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62 Cards in this Set
- Front
- Back
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How much of the earth's surface does the ocean cover in the northern hemisphere?
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61%
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How much of the earth's surface do Oceans cover?
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Over 71%
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how many basins are the ocean separated into?
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four
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Which ocean is the largest and deepest?
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The Pacific; it's almost as large as all the other oceans combined
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Which two oceans are similar in size and depth?
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The Atlantic and the Indian
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Which ocean is the smallest and shallowest?
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The Arctic
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Where is the deepest place in the world?
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The Mariana Trench in the Pacific Ocean @ more than 36,000ft deep
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What is the most important aspect of the global ocean concept?
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The movement of water within the world ocean moderates the world's climate
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How is the world's climate moderated?
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The global ocean distributes heat from the equator to the poles
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What is the Southern Ocean?
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The continuous body of water that surrounds Antartica
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When was the earth formed?
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4.5 billion years ago
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What did Sir Francis Bacon notice in 1620?
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The coasts on either side of the Atlantic fit together like pieces in a puzzle
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What early evidence was found to support Sir Francis Bacon's theory?
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-geological formations (ex rock type, coal deposits and fossils) match up on the now separated continents
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Approx how many years did it take for the continental drift theory to be formally proposed after sir frances bacon thought of it?
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660 years
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What is the Continental Drift theory?
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all land masses were one supercontinentent called Pangea & started breaking up 180 million years ago
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What was the one large ocean that surrounded Pangea?
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Panthalassa
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When did Pangea start breaking up?
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180 million years ago
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What is the outer crust made up of?
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Continental and Oceanic plates
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These plates are older & lighter
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Continental plates
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These plates are younger & heavier
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Oceanic plates
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Why are oceanic plates heavier?
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Because they are made of a heavier rock called basalt
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What is the lithosphere?
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the uppermost layer of the mantle & the crust
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Can a plate have both oceanic and continental crust?
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Yes, and they can also have each individually
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What are plate tectonics REALLY?
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The lithosphere moving around on top of the asthenosphere
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How fast do the earths plates move?
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>7 inches a year
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2 plates diverging
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occurs when two lithospheric plates move AWAY from each other
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What are the two main geologic features that 2 plates diverging creates?
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1. mid-oceanic ridge
2. hydrothermal vents |
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mid-oceanic ridge
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the longest continuous chain of volcanic submarine mountains in the world, they occasionally rise so high that they break the surface and form islands
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what happens when new plates spread or move apart?
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new sea floor is formed, a rift (crack) forms in the crust, the new mantle rises through the rift, hits the cold water and forms a new crust and ridge
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hydrothermal vents
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cracks in the sides of the rift that allow seawater to seep in and hit the hot mantle--the water heats up and comes back out of the crust forming vents
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2 plates colliding
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this occurs when two plates converge (collide) together
-depending on which plates are involved many different things can happen |
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Oceanic Plate (colliding) Oceanic Plate
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-forms a subduction zone because one plate subducts (goes under) the other
-as one plate sinks, it causes EARTHQUAKES, the subducted plate eventually gets so hot that it melts -some of the molten material rises to form volcanoes which sometimes they get so big they break the surface and form island archs -oceanic trenches (the deepest parts of the ocean) are also formed ***this occurs at all subduction zones |
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Oceanic plate (colliding) Continental Plate
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-the heavier, oceanic plate subducts (under) the lighter continental plate and forms another subduction zone
-because it involves a continental plate this can form continental trenches, volcanoes and coastal mountain ranges ex: Andes mountains |
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Continental plate (colliding) Continental plate
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-since both plates are light, no trench is formed, instead a convergent zone occurs
-the land pushes together to form large mountain ranges ex: himalayas & the appalachians |
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How were the Andes mountains formed?
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The South American plate collided with the Nazca plate, the Nazca plate subducted under the South American plate forming continental trenches as well as a coastal mountain range
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How were the Aleutian Islands formed?
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Two oceanic plates collided creating volcanoes which formed an island arch
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How are Transform plate boundaries formed?
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When plates move laterally against each other
-these create a lot of friction which creates earthquakes ex: San Andreas Fault |
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Can plates both converge and move laterally against each other at the same time?
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Yes
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Can more than two plates interact at once?
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Yes! Plate tectonics is rather complex
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What is an ice age?
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They are cold periods during Global Climate change
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What is an interglacial period?
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warm periods inbetween ice ages
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When did the last major ice age occur and how thick was the ice over N America?
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18,000 years ago; the ice was 2 mi thick
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What happens to the sea level during an ice age?
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It falls because the water is trapped in glaciers on top of continents
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Why aren't we in an ice age now?
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Some scientists believe that we would be if humans hadn't intensified the greenhouse effect causing the glaciers to melt
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continental margins
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-boundary between continental and oceanic plates
-they consist of four sections |
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What are the four sections of the continental margins?
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1. continental shelf
2. continental slope 3. continental rise 4. abyssal plane |
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continental shelf
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-slopes very gently and is the most shallow part of the margin
-this is the edge of the continent that is underwater and it ends very abruptly at the shelf break -has the most organisms |
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continental slope
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-very steep
-the closest thing to the exact edge of the continent -the bottom of the slope occurs at >10,000 ft -submarine canyons that go down the slope funnel sediments to the sea floor |
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continental rise
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-a thick layer of sediment that streams down from the continental slope
-it piles up on the sea floor into deposits called deep-sea fans -these are similar to the river delta -when these deep sea fans overlap they form the continental rise |
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abyssal plane
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-the sea floor
-very deep 10,000-16,500ft deep -almost the entire floor is flat except for a) sea mounts-submarine volcanoes b) seam of mid-oceanic ridge c) deep sea trenches |
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What is the difference between an active margin and a passive margin & where would you find each of them?
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active margin- active geologically (earthquakes, volcanoes, etc) ex: South America's West Coast
passive margin- not geologically active ex: South America's East Coast |
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What is a hot spot?
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Where a plume of hot magma rises from deep in the mantle of the earth to erupt in volcanic activity
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how does a chain of volcanoes form?
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as the pacific plate moves over the stationary hot spot, new eruptions of magma break out in different places forming a line of volcanoes
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which is the youngest hawaiian island, how old is it?
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Hawai'i 0.8 million years old
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Which is the oldest hawaiian island, how old is it?
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Kaua'i 3.8-5.6 million years
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As you move to the northwest of the main Hawaiian Islands, do the islands get older or younger?
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Older
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How old are the Midway & Meiji Seamount?
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Midway- 25 million years
Meiji Seamount- 70 million years old |
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Why is there a bend between the Hawaiian ridge and the Emperor Plate?
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It is thought to have occurred when the Pacific Plate changed direction
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What is Loihi and when will we see it?
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Loihi is the newest hawaiian island and we will see it in 100,000 years
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what is density?
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the mass of a given volume of a substance
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how old are the oldest oceanic and continental crusts?
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oceanic- less than 200 million years
continental- as much as 3.8 billion |
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which coast has a larger continental shelf? why?
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the east coast has a larger continental margin
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