The Earth’s Layers Scientists have spent many years determining what is inside the earth. Geologists can’t use x-rays to see inside the earth or dig a hole deep enough to explore what is deep inside the Earth. They have used instruments to measure earthquake waves move through the Earth. These waves pass through different materials at different rates. By analyzing earthquake waves, geologists have theorized that the interior of the earth consists of layers.

Students will … illustrate the structural layers of Earth, including the inner core, outer core, mantle, crust, asthenosphere, and lithosphere. [6.10A]

Earth’s Layers Each layer of the Earth has its own unique properties. There are three distinct layers – the crust, mantle, and core – which can then be subdivided into more layers. Each layer is made up of specific elements.

Simple Layers Crust Mantle Core Scientists have identified three main layers. At the center of the earth, is the core which is 750 miles in diameter. Next we find the outer core at 1,430 miles thick. Then we have the mantle at 1,800 miles. Finally, we have the earth’s crust which is very a thin layer in comparison to the rest of the earth at 10-25 miles.

Into the Earth…

The Crust Outermost layer Thinnest layer and much cooler than others 2 types of crust Oceanic (very dense, made of basalt) Continental (less dense, made of granite)

Oceanic and Continental Crust Thinnest beneath ocean and thickest beneath mountain ranges

The Mantle Layer beneath crust Middle layer Very thick layer Made up of more iron and magnesium so is very dense Convection currents occur in the mantle

Mantle Is Divided into … Lithosphere Asthenosphere Consists of the crust and the upper part of the mantle Solid and rocky Broken into large pieces called tectonic plates Earthquakes can occur in the lithosphere Made up of elements Oxygen and Silicon Beneath the lithosphere Partially molten The rock is pliable or plastic-like Rock here bends, stretches, and flows The tectonic plates float on this layer

Tectonic Plates Earth’s crust is broken into about a dozen major plates and several minor plates These plates constantly move on top of the Asthenosphere

The Core Made up of the elements iron and nickel 1/3 of the Earth’s mass The core is larger than Mars! The core is very hot and dense

The Core is Divided Into… Outer Core Inner Core The outer core is a liquid The material of the outer core is considered molten as it is extremely hot Less dense than the inner core Made up of Iron and Nickel The inner core is the most dense It is solid even though the temperature is very hot due to the extreme pressure The inner core is composed mostly of Iron

Earth’s Layers How are the Earth’s layers similar to an egg? Shell=crust Egg white=mantle Yolk=core

Physical Structure of the Earth Layers Reviewed Crust and Lithosphere- rigid outer layer Mantle and Asthenosphere- solid rock that flows slowly (like hot asphalt) Outer Core- liquid layer Inner Core- solid, very dense

References http://geomaps.wr.usgs.gov/parks/pltec/#crust http://pubs.usgs.gov/gip/dynamic/dynamic.html