plate tectonics liz larosa for use with my 5 th grade science class 2009

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