Chapter 9 51-65 Astronomy

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What process has shaped Earth's surface more than any other? plate tectonics
Why are there fewer large craters on the seafloor than on the continents? the seafloor crust is younger than the continental crust
How does seafloor crust differ from continental crust? seafloor crust is thinner, younger, and higher in density
Why is continental crust lower in density than seafloor crust? continental crust is made from remelted seafloor crust and therefore only the lower-density material rises to form it.
Which of the following is not evidence for plate tectonics on Earth? existence of volcanoes
How fast do plates move on Earth? a few centimeters per year
How long, approximately, do geologists estimate it takes for the entire seafloor to be replaced due to plate tectonics? 200 million years
What drives the motion of the tectonic plates on Earth? convection cells in the mantle
Ridges in the middle of the ocean are places where hot mantle material rises upward and spreads sideways, pushing the plates apart.
Deep trenches in the ocean mark places where one plate slides under another, returning older crust to the mantle
Some of the oldest continental crust on Earth lies in Northeastern Canada.
Which of the following regions was the result of plumes of hot mantle rising in a hot spot within a plate? the islands of Hawaii
The geysers and hot springs of Yellowstone National Park result from plumes of hot mantle rising in a hot spot within a plate.
Mineral evidence shows that Earth's oceans have existed for over four billion years
Which of the following does not provide evidence for water on Mars?

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