Shared Flashcard Set

Details

Exam 1
Mostly plate tectonics, also earthquakes and tsunami
38
Geology
Undergraduate 1
09/27/2011

Additional Geology Flashcards

 


 

Cards

Term
What are the planetary groups?
Definition
Terrestrial and Jovian
Term
How much of the mass of the solar system does the sun account for? How much for Jupiter?
Definition

99.8%

0.2%

Term
What elements are the most plentiful in the universe?
Definition
H2 and He
Term
What change to elements occurs following the fusion energy of a collapsed star?
Definition
Heavier elements are produced.
Term
What four events lead to the universe as we know it today following the Big Bang?
Definition

Protons and neutrons formed

Hydrogen nucleii fused to make He

Expansion and cooling creates molecules like H2

Nebulae form from clouds of gas

Term
What is big bang nucleosynthesis?
Definition
The creation of elements like He from fused nucleii, occurring during the big bang.
Term
What are volatile and refractory elements?
Definition

Volatile elements are gases on Earth and ice in space.

 

Refractory elements melt at high temperatures. The Earth and other terrestrial planets are made of refractory elements.

Term
What four elements are the primary components of Earth?
Definition

Iron

Oxygen

Silicon

Magnesium

Term
What is the approximate radius of Earth?
Definition
6400Km
Term
What are the names for the layers of the Earth, starting from the surface to the center?
Definition

Crust

Lithosphere

Mantle

Core

Term
What is the approximate age of the Earth?
Definition
4.57Ga
Term
What technique was used to date the Earth?
Definition
Radiometric dating.
Term
What are the eons of the Earth, from oldest to most recent?
Definition

Hadeon

Archeon

Proterozoic

Phanerozoic

Term
The lithosphere floats atop what type of geological feature?
Definition
The athenosphere.
Term
Who came up with the Continental Drift theory and what were the peices of evidence that suggested it?
Definition

Wegener.

 

Coastal fit

Location of glacial till

Distribution of sedimentary deposits

Matching fossils

Matching rocks and mountain belts

Term
What is Paleomagnetism and what is its use in the plate tectonics theory of the Earth?
Definition

Cooling igneous rocks orient toward the Earth's magnetic field. Their declination and inclination is their paleomagnetism.

 

It was observed that the inclination of many rocks across continents showed a path of movement.

Term
How was bathymetry used to support plate tectonics?
Definition
SONAR mappings showed trenches and other sea floor features that suggested plate boundaries.
Term
What is the sea floor spreading hypothesis and who is responsible for proposing it?
Definition

Hess proposed the theory.

 

The essential theory is that crust is created in mid-ocean ridges and destroyed in trenches.

Term
What is magnetic reversal and how did it lead to acceptance of the Plate Tectonics theory?
Definition
The magnetic poles of the Earth occasionally flip. The paleomagnetism of rocks can show this. A symmetric pattern was shown around mid-ocean ridges, suggesting crust was created there and spread away from it.
Term
What causes Earthquakes?
Definition
The breaking of lithosphere.
Term
What are the three types of plate boundaries?
Definition

Divergent

Convergent

Conservative

Term
What are the characteristics of a divergent plate boundary? What are the two types?
Definition

Young crust

Shallow earthquakes

Volcanic activity

 

The two types are mid-ocean ridges and continental rifts. Continental rifts lead to mid-ocean ridges, eventually (if they are successful).

Term
What are the charcteristics of convergent plate boundaries?
Definition

Deep earthquakes generated by subducting plate

Volcanoes generated by subducting plate

 

Term
What type of plate will always subduct at a convergent plate boundary?
Definition
Oceanic lithosphere
Term
What is the Benioff Zone?
Definition
The zone of earthquakes caused by a subducting plate.
Term
What force drives plate tectonics?
Definition

Convection in the asthenosphere, powered by radioactive decay and residual heat.

 

Slab pull and ridge push also contribute.

 

Finally, ridge push, due to the curve of the Earth.

Term
What is the elastic rebound theory and what does it describe the cause of?
Definition
Elastic rebound theory states that strike-slip behavior at plate boundaries causes earthquakes.
Term
What are the four types of seismic waves, from fastest to slowest?
Definition

P wave

S wave

Love waves

Rayleigh waves

Term
What magnitude of speed do seismic waves travel at?
Definition
Km/s
Term
What time interval is used to calculate the distance from the focus of an earthquake?
Definition
The S-P interval, measuring the time between the arrival of the P wave and the S wave.
Term
What two scales are used to measure Earthquakes?
Definition

The richter scale

The modified mercalli scale (aka Shake Maps)

Term
How must the water column be disrupted to cause a tsunami?
Definition
The water column must be vertically displaced by an impulsive distrubance.
Term
How is the wavelength of a wave related to the depth it is felt at?
Definition
They are approximately equal.
Term
How does a wave change as it reaches the shallow shore?
Definition
Its wavelength decreases, the waves become higher and deeper, waves become slower. 
Term
How long, on average, is the wavelength of a tsunami wave?
Definition
Greater than 100Km
Term
What is the average depth of the ocean?
Definition
4Km
Term
Tsunami waves behave like shallow waves. What is the equation we can then use to estimate the velocity of the waves?
Definition
v = sqrt(gD)
Term
How high is the amplitude of a tsunami wave at sea, and what is the implication of the measurement?
Definition
The amplitude is about 1m, which means it is safer to be at sea during a tsunami.
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