Earth’s Structure

Crust

There are two different crusts on our planet, the continental and the oceanic.

The continental crust is the thicker crust, made of land, which is made up of silicon,aluminum, and oxygen. It is also less dense than oceanic crust.

The oceanic crust is the thinner crust made up of water, and is denser than the continental crust.It is also made up of silicon, aluminum, and oxygen.

Oceanic Crust

Continental Crust

Mantle

This is the thickest layer of the Earth containing most of its mass.No one has ever been to the mantle because they can’t drill through the crust, and the heat is to hot to bear.

Scientists have figured out that magma pushes out from the mantle and has to be at the bottom of the ocean.

Mantle

Asthenosphere

This is the soft layer of the mantle on which tectonic plates move.It is made up of solid rock that flows very slowly.

Lithosphere

This is the solid outer layer of the Earth that consists of the crust , and the rigid upper part of the mantle.The lithosphere is divided into pieces called tectonic plates.

Lithosphere

Outer Core

This is the liquid layer of the Earth’s core. This lies beneath the mantle and surrounds the inner core.

Inner Core

This is the solid dense center of our planet that extends from the bottom of the outer core to the center of the Earth which is the hottest on our planet.

Continental Drift

This is the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations.

Pangea, a super continent, broke apart from each other to their present locations.Wegener,a scientist could never get it approved.

Glossopteris, an ancient plant, has been found on all continents proving Wegener’s hypothesis.

He also proved continental drift with sea-floor-spreading and plate tectonics.

Continental Drift

Wegener proved continental drift because of geologic, fossil, and climate evidence.

Geologic evidence- the evidence of how all the shore lines and mountain ranges are lined up.

Fossil evidence- the evidence in where the fossils are found. Example: Glossopteris

Climate evidence- the evidence that the climate has changed.

CONTINENTAL DRIFT

Geologic Time

Geologic time has been classified into three different parts. Cenozoic, Paleozoic, and Mesozoic.

Cenozoic is the era we live in. It is sometimes referred to it as the “ Age of the Mammals”.

Paleozoic is the first era. It was the age of animals. It is also the longest era.

Mesozoic is the middle era. It was when the dinosaurs roamed the Earth.

Era vs. Epoch vs. Period

Eon is the largest division of geologic time. Era, the second largest time period, usually

consists of two or more periods. Period, the third largest time period, is a unit of

geologic time which eras are divided. Epoch, is the smallest division of geologic time.

Fossils

There are many types of fossils, but the major ones are the trace fossils and index fossils.

Trace fossils- the mark that is formed in soft sediment by the movement of an animal.

Index fossil- a fossil that is found in the rock layers of one geologic age.