A Journey to the Center of the Earth The Earth’s Structure A Journey to the Center of the Earth

The Earth’s Surface Hydrosphere: Atmosphere: All the Earth’s water The earth is 71% covered by water 97% is salt water Atmosphere: Thick blanket of gases surrounding the earth

The Interior of the Earth

The Earth’s Layers Earth can be divided into three main layers – the crust, mantle and core. The layering is due to differences in density Temperature and pressure in Earth’s interior increase with depth

The Crust Rocky outer layer of Earth Made up of Silicates Two types of Crust Continental Crust – rocks that make up continents; thickness between 8 -75 km Oceanic Crust – rock that makes up ocean floor; average thickness 7 km

Review What does the prefix hydro- mean? List the three main layers of the earth’s interior? Explain why the layers of the earth stay in place? Water makes up ____ of the earth’s surface. Name the two types of crust. What is the difference between the two types?

The Mantle A thick layer of hot semi-solid dense rock Approximately 2850 km thick Composed of mostly iron, magnesium and aluminum. Makes up about 84% of Earth’s volume

The Moho The boundary between the crust and the mantle. The mantle is denser than its crust Mohorovicic discontinuity

“Sub Layers” w/n Crust & Mantle Lithosphere – composed of the oceanic and continental crust and the rigid upper mantle; thin outer shell of Earth; broken up into “plates”. Asthenosphere – softer and weaker rock in the mid-mantle; can flow slowly when under pressure Mesosphere – stronger lower part of the mantle

The Core A large sphere of metal that occupies Earth’s center Composed mostly of iron and nickel Divided into 2 parts: Outer core – composed of liquid metal; 2260 km thick Inner core – solid due to very high pressure; 1220 km thick

https://www.youtube.com/watch?v=Q9j1xGaxYzY https://www.youtube.com/watch?v=vNaXxXNFOjM

How do Scientists study Interior of Earth? Use of Seismic Waves (Earthquakes) 2 Types of Seismic Waves: S & P waves P waves: Travel through solids, liquids and gases Faster than S waves S waves Travel only through solids

How do Scientists study Interior of Earth? Speed and direction of both waves are affected by the composition of material they are traveling through For example: The changes in the seismic waves mark the boundary between the mantle and outer core. Both P and S waves travel faster through more rigid materials

Shadow Zones Locations on Earth’s surfaces where neither S or P waves are detected S waves will not travel through liquid core P waves speed and direction change causing them to bend

Review What are the two types of seismic waves? How are seismic waves used to determine the layers of the earth? Which layer is a liquid? Which layers compose the lithosphere? What state of matter is the inner core?

What is a compass?

The Earth as a Magnet Source of the earth’s magnetic field is the movement of liquid iron in the outer core. The motion produces electrical currents which create a magnetic field.

Magnetosphere The region of space which is affected by the earth’s magnetic field. affects the earth and an area that extends beyond the atmosphere.