Lesson 5.1 (7.10A)

Changes of the Earth

continental drift

hypothesis which suggests that continents are in constant motion on the surface of Earth.

fossil

the preserved remains or evidence of past living organisms.

superposition

the principle that in undisturbed rock layers, the oldest rocks are on the bottom.

plate tectonics

states that Earth's surface is divided into large plates of rigid rocks that move with respect to each other

seafloor spreading

the process by which new oceanic crust forms along a mid-ocean ridge and older oceanic crust moves away from the ridge.

mid-ocean ridge

the mountain ranges in the middle of the oceans.

magnetic reversal

Earth's magnetic field reverses direction.

asthenosphere

the solid layer of Earth’s mantle below the lithosphere that is so hot it behaves like a plastic material.

lithosphere

the rigid outermost layer of Earth that includes the uppermost mantle and crust.

Pangea

A supercontinent or big continent that existed in which all the land on Earth was connected.