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GLGY 209
First Midterm
107
Geology
Undergraduate 1
02/05/2014

Additional Geology Flashcards

 


 

Cards

Term
Age of the universe
Definition
13.7 billion years
Term
The Earth was made of what substances that came together
Definition
Dust particles and stony debris
Term
Planetesimals...
Definition
... accumulate to create a lumpy planetoid
Term
Frost Line
Definition
The distance from the Sun beyond which water ice could condense
Term
At the simplest division, how many layerse does the Earth have?
Definition
three
Term
At the next level of detail, how many layers does the Earth have?
Definition
five
Term
How many types of crust exist on Earth?
Definition
Two. Continental and Oceanic
Term
How many types of lithosphere exist on Earth?
Definition
One
Term
What is/are necessary for a planet to have a magnetic field?
Definition
A convecting liquid core and sufficiently rapid rotation
Term
What are the layers of the Earth?
Definition
  • Inner core 
  • Outer core 
  • Inner mantle 
  • Outer mantle 
  • Crust
Term
Alfred Wegner
Definition
German meteorologist, hypothesized that the continents used to fit together as a single supercontinent he named Pangea.
Term
What major evidence exists in favor of Pangea/ super continent?
Definition
Similar belts of rock, fossils, minerals, and various deposits are found on different continents where they used to fit together
Term
Do the magnetic poles move?
Definition
Yes, they are not parallel with the rotational axis.
Term
Harry Hess
Definition
Compiled the evidence that new sea floor is created at mid-ocean ridges, moves away from the ridges, and then subducts back into the mantle
Term
Positive anomalies
Definition
Form when sea-floor rock has the same polarity as the present (normal) magnetic field
Term
Negative anomalies
Definition
Form when the polarities are opposed
Term
Magnetic anomaly stripes are created as...
Definition
... the mid-ocean ridge adds new basalt to the spreading oceanic crust
Term
Divergent boundary
Definition

[image]

seafloor spreading - mid ocean ridge (plates moving away from each other)

Term
Convergent boundary
Definition

[image]

subduction zone - trenches (plates moving into each other)

Term

Transform boundary

 

Definition

[image]

fracture zone (plates moving past one another)

Term
Lithosphere
Definition
Rigid and composed of the crust and upper mantle. It is brittle, faults occur here.
Term
Aesthenosphere
Definition
The highly viscous, mechanically weak and ductilely-deforming region of the upper mantle of the Earth. 
Term
Process of subduction
Definition
[image]
Term
Hot Spot volcanoes
Definition

Mantle plumes. As a plate drifts over the hotspot, a chain of extinct volcanoes (a "hot spot track") forms

 

e.g. - hawaiian islands 

Term
The zone of the Earth that is divided into plates is the ________
Definition
lithosphere
Term
The observation of magnetic anomalies that constitute magnetozones are found as far back in time as one can find appropriate rocks to measure indicates that
Definition
the Earth has always had a convecting portion of its core over that time period
Term
The Earth's ocean floor has been created and destroyed at least _______ times over the age of the planet
Definition
age of the earth (4.5 billion) / ocean crust age (180 million) ~ 22.5
Term
Oceanic crust
Definition
Mafic rock, apprx 7km, rich in Fe and Mg
Term
Continental Crust
Definition
Felsic, intermediate, and mafic rock. 18-40km, rich in salica
Term
Mantle
Definition
ultramafic rock
Term
Geoid, Spheroid, Sphere
Definition
[image]
Term
Moment of Inertia
Definition
How the Earth's rotation changes  the shape of our planet and how our planet responds to tides
Term
Isostasy
Definition
Buoyancy effect determines altitute of large scale things
Term
Spheroidal Oscillation
Definition

(0P2) goes one way, then returns and oscillates the other way 

 

e.g. - jello

Term
Toroidal Oscillation
Definition

(0T1) oscillates back and forth

 

e.g. - cars

Term
Seismic waves
Definition

BODY WAVES

P-waves and S-waves 

Term
P waves (compression)
Definition
  • Displacement is in the direction of its motion
  • e.g. - sound waves
  • Gases and liquids ONLY support p waves as they are not elastic 
Term
S waves (shear)
Definition
  • Displacement is perpendicular to its motion
  • Move through different kind of rocks, depending on their elasticity and velocity of the wave
  • P waves are always faster than S waves
  • Porous rocks have a slower wave velocity 
Term
Higher density =
Definition
Faster wave
Term
Earthquakes travel in
Definition
Curved lines, depending on the density of the rock and the velocity of the wave
Term
Geotherm
Definition
Plot of temperature vs. depth within the Earth
Term
P wave shadow zone
Definition
[image]
Term
S wave shadow zone
Definition
[image]
Term
We know the inner core is at least partially a liquid because
Definition
P waves can travel through it
Term
What is the geoid?
Definition
the surface of uniform gravity on Earth
Term
What do the s wave shadow zone map out?
Definition
the core - mantle boundary
Term
Seismic wave velocities in the earth...
Definition

generally increase with depth

 

Term
Hadeon Eon
Definition
  • Magma
  • Asteroids bombarding the surface constantly
  • Toxic atmosphere (no oxygen)
Term
Archeon Eon
Definition
  • Crusts forming (continental and oceanic)
  • First signs of primitive life (single cell organisms)  
Term
Proterozoic Era
Definition
  • First signs of abundant life
  • Lasting almost 2 billion years
  • Earth becomes a giant snowball for a while 
  • But it did melt eventually, and lots of life happened because of it
Term
Phanerozoic Era
Definition
  • phaneros = visible, zoic = life
  • Paleozoic - ancient life, Mesozoic - middle life, Cenozoic - recent life
  • continents become more similar to present day
  • water organisms eventually followed the bugs out of the water as flora and fauna began developing
  • coal swamps
  • dinos
Term
Classes of Deformation
Definition
  • Displacement
  • Rotation
  • Distortion
Term
Displacement
Definition
Change in location (relative to the things around it)
Term
Rotation
Definition
Change in spectral orientation (tilting)
Term
Distortion
Definition
Change in shape
Term
What causes deformation?
Definition
  • stress (force per unit area)
  • strain (fraction of volume change)
Term
Strain
Definition
  • Stretching
  • Shortnening
  • Shear
Term
Stretching
Definition
Pulling apart
Term
Shortening
Definition
Squeezing together
Term
Shear
Definition
Sliding past
Term
Deformation styles
Definition
  • Brittle: shallower crust, rocks break by fracturing
  • Ductile: higher P and T conditions which causes rocks to deform by flowing and folding 
Term
Whether you have brittle or ductile depends on...
Definition
  1. temperature
  2. pressure
  3. strain rate (composition)
Term
Types of stress
Definition
Tension
Shear
Pressure
Term
Tension
Definition
occurs when the ends of an object are pulled apart, which stretches and thins the material
Term
Shear
Definition
Develops when surfaces slide past one another
Term
Pressure
Definition
occurs when an object feels the same stress on all sides
Term
Faults
Definition
normal fault
reverse fault
thrust fault
Term
Normal Fault
Definition
the hanging wall moves down the fault slope (most common in regions experiencing crustal tenstion
Term
Reverse fault
Definition
the hanging wall moves up the fault slope. (most common in regions experiencing horizontal compression)
Term
Thrust fault
Definition
a special type of reverse fault with a dip below 35 degrees
Term
Strike slip faults
Definition
fault motion parallel to the strike of the fault.
left lateral - opposite block moves to observer's left
right lateral - opposite block moves to the observer's right
Term
Folds
Definition
Layered rock may be deformed into complex folds by tectonic compression
Term
Generating folds
Definition

Horizontal compression causes rocks to buckle Shear causes rocks to fold over themselves

 

Term
Anticline and Syncline
Definition
[image]
Term
Plunging Fold
Definition
Where hinges are lifted (elevated)
Term
Dome
Definition
A fold with the appearance of an overturned bowl. A dome exposes older rocks in the center
Term
Basin
Definition
fold shaped like an upright bowl. A basin exposes younger rocks in the center.
Term
Joints
Definition

planar rock fractures formed from tensile stress in brittle rock

[image]

Term
Veins
Definition

fractures filled with minerals

[image]

Term
Mountain building
Definition
  1. continental collision
  2. convergent boundaries
  3. continental rifting
  4. delamination
Term
Orogenic Collapse
Definition
Ductile rock eventually flows out from beneath high mountains, which then settle downward like soft cheese. The upper brittle crust breaks into  faults.
Term
Craton
Definition
continental crust that hasn't been deformed in 1 Ga
Term
Shields and Platforms
Definition

Shields: consist of Precambrian igneous and metamorphic rocks

Platforms: sedimentary cover that is draped over shield rock

Term
What is stress?
Definition
force divided by area
Term
What is strain?
Definition
deformation expressed as a fraction of original body geometry
Term
If a rock has deformed by faulting this is an indication that the deformation occured in
Definition
the brittle regime
Term
Earthquakes
Definition
represent the release of energy stored as elastic deformation of rocks propagated by seismic waves
Term
Faults form when...
Definition
tectonic forces add stress (push, pull, or shear) to rock
Term
Richter scale (Mr) is best used near...
Definition
The epicenter. Moment Magnitude scale (Mw) is the most accurate.
Term
M0=
Definition
Rupture Area* Displacement Amount * Rock Shear Strength
Term
Mw=
Definition
2/3 log (M0)-6
Term
Hypocenter (or focus)
Definition
location where the fault slip occurs. It is usually on a fault surface
Term
Displacement (or offset)
Definition
is the amount of movement accross a fault
Term
Foreshocks
Definition
Smaller tremors indicating crack development in rock. They may warn of an impending large earthquake
Term
Convergent plate boundaries have...
Definition
shallow, intermediate, and deep earthquakes
Term
Earthquakes cease below...
Definition
660 km
Term
Body Waves
Definition
p waves, s waves
Term
Surface Waves
Definition
Rayleigh Waves, Love Waves
Term
R waves
Definition
intersect the ground. Make the found ripple like water in the wind. Up and down motion
Term
L waves
Definition
perpendicular to the way they travel, side to side motion
Term
Order of waves during an earthquake
Definition
  1. Vertical P waves
  2. Vertical S waves (cause extensive damage)
  3. L waves
  4. R waves 
Term
Why do earthquakes kill people?
Definition
They don't. Buildings do.
Term
Earthquake Hazards
Definition
  1. Ground shaking
  2. Liquefaction (causes soil to lose all strength)
  3. Landslides and Avalanches
  4. Tsunamis
Term
Earthquakes have precursors, they are:
Definition
  • clustered foreshocks
  • crustal strain
  • level changes in wells
  • gases (Rn, He) in wells
  • unusual animal behaviour
Term
Directivity
Definition
earthquakes acting like lasers
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