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oceanography test 1
na
46
Science
Graduate
05/01/2011

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Term
How do we know that the mantle is mostly solid and not molten ?
Definition
seismic shear waves pass through it
Term
according to the principle of isostatic equilbrium a section of plate will be more buoyant (ride higher on the mantle) If it is?
Definition
warm
Term
Beneath which of these locations is the crust likely to be thinnest?
Definition
Mid-atlantc ridge
Term
why are there ocean basins?
Definition
ocean crust is thinner and denser than continental crust
Term
why is the oldest ocean crust only 180 million years old?
Definition
All older ocean crust has been subducted 
Term
if there were no other sources of heat the increase of pressure with increasing depth in the earths interior woul cause temp to___ and heat to__
Definition
increase...remain unchanged
Term
what is required to drive mantle convection?
Definition
a heat source and a heat sink
Term
How does convecting mantle rock lose heat in order to sink? 
Definition
by conduction through lithosphere
Term
which of the following is not major force driving seafloor spreading?
Definition
heating by hotspots
Term
the rigid plates of plate tectonics are also known as?
Definition
lithosphere
Term

which of the following is not a piece of evidence that supports the theory of plate tectonics?

 

Definition
geosynclines
Term
why does mantle rock melt as it rises buoyantly?
Definition
gets heated by lava
Term
why do volcanoes form near subduction zones 
Definition
water from sub ducting plate causes mantle rock to melt
Term
which of these plate boundaries are convergent
Definition
mariana trench
Term
what is the half spreading rate of the east pacific
Definition
~5cm per year
Term
which feature is not typically found at the crest of a mid ocean ridge
Definition
thick sediments
Term
if 2 plates overlain by ocean crust meet at a convergent boundary which one will likely subduct?
Definition
the older one
Term
choose the correct order of the sediment sizes, from smallest to largest
Definition
clay-silt-sand-granule
Term
according to stokes law which 2 variables would both increase the sinking rate of a spherical particle  through a still fluid?
Definition
large particle size  and high particle density
Term
what variable affects the amount of frictional resistance acting on a sinking particle?
Definition
particle surface area to volume ratio
Term
what type of sediment would you find dominating the middle of the deepest pacific far from land and far from any biologically productive surface waters
Definition
clays
Term
what condition is clcium carbonate more likely to dissolve in seawater
Definition
cold water, high pressure
Term
the 2 main biogenic minerals found in sediments are
Definition
calcium carbonate and opal
Term
if you find a pebble size terrigenous grain on te abyssal plain how did it most likely get there
Definition
iceberg
Term
the water molecule is said to be polar bc it is assymetrical and
Definition
has a slight charge at each end
Term
what single factor best explains why liquid water has a higher heat capacity than most substances 
Definition
hydrogen bonding
Term
where does most of the heat in ocean waters orriginate
Definition
solar radiation 
Term
as heat is added to pure ice what happens when its temp reaches 0 c
Definition
remains at 0 as ice begins to melt
Term
how does waters high latent heat of vaporization moderate air temps
Definition
evaporation consumes heat in warm environments and condensation releases heat in cold environments
Term
How does waters high latent heat of fusion moderate air temps
Definition
melting consumes heat in summer and freezing releases heat in winter
Term
why dosent the pressure of the deep ocean increase seawater density very much
Definition
liquids are relatively incompressible 
Term
which of these greenhouse gases account for most of the natural greenhouse effect
Definition
water vapor and carbon dioxide
Term
assuming the earths heat budget is at steady state what physical law determines the radiating temperature of the planet
Definition
amount of radiation emitted depends on temp of emitter
Term
solar energy absorbed by the earth is returned to space as 
Definition
infrared radiation 
Term
in computing the energy budget for the earth which of the following is treated as a feedback rather than a direct radiative forcing factor
Definition
clouds
Term
characterize the heat absorbed by upper ocean in recent decades
Definition
more than absorbed by land
Term
the main reason that the earths inner core is solid is its high__. the main reason that the earths crust is solid is its low ___
Definition
pressure....temperature
Term
how will negatively buoyant mantle rock tend to move within the mantle
Definition
it will sink toward the core
Term
the least dense rocks on earth are generally found in 
Definition
continental crust
Term
satellite altimetry can measure seafloor topography because
Definition
gravity deforms the sea surface 
Term
the speed of sound in seawater is about ___than the speed of sound in air
Definition
5 times faster
Term
why is it difficult for oceanographers to "see" through seawater and study the deep sea
Definition
electromagnetic radiation is readily absorbed by seawater
Term
in what environment do most scientist now think life likely originated?
Definition
hydrothermal vents
Term
the world ocean contains what percentage of H20 at the earths surface?
Definition
97%
Term
the world ocean is said to have an aspect ratio (area compared to thickness or depth) comparable to
Definition
a sheet of paper
Term
which color of visible light is most efficiently transmitted through seawater
Definition
blue
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