Earth science
Download
1 / 31

Earth Science - PowerPoint PPT Presentation


  • 116 Views
  • Uploaded on

Earth Science. Coach Williams Room 310B. Chapter 17. Plate Tectonics. Section 17.1: Drifting Continents. Objectives Describe one piece of early evidence that led people to suggest the Earth’s continents my have once been joined. Discuss evidence of continental drift

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Earth Science' - lisandra-lopez


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
Earth science

Earth Science

Coach Williams

Room 310B


Chapter 17
Chapter 17

  • Plate Tectonics


Section 17 1 drifting continents
Section 17.1: Drifting Continents

Objectives

  • Describe one piece of early evidence that led people to suggest the Earth’s continents my have once been joined.

  • Discuss evidence of continental drift

  • Explain why continental drift was not accepted when it was first proposed.


Early observations
Early Observations

  • Fit of continents across Atlantic Ocean

  • Gondwanaland: southern continents



Continental drift
Continental Drift

  • Theory that Earth’s continents were once joined.

  • Continents had slowly drifted apart

  • Pangaea: “all the Earth”


Continental drift evidence
Continental Drift Evidence

  • Rocks: similar rocks

  • Fossils: animal/plant remains

  • Ancient Climate: coal in Antarctica


Rejected hypothesis
Rejected Hypothesis

  • 2 Reasons the theory was rejected

    • 1) What forces could cause them to move?

    • 2) How could continents move and not shatter?


Section 17 2 seafloor spreading
Section 17.2: Seafloor Spreading

Objectives

  • Summarize the evidence that led to the discovery of seafloor spreading.

  • Explain the significance of magnetic patterns on the seafloor.

  • Explain the process of seafloor spreading.


Help from technology
Help From Technology

  • Sonar- sound waves to determine depth

  • Magnetometer- detects changes in magnetic fields

  • Map the ocean floor


Ocean floor topography
Ocean Floor Topography

  • Mountain ranges (ridges), trenches

  • Earthquakes & volcanoes



Ocean rocks and sediments
Ocean Rocks and Sediments

  • Varying ages of rocks: pattern

    • Younger rocks near ridges

    • Older rocks farther away

  • Sediments

    • Thinner than continental crust

    • Thickness increased farther away from ridge


Magnetism
Magnetism

  • Paleomagnetism: study of magnetic record

    • Basalt(Iron) = compass needle

  • Magnetic reversal: change in Earth’s magnetic field

  • Magnetic symmetry: matching strips on each side of ridge


Seafloor spreading
Seafloor Spreading

  • New crust created at ridges

  • Crust is destroyed at trenches

  • Magma comes out of ridges

  • New rock pushes crust outward

  • Provided evidence for continental drift





Section 17 3 theory of plate tectonics
Section 17.3: Theory of Plate Tectonics

Objectives:

  • Explain the theory of plate tectonics

  • Compare/contrast the three types of plate boundaries and the features associated with each.


Theory of plate tectonics
Theory of Plate Tectonics

  • Earth’s crust: large slabs called plates

  • Major and smaller plates



Plate boundaries
Plate Boundaries

  • Plate boundaries: where plates meet

    • Divergent

    • Convergent

    • Transform




Divergent plate boundaries
Divergent Plate Boundaries

  • Plates moving apart

  • Most on ocean ridges

  • Rift valley: narrow valley along divergent boundary


Convergent plate boundaries
Convergent Plate Boundaries

  • Plates moving together

    • Oceanic crust – oceanic crust: volcanoes

    • Oceanic crust – continental crust: volcanoes

    • Continental crust – continental crust: mountains

  • Subduction- one plate goes below the other



Transform plate boundaries
Transform Plate Boundaries

  • Plates slide horizontally


Section 17 4 cause of plate motions
Section 17.4: Cause of Plate Motions

Objectives:

  • Explain the process of convection

  • Summarize how convection in the mantle is related to the movements of tectonic plates

  • Compare/contrast the processes of ridge push and slab pull


Mantle convection
Mantle Convection

  • Convection: movement due to temperature differences

  • Mantle has convection currents

  • Currents move plates

  • Ridge push- weight of ridge pushes plate down

  • Slab pull- weight of plate pulls plate down


Push and pull
Push and Pull


ad