Prelim 1 Flashcards
Where did all of the heavy elements that are found inside your body get created?
100% of the heavy elements were created inside of stars or when stars exploded
How are stars formed?
b. They started forming after the intense heat of the Big Bang cooled and cold matter began condensing into large-mass objects due to gravitational attraction. When an object’s mass becomes very large, the gravitational compression within the center of the object makes its interior hot enough to ignite thermonuclear fusion reactions.
How do we know that our sun is made from the dust of a previously exploded star?
the sun is composed of hydrogen and a range of heavier elements
Where did most of the water come from that fills the earth’s oceans?
asteroids
If you were on a boat at 10N and 160W, which ocean would you be in?
Pacific
How was our moon formed?
a mars-sized object hit the earth and the ejected material subsequently coalesced to form the moon
How quickly did life appear on earth after it cooled and the oceans filled?
remarkably quickly (500 million years)
where did the oxygen in the atmosphere come from?
photosynthesis
Life on earth began in the oceans billions of years ago. When did life on land begin?
about 550 million years ago
How long ago did a large asteroid hit the earth that caused the extinction of most dinosaurs and subsequently gave rise to large mammals dominating the earth?
about 65 million years ago
How far back can you trace the evolutionary origin of your own backbone?
the first vertebrates were fish
Does the rigid outer crust of the earth actually float on the underlying mantle?
yes, the rigid crust floats on top of the underlying mantle and acts sort of like a cork floating on water
What strong evidence led Alfred Wegener to confirm that the continents had drifted over geologic time?
fossil and mineral belts on separate modern-day continents aligned when the continents were artificially moved into a single super-continent
Why is the symmetric banding of magnetic anomalies along mid-ocean ridges considered to be strong evidence to seafloor spreading?
because magnetic anomalies are a proxy for the age of the rock and when dated, they show the crust getting symmetrically older as you move away on either side
What kind of tectonic process takes place in deep-sea trenches?
this is where ocean crust continuously sinks back into the mantle
How are continents moved around on earth over geologic time?
continents move when the tectonics plates that they are embedded in move
What is the driving mechanism for plate tectonic motion?
- mantle convection
- slab pull
are divergent boundaries only found at mid-ocean ridges?
no
Which of the following is a geographic region where ocean crust is currently colliding with ocean crust?
Aleutian Islands of Alaska
Why did India not slide back down into the mantle during its initial collision with Eurasia?
India was too buoyant to sink back into the mantle
How were Hawaiian Islands created?
mantle hot spot that upwelled magma to the surface to form underwater mountains that eventually grew to become islands
What kind of earth history is recorded in marine sediments?
- past climate change
- biological activity
- large volcanic activity
- extinction events
Approximately how fast do sediments accumulate?
1 to 5 cm per thousand years
Chemical isotope ratios obtained from marine shells preserved in marine sediments can give some information about past surface ocean temperatures.
True
How many mass extinction events have occurred on earth, including the current one being caused by humans?
6
Imagine you are on a beach and watch a nice clean set of large waves of similar wavelength coming ashore. What can you say about the storm that created these waves?
the storm probably occurred fairly far away from your beach
What typically happens to wave energy as it approaches a headland point of land?
the wave energy is focused to produce stronger waves
If you are caught in a rip current, what should you do?
swim along the shore for 10 to 20 meters, then back to shore
What factor or set of factors determine wave height?
wind speed, duration, fetch
What is a storm’s fetch?
it is the diameter of the storm system
How fast does a tsunami wave propagate?
about 500 miles per hour
Why is it so difficult to predict the height of a tsunami wave for a specific location?
the constructive and destructive addition of wave crests and wave troughs, associated with the multiple individual tsunami waves created during a single event are hard to predict
Which force is involved in the creation of the tidal bulge location on the side of the earth?
- ekman forcing
- geodynamic force
- coriolis force
- gravitational force
- -> NONE OF THE ABOVE
Semi diurnal tides are expected
along the equator
When do spring tides occur?
during a full moon
Why do tides occur in the ocean but not in ponds and small lakes?
Most of the tidal elevation comes from a lateral pull/pinch of water far to the side of the direct centerline between the earth and moon. In small lakes, there is only the direct line under the moon so there is no tide.
Why do we get rotary tides?
the combination of Coriolis force and blocking by continents
Why is the tidal range in Hawaii small relative to the west coast of the United States?
Hawaii is near an amphidromic point
Why is the atmosphere heated from below by a modestly warm earth surface and not above by the sun?
because the atmosphere does NOT absorb short wavelength radiation but does for long wavelength
Which type of column produces higher atmospheric pressure at sea level?
a column of dry air
Why do the surface Trade Winds blow in the westward direction when the pressure gradient force that drives the winds is actually directed toward the equator?
the winds are turned westward by the Coriolis force
What happens to the surface ocean mixing depth in temperate regions as the surface ocean layer is cooled during fall and into winter?
mixing depth becomes deeper
What is Ekman transport?
the movement/transport of a relatively thin slab of surface water in response to wind forcing
How does the mound of surface water in the middle of the subtropical gyre get formed?
the action of the trade winds and the westerly winds drives Ekman Layers into the middle of the subtropical gyre
If the winds are blowing from the south to the north along the west coast of the United States, would you expect to see coastal upwelling?
No
How are the subtropical gyres forced to rotate in a clockwise direction in the northern hemisphere and counter clockwise in the Southern hemisphere?
the trade winds and the westerly winds pile water up in the center of the gyre and this creates a downward pressure force that leads to the turning of the gyres
How are deep water masses identified?
based on characteristic temperature and salinity signatures
How long does it take for deep ocean to move from the North Atlantic to the North Pacific?
about 2000 years
What would happen if the conveyor belt circulation were to slow down due to climate change?
it would decrease the transport of heat from the equator to high latitudes
