Inside the Earth

Ch 7 Section 1 P. 190-197

How do we identify physical layers of the earth?

Composition Physical Properties

Composition Divided into 3

layers: Crust Mantle Core

Based on Compounds that make up each layer A substance

composed of 2 or more elements

Composition Cont’d

Less dense compounds make up crust & mantle. Most dense portion of earth=core

Heavier elements are pulled to the center of the earth by gravity.

Elements with less mass are further from the center of the earth.

Crust Outermost layer of

the earth Thinnest layer 2 types:

continental & oceanic

Oceanic crust more dense than continental

Mantle

Layer of earth between crust and core.

Thicker than the crust and contains most of the earth’s mass.

Too deep in earth for humans to visit Learn info about mantle from rocks

that are pushed to the surface through a volcano.

Physical Structure of the earth

Divided into 5 physical layers Lithosphere: Asthenosphere Mesosphere Outer core Inner core

Tectonic Plates Pieces of the lithosphere that move

around on top of the asthenosphere. Each tectonic plate has a name. Tectonic plates fit together like a

puzzle. Different sized plates Some plates include both oceanic and

continental crust, some only have one.

Like Ice Cubes in Punch

Tectonic plates “float” on the asthenosphere similarly.

The lithosphere displaces the asthenosphere.

Thick plates like the continental displace the asthenosphere more than the oceanic lithosphere.

How do we know about Earth’s Interior?

Volcanic eruptions Earthquakes

Speed depends on density and composition of material they pass through. Seismic waves travel faster through solids

than liquids. Seismotologists use distances and travel

times to calculate the density and thickness of each physical layer of the earth.