Download Indirect evidence

The Inner Earth
Continental Drift
Convection Currents, and
How Heat Works
Chapter 5
Updated January 2012
1.The Earth does not look the same today as it did millions of
years ago because it’s surface has been lifted up, pushed down,
bent, and broken apart.
2.Scientists use both direct and indirect evidence to study the
inside of the earth.
Direct evidence- rock samples
Indirect evidence- seismic waves through the earth
Rock samples can tell us what the conditions may have been like on
Earth when the rock formed.
Seismic waves
Geologists can measure the speed at which the waves travel through
the earth to determine the structure of the planet.
Just as you may knock on a wall to find a stud while hanging a picture.
It sounds hallow if there is nothing behind it; and solid if there is.
A Journey to the center of the Earth
Temperature
5. As you travel toward the center of the earth it gets hotter
because you are getting closer to the core, just as you get warmer
the closer you get to a camp fire.
6. The center of the Earth is hot because of two reasons:
1. There is leftover heat from the formation of the planet
billions of years ago
2. The main reasons is because of radioactive materials
decaying in the core. The core is basically a nuclear
reactor.
Pressure
7. Pressure increases the deeper you go because there is more and
more weight on top. If you go down one mile, there is a mile of
rock above pushing down.
The Crust
8. The crust is the outer layer of rock that forms the outer skin
that includes dry land and the ocean floor.
a). The crust beneath the ocean is called the oceanic crust it is
made from basalt.
b).In most places the crust is between 5 and 40 km thick. It
can be up to 70 km thick under mountains.
The Mantle
9.The mantle is made up of very hot rock but solid. It is divided up
into layers depending on the physical characteristics of that layer.
The mantle is approximately 3,000 km thick.
10.The lithosphere is the uppermost part of the mantle similar to the
crust. Approximately 100 km thick.
11.The asthenosphere is the soft part of the mantle just below the
lithosphere.
12.The lower mantle is beneath the asthenosphere and extends all
the way to the core.
The Core
13. The core consists of two parts, the inner and outer. It is
made mostly of the metals iron and nickel.
-The outer core is liquid
-The inner core is solid
Together the core is approximately 3, 486 km thick.
The immense pressure does not allow the inner core to become
a liquid.
The core and the Earth’s magnetic field
14. Scientists believe the earth’s magnetic field is caused by the
movements in the liquid outer core.