3.p3A)
(Chapter 17 section 1)
 We started to get a good idea of what the continents looked like after Columbus took his
first voyage
 South America and Africa look like they fit together (like a jigsaw puzzle)
Theory of Continental Drift
 Alfred Wegener- curious about continents
- hypothesized that all the continents were once joined together in a large land masscalled it Pangaea (“all lands”)
- About 20 million years ago, Pangaea started to break apart and continents have been
drifting ever since- this is known as continental drift
- First published this theory in 1915 (The Origin of Continents and Oceans)
 Three Forms of Evidence for Continental Drift
1. Landforms- Mountain range in South America “lined up” with mountain range in
Africa
- indicated they were once connected as a giant landmass
2. Fossils (ancient organism(s) preserved in rock)- Same animal and plant fossils were
found in continents that are now separated by water
- Animals found could not have swum across the great length of the ocean
- Plant seeds could not have been carried by wind, water, or animals
3. Climate Change- Change in climate over time
- Spitsbergen- Norwegian island has tropical plant fossils  too cold of a climate
today to have plant life
- South Africa- Has ancient glacial “scars”  too warm of a climate to have
glaciers today
- Because of these changes in climate, Wegener concluded that these landmasses
have drifted, or changed locations on the earth
 Scientists rejected Wegener’s theory because he could not give a good explanation as to
what force pushed or pulled the continents apart.
 They also butted heads on the formation of mountains
- Wegener- Mountains formed when continents collided
- Scientists- Mountains formed as earth cooled, shrunk, and shriveled up like a raisin
Sea Floor Spreading (E3.p3B) (E3.3A) (E3.3B)
(Chapter 17 section 2)
Starts at the Mid-ocean ridge- a long, continuous chain of mountains that extends into all of the
Earth’s oceans  most are underwater, but some emerge from the water as islands or volcanoes
(E3.p3B)
Forms along a crack in the oceanic crust
1. Molten (liquid) material erupts from the mantle
2. Spreads out on both sides of the ridge and cools
3. As new material erupts, it pushes old rock aside
This process of new rock pushing old rock aside is termed sea-floor spreading (E3.3A)
Evidence for Sea-Floor Spreading
1. Pillow Rocks- Group of divers called Alvin’s Crew went 4 km down into the ocean and
found pillow-like rocks which can only be formed from molten material cools under
water
2. Alternating Magnetic Stripes- Alternating magnetic “stripes” on both sides (N, S, N,
S, etc.)
3. Rock Samples (young and old rocks)- Group of men drilled for rock samples along
mid-ocean ridge. Found that rocks closest to the mid-ocean ridge are younger than those
found further from the ridge.
Close = Young Rock
Far Away = Old Rock
Subduction at Deep-Ocean Trenches (E3.3A)
 Subduction- to sink below
 Older oceanic crust becomes more dense and sinks beneath the trench and back into the
mantle and becomes molten rock again (E3.3B)
** When volcanoes erupt, they emit gases (like CO2) into atmosphere. This is just another
example of interacting earth systems (geosphere and atmosphere). (E2.1B)
** The cyclical process of sea-floor spreading and subduction is like a conveyor belt
Takes approximately 20 million years to go through this process and renew the ocean
floor.


Pacific Ocean- because it is outlined by many trenches, the Pacific Ocean is actually
shrinking because more crust is sinking in the trench than is being produced by the midocean ridge
Atlantic Ocean- because it has few trenches, the Atlantic Ocean is producing more crust
than it is losing, so the ocean is getting larger
The Theory of Plate Tectonics (E3.p3B) (E3.3A) (E3.3B)
(Chapter 17 section 3)
 Combination of sea-floor spreading, continental drift, and plate movement
 Theory that earth’s plates (lithosphere) are slowly moving on top of asthenosphere,
caused by convection currents in the mantle (E3.3B)
 As plates move, they collide, spread apart or grind against one another
This causes changes in earth’s surface: volcanoes, mountains, trenches (E3.3A)
Plate Boundaries- the edges of plates (E3.p3B) (E3.3A)
 Faults- breaks in crust where plates move (E3.p3B)
 3 types of boundaries, 3 types of movement
1. Transform Boundaries
2 plates slip past each other, moving in opposite directions
Crust is neither created nor destroyed
Earthquakes are shallow (25 km) and less than 8.5 in magnitude (E3.3d)
2. Divergent Boundaries
2 plates move away from each other
Mid-Ocean Ridge
Rift Valleys- continental crust moves apart, forming a gap in the land
Could eventually cut deep enough for water to fill
Earthquakes are shallow and less than 8 in magnitude (E3.3d)
3. Convergent Boundaries
2 plates come together, move toward each other
3 different types: (E3.3A)
continental-continental  forms mountains
oceanic-oceanic  subduction (one sinks below the other)
oceanic-continental  subduction (OC sinks below CC)
** Remember: oceanic crust is MORE DENSE than continental crust
Earthquakes are deep (700 km) and more than 9 in magnitude (E3.3d)
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Plates move VERY slowly (2-10 cm per year)- about as fast as fingernails grow (E3.3C)
 Use distance, rate and time to find the unknown variable
 Reference: 100,000 cm in a km
About 260 million years ago, all continents were joined together in one large land-mass
called Pangaea
There are approximately 15 large tectonic plates
Scientists believe all plates will continue to move and come together to eventually join
into another Pangaea (in the future).
Careers in Plate Tectonics (E1.2E)
Geosciences
Geologist
Professor
Seismologist- study earthquakes
Volcanologist- study volcanoes
Geochemist- studies chemical properties of Earth’s interior
Links
General Plate Tectonics
* Contains ppt on Plate Tectonics
http://www.earth4567.com
* UCMP
- contains good pics to show movement of continents through time
http://www.ucmp.berkeley.edu/geology/tectonics.html
* Plate Tectonics.com
http://www.platetectonics.com/index.asp
* UNR
http://www.seismo.unr.edu/ftp/pub/louie/class/100/plate-tectonics.html
* Enchanted Learning
http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml
* USGS- Good explanatory site on theory of plate tectonics
http://pubs.usgs.gov/publications/text/dynamic.html#anchor10790904
* Plate Tectonics and how they relate to oceans
http://www.mos.org/oceans/planet/change.html
* Plate Tectonics Info and Pics
http://johnshen.bol.ucla.edu/home.html
* From Pangaea to the present
http://volcano.und.nodak.edu/vwdocs/vwlessons/lessons/Pangea/Pangea1.html
GOOD site on Geology and pics to help
http://www.earth.northwestern.edu/people/seth/107/
Earth’s Interior
* Science Mysteries- deepest hole in the earth
http://www.all-around-us.com/science/geology/s-t-scie.htm
* Scale model and info
http://pubs.usgs.gov/publications/text/inside.html
* VERY good site with lots of good info
http://www.gpc.edu/~pgore/Earth&Space/GPS/earthinterior.html
* Info with pics
http://www.windows.ucar.edu/tour/link=/earth/Interior_Structure/overview.html&edu=elem
* Info and worksheets to label
http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Inside.shtml
* Info and good pic to diagram
http://www.solarviews.com/eng/earthint.htm
Crust
http://quake.wr.usgs.gov/research/structure/CrustalStructure/
http://www.windows.ucar.edu/cgi-bin/tour_def/earth/interior/earths_crust.html
Earth’s Magnetic Field
http://csep10.phys.utk.edu/astr161/lect/earth/magnetic.html
- Article on why Earth’s magnetic field flips
http://news.nationalgeographic.com/news/2004/09/0927_040927_field_flip.html
Heat Transfer
http://sol.sci.uop.edu/~jfalward/heattransfer/heattransfer.html
Convection
* Info and animation
http://earth.leeds.ac.uk/~greg/Conv.html
* Pic of convections currents inside the Earth
http://ffden-2.phys.uaf.edu/211_fall2002.web.dir/Cheryl_Robar/Phys211%20Folder/convection.JPG
* Info and questions
http://www.mec.edu/gltech/library/htmlaps/mackenzie/mackenzie.htm#Convection
Convection Activity
http://www.mrsciguy.com/convection.html
Conduction
* Info and questions
http://www.mec.edu/gltech/library/htmlaps/mackenzie/conduction.htm
Radiation
* Info and questions
http://www.mec.edu/gltech/library/htmlaps/mackenzie/radiation.htm
Continental Drift
Alfred Wegener and Continental Drift
http://www.ucmp.berkeley.edu/history/wegener.html
http://pubs.usgs.gov/publications/text/wegener.html
Theory Info and pics
http://www.enchantedlearning.com/subjects/dinosaurs/glossary/Contdrift.shtml
http://kids.earth.nasa.gov/archive/pangaea/index.html
http://www.historyoftheuniverse.com/condrift.html
http://www.oceansonline.com/continen.htm
Plate Tectonics and Continental Drift Links
http://members.aol.com/bowermanb/tectonics.html
Evidence for Continental Drift
http://www.lhs.sad49.k12.me.us/ljhs/Website%20Resources/continental_drift.htm
Future of the Plates
Pictures of Earth Past and Future
http://www.historyoftheuniverse.com/cf200.html
Future Pangaea PIC
http://science.nasa.gov/headlines/y2000/ast06oct_1.htm
E3.3C
Continental Plates and Their Rate of Movement
http://hypertextbook.com/facts/ZhenHuang.shtml
Sea Floor Spreading
Info with pics
http://www.geo.lsa.umich.edu/~crlb/COURSES/270/Lec12/Lec12.html
http://atlas.geo.cornell.edu/education/student/tectonics/sea_floor_spreading_i.html
http://www.windows.ucar.edu/tour/link=/earth/interior/seafloor_spreading.html&edu=elem
Harry Hess
http://pubs.usgs.gov/publications/text/HHH.html
Animations
Sea-Floor Spreading
http://www.uwsp.edu/geo/faculty/ritter/glossary/s_u/sea_flr_spread.html
http://education.sdsc.edu/optiputer/flash/seafloorspread.htm
Age of Rocks
http://www.windows.ucar.edu/tour/link=/earth/interior/seafloor_spreading_interactive.html
Magnetic Strips/Reversal
http://www.edumedia-share.com/media.php?id=1325
Subduction
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0902/es0902page01.cfm
Subduction zones
http://www.lincoln.smmusd.org/staff/Vanderveen_Web/geology/subduction/seafloorsubduction.htm
Mid-Ocean Ridge
http://pubs.usgs.gov/publications/text/baseball.html
http://www.ocean.udel.edu/extreme2001/mission/location/ridge.html
http://volcano.und.nodak.edu/vwdocs/vwlessons/volcano_types/spread.htm
Plate Tectonics
GOOD INFO with Evidence
http://csep10.phys.utk.edu/astr161/lect/earth/tectonics.html
Plate Boundaries
Cool Map with satellite images and zoom in capabilities
http://geology.com/plate-tectonics.shtml
Info with animation
http://scign.jpl.nasa.gov/learn/plate4.htm
Pic with Info
http://pubs.usgs.gov/publications/text/Vigil.html
3 types of plate boundaries
http://pubs.usgs.gov/publications/text/understanding.html
SWEET animations of what goes on at plate boundaries
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0804/es0804page01.cfm?chapter_no=visualization
Determining Plate Boundaries from earthquake information (E3.3d)
http://w3.salemstate.edu/~lhanson/gls100/gls100_plate_tec.htm
http://www.seismo.unr.edu/ftp/pub/louie/class/100/plate-tectonics.html
http://www.visionlearning.com/library/module_viewer.php?mid=66
Geology Careers
http://www.earthscienceworld.org/careers/brochure.html
Good Computer Stuff
Continental Drift Animation
http://www.ucmp.berkeley.edu/geology/anim1.html
Mountain Maker, Earth Shaker Animation
http://www.pbs.org/wgbh/aso/tryit/tectonics/#
*also gives good info on the subject of plate tectonics
Activities
* Draw the earth’s interior (LARGE)
http://www.eas.purdue.edu/~braile/edumod/earthint/earthint.htm
Pics and Images
http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/framework.html