Journey to the Center of the Earth

There will be temper= ature and pressure changes as you go through the layers of the Earth to the center core. There are three main la= yers and each layer has its own conditions and materials. These layers vary greatly in size, composition, temperature, and pressure.&nb= sp; The three main layers that make up the Earth’s interior are:

The Crust
The Mantle
The Core

The Crust is a = layer of rock that forms Earth’s outer skin.&= nbsp; On the crust are rocks and mountains. The crust also included the soil a= nd water that covers large parts of Earth’s surface. The crust includes the dry land an= d the ocean floor. The crust is thi= nnest beneath the ocean. The crust = is thickest under high mountains. The crust is from 5 to 40 kilometers thick.&nb= sp; The crust beneath the ocean is called oceanic crust and is mo= stly of basalt rock. Basalt= is a dense, dark rock with a fine texture. The land crust, which forms the continents, is continental crust<= /b> and is made of mostly granite. Granite is a rock with larger crystals than basalt. Granite is less dense and usually a light color.

The Mantle is below the basalt and granite. The m= antle has a layer of solid hot rock. The crust and the uppermost part of the mantle are very similar. Together they form a rigid layer c= alled the lithosphere. The lithosphere is broken into a number of plates that move over the asthenosph= ere beneath it. Below the lithosp= here the heat and pressure make the mantle less rigid. This part is like road tar softene= d by the heat of the sun. This soft layer of the mantle is the asthenosphere. The material in this layer can flow slowly. The lithosphere float= s on top of the asthenosphere. Ben= eath the asthenosphere, sold mantle material extends all the way to Earth’s core. The mantle is about 3000 kilometers thick. Compared wi= th the crust, the mantle is very thick and contains most of the Earth’s mass. In some places mantle r= ock has been pushed up to the sur= face by tectonic forces. This allo= ws scientists to observe the rock directly.

The Core is a layer of molten metal that surroun= ds the inner core. The outer core= behaves like a thick liquid. = The inner core is a dense ball of solid metal.&n= bsp; The pressure at this depth squeezes the atoms of iron so tightly that they cannot become liquid. Th= e core is made mostly of the metals iron and nickel and possibly some sulfur and oxygen.

Currents in the liqu= id outer core force the solid inner core to spin inside Earth slightly faster than t= he rest of the planet. This movement creates Earth’s magnetic field.<= span style=3D'mso-spacerun:yes'> This makes the planet act like= a giant bar magnet. =

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Convection Currents and the Mantle

Heat transfers from = a warmer substance to a cooler substance. There are three types of heat transfer:

Radiation

Conduction

Convection

The transfer of heat= through empty space is called radiation.&nb= sp; Sunlight is radiation that warms the surface of the Earth. When heat is transferred by radiat= ion, there is no direct contact between the heat source and an object. Heat from an open flame is radiant= heat.

The direct transfer = of heat in solid material is called conduction. The heat is still transferred form = the higher heat to the lower heat. An example is placing a spoon in hot tea.&nbs= p; The heat from the tea transfers to the spoon. If you touch the spoon, the heat f= rom the spoon will transfer to you. You will feel the heat. This transfer within a material or between materials that are touching is called conduction.=

Heat that is transfe= rred by the movement of a heated liquid is convection. Heated particles of fluid begin to= flow during convection. This trans= fers heat energy from one part of the fluid to another part of the fluid. Differences in temperature and den= sity in the fluid causes the heat to transfer by convection. A convection current is the= flow that transfers heat within a fluid. The heating and cooling of the fluid, changes the fluid’s dens= ity, and the force of gravity combine to set convection currents in motion. Heat from the core and the mantle = causes convection currents in the mantle.

In the mantle hot co= lumns of mantle material rise slowly through the asthenosphere where the material spreads out and pushes the cooler material out of the way. The cooler material sinks back int= o the asthenosphere. The cycle happ= ens over and over again as these convections currents have been moving inside Earth for more than four billion years.

Review: The Earth is divided into five main physical layers:

The lithosphere

The asthenosphere

The mesosphere

Outer Core

Inner Core

The Lithosphere is the outermost rigid layer of the Earth .&n= bsp; The lithosphere is made of two parts. The crust and the rigid upper part= of the mantle make up the two parts of the lithosphere. The lithosphere is divided into pi= eces called tectonic plates.

The asthenosphere= is a soft layer of the mantle on which pieces of the lithosphere move. It is made up of solid rock that flows like tar or putty. It flows very slowly similar to th= e rate your fingernails grow. <= /o:p>

The mesosphere is beneath the asthenosphere and is the strong lower part of the mantle. The mesosphere extends from the bo= ttom of the asthenosphere down to the Earth’s core.

The core is d= ivided into two parts called the inner c= ore and the outer core. The outer core is the liquid layer= of Earth’s core. It lies b= eneath the mantle and surrounds the inner core.

The inner core is the solid, dense center of Earth that extends from the bottom of the outer core= to the center of the Earth. You = are now 6,378 kilometers beneath the surface of the Earth.