Chapter 9- Plate Tectonics

Question 1

continental drift

Answer 1

hypothesis proposed by Alfred Wegner that states continents have moved slowly to their current locations on Earth

Question 2

Pangea

Answer 2

single large landmass Ade up of all the continents connected together that broke apart about 200 million years ago

Question 3

seafloor spreading

Answer 3

theory that magma from below Earth’s crust is forced upward toward the surface at a mid-ocean ridge and becomes new seafloor

Question 4

plate tectonics

Answer 4

theory that Earth’s crust and upper mantle are broken into sections that move around on a plasticlike layer of the mantle

Question 5

lithosphere

Answer 5

rigid, outer-most layer of Earth that is about 100 km thick, and is composed of the crust and part of the upper mantle

Question 6

asthenosphere

Answer 6

plasticlike layer below the lithosphere

Question 7

convection current

Answer 7

cycle of heating, rising, cooling, and sinking that is thought to be the force behind plate tectonics