Prelim 1 Flashcards
When did Big Bang happen?
15 billion years ago
The elements in your body came from ____?
the center of stars
Inner planets are? Outer planets are?
rocky; gaseous
When was Earth formed?
4.6 billion years ago
What are the 5 oceans?
1) Pacific
2) Atlantic
3) Indian
4) Arctic
5) Southern
T/F There is an Antarctic Ocean
FALSE!! its the southern ocean
What is the average depth of the ocean?
4 km
Suppose you’re on a boat, 45 degrees north, 150 degrees west. What ocean are you in?
Pacific
Suppose you’re on a boat, 45 degrees north, 20 degrees west. What ocean are you in?
Atlantic
180 degrees west of the Prime Meridian in Greenwich England is where?
International Date Line in Japan
What is bathymetry?
topography of the bottom of the ocean
What are magnetic anomalies? How do they work?
proxy measure of geologic time; When new rock comes to surface (lava) magnetic minerals can orient to magnetic pole at that time; rock cools, minerals are locked in in one direction, others get locked in the opposite; positive and negative anomalies; seeing symmetry of those dates is really strong evidence that dead center has new rock, nailed this idea that axes are places of new rock formation
What are the driving mechanisms of plate tectonics?
convection in the mantle and slab pull
Define convection
Warm, buoyant magma like hot air balloon rises up and creates new oceanic material that moves ridges apart
Define Slab Pull
As you move away, you get older rock and colder and contracting, denser, to a point where you’re so dense that you’re heavier than the mantle, i.e. blankets hanging off bed and starts to pull whole rest of blanket behind it
Where does hot molten rock rise via convection?
divergent boundaries
Where does rock get pulled by gravity into the mantle?
subduction boundaries
Where do divergent boundaries occur? Only in mid-ocean ridges?
where plates are moving apart; most are mid-ocean ridges, less commonly continental rifts
Give an example where continental crust is colliding with oceanic crust
Andes Mountains, Cascade Mountains
Give an example where oceanic crust is colliding with oceanic crust
Japan
Where does sediment get its name?
from dominant material
What is a sediment accumulation rate?
1 cm/1000 years
How do you find proxy temperatures?
you can take isotopic ratios of Oxygen 18 and 16 in lab grown organisms to determine the proxy temperature of the ocean to find geologic past ocean temperature
What is wave dispersion?
B/c longer wavelength waves travel faster than short wavelength waves, the waves gradually sort out
If theres a storm off the coast of California, would you wanna go surfing? What if its way off the coastline?
no then yes b/c wave dispersion will have sorted out the waves
What is wave refraction?
wave comes in at an angle, one end of wave hits shallow water and slows down, deeper end stays fast, creates a bending of shallow-water wave fronts
What happens when a wave hits a headland?
underneath headland is ridge, center of wave crest is being slowed down b/c of shallower water, faster waters bend in on itself and focuses wave energy on point
What happens when a wave hits a bay?
bay has a low spot extending out perpendicular to beach that is shallower on either side, wave crest moves faster in middle, bends wave outward and defocuses energy, calm beach to swim in
Suppose u got up at 6, wanted to look during lowest tide. When could you wake up the next day? Why?
you could sleep in a little bit later; about 50 minutes later; b/c earth rotates on axis, moon is orbiting in same position, so earth has to move more to go back under the moon
Suppose you’re backpacking along washington state and you want to camp on the beach, want to get your tent close to the beach. Would full moon indicate being cautious?
YES! Exaggerated tide
Why do we get ocean tides, but no tides in lakes and ponds?
directly below the moon, the earth’s downward gravity almost completely balances moon’s gravity (small lake)
other locations are not under the moon, and ocean tides are pinched upwards from the cumulative lateral pull by the moon on all the ocean
AT GEOPHYSICAL SCALES, OCEAN BASIN SCALES, NORTHERN HEMISPHERE PUSHES TO THE _____ by Coriolis, SOUTHERN HEMISPHERE PUSHED TO THE _____ by Coriolis
right; left
Why do you not get a significant tidal range in Hawaii?
Hawaii is near amphidromic point
Winds are named from the direction __ ___ ___ ____
from which they come
How can you tell where water originated in oceans?
distinct temperature and salinity from exchange with air before submerging and getting traits locked in
Most of deep water started in ___ ____
north atlantic
How long does it take to move deep ocean water from North Atlantic to North Pacific?
almost 2,000 years
What is the net temperature result of global conveyer belt circulation?
pull heat away from the equator i.e. gulf stream warms Europe
What warms Earth?
from below; oceans
A lot of water vapor = ___ density
low
What pressure at the equator?
low pressure; intense heating, warm moist air
As you move from winter into summer, surface waters get _____, it’s like blowing up a _____; warm water is super buoyant, mixing depth gets ______
warmer; beach ball; shallower
Ekman Transport is ____ degrees from the wind direction
90
Geostrophic currents follow ___ __ ____ _____
lines of constant pressure
What are geostrophic currents?
currents that have reached geostrophic balance move w/steady speed w/Coriolis and pressure gradiant forces in perfect opposition
What piles up mounds of water?
trade winds and westerlies
Why is pressure high in the middle of water mound?
more water piled on top pushing down
How much longer do we have before out sun dies vaporizes the earth?
4 billion years
How did moon form?
mars-sized planet ran into earth, ejected material that coalesced
When did we get oxygen in earth’s atmosphere?
after photosynthesis evolved
What was earth’s early atmosphere made of?
hydrogen and helium
Where did earth’s water come from?
asteroids
When did we get Cambrian explosion (life on land)?
550 million years ago
When did the asteroid hit earth and kill the dinosaurs?
65 million years ago
When did the biggest extinction event ever occur?
250 million years ago
Convergent boundary: Give example of Continental Crust with Continental Crust
Himalayas
Is oceanic crust or continental crust heavier? at convergent zones which is more likely to sink?
oceanic
What happened when India collided with Asia?
both buoyant continental crusts, neither wanted to sink under, mountain range created
Since crust is the thing that moves, hot spots in mantle act upon crust until it moves; whats example of hot spot?
hawaii
What qualifies as deep water waves?
bottom depth deeper than 1/2 wavelength
How do you determine speed of deep water waves? What moves faster?
speed is a function of wavelength only; long wavelength waves move faster
What qualifies as shallow water waves?
bottom depth is shallower than 1/20 wavelength
How do you determine speed of shallow water waves? What moves faster?
speed is function of depth only; waves in shallow water move slower
What happens to sand in the summer vs. winter?
gentle waves offshore sandbar to create wide and gently sloping sandy beach vs. storm waves drag sand off beach resulting in rocky winter beach
What 3 factors determine the wave height?
- wind speed- sets upper possible limit
- duration d event- modulates upper limit i.e. storm didn’t last long enough to reach it
- fetch- distance wind blows w/out obstruction i.e. wave propagates out from under small storm; diameter
What has to happen for a tsunami to occur?
sea floor HAS to move, doesn’t happen if earthquake in mantle
tsunami is speed of ?
jet liner
At what latitudes are there diurnal tides?
high
At what latitudes are there mixed semi-durnal tides?
mid-latitudes
At what latitudes are semi-durnal tides?
equator
What are diurnal, semi-diurnal, and mixed semi-diurnal tides?
diurnal: one high tide and one low tide per day
semi-diurnal: two equal high tides and two equal low tides per day
mixed semi-diurnal: two unequal high tides and two unequal low tides
When do spring tides occur?
when the moon pulls along the same line as the sun (new and full moon)
When do neap tides occur?
when the moon pulls at 90 degree to the sun (first and quarter moon)
Describe amphidromic point
b/c of blocking from continents and Coriolis, you get tide wave that sloshes around in ocean basic; at center of spin, almost no tidal range
What causes high tide to arrive late/after moon passes overhead?
moon moves around earth at certain speed but a freely propagating shallow water wave moves much slower, which forces it to go slower than moon would like it
