Key concepts
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Key concepts. Earth Composition. Crust: thinnest layer, least dense Mantle: upper most part is able to flow very slowly (asthenosphere) Core: Lower area is a solid and outer area is a liquid. Makes up 1/3 of Earth’s mass. The hottest layer with the most pressure.

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Key concepts

Key concepts

Earth Composition

Crust: thinnest layer, least denseMantle: upper most part is able to flow very slowly (asthenosphere)

Core: Lower area is a solid and outer area

is a liquid. Makes up 1/3 of Earth’s mass.

The hottest layer with the most pressure.


Key concepts

starryskies.com/.../Earth/ under_the_surface.html


Key concepts

Key concepts

  • Evidence of “continental drift”—

  • .

  • Physical fit of continents

  • Fossil evidence

  • Measurements of movement

  • Rock layer sequences

  • Glacial evidence

Alfred Wegener


What is the theory of continental drift

What is the theory of continental drift?

  • the idea that the continents were once all joined together in one super-continent called Pangaea and slowly moved to their current positions


Key concepts

http://wrgis.wr.usgs.gov/docs/parks/animate/A08.gif


Key concepts

What evidence supports the theory of continental drift?


Key concepts

Shoreline Fit of the Continents

http://www.abdn.ac.uk/zoohons/lecture1/img008.GIF


Fossil evidence

Fossil Evidence

The fossils from the exact same animals are found on continents separated by vast oceans.


Matching rock layers

Matching Rock Layers


Glacier evidence

Glacier Evidence

Glaciers scars are found on continents which are today too warm for glaciers.


How fast are the plates moving

How fast are the plates moving?


You may wonder

You may wonder…

Why are the continents moving?


Key concepts

Seafloor Spreading

The oceans are widening along the mid-ocean ridges.


Volcanoes located along ocean ridges erupt creating new ocean floor

Volcanoes located along ocean ridges erupt, creating new ocean floor.


Key concepts

Key concepts

Plates—continental crust, oceanic crust

Features—faults, trenches, mid-ocean ridges, folded mountains, hot spots, volcanoes

Related actions —earthquakes, volcanic activity, seafloor spreading, mountain building, convection in mantle.


The earth s lithosphere is broken into huge sections called plates that are in constant motion

The earth’s lithosphere is broken into huge sections called plates that are in constant motion.


What are the plates made of

What are the plates made of?

  • Ocean plates are made of basalt.

  • Continental plates are made of granite.


Divergent plate boundaries

Divergent Plate Boundaries

Two land or ocean plates move apart in opposite directions. Magma flows to the surface between them creating new crust.


Mid atlantic ridge divergent boundary

Mid-Atlantic Ridge = Divergent Boundary


Http www geo lsa umich edu crlb courses 270 lec12 spreexamples jpeg

http://www.geo.lsa.umich.edu/~crlb/COURSES/270/Lec12/spreexamples.jpeg


Iceland a continent directly over the mid atlantic ridge

Iceland – a continent directly over the Mid-Atlantic Ridge


Subduction zones

Subduction Zones

  • An ocean plate and a continental plate hit head-on. The ocean plate subducts under the continent forming a trench. The subducting plate melts. Magma rises to the surface creating a string of volcanic mountains parallel to the shoreline.


Andes mountains

Andes Mountains

Subduction zones form chains of volcanic mountains along the shoreline.


Collision zones

Collision Zones

Two continents hit head-on, crinkling up the land into a high mountain chain.


India s collision with asia

India’s Collision with Asia

Himalayas


Key concepts

The Himalayas Are Born…


Island arcs

Island Arcs

Two ocean plates hit head-on. One ocean plate is forced to subduct under the other forming an ocean trench. The subducting plate melts. Magma rises to the surface forming a string of volcanic islands parallel to the trench.


The aleutian islands

The Aleutian Islands


Key concepts

Key concepts

Forces—tension, compression shearing

Ask a Geologist

Ask an earth scientist


How does tectonic activity affect the earth s crust

How does tectonic activity affect the earth’s crust?

  • Builds mountains

  • Creates deep ocean trenches

  • Causes earthquakes

  • Create volcanoes


Ocean trenches

Ocean Trenches

http://www.nhusd.k12.ca.us/ALVE/wow/Ocean/seafloor.gif


Key concepts

Volcanoes


Most volcanoes occur at plate boundaries

Most volcanoes occur at plate boundaries…


Key concepts

http://www.thirteen.org/savageearth/hellscrust/assets/images/ringoffire.jpg


Key concepts

Real-world contexts:

Recent patterns of earthquake and volcanic activities;

maps showing the direction of movement of major plates

and associated earthquake and volcanic activity

Compressional boundaries: folded mountains, thrust faults, trenches, lines of volcanoes (e.g. Pacific “ring of fire”)

Tensional boundaries: mid-ocean ridges, rift valleys

Shearing boundaries: lateral movement producing

faults (e.g. San Andreas Fault).


Key concepts

http://www.gfz-potsdam.de/pb2/pb22/projects/mamba.html


Resources

Resources

  • http://www.calstatela.edu/faculty/acolvil/plates/pangaea.jpg

  • http://platetectonics.pwnet.org/img/wegener.jpg

  • http://home.tiscalinet.ch/biografien/images/wegener_kontinente.jpg

  • http://library.thinkquest.org/17457/platetectonics/comic.jpg

  • http:[email protected]/carlsberg/images/fossil_correlation_lge.jpg

  • http://earthobservatory.nasa.gov/Library/Giants/Wegener/Images/plate_boundaries.gif

  • http://www.calstatela.edu/faculty/acolvil/plates/atlantic_profile.jpg

  • http://pubs.usgs.gov/publications/graphics/Fig16.gif

  • http://cps.earth.northwestern.edu/SPECTRA/IMG/basalt.png

  • http://cc.usu.edu/~sharohl/granite.jpg

  • http://tlacaelel.igeofcu.unam.mx/~GeoD/figs/tgondvana_ice.jpg

  • http://www.physics.uc.edu/~hanson/ASTRO/LECTURENOTES/F01/Lec11/Pangaea.gif

  • http://www.poleshiftprepare.com/glacial_striation.jpg


Key concepts

  • http://www.ggs.org.ge/plates.jpg

  • http://earth.geol.ksu.edu/sgao/g100/plots/1008_world_volc_map.jpg

  • http://www.aeic.alaska.edu/Input/affiliated/doerte/personal/aleutians/ak_map_big.jpg

  • http://www.4reference.net/encyclopedias/wikipedia/images/Aleutians_aerial.jpg

  • http://www.avo.alaska.edu/gifs/2-3/02-95-03.jpg

  • http:[email protected]/carlsberg/images/island_arc.jpg

  • http://nte-serveur.univ-lyon1.fr/nte/geosciences/geodyn_int/tectonique2/himalaya/images/Fig5a_inde.gif

  • http://terra.kueps.kyoto-u.ac.jp/~sake/himalaya.jpg

  • http://www.andes.org.uk/peak-info-5000/sabancaya.jpg

  • http://www-step.kugi.kyoto-u.ac.jp/~keizo/photos/andes.JPG

  • http://www.letus.northwestern.edu/projects/esp/top10/andespage/andesphysical.jpg

  • http:[email protected]/carlsberg/images/atlantic_tectonics%20.jpg


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