Key concepts
Sponsored Links
This presentation is the property of its rightful owner.
1 / 52

Key concepts PowerPoint PPT Presentation


  • 53 Views
  • Uploaded on
  • Presentation posted in: General

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.

Download Presentation

Key concepts

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


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.


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


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?

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


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


What evidence supports the theory of continental drift?


Shoreline Fit of the Continents

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


Fossil Evidence

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


Matching Rock Layers


Glacier Evidence

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


How fast are the plates moving?


You may wonder…

Why are the continents moving?


Seafloor Spreading

The oceans are widening along the mid-ocean ridges.


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


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.


What are the plates made of?

  • Ocean plates are made of basalt.

  • Continental plates are made of granite.


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


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


Iceland – a continent directly over the Mid-Atlantic Ridge


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

Subduction zones form chains of volcanic mountains along the shoreline.


Collision Zones

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


India’s Collision with Asia

Himalayas


The Himalayas Are Born…


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


Key concepts

Forces—tension, compression shearing

Ask a Geologist

Ask an earth scientist


How does tectonic activity affect the earth’s crust?

  • Builds mountains

  • Creates deep ocean trenches

  • Causes earthquakes

  • Create volcanoes


Ocean Trenches

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


Volcanoes


Most volcanoes occur at plate boundaries…


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


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).


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


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://www.soc.soton.ac.uk/CHD/classroom@sea/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


  • 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://www.soc.soton.ac.uk/CHD/classroom@sea/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://www.soc.soton.ac.uk/CHD/classroom@sea/carlsberg/images/atlantic_tectonics%20.jpg


  • Login