earth science 14 Flashcards
how much percent of the eaerth is covered by the ocean
71%
what is bathymetry
the measurment of the oceans depth
what was the first ship that explored the ocean floor
the hms challenger
what were some things that people used for exploring the oceans
Sonar, Satellites, and submersibles
what is a continental margin
it is the area of transition between a continent and the adjacent ocean basin floor.
what is the continental shelf
it is the first area of ocean floor you would encounter . it is the gently sloping submerged surface extending from the shoreline.
what is the continental slope
it starts at the end of the continental shelf and is steeper. is boundary between continental and oceanic crust.
what are submarine canyons
they are steep sided valleys that are cut into the continental slope.
what are turbidity currents
occasional movements of dense sidemeat-rich water against the continental shelf
what is continental rise
occurs in areas of no trenches, and consists of a thick layer of sediments that moved from the shelf to deep ocean
what is the ocean basin floor
Between the continental margin and mid ocean ridges lies the ocean basin floor.
what is an abyssal plain
extremely flat and deep areas-usually 4,000-6,000m deep.
what are deep ocean trenches
long steep sided depressions in the ocean floor.
what are seamounts
seamounts are volcanic peaks that are not tall enough to break through the ocean surface, are steep sided like volcanoes on land.
what are guyots
results from a volcanic island that erodes away by running water or waves. Once the island is submerged by water its referred to as a guyot.
what are mid ocean ridges
an interconnected system of mostly underwater mountains that have developed on newly formed ocean crust.
what is seafloor spreading
it occurs at divergent plate boundaries where two lithospheric plates are moving apart. NEW OCEAN FLOOR IS FORMED AT MID OCEAN RIDGES AS MAGMA RISES BETWEEN THE DIVERGING PLATES AND COOLS
what are hydrothermal vents
they form along mid ocean ridges. These are zones where mineral rich water, heated by the newly formed crust escapes through cracks in oceanic crust.
where do reefs grow
above continental shelves or around volcanic islands
what are the different type of coral reef
a reef may evolve overtime into an atoll.
it begins as a fringing reef that surrounds the volcanic island edge. As the seafloor sinks and the volcano gets dense and sinks the reef still keeps growing.
a barrier reef
it is formed as more water separates the reef from the island, this is because as the volcano island sinks the top of the volcano is narrow.
at atoll
an atoll forms as the island continues to sink until it is entirely underwater. and atoll is a ring-shaped reef surrounding a shallow lagoon.
life around a reef
reefs can have a variety of shapes and animals.
resources from the seafloor
besides living organisms the ocean contains valuable nonliving resources but because of depth it is too hard.
what are the main energy resources from the ocean
oil and natural gas as the main energy resource. they form from the remains of dead marine organisms.
what are gas hydrates
they are compact chemical structures made of water and natural gas. The most common type is methane.
Most form when bacteria break down organic matter trapped in ocean floor-sediments.
what are some other resources from the ocean
evaporative salts, sand, gravel, manganese
evaporative salt
as seawater evaporates the salt concentration increases until they are no longer dissolved, they precipitate out of solution forming salt deposits.
what is desalination
the process of extracting freshwater from seawater
sand and gravel
sand and gravel which includes rock fragments that are washed out to sea and shells of marine organisms are mined by offshore barges. They could be used to full in beaches or make concrete.
manganese nodules
they are hard lumps of manganese, iron, and smaller amounts of copper, nickel and cobalt. They precipitate around smaller objects
what are some sources of sea salts
rivers and ground water slowly dissolves calcium sulfate sodium and magnesium from rocks and minerals. another source is underwater vents and volcanoes that release gases.
salinity
the measurement of the amount of solids dissolved in water.
what are the processes that effect salinity (lower)
- adding freshwater to it by rain, snow melting icebergs.
- mouths of large rivers add lots of fresh water
what are some processes that effect salinity (higher)
1.evaporation near dry tropical areas.
2.near the poles the salt water freezes into ice leaving the salt behind.
factors affecting sewater density
seawater density is influence by two main things: salinity and temperature.
density variation with depth
temp and salinity and the waters resulting density vary with depth.
what is the pycnocline
the layer of ocean water between about 300m-1000m where there is a rapid change of density.
what is the surface mix zone
it has the highest temp due to direct solar contact. this layer has mixing of water by waves currents and tides.
what is the transition zone
the temp drops abruptly with depth. this layer is where the thermocline and pycnocline is located.
what is the deep zone
sunlight does not reach this zone. it has 80% of ocean water in this zone. water temperature is a few degrees above 0 degrees celcius.
what are plankton
are tiny algae and animals that float in the water and are carried by wave and currents. planktos=wondering
what are nekton
they are free swimming animals that can move throughout the water column independently of ocean currents. nectos=swimming
what are benthos
organisms that live on or in the ocean floor, like crabs lobsters etc. most live in the shallow part of the ocean.
the availability of sunlight`
the part of the ocean into which sunlight penetrates is called photic zone.
Euphoric zone is near the surface where light is strong enough for photosynthesis.
the lower photic zone does not have enough light for photosynthesis.
the aphotic zone is the zone below the photic zone and has no light.
distance from shore
this is another wat to subdivide marine life zones. the physical conditions of each zone help determine which organisms can live in that zone.
