Composition and Physical Layers of the Earth Plate tectonics Composition and Physical Layers of the Earth

Composition The Earth is composed of three main layers based on the differences in chemical make up 1. the crust 2. the mantle 3. the core

Composition of the Earth’s crust Continental crust (found on land) is made up mostly of granite rock. Oceanic crust (found under the oceans) is made up mostly of basalt rock Basalt rock is more dense than Granite rock The crust is less than 1% of the Earth’s total mass

Composition of the Earth’s mantle The Earth has an upper mantle and a lower mantle. The upper mantle is partially melted (molten) and contains iron and silicon metal compounds The lower mantle is completely molten and also contains iron. Magnesium, silicon and oxygen are also present.

Composition of the earths core The Earth has an inner core and an outer core They both contain large quantities of the element iron and small amounts of the elements nickel, sulfur and oxygen

Cool fact! The solid inner core of the Earth spins faster than the rest of the planet. The Earth’s outer core is hot liquid iron and other minerals that conduct electricity . The combination of the spinning inner core and the electrical moving outer core generates the Earth’s magnetic field!

Physical layers The earth is also separated into 5 physical layers based on differences in temperature and pressure 1. Lithosphere 2. Asthenosphere 3. Mesosphere 4. Outer core 5. Inner core

Earth Physical Layers * Differences in pressure and temperature cause STRESS which separates the Earth into physical layers. For example if rock gets hot enough it will melt and become a liquid but if we put enough pressure on the liquid rock it can be come a solid again

Lithosphere Outermost physical layer of the earth Called the Rock sphere Consists of the crust and the upper part of the mantle This layer makes up the “Tectonic Plates”! 15 – 300 km thick Why do you think the thickness varies?

Asthenosphere Called the weak sphere It is the “soft” layer of the mantle The “tectonic plates” move on top of this layer 250 km thick

Mesosphere Strong lower part of the mantle 2,550 km thick

Outer Core Liquid molten iron Conducts electricity Continuously moving by convection. - remember studying convection in weather? 2,200 km thick

Inner core Solid iron Spins faster than the rest of the planet Why is the inner core solid and the outer core liquid when they are both made up of the same element iron?

How do we know about these Layers? Seismic waves (vibrations) created by earthquakes travel at different speeds depending on the density of each layer The denser the material the faster the waves travel

Let’s review!! What are the layers of the earth that are described by their composition? What are the two types of crust? What type of rock is found on each type of crust? Which type of rock is most dense?

Review continued! What causes stress in the Earth’s layers? What are the five physical layers of the earth? Which physical layer makes up the tectonic plates? Which layer is soft and the plates move on top of it? Which layer is liquid, has strong magnetism and conducts electricity?

Pictures cited http://www.yorku.ca/esse/veo/earth/image/1-2-10.JPG http://www.ncad.net/GP/Erla/EarthCore.gif http://www.geocities.com/cdegonia/Picture5.gif http://upload.wikimedia.org/wikipedia/en/7/7a/EarthCrustMantleCore.png http://anshsmagnetism.files.wordpress.com/2009/01/earth-magfield.jpg http://www.plate-tectonics.org/Lithosphere%20and%20Asthenosphere.gif http://www.architectjaved.com/earthquakes/crust1.jpg http://www.geography.info/images/interior.gif http://bprc.osu.edu/education/rr/layers_of_the_earth/layers_of_the_earth_diagram.jpg http://students.usiouxfalls.edu/mologan/Earths%20structure_files/slide0004_image035.gif http://www.lbl.gov/Science-Articles/Archive/assets/images/2003/May-09-2003/Earth_cutaway.jpg