The study of the forces that change the earth’s surface. What is Geology? The study of the forces that change the earth’s surface.

These forces can either build up (constructive) or wear down (destructive) the earth’s crust.

Forces that build up the earth. Constructive forces Forces that build up the earth. Example: Volcanic eruptions add new landmass

http://english. peopledaily. com. cn/200607/21/eng20060721_285295 http://english.peopledaily.com.cn/200607/21/eng20060721_285295.html Mayon volcano, Philippeans

http://top-10-list. org/2009/04/20/top-10-worst-volcanic-eruptions/ Mt http://top-10-list.org/2009/04/20/top-10-worst-volcanic-eruptions/ Mt. Krakatoa, Indionesia

Forces that wear away the earth’s surface. Destructive forces Forces that wear away the earth’s surface. Example: Weathering & Erosion caused by wind or water.

Grand Canyon, USA

Main layers that make up Earth 1. Crust 2. Mantle 3. Outer Core 4. Inner Core

Earth’s Crust The layer of the earth that forms the outer “skin.” Includes both continental land and the ocean floor.

Oceanic crust forms beneath the ocean and is made from… BASALT

http://www.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousCompositions/3Basalt/BasaltSmallVesicOlPheno.jpg http://www.explorevolcanoes.com/volcanoimages/spreading%20ridge%20Press%20and%20Siever.jpg

Continental crust forms above the ocean and is made mostly from … GRANITE

http://www.earth.ox.ac.uk/~oesis/field/medium/granite1.jpg http://images.google.com/imgres?imgurl=http://www.beg.utexas.edu/mainweb/publications/graphics/granite-400.jpg&imgrefurl=http://www.beg.utexas.edu/mainweb/publications/graphics/granite.htm&usg=__0de5K-fYX3ZSELLMQs78BEQCxqI=&h=300&w=400&sz=78&hl=en&start=1&um=1&itbs=1&tbnid=KHAn81O-WrYHiM:&tbnh=93&tbnw=124&prev=/images%3Fq%3Dgranite%26hl%3Den%26sa%3DN%26um%3D1

Density and Thickness of Earth’s Crust Continental crust is thicker but less dense than oceanic crust. Oceanic crust is thinner but more dense than continental crust.

Earth’s Mantle A layer of hot rock material located beneath the crust. More than 82% of Earth’s volume at about 2,900 km thick. Divided into several layers. Upper mantle is made up of the lithosphere and asthenosphere Lower mantle is called the mesophere

The Lithosphere The layer of rigid rock that includes all of the Crust and the upper portion of the Mantle. It’s about 100 km thick

The Asthenosphere A layer of solid rock that behaves like a fluid (it flows and moves like a liquid). Found in the Mantle beneath the lithosphere. The lithosphere floats on top of the asthenosphere.

Earth’s Core The inner core and the outer core together make up the structure of the Earth’s core. Both the outer and inner cores are composed of iron and nickel. The outer core is liquid (molten) metal and the inner core is solid metal.

How do geologists know the structure inside the Earth? Because the actual interior of the Earth cannot be seen, geologists use indirect observations.

What is indirect evidence? Indirect evidence is evidence that you get without actually seeing or touching the object you are studying.

Waves of energy generated by earthquakes. What are seismic waves? Waves of energy generated by earthquakes.