Exam 1 Flashcards
What formed our moon?
Created from a collision with earth
What is the theory of moon formation called?
Giant impact hypothesis
What were the consequences of the impact?
Stabilized earth’s rotation, created varying seasons
What is our current axial tilt?
23 degrees
What most likely sourced our planetary water?
First theory: solar nebula contained ice that continues to be recycled through the earth’s mantle.
Second: ice rich asteroids (carbonaceous chondrites) brought water after the collision
What is carbonaceous chondrite?
ice rich asteroids, some of the most primitive known meteorites, brought water post-collision
Where did life likely originate on our planet?
Hydrothermal vents
What is chemosynthesis?
Likely the origin of life on earth
Compare chemosynthesis to photosynthesis?
Chemosynthesis: the use of energy released by chemical reactions (instead of the sun’s energy) to produce food
What are extremophiles?
Prokaryotic bacteria
What organic compound did the Rosetta mission find on the comet?
Phosphorous and Glycine
Did the Rosetta mission prove that comets sourced our planetary water? Why or why not?
No, the water on comets had different isotopic properties than water on earth
Describe how our early oxygens became oxygenated
Cyanobacteria absorbed sunlight and released oxygen in the process
What are cyanobacteria?
Prokaryotic microorganisms capable of photosynthesis, earliest form of life
What is a stromatolite?
A mound built up of layers of cyanobacteria, earliest fossil evidence of life on earth
Prior to photosynthesis, how did life collect energy?
Getting energy from sulfate
What is the leading theory for the cause of the Permian-Triassic extinction event?
Flood volcanism
When did the PT extinction happen?
250 million years ago
What percentages of terrestrial vertebrates (70%) and marine species (95%) perished?
95%
What were some navigational techniques that the Polynesian Seafarers used?
Guiding by the stars/astronomy, stick charts, bird flight patterns, and ocean swells (observed waves and currents)
What were some of the Polynesian Seafareres contributions to Oceanography?
oceanographic maps called stick charts, bird flight patterns, stars, ocean swell
What contributions did Admiral Zhen He’s fleet make to oceanograph?
(advanced navigation maps, large sailing ships, compasses)? oceangoing vessels with compasses.
How long was the HMS Challenger mission?
(4 years – 1872-1876)
What were some of the contributions (first broad outline of oceans, ocean current plots, sea surface temperatures, 50 volumes of research, seafloor sediments)?
Described organism physiology in deep and shallow water via 50 volumes of research, discovered undersea mountains along the mid-Atlantic ridge, samples of seafloor sediment
What was the goal of the Jeanette Expedition?
to prove the open polar sea theory
How did the Jeannette Expedition fail?
the boat got stuck in ice
Where did the wreckage of the Jeannette Expedition finally settle?
Julianehab - near the southwestern corner of Greenland
What inspired Fridtjof Nansen to undertake the Fram Expedition?
Failure of the Jeannette expedition
What is the Transpolar Drift?
Major ocean current of the Arctic Ocean, transports sea ice around the Arctic ocean
What was Nansen able to prove?
The north pole was not located on land nor on a permanent ice sheet but that it is a shifting, unpredictable pack of ice
Describe Charles Darwin’s theory on atoll formation?
Caused by sinking islands and upward developing coral reef in layers
What is the difference between a fringing reef and a barrier reef?
Fringing = coal grows Barrier = a lagoon opens between the island and the reef
Why do Oceanic volcanic islands sink?
Plate tectonics (even though it wasn’t accepted at the time) weight of coral also causes islands to sink
Where and when were deep ocean chemosynthetic ecosystems discovered?
Galapagos Rift 1977 - deep sea vents
What provides the foundation of these vent communities?
Chemolithoautotrophic bacteria use energy from vents
How big are giant tube worms?
8 feet
How do giant tube worms survive?
Chemosynthesis (found near hydrothermal vents)
In what direction do hurricanes rotate in the northern hemisphere?
Counterclockwise
What happens to cold water beneath a hurricane travelining across the ocean?
Surface diverge forms as hurricane sends heat/air up, surface diverge fills with cold deep water, nutrient-rich, upwelling occurs
What is the tallest “mountain” on earth with respect to the ocean’s floor
Muana Kea, Hawai’i
How tall is Muana Kea (the tallest mountain on earth with respect to the ocean floor)
32,000 feet
What is the earth’s longest mountain range?
Mid-Atlantic ridge
What is the depth in feet of the deepest ocean trench?
Mariana Trench 36,070 feet
How old are the oldest fossils on this planet?
3.7 billion years old
What are the oldest fossils on this planet?
Bacteria-like organism that photosynthesized and released oxygen into the atmosphere?
Where are the oldest fossils on this planet found?
northwestern Australia
What is the lithosphere?
(rigid, less dense) crust and extreme upper mantle
What is the asthenosphere?
(deformable, more dense) most of the upper mantle
Which is more dense, the lithosphere or the asthenosphere?
Asthenosphere
What are the chemical components of the crust?
Basalt ocean, granite contents
What are the chemical components of the mantle?
O2, Fe, Mg, Si
What are the chemical components of the cores?
Fe and Ni
Which is more dense - oceanic or continental crust?
Oceanic
Significance of March 27, 1964?
Alaska’s Good Friday Earthquake, 9.2 magnitude, 2nd most powerful earthquake ever recorded.
What did the Alaskan earthquake reveal?
It provided the P and S wave source that confirmed the theories of the earth’s interior layering.
What does “Seismic “ mean?
Relating to earthquakes or vibrations of earths crust
What are the 3 types of seismic waves?
Primary body waves, secondary body waves, surface waves
Describe primary body waves
compression, slinky, fastest, penetrate sold and liquid
Describe secondary body waves
snake-like, slower than P, can penetrate solid but NOT liquid
Describe surface waves
Ripple along surface, cause the most damage, slowest
Which are considered body waves?
P and S waves
Which waves travel the fastest?
P waves
Which waves travel the slowest?
surface waves
Which waves cause the most damage?
surface waves
How do body waves travel?
through the earth’s interior in all directions
What are body waves speed influenced by?
Density
Waves travel ____ through higher density
faster
Waves refract ____ from higher density
away
Which of the body waves can travel through solids and liquids?
P waves
Our planet has a ____ inner core and a ____ outer core
solid inner core, liquid outer core
Our earth is ____ stratified
Density
What evidence did Alfred Wegener provide for his continental drift theory?
Similar animals and plant fossil found in different areas of the globe, coastlines align
Between the period of 1920-1960, what 5 additional scientific observations were made that supported Wegener’s theory? CMMSS
- Clear patterns of earthquakes
- Max age of seafloor is 2 million years old
- Mid-ocean ridges conform to coastlines
- Seafloor sediments thickest at ocean edges, sediments thinnest at mid-ocean ridges
- Seismic waves slow down in the upper mantle
What ocean geological features are associated with the deepest earthquakes?
Trenches at subduction zones (convergent boundaries)
What is the half-life (in Billions of years) for Uranium 238? What is its decay product?
Half-life is 4.5 billion years, decay product is Lead 206
What do mid-ocean ridges conform to?
coastlines
Where are the thickest sediments found in the ocean?
At the edges of the ocean
Where are the thinnest sediments found in the ocean?
At the mid-ocean ridge
According to seafloor spreading theory, new seafloor develops at the ____ and spreads _____
ridge/rise
out
Whats the source of power for sea floor spreading?
convection currents
What term refers to the destruction of crust?
subduction
When was sea floor spreading theory presented?
1962 by Hess & Deitz
What 3 theories most contibuted to the theory of plate tectonics?
Wegener - continental drift
Hess & Deitz - seafloor spreading
Vine & Matthews - paleomagnetisim/magnetic striping
How many lithospheric plates were originally thought to exist?
about a dozen
Who is credited with the plate tectonics theory?
Wegener (continental drift)
Hess & Dietz (seafloor spreading)
What were Marie Tharp’s contributions to oceanography?
Mapped mid-ocean ridges
confirmed seafloor spreading theory
What is the periodicity of earth magnetic field polarity shifts?
Stripes of reversing polarity; one polarity will last between 0.1 and 1 million years; reversals take between 1,000 and 10,000 years
What is the age of the oldest oceanic crust?
200 million years old
Where is the oldest oceanic crust found?
Mediterranean
What are the 3 types of seismic waves?
Surface waves, P waves, S waves
How do surface waves propagate?
ripple along the surface
How do P waves propagate?
slinky - penetrate solid and liquid
How do S waves propagate?
snakey - penetrade solid but not liquid
Convergence and Divergence
Convergence- two plates coming together, destroying crust
Divergent- mid ocean ridge, creating new crust
Spreading and Subduction
Spreading- mid ocean ridge, divergent boundary
Subduction- convergent boundary, destroying crust
Creating and Destroying Crust
Creating- divergence, mid-ocean ridge
Destroying- convergent, subduction zones
Passive and Active (Seismic Activity)
Passive- continental shelf, no seismic activity, East Coast
Active- subduction zone, volcanic/EQ activity, West Coast
How do magnetic “stripes” on the ocean floor prove that oceanic crust is being created at a ridge?
Paleomagnetism: alternating “stripes” of polarity on seafloor. New seafloor develops at mid-atlantic ridge, spreads outward, alternating in polarity
When does oceanic crust conform to the earth’s polarity?
Oceanic crust created during normal event, when north pole aligned with geographic north, would have polarity aligned with the earth’s current magnetic field
Which is spreading faster – The Mid Atlantic Ridge or the East Pacific Rise?
Mid Atlantic ridge
How do we know the mid-Atlantic ridge is spreading faster?
age of seafloor near continents is younger on the west side of south america than on the east side
Which magnificent 7 is the Peru Chile trench?
o/c/c
Oh its the peru Chile trenCh
What are the Andes mountains?
mountain arc
How are the Andes mountains aligned to the trench?
Parallel to trench
Howa re the Andes mountains aligned to plate motion?
Perpendicular to plate motion
Which magnificent 7 is the Juan/De Fuca ridge?
o/c/c
Juan was on the OC
How were the Cascade mountains formed?
subduction of Juan de Fuca plate under the North American plate
Which magnificent 7 is the Aleutian trench?
o/o/c
What are the Aleutian islands?
island arc
How are the Aleutian islands aligned to the trench?
parallel to trench
How are the Aleutian islands aligned to plate motion?
perpendicular to plate motion
What formed the Hawaiian islands?
hot spots
Are the Hawaiian islands an island arc or island chain?
island chain
How are the Hawaiian islands aligned with respect to plate motion?
parallel
Which magnificent 7 is the east pacific rise?
o/o/d
Which magnificent 7 is the Marianas trench?
o/o/c
Which magnificent 7 is the Himalayan mountains?
c/c/c
Which magnificent 7 is the Sumatra trench?
o/c/c
What formed the Emperor seamounts?
Volcanism from pacific plate passing over a hotspot?
Are the Emperor seamounts a submerged island arc or island chain?
island chain
How are the Emperor seamounts aligned with respect to plate motion?
parallel to plate motion
Which magnificent 7 is the red sea/gulf of aden, east africian rift zone
c/c/d
Which has rifted the most: Red Sea, Gulf of Aden, East Africian rift zone?
Red sea
What type of plate boundary is associated with the San Andreas fault?
continent/continent transform
How old are the rockies?
300 million years old
modern is 70-55
How were the rockies formed?
Shallow angle subduction of Farallon Plate. (Another answer:) a shallow subduction because it is warmer, young. Ridge producing ocean crust, subducting/less dense and less steep causes a compression that elevated the Rockies
How old are the rocks that make up the flatirons?
280 million
When were the flatirons uplifted?
65 million
how old are the rocks that make up flagstaff peak in boulder?
1.7 billion
What is convergence?
2 plates coming together, destroying crust
What is divergence?
mid-ocean ridge, creating new crust
What is spreading?
mid-ocean ridge, divergent boundary
What is subduction?
convergent boundary, destroying crust
What is creating crust?
divergence, mid-ocean ridge
What is destroying crust?
convergent, subduction zones
What is passive seismic activity?
continental shelf, no seismic activity, east coast
What is active seismic activity?
subduction zone, volcanic/earthquake activity, west coast
What are the 3 primary categories of plate boundaries?
convergent, divergent, transform fault
What are the magnificent 7?
ocean/ocean convergent
ocean/ocean divergent
ocean/continent convergent
continent/continent convergent
continent/continent divergent
transform fault
Mag 7: what is the Marianas trench?
ocean/ocean convergent
Mag 7: what is the Aleutian trench?
ocean/ocean convergent
Mag 7: what is the mid-atlantic ridge?
ocean/ocean divergent
Mag 7: what is the east pacific ridge?
ocean/ocean divergent
Mag 7: what is the peru chile trench?
ocean/continent convergent
Mag 7: what are the Himalayan mountains?
continent/continent convergent
Mag 7: What is the red sea?
contient/continent divergent
Mag 7: what is the San Andreas fault?
transform fault
What will we find at an ocean/ocean convergent boundary?
trench
What forms on the backside of that feature?
island arcs
What will we find at an ocean / continent convergent boundary?
trench
What forms on the backside of an ocean / continent convergent boundary?
mountain arc
Ocean ridges/rises are associated with ___ plate motion and ___ oceanic crust
Ocean Ridges and Rises are associated with divergent, passive plate motion and the creation of oceanic crust.
Trenches are associated with ____ plate motion and _____ oceanic crust.
Trenches are associated with convergent, active plate motion and the destruction of oceanic crust.
Ridges / Rises create __
new oceanic crust
Provide an example of an Ocean / Ocean Convergent Boundary
Aleutian islands
Provide an Example of an Ocean / Continent Convergent boundary
Andes mountains
What is the subduction angle difference between the plate that produced the Rockies and the Andes Mountains in South America?
The Rockies formed from the subduction of younger and hotter oceanic crust thus resulting in a shallower angle. The Andes formed from older and cooler oceanic crust subduction, resulting in a steeper angle.
What is the age of the oldest ocean crust on the planet?
200 million years
Which is spreading faster, the Mid Atlantic Ridge or the East Pacific Rise?
east pacific rise
Which type of plate boundary constructed the Himalayan mountains?
continent/continent convergence
What is the utility of satellite radar altimetry?
satellites measure gravity by microwaves
The basic premise for satellite altimetry is that gravity causes the sea surface to ___ over sea mounts and ___ over trenches
The basic premise for satellite altimetry is that gravity causes the sea surface to elevate/rose over sea mounts and sink/depress over trenches
What forms on the “back side” of an Ocean / Ocean Convergent plate boundary?
island arc
What forms on the “back side” of an Ocean / Continent Convergent plate boundary?
mountain arc
What formed the Hawaiian Islands?
pacific plate moving over hotspot
how are islands aligned in relationship to plate motion?
parallel to plate motion
hat are the three features associated with a Transform (fault)?
fracture zone, transform fault, ridge
which of the three features are seismically active?
transform fault
What feature differentiates the difference between an Active and Passive Margin?
Active- EQs, volcanism, trench, subduction, convergent boundary
Passive- continental shelf, no EQs/volcanism
Identify whether Continental Margins are: passive or active
active if it has a trench, passive if it doesn’t have a trench
Identify whether Continental Margins are: seismic or not
seismic if it has a trench
Identify whether Continental Margins are: pacific or atlantic type
pacific = no trench passive = atlantic
Hurricanes rotate clockwise in the
southern hemisphere
he oldest ocean’s crust age is approximately
200 million years old
Seismic body waves travel ___ through a higher density medium
faster
Seismic body waves ___ from higher density layers of our inner earth structure
refract away
Seismic body waves refract away from ___ density layers of our inner earth structure
higher
Additional evidence for Alfred Wegener’s continental drift hypothesis:
clear patterns of earthquakes and volcanoes associated with ridges, trenches, and faults, radiometric dating, mid-ocean ridges conforming to coastlines, varying sedimentology- older oceanic crust (farthest from ridge) had thicker sediment
Magnetic striping theory:
symmetrical patterns of alternating earth polarity on each side of a spreading center (ridge)
New oceanic crust is created at
ridges
New oceanic crust is destroyed at
trenches
Twin convective cells in the upper mantle provide a ___ stress to lithospheric plates underneath ___
divergent
ridges
he Aleutian trench is a ___ plate boundary
convergent
What convergent boundaries produce island arcs?
ocean to ocean plate convergent boundaries produce island arcs
Volcanic island arcs are aligned ____ to plate motion
perpendicular
Island chains are produced by ___and are aligned ___ to plate motion
hot spots
parallel
The basic premise for satellite altimetry is that
The basic premise for satellite altimetry is that gravity causes the sea surface to elevate/rise over sea mounts and depress/dip over trenches
The Himalayan mountains were formed by ____ plate activity
The Himalayan mountains were formed by continent/continent convergent plate activity
What forms on the backside of of an ocean/ocean convergent plate boundary (trench)?
island arc
How is a mountain arc alignment related to plate directional motion?
perpendicular
Transform faults are seismically ___
active
