Plate Tectonics Liz LaRosa for use with my 5 th Grade Science Class http://www.middleschoolscience.com 2009
Dec 13, 2015
Plate TectonicsLiz LaRosa for use with my 5th Grade Science Class
http://www.middleschoolscience.com 2009
Earth’s LayersThe Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed.
This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.
The Crust
• Outermost layer• 5 – 100 km thick• Made of Oxygen, Silicon, Aluminum
The Mantle• Layer of Earth
between the crust and the core
• Contains most of the Earth’s mass
• Has more magnesium and less aluminum and silicon than the crust
• Is denser than the crust
The Core
• Below the mantle and to the center of the Earth
• Believed to be mostly Iron, smaller amounts of Nickel, almost no Oxygen, Silicon, Aluminum, or Magnesium
Tectonic Plates
Plate Tectonics
• Greek – “tektonikos” of a builder• Pieces of the lithosphere that move around• Each plate has a name• Fit together like jigsaw puzzles• Float on top of mantle similar to ice cubes
in a bowl of water
Continental Drift
http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml
Alfred Wegener 1900’sContinents were once a single land mass that drifted apart.
Fossils of the same plants and animals are found on different continents
Called this supercontinent Pangea, Greek for “all Earth”
245 Million years ago
Split again – Laurasia & Gondwana 180 million years ago
Evidence of Pangea
Sea Floor Spreading
Sea Floor Spreading
• Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins
• Magma rises to the surface and solidifies and new crust forms
• Older Crust is pushedfarther away from the ridge
How Plates Move
http://pubs.usgs.gov/gip/dynamic/unanswered.html
Bell work p.20
What is the name of the place where two plates meet?
Content Goal:To be able to explain the three types of plate boundaries.
2/5 BELL WORK
1. Take out a piece of notebook paper.2. Put your full name and period in top right
corner.3. Number your paper 1-34. Skip a line, add number 45. Skip 3 lines, add number 56. You will have ten minutes to complete pop
quiz
Different Types of Boundaries
http://pubs.usgs.gov/gip/dynamic/understanding.html
Divergent Plate Boundaries
• Plates separate• Usually on ocean floor• New rocks formed• Called rift valley• Examples: Mid-Atlantic Ridge, Iceland (above
sea level)
Divergent Boundary – Iceland
http://pubs.usgs.gov/gip/dynamic/understanding.html
Iceland rift valley
Progression of Rift Valleys
Divergent Boundary – OceanicSea Floor Spreading
http://www.geology.com
Divergent Boundary - Continental
http://www.geology.com
Divergent Boundary – Arabian and African Plates
AFRICAN RIFT VALLEY
Convergent Plate BoundariesOcean-Continental
• More dense plate subducts when plates converge
• Oceanic crust subducts under continental plate
• Forms volcanic mountain chains to east of subduction
• Deep earthquakes to the west of subduction
Convergent Boundary – Oceanic & Continental
http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com
Mt Ranier and Crator Lake
Oceanic-Oceanic Convergent Plate Boundaries
• More dense plate subducts• Forms a deep open trench to west of subduction
zone• Island arcs form 300km to east of subduction
zone
Convergent Boundary – Oceanic & Oceanic
http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com
Aleutian Islands in Alaska/Japan/Phillipines
Continental-Continental Convergent Boundaries
• More dense plate subducts, often both plates are of same density
• Major mountain ranges form
Convergent Boundaries - Continental
http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com
Great Smoky Mountains/Appalachian
Mountains/Rocky Mountains
Convergent Boundary – Indian and Eurasian PlatesHimalayan Mountain Range - Mt. Everest
Hot Spots
Transform Boundary – San Andreas Fault
www.geology.com
Review
• Name the 3 main layers of the Earth• What is a tectonic plate?• What was Pangea?• What is Sea-Floor spreading?• Name the three different types of plate
boundaries and one location on Earth for each one