Layers of the Earth

Earth Layers The Earth is divided into four main layers: - crust - mantle - outer core - inner core

The Crust Like the skin of an apple; very thin compared to other layers. 5 - 70 km thick Solid rock (includes soil & water) Makes up 1% of the Earth Broken into many pieces called plates.

Two Types of Crust CONTINENTAL CRUST - 20 and 60 km thick - made of granite, less dense - most is above sea level - light color, coarse OCEANIC CRUST - only about 10 km thick - made of basalt, very dense - below sea level - dark color, fine texture

Crust

The Mantle Below the crust Semi-solid layer (magma) Hot, iron-rich silicate rocks Largest layer (3,000 km thick) Divided into three parts

Upper Mantel Lithosphere - a combination of the upper-most part of the mantel and the crust Rigid (brittle) 100 km thick Asthenosphere – soft layer below the lithosphere Hotter; increased pressure Less rigid (can bend like plastic) Capable of flow Lithos - means stone Asthenes – means weak

Lower Mantel Lower mantel – a solid layer beneath the asthenosphere Goes all the way to the Earth’s core

Think-Pair-Share What characteristics does the lithosphere have? What characteristic s does the asthenosphere have? Why does rock in the asthenosphere behave differently from the rock above?

Apply Your Knowledge How much time does it take for a piece of taffy to flow when you pull on it? How much time does it take for rock in Earth’s asthenosphere to flow? Long time! Rates are measured in centimeters per year

Heat Transfer Flow in the mantle is caused by convection currents hot material in the mantle rises, cools and then sinks Slow movement (like fingernail growth)

Outer Core Layer of liquid metal made of iron & nickel very dense (1/3 of Earth’s mass)

Inner Core Dense ball of solid iron & nickel. Pressure from upper layers squeeze the metals together, so they can’t move Iron normally melts at 1,5350C, but in the inner core it could withstand 4,0000C with no melting

Earth’s Magnetic Field Scientists believe that movements in the liquid outer core create the Earth’s magnetic field.

Review What are the main four layers of the Earth? 2) The Earth’s crust is very ______. 3) The mantle is the largest layer of the Earth. (True or False) 4) Is the Outer Core a liquid or a solid?

Answers Crust, Mantle, Outer Core, Inner Core 2) Thin 3) True 4) Liquid