http://www.ldeo.columbia.edu/~richards/Jefflec.html

Here is one common model of Earth’s Interior Layers

Earth’s Interior LayersHow do we know what they are like?

Since Scientists cannot study Earth’s Interior directly, they student seismic waves

(earthquake waves) . Geologists record the seismic waves of earthquakes and study how they travel through the media of the Earth. The speed of the waves and the paths they take reveal how the planet is put together. Using data collected from seismic waves,

geologists have learned that Earth’s interior is made up of several layers.

• Technology has often led to new• discoveries• • Telescope• • Microscope• • X-ray machines• • Radar and Sonar• • Satellite multispectral cameras• • Hubble Space Telescope

Seismograms from many earthquakes proved that P-waves (Primary Waves) were refracted (bent) as they moved through the Earth, and S-waves (Secondary Waves) werestopped by liquids. L-waves (Land Waves) are “P” Waves as they reach the surface. They do the damage.

• Therefore, geologists were able to conclude that “P” Waves could move through all the layers of the Earth, but slowed down when they came to certain layers while “S” Waves could NOT move through liquids. They could not travel to the surface of the Earth because they could not get through the mantle or outer core.