Download The Geosphere

Overview
The Geosphere
PSC 152
In this section:
What is the structure of the Earth?
What are the properties of each layer?
How did these layers form?
How do we learn about the interior?
Geosphere layers
Structure of the geosphere
Crust
Mantle
Outer core
Inner core
Definitions from vocabulary
Physical Properties
For each layer, you should know…
Location
Composition
Phase
Relative thickness
Relative temperature
Crust
What do you know about it?
Thin, rigid surface layer
Rocky, mostly silicates
Coolest of all layers
Oceanic verses Continental
Mantle
What do you know about it?
Layer under crust
mostly silicates, but denser than crust
“plastic solid”
Largest volume
Warmer than crust
Outer core
What do you know about it?
Liquid metallic
Primarily iron and nickel
Extremely hot
Not as thick as mantle
Inner core
What do you know about it?
Solid metallic
Primarily iron and nickel
Hottest region
Extremely high pressure
Formation
How did this structure form?
Two main factors:
Gravity
Heat
Differentiation
Gravity pulls into sphere
Heat melts
Densest material pulls to center
See animation
Density
Mass/Volume
Related to composition
Earth on average = 5.5 g/cm3
Density of water = 1 g/cm3
Density of ordinary rocks = 3 g/cm3
Density of iron = 8 g/cm3
So earth must be a mixture rock and iron
Scientific Method
How do we know what we know about the structure
of the earth?
We do not have direct access to the interior of the
geosphere …
We must use indirect methods to gain information
and test our hypothesis.
Earthquake Waves
Waves can travel through the earth
Velocity depends on density and phase of the
material it is going through
Same method used for ultrasound on pregnant women
You will be exploring this concept in the homework
assignment
Energy in the Geosphere
Energy Source
What is the dominate energy source in the
geosphere?
Thermal (heat) energy
Affects of energy
How does thermal energy cause change?
Heat transfer
Heat from interior is transferred toward surface
Energy is transferred in the process
Where did the heat energy come from?
Kinetic energy from formation
Nuclear energy from radioactive decay
Heat transfer mechanisms
3 ways for heat to be transferred
Conduction
Convection
Radiation
For now, we only care about convection
Convection
Heat transfer through the motion of a hot material
When a material heats, it expands
The expanded material is less dense
The material then rises, carrying heat
animation
Convection currents
In a liquid or gas, the convection easily caused
material to move and it forms circular currents
In a solid, only a large heat gradient, will provide
enough energy to cause very slow movement by
convection
In-Class activity
Write 2-3 sentences for each of the following:
What concept in today’s lecture:
Did you find the hardest to understand
Did you find the most interesting