EARTH’S MOVING SURFACE CHAPTER 4 LESSON 1 EARTH’S MOVING SURFACE

4.1 INFORMATION

WHY PLATES MOVE

DENSITY The amount of matter per unit of volume

DENSITY Density = mass / volume How heavy it is divided by how much space it takes up

DENSITY

DENSITY When a fluid is heated, its molecules spread out and it becomes less dense.

DENSITY When fluids heat unevenly, the warmer, less- dense fluid rises, and the cooler, denser fluid sinks.

CONVECTION the circulation within fluids caused by differences in density and thermal energy.

CONVECTION

CONVECTION Convection in the mantle can drag plates over Earth’s surface.

CONVECTION

SUBDUCTION Plates can also move as a result of subduction.

SUBDUCTION When two plates collide, one can subduct or sink into the hotter, less-dense mantle.

SUBDUCTION The sinking part of a plate pulls the rest of the plate along.