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The ocean interacts with
chemistry, physics, society, geology, and biology
Problems in the world that have an effect on the ocean
climate change, acidification, deoxygenation, and pollution
Seafloor bathymetry is studied using
echo sounders and satellites
How do we know the earth is layered?
seismic waves and earthquakes
What are p-waves?
primary compressional waves that are extremely fast, like a slinky, not destructive, travel through solids and liquids, and are first to be recorded on seismographs
What is Moho discontinuity?
changes in p-wave velocity and angles due to the boundary between the crust and the mantle
What are s-waves?
secondary shear waves that pass through the earth moderately fast, go up and down, are not destructive, travel through solids, and stop traveling in the Shadow Zone
What waves travel along the earth’s surface?
L-waves and R-waves
How did the earth become layered?
density
What relationship do density and temperature have?
inverse
Where is the earth the most dense?
the core
Warmer temperature =
less density
Colder temperature =
more density
A liquid moves to areas of equal density as itself. Density below this liquid is ____, and density above this liquid is ____.
higher, lower
The earth is how many years old?
4.6 billion years
Reasons for the formation of the earth
cold accretion, solar winds, and added heat
What happens during cold accretion?
unsorted materials are very cold, which eventually become layered
How did solar winds influence the formation of the earth?
gravity compacted the earth, solar winds boiled away lighter elements, and heat arose from collisions
How did added heat influence the formation of the earth?
the earth heated up due to gravitational contraction, radioactive decay, and large meteorite impacts
What is differentiation?
materials becoming molten due to high temperatures (ex: iron and nickel sink to create the core)
What happens to the lighter materials due to differentiation?
they compose the surface crust
What happens to the mantle due to differentiation?
it becomes magnesium
What is the lithosphere?
the rigid layer composed of all the crust and part of the upper mantle
What is the asthenosphere?
the part of the mantle that can flow, which is not liquid
What is the continental crust?
basement rocks that are very old; 31% is submerged; rich in aluminum silicates
What is the oceanic crust?
younger and thinner crust than continental; has 3 layers; rich in magnesium silicates
How is the outer shell of the crust different than the mantle?
different chemistry that includes oceanic and continental crust
What is convection overturn?
internal heat from the interior that is transferred to the surface by convection
The earth has been cooling since ____________
4.4 Ga and is still cooling
Who came up with the theory of continental drift and Pangaea?
Alfred Wegener
What evidence is there for Pangaea’s existence?
paleoclimate data, distribution of fossils, and matching geologic units
How is paleoclimate data evidence for Pangaea?
certain biomes were at different latitudes in the past
How is the distribution of fossils evidence for Pangaea?
same species fossils are found on distant continents
How are matching geologic units evidence for Pangaea?
rock layers are the same on different continents (ex: mountain ranges)
What observation did Harry Hess make?
seafloor spreading, as thickness of sediment decreases towards ocean ridges, deep sea drilling, and the age of the crust were evidence for it
How were deep sea trenches and ocean ridges discovered?
sonar and bathymetry during WWII
What exist along continental margins?
shelfs, slopes, and rises
Where is ocean sediment thickest and thinnest?
thinnest at mid-ocean ridges and thickest at continental margins
What is ocean crust made of, and what is continental crust made of?
basalt and granite
What causes uneven heat distribution beneath mid-ocean ridges?
more heat rises there
What is seafloor spreading?
magma rising that pushes mid-ocean ridges apart
Where is earth’s magnetic field strongest?
near the poles
What is geomagnetism?
earth’s magnetic field polarity reverses poles periodically
What is paleomagnetism?
iron bearing minerals align with earth’s magnetic field when magma cools
What is the plate tectonic theory?
plate movement causes continents to move and interactions at boundaries result in earthquakes, volcanoes, and mountain building
What is the Ring of Fire?
where a lot of seismic activity occurs around the Pacific plate
How many plates does the lithosphere consist of, and where are they located?
20, in the lithosphere which floats on the soft asthenosphere
What is the ridge push force?
the force that drives plates away from mid-ocean ridges
What is the slab pull force?
the force that down going slabs apply to the lithosphere at a convergent margin
What are the types of plate boundaries?
divergent, convergent, and transform
What happens at divergent plate boundaries?
plates move apart, new crust is formed, and earthquakes/small volcanic eruptions occur
Where are divergent plate boundaries found?
in oceans and mid-ocean ridges
Explain seafloor spreading at divergent boundaries
the seafloor is elevated, forming oceanic ridges, where some have deep rift valleys along their axis
What is continental rifting?
divergent plate boundaries that develop within a continent
What happens at convergent plate boundaries?
plates move together, the more dense plate sinks under the less dense plate, one plate is consumed, and earthquakes/large volcanic eruptions occur
What happens during a convergent oceanic-continental collision?
continental volcanic arcs and felsic rocks are formed (ex: Chile)
What happens during a convergent oceanic-oceanic collision?
ocean island arcs and felsic rocks are formed (ex: Aleutian island arc)
What happens during a convergent continental-continental collision?
mountain ranges and metamorphic rocks are formed (ex: Himalayan mountains)
What happens at transform plate boundaries?
plates move along each other and earthquakes occur
What is an example of a transform boundary?
the San Andreas Fault
What are the types of continental margins?
passive and active
Describe passive continental margins
not on a plate boundary, wide shelf, shallow slope, and no earthquakes/volcanoes
Describe active continental margins
on a plate boundary, narrow shelf, steep slope, and has earthquakes/volcanoes
What is a hot spot?
at the base of the lithosphere where high temperatures cause melting
How do hot spots create island chains like Hawaii?
the hot spot under oceanic crust stays in the same place while the lithosphere above moves
What is an atoll?
forms around a hot spot as the island created moves off the hot spot; causes coral reef and lagoon formation
What is a triple junction?
meeting point between 3 plates
How are ocean basins formed?
through continental rifting
Between what temperatures does water exist at?
273-373 K
What is used as an alternative for testing how much water is in the mantle?
meteorites
What is the cometary ice hypothesis?
the theory that ocean water came from comets
What are the sources of water on earth?
outgassing and cometary ice
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