Transcript The Earth’s Interior

 Layers do not have a uniform or “perfect” boundary.
 Example- Earths crust is as small as 5 km in some places and as deep as 70 km in
others.
 It is the thinnest and outer most layer that makes up planet Earth.
 It goes from the ground we stand on to about 40 km down ( on average).
 Earths crust is comprised of continents and ocean basins.
 The oceanic crust is the portion of Earth's crust that makes up the seafloor.
 It is between 5 to 12 kilometers (3 -8 miles) thick
 The rocks of the oceanic crust are denser (3.0 g/cm3 ) than the rocks that make up
the continents.
 The continental crust is the portion of Earth's crust that makes up the continents.
 It is 40 kilometers thick on average, but it varies a lot. It can be much thicker in
mountain ranges (70 km).
 On average, continental crust is much less dense (2.7 g/cm3 ) than oceanic crust.
Since it is less dense, it rises higher above the mantle than oceanic crust.
 Scientifically - mass per unit volume.
 Generally- the amount of mass in a given space. If two objects are the same size
and one has a mass of 25g and the other is 40g then the one with the higher mass is
more dense. (heavier)
 The mantle is about 2900 km (1,800
mi) thick, making up about 84% of
Earth’s total volume,
Lithosphere
Asthenosphere
 Includes the crust and the upper
 The asthenosphere is solid middle
most mantle.
 The lithosphere is about 100
kilometers thick.
 It is brittle and can break when
stressed (earthquakes)
mantle material that is so hot that it
behaves plastically and can flow.
 We say it is solid, but bendable.
 The lithosphere rides on the
asthenosphere.
Outer core
Inner core
 Liquid
 Solid
 Both contain heavy metals (nickel
 Both contain heavy metals (nickel
 Both responsible for the magnetic
 Both responsible for the magnetic
and iron)
field
and iron)
field
 The first source is heat left over from
the formation of the Earth.
 The next source is gravitational
pressure put on the core by tidal
forces and the rotation of the Earth.
 The last known source of heat is the
radioactive decay of elements in the
inner part of the Earth.
Direct Evidence
Indirect Evidence
 Geologists use direct evidence from
 Geologists record the seismic waves
rock samples to gather clues about
Earth’s structure.
 Volcanos and lava are also places to
gather information
 The deepest geologists have ever
drilled is on the Kola Peninsula in the
Soviet Union. They reached 12.26 km
(7.5 mi) into the Earth’s crust. This
took for years to dig.
and study how they travel through the
Earth.
 The speed of seismic waves and the
paths they take reveal the structure of
the planet.
 The waves travel at different speeds
due to changes in density of earths
interior
 Radiation is energy transferred by electromagnetic waves (or photons).
 Convection typically arises from the movement of gases or liquids over large
distances.
 Conduction occurs through touch and flows from hot to cold.
 Energy transferred by radiation from the sun travels millions of kilometers through
the vacuum of space before reaching the Earth.
 Some of this energy is visible radiation (sunlight, for example), while other energy
is invisible.
 Heat radiation is an example of invisible radiation.
 When you sit next to a campfire or a fireplace and feel all warm and cozy, thank
radiation! It is the flow of radiation from the fire that warms us.
 Convection takes place throughout the Earth’s atmosphere all the time.
 Heated air is less dense than cooler air, so it rises. As the air rises, it cools down
and becomes denser. The air then falls back to the ground where it is heated
again, and the process repeats.
 A convection cell, which is a circulating pattern of moving energy, is now
created.
 Convection takes place in the mantle and is believed to be the cause of our
tectonic plates movement over time
 Within the Earth’s interior, large convection currents in the asthenosphere transfer
heat from the core to the surface, where it becomes cooler and more dense.
 The less dense, hot material rises. Cold, denser material convects downward
because of grav- ity and the cycle continues.
 Conduction happens when a temperature difference exists, causing the molecules
of an object to transmit energy throughout the object
 Conduction is the transfer of kinetic energy from one molecule to another by
molecular collision.
 Conduction occurs, for example, when a metal spoon is put into a hot cup of tea
and the handle of the spoon gets hot. This means, of course, that you don’t want to
grab the handle of a copper (or any metal) pot when it’s being heated on your
stove.