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What is geology?

The study of Earth including:



Expanding Universe Theory

Hubble observed all light from all galaxies exhibits red shift

Means all galaxies are moving away from the Earth very quickly

Creates the basis for big bang

Universe has been expanding since the big bang

Assumption of the law is that we are a stationary observers 



Big Bang Theory

A cataclysmic explosion that scientists suggest represent the formation of the universe

before this, all matter and energy was packed into one volumeless point

There was no big “explosion” from single point, “simultaneous appearance of space everywhere in the universe”
Big Bang theory doesn’t explain what universe expands into
Big Bang theory doesn’t address what caused expansion to begin

during first second= protons and neutrons form


Nebular Theory

The protoplanetary disk was hotter at center, cooler at edges
Thus rings of dust accumulates toward center, rings of ice at outskirts

As disk flattens- separation of volatiles and refractory materials- separates into gaseous planets and rocky planets

formed our solar system



Scientific Theory

group of related observations
  based on proven hypotheses
  verified multiple times
  independent researchers

may be modified



Constant speed of Light

discovered by einstein

300,000 km/sec


Light year

9.5x10^12 km/yr

or 95 trillion kilometers a year

mesaure of distance not time



Doppler Effect

Assuming a stationary observer and moving source of sound or light:
wave frequency increases in direction of motion


Red shift/Blue shift

Blue shift, or higher frequency of light when an object is moving towards, and a red shift, or lower frequency, when an object is moving away from a person


Hubble's Law

recessional velocity is directly proportional to distance

Means more distant objects move more quickly away from Earth



Law of Conservation of Matter and Energy

Fixed amount of matter and energy in universe



How old is the universe?

13.7 billion years ago 



How old is our planet?

the same age as our solar system, 4.6 billion years old



Big Bang Nucleosynthesis

fusion of protons to create elements with low atomic numbers (H, He, Li, Be, B)

aka formation of the lighter elements

Nucleosynthesis--> creation of nuclei by fusion of very close protons --> can create up to boron 



Gases clump together into a cloud or pillar 

Larger nebulae:
  more mass
  more density

Nebulae--> stars

More mass--> more density--> gravity collapse inward and start to rotate (imagine ice skater spinning and then pulling arms and legs in)



Accretionary disk

spinning mass of gas and dust from which stars and planets form

Hydrogen nuclei at center fuse to make Helium--heat and light create star

See mass start to flatten out after spinning


Stellar Nucleosynthesis

formation of higher atomic number elements within stars by:
1.  Fusion--small nuclei fuse
2.  Neutron capture and decay
  - neutron sticks to nucleus (so atomic mass goes up
  - neutron releases e-, so now p+ (so atomic number goes up)

Need to have stars present before heavier elements become present
Mostly nuetron capture and decay= neutrons that are available stick to nucleus-->higher mass-->decay--> release of electron to it becomes a proton-->change in atomic number



A shortlived very bright object in space that results form the cataclysmic  explosion marking the death of a very large star 

ejects very large quantities of matter into space to form new nebulae



How old is our solar system?

4.6 billion years old (same age as the earth)



has ingredients available to create planets

Ex: the accretionary disk of our sun was this



gas or ice (H2, He, CH4, NH3, H2O, CO)


Refractory materials

rocky or metallic materials (heavier elements)


How do we know that layers exist in a planet?

Earthquakes generate seismic waves

Energy from waves reflected or refracted at boundaries between different materials

Seismic waves travel at different speeds in different materials

Differences in density--> different speeds of seismic waves
Some waves can only go through some materials
Less dense material= slower wave
More dense/homogenous material= faster wave


Seismic Waves

waves of energy emitted from the focus of an earthquake

Differences in density-->different speeds of seismic waves
Some waves can only go through some materials
Less dense material= slower wave
More dense/homogenous material= faster wave


Physical Differentiation

Earth has 4 layers based on physical characteristics like density and the material’s ability to flow:
Lithosphere (rigid solid)
Asthenosphere (plastic solid)
Outer core (liquid)
Inner core (solid)



Chemical Differentiation

core, mantle, and crust

Core= iron
mantle= iron, silicon, oxygen
Crust= silicon and oxygen
Mantle is a blend of both- b/c the core is recycled over time through plate tectonics and mix in the mantle



lighter in color

higher silicon content 

melts at lower temperatures




darker color

higher magnesium and iron content

melts at higher temperatures 


Continental Crust

Average thickness = 35 – 40 km
Continental crust has felsic composition


Oceanic Crust

Average thickness = 7-10 km
Oceanic crust has a mafic composition