sea floor spreading n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Sea Floor Spreading PowerPoint Presentation
Download Presentation
Sea Floor Spreading

Loading in 2 Seconds...

play fullscreen
1 / 9

Sea Floor Spreading - PowerPoint PPT Presentation


  • 125 Views
  • Uploaded on

Sea Floor Spreading. Mid-Ocean Ridges. Mid-ocean ridges are an undersea mountain chain where new ocean floor is produced. In the mid-1900’s, scientists begin mapping the mid-ocean ridges using SONAR. Mapping mid-ocean ridges, made scientists more curious. What are these ridges?

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 'Sea Floor Spreading' - armani


Download Now 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
mid ocean ridges
Mid-Ocean Ridges
  • Mid-ocean ridges are an undersea mountain chain where new ocean floor is produced.
  • In the mid-1900’s, scientists begin mapping the mid-ocean ridges using SONAR.
  • Mapping mid-ocean ridges, made scientists more curious.
    • What are these ridges?
    • How did they form?
sea floor spreading1
Sea-Floor Spreading
  • In sea-floor spreading, the sea floor spreads apart along both sides of a mid-ocean ridge as a new crust is added.
    • The ocean floor moves like a conveyor belt, carrying the continents along with them.
  • Along these ridges, molten material that has formed several km beneath the surface rises and erupts.
    • As the molten material cools on the ridge, new solid rock is formed, more molten material flows into the cracks and new strips of rock is formed.
evidence of sea floor spreading
Evidence of Sea-Floor Spreading

Evidence from molten material

In the 1960’s scientists sent Alvin, a submarine that could withstand the crushing pressures deep in the ocean.

Strange rocks were found. Rocks that looked like toothpaste squeezed from the tube. These types of rock only form when molten rock cools and hardens quickly after erupting.

more evidence of sea floor spreading
More Evidence of Sea-Floor Spreading

Evidence from Magnetic Stripes

Evidence from Drill Samples

  • History shows that the earth’s magnetic field has reversed many times.
  • Rocks that make up the ocean floor reveal this pattern in magnetized stripes.
  • These rocks contain iron. As they cool and harden, the iron lined up in the direction of the Earth’s magnetic field.
  • Rock samples from drilling into the ocean floor are the final proof of sea-floor spreading.
  • The Glomar Challenger sent pipes 6 km deep in the ocean to drill hole sin the ocean floor.
  • Scientists found that the farther away from the ridge, the older the rock sample were.
subduction at trenches
Subduction at Trenches
  • Deep-ocean trenches are deep underwater canyons, where the oceanic crust bends downward.
  • SUBDUCTION is a process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.
  • It takes about 200 million years for new rock to form, move across the mid-ocean ridge, move across the ocean, and sink into a trench.
did you know the pacific ocean is shrinking and the atlantic ocean is expanding
Did you know the Pacific Ocean is Shrinking and the Atlantic ocean is expanding?
  • Sometimes a deep ocean trench swallows more oceanic crust than a mid-ocean ridge can produce.
      • This is why the Pacific Ocean is shrinking
  • The opposite is happening to the Atlantic Ocean.
    • More oceanic crust is being produced at mid-ocean ridges that the deep ocean-trenches and swallow up.