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Who is Harry Hess?

Who is Harry Hess?. Harry Hess was a geologist and Navy submarine commander during World War II. Part of his mission had been to study the deepest parts of the ocean floor. Scientists began to use magnometers to study the ocean floor in the 1950s.

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Who is Harry Hess?

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  1. Who is Harry Hess? • Harry Hess was a geologist and Navy submarine commander during World War II. • Part of his mission had been to study the deepest parts of the ocean floor.

  2. Scientists began to use magnometers to study the ocean floor in the 1950s. • The Great Global Rift (mid-ocean ridge) was discovered. • What are mid-ocean ridges?

  3. What are mid-ocean ridges? • Mid-ocean ridges are underwater mountain ranges that extend into all of Earth’s oceans.

  4. They curve like the seam of a baseball along the sea floor.

  5. What did Harry Hess propose? • The discoveries inspired Hess to look back at his data from years before. • In 1960, Harry Hess, proposed that the movement of the continents was a result of sea-floor spreading. • What is sea-floor spreading?

  6. What Is Sea-Floor Spreading? • In sea-floor spreading, the sea floor spreads apart along both sides of a mid-ocean ridge as new crust is added. As a result, the ocean floors move like conveyor belts, carrying the continents along with them.

  7. Convection Currents and Sea-Floor Spreading

  8. What is the evidence for Sea-Floor Spreading? • Several types of evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic strips in the rock of the ocean floor, and the ages of the rocks themselves. • What are magnetic strips?

  9. The Earth acts like a giant magnet.

  10. What causes the magnetic field? • Scientists think that the movements in the liquid core create Earth’s magnetic field.

  11. The magnetic poles are constantly changing and this is recorded in the Earth’s rocks.

  12. This is a reading of the magnetic strips along the Mid-Atlantic Ridge. http://openlearn.open.ac.uk/file.php/2717/S279_1_006i.jpg

  13. Magnetic minerals within igneous rocks align themselves with the magnetic poles.

  14. Do we track plate movement? Scientists use satellites to track the movements of the Earth’s plates.

  15. Interesting Fact! Because of sea-floor spreading, the distance between Europe and North America is increasing by a few centimeters per year.

  16. Rock samples • Scientists have also collected core samples.

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