Oceanography Flashcards
What ocean is on the west side of the US
The pacific
What ocean is on the east side of the US
The Atlantic
What ocean is on the east side of Africa
The Indian
What ocean is on the northern tip?
The arctic
What ocean is from the coast of Antarctica south?
The southern ocean
What is the largest ocean by surface area and depth?
The pacific
Rank the oceans from largest to smallest
Pacific, Atlantic, Indian, southern, arctic
What is a continental margin?
The transition from land to deep sea floor. Basically from crust to crust.
What is an active continental margin? Give an example in the US
A margin where a tectonic plate boundary also lies. Has more geographical activity.
Ex: the west coast is also the plate boundary between the pacific and North America.
What are the characteristics of an active continental margin?
More narrow shelves, steeper slopes, and little to no rise.
What is a passive continental margin? Give an example in the US.
A margin where no tectonic plate boundary occurs, has less geographical activity.
Ex: the East coast of the US
What are the characteristics of a passive continental margin?
Wider shelves, gentle slopes, and a developed rise from long periods of stability.
What is a continental shelf? Is it considered continental or oceanic crust? What is the average extension of a shelf from the coast?
The top part of the continental margin that is shallow and flooded. It is continental crust. Average extension is 80 km.
What part of the continental margin is the most biologically rich?
The continental shelf.
Is the continental shelf smooth or rough? Why?
Smooth, from repeated wave action, being submerged and then I submerged, and other erosion.
What is the shelf break?
The part of the continental margin where the shelf ends and the slope begins and the angle of the sea floor gets steeper.
What is the continental slope? What is it’s average depth?
Area of advance steepness of the continental margin. Usually 3000-5000m deep.
What part of the continental margin do sub marine canyons form? Why?
The continental slope, they form from sediments from land and shelf falling.
Name the parts of the continental margin starting with the most shallow.
Continental shelf, shelf break, continently slope, continental rise, abyssal plain.
What is the continental rise?
The part at the bottom of the slope where continental crust meets oceanic crust.
Why is it difficult to tell where the slope ends and the rise begins?
Because the rise can be covered by layers of accumulated sediment.
What is the abyssal plain?
The deep ocean floor.
What is the flattest region on earth?
The abyssal ocean plains.
What is the benthic zone? What are the organisms called that live there?
The bottom of the ocean and all organisms that live there called benthos.
What is the pelagic zone?
The water column where all swimming and floating organisms live.
What are the two provinces of the pelagic zone? What are they?
The neitic and the oceanic. Neritic is all water from low tide to the shelf break, oceanic is all other open ocean regions.
How many depth zones is the oceanic province are there? List them by name and depth.
Five
1: epipelagic: 0-200
2: mesopelagic 200-1000m
3: bathypelagic 1000-4000m
4: abyssopelagic 4000-6000m
5: hadopelagic 6000 plus
What depth zone of the oceanic province can light reach?
The epipelagic zone receives full sunlight, mesopelagic gets some light but not enough for photosynthesis.
What depth zone is 75% of the ocean at?
The bathypelagic
What depth zone is the water in the deep trenches?
The hadopelagic/hadalpelagic
How many zones is the benthic zone split into? Name them.
1: littoral
2: sublittoral
3: bathyal
4: abyssal
5: hadal
What zone of the benthic zone is only sometimes submerged?
The littoral zone. Also called the spray zone.
What is bathymetry?
The process of measuring the oceans depth.
What is sounding? What are its drawbacks?
A process of measuring used early on that consisted of letting out a lead line until it touched the bottom. It’s only limited to one point at a single moment and it is only useful in shallow waters, very time consuming.
What is a unit of depth called? What is it in feet?
Fathom. 6 feet.
what is sonar?
Sound navigation and ranging.
What is an echo sounder?
The device used in sonar that sends out a pulse then listens for the returning echo. The timing of the returned echo is used to measure depth.
What is the equation for an echo sounder?
D=1/2 VT (depth=1/2 (x) pulse velocity in water (x) time
What are satellites used for in regard to the ocean?
Large scale mapping that uses radio waved to measure height of sea surfaces. Gives us topography under the surface.
Who was Marie Tharp?
A pioneer in mapping the sea floor and provided evidence for the plate tectonics theory. Found that “v” on her map was caused by land masses moving. Mis ocean ridges lined up with earthquakes. Supported continental drift theory.
What four hemispheres is Earth divided into?
Northern and southern and Eastern/Western
What is the line going East to West across the Earth called?
The equator
What is the line going North to South on the Globe called?
The prime meridian
What line does latitude follow?
The equator
What line does longitude follow?
The prime meridian
How detailed can latitude and longitude locations get?
Down to the minutes and seconds
What is latitude?
From the Equator, to the center of the Earth, to your position on the Earth’s surface. It’s the angle from the equator.
What are parallels?
Lines of equal latitude that are always the same distance
What directions are latitude expressed in?
North and South
What are the latitude poles at degree wise?
90 north/south
What natural point can you use to detect latitude and why?
The angle of the North Star because it always sits over the. North Pole.
What is longitude?
The distance east or west from the prime meridian
What degree is the prime meridian at?
0
What are meridians?
Lines of longitude in great circles. All the same length and both parallel, converge as they near the poles.
What do you need to measure longitude?
Accurate time at current location and time at random distant point at the same instant.
What does GPS stand for?
Global Positioning System.
How is GPS used to determine latitude and longitude.
A system of orbiting satellites that emit signals containing time and their position. GPS receives these signals and then triangulates them to calculate position.
How many satellites does GPS need to accurately work
At least 24 functional at one time.
What are some issues that have occured when trying to map the globe?
- difficult to accurately measure a 3 dimensional sheprical object on a flat 2 dimensional surface.
- 2 d maps are distorted in representing earths true area, direction, distance, and shape.
What have we done to combat the issues with mapping the globe?
Use different map projections
What map projection is the standard for navigational charts?
Mercator
What is a Mercator map projection? What is its drawback?
Latitude and longitude are represented as straight, parallel lines intersecting at right angles. (Looks like a grid) Sometimes very colorful.
Drawback: size and distance are distorted.
What is the Goode homolosine map projection? What is the drawback?
Another map used for navigation. Does not exaggerate distance as much as Mercator.Drawback: either the oceans or the continents are disrupted. (Looks like an M with an extra leg)
What is a bathymetric map?
Similar to topographical maps with lines connecting areas of equal depth. The closer together the lines the steeper the feature. Red = shallow water, blue/purple = deep water
What is a pysiographic ma?
A map that turns a bathymetric map into a 3D representation or relief map to show ocean features. Tend to show significant vertical exaggeration.
Who is Alfred wegener?
An astronomer from teh late 1800’s to early 1900’s.
What concept was Alfred Wegener known for that became supported after he died?
The theory of continental drift.
What is continental drift?
The theory that the continents were once together and drifted apart.
What is the term “continental drift?” Inaccurate and what do we sue instead?
Because we now know that it’s not just the continents that move, but the tectonic plates below them. We now call it plate tectonics.
What is some evidence that Alfred Wegener found that led him to believ in continental drift?
1: similar fossils in different parts of the world.
2: matching geological patterns across the world.
Who coined the term “Pangea” and what was it? What were the two others that came after Pangea?
Alfred wegener, “all land” for the one super continent. Split into two other supercontinents called “Laurasia and Gondwana”what
What modern continents came out of the supercontinent Eurasia?
North America, Europe, Asia
What modern continents came from the supercontinent Gondwana?
South America, Africa, India, Australia, and Antarctica
Why was Alfred wegener theory dismissed by geologists of the time?
Because he could not explain what force could move the continents. Just that they did move.
Who noticed that coast lines seemed to fit together whcih supported Pangea?
Francis Bacon from the 17th century.
What type of water do corals best grow in?
Warm, clear, tropical water
What do corals rely on to create energy?
Photosynthesis
What living in coral tissue also needs photosynthesis?
Algae
What type of reef is close and connected to the shore?
Fringing reefs
What type of reef is offshore and seperated from land by an expanse of water? But still has a land mass in the center of it.
Barrier reef
What type of reef is circular/oval and surrounded by a lagoon without any central land mass in the lagoon?
An Atoll reef
What did Darwin speculate in regard to reef development?
That reefs go from fringing, to barrier to atoll as islands sank.
What will happen to a fringing reef if the sea level does not change or the land doesnt’ sink?
The reef will not develop beyond being a fringing reef.
What happens with coral as the land begins to sink?
They continue to grow upwards to receive photosynthesis.
What happened by the end of 1967 in regard to plate tectonics?
The earth was mapped out into a series of plates
What are the three different categories of tectonic plates?
1: major plates
2: small plates
3: sub plates
What are the 8 major plates?
Eurasia, Pacific, India, Australia, Norther America, South America, and Antartica
What is the makeup of the continental plates? What does this allow for?
Made up of crustal and lithospheric mantle. This means that a single plate can have both oceanic and continental crust.
What is the average rate of motion for he major plates?
Less than 1 cm a year to over 10 cm a year.
What is the fastest moving tectonic plate?
Pacific (10cm/year)
What is one of the slowest continental plates?
North American (1 cm in the south and 4 in the north)
Why could the northern part of a plate move at a different rate than the southern?
Because plates move in a rotational matter.
What is happening to the pacific and Atlantic oceans with the plates moving?
The Atlantic is getting bigger and the pacific is getting smaller.
What will happen to Africa with the plates moving
It will eventually split apart
What will happen to California with the plates?
The western part will split away.
