| A | B |
|---|
| Earth's composition and layers | are how scientist look at the earth. |
| The outermost layer of the earth | the Crust |
| The thinnest layer of the Earth | 5 to 100 km thick |
| Two types of Crust | oceanic and continental |
| Continential crust | composition like granite |
| Oceanic crust | composition like basalt |
| Oceanic crust is denser than | Continential crust |
| The layer of the earth between the crust and the core | is the mantle |
| The mantle is thick | and contains most of the Earth's mass |
| Volcanic vents on the ocean floor | provides a good look at what the mantle is like |
| The Earth's core is made mostly of | Iron |
| The core makes up | 33% of the Earth's mass |
| The mantle makes up | 76% of the Earth's mass |
| The crust makes up | less than `% of the Earth's mass |
| The Earth is divided in five main physical layers | the lithospehere, asthenospehre, mesosphere, outer core, and inner core |
| Lithosphere | the crust and the rigid upper part |
| the lithosphere is divided into | tectonic plates |
| Asthenosphere--weak sphere | made of solid rock and flows slowly as putty |
| Mesophere--middle sphere | strong lower part of the mantle |
| Outer Core | liquid layer beneath the mantle and surrounds the inner core |
| Inner core | solid, dense center of the planet |
| Tectonic Plates | pieces of the lithosphere that move around on top of the asthenosphere |
| # of tectonic plates | 10 |
| Major provider of information about the center of the earth | earthquakes |
| seismographs | measures the difference in the arrival times of seismic waves and record them |
