The Earths Crust Outermost layer of the Earth 5 – 100km thick Less than 1% of the mass of the Earth, yet humans have not ever drilled all the way through it. Two types: –Continental Crust –Oceanic Crust
Oceanic Crust - Thinner and more dense Continental Crust - Thicker and less dense Mantle
The Earths Mantle Between the crust and the core 2900 km thick 67% of the Earths mass Three parts –Lithosphere (half in the crust) –Asthenosphere –Mesosphere
Layers of the Mantle
-- Lithosphere is the rigid layer of the Earth that includes the crust and the upper part of the mantle.
Layers of the Mantle -- Asthenosphere is the soft plastic-like layer of the mantle on which the pieces of the lithosphere float.
Layers of the Mantle -- Mesosphere is the strong lower part of the mantle.
The Core Innermost layer of the Earth 3430 km radius 33% of Earths mass Made mostly of iron Two layers –Outer core –Inner core
Layers of the Core -- Outer Core is liquid
Layers of the Core -- Inner Core is solid
Tectonic Plates Pieces of the lithosphere that move around on top of the asthenosphere These plates are made up of both continental crust and oceanic crust.
Mapping the Earths Interior Scientists have figured out what the Earths interior looks like by studying how earthquake (seismic) waves travel through the Earth.
Seismic waves travel at different speeds when they travel through materials with different densities.
Scientists measure how long it takes the waves to travel through the Earth to different locations, then make calculations to figure out what the inside of the Earth is composed of.
Seismologists can then use the distances and travel times to calculate the density and thickness of each layer of the Earth.
USGS Earthquake Hazards Program: Animation of Seismic Waves: CENTRAL ALASKA
Seismograph Scientists us a device called a seismograph to measure arrival time and magnitude of seismic waves around the Earth.