Seafloor Spreading

Where does seafloor spreading occur?

• Near mountain chains

• At Mid-Ocean Ridges

• At transform plate boundaries

• Near Volcanic Mountain chains

Who discovered Seafloor Spreading?

• Marie Curie

• Charles Darwin

• Alfred Wegner

• Harry Hess

How did Harry Hess discover the topography of the Seafloor?

(a)  

The ocean floor is considered to be primarily

• Granite

• Basalt

• Limestone

• Sandstone

Is the density of the Oceanic Crust greater or less than the density of the Continental Crust?

(a)  

Which is the best evidence supporting the concept of seafloor spreading?

• Earthquakes occur at greater depths

• Sandstone and limestone can be found both in North America and Europe

• Volcanoes appear at random within the oceanic crust

• Rocks along the mid-ocean ridges are younger than those farther from the ridges.

Is the Continental Crust more or less thick than the Oceanic Crust?

(a)  

Describe how the age of the sea floor changes the farther you go from a mid-ocean ridge.

What causes lava to rise to the surface and harden into new oceanic crust?

(a)  

Which of the following are evidences for sea floor spreading

• Shifts in the magnetic polarity recorded in rock

• The relative heat differences in the rock layers

• The thickness of the rock layers

• The age of the rocks relative to their position to ocean ridges