11.1 Flashcards
How much of the earth is covered by oceans?
A little over 2 thirds
What are the 5 major oceans labeled biggest to smallest?
Pacific Atlantic Indian southern Arctic
What are the low points on earths surface called?
Basins
What are oceans?
Basins into which water has flowed and accumulated
What are oceans so important
Controls earth temperature, making the planet liveable; they create the weather patterns; and they are the source of the water that falls as fresh water on land, supporting all life forms
How long have oceans been on earth
Scientists believe about 3 billion years
How long ago did the planet form?
4.5 billion years ago
How did oceans form?
Earth Started out as a hot ball of molten rock. The outside of the earth gradually cooled, but heat continued to be released deep within the planet by volcanoes. Water trapped inside the volcanic materials was also released into the atmosphere as water vapour. As the water vapour cooled and condensed, it fell to earths surface as precipitation. The water started collecting in the lowest parts of earth surface, ocean basins
What’s another way oceans formed?
Came from the ice on comets that hit the young earth
What are 5 features on land taht are also in the ocean?
Mountain ranges, valleys, flat plains, canyons, volcanoes
What are the oceans 2 distinct parts called?
Ocean basins and continental margins
Ocean basins?
The large middle part of the ocean
Continental margins?
Rising outside edges of the ocean
What do storm waters do?
Erode coral reefs
What do icebergs do on the ocean?
Gouge deep grooves in the ocean floor
What’s the greatest in shaping the ocean floor?
Tectonic processes
What is the entire surface of the earth made of?
Large sections of rock called tectonic plates
What do tectonic plates lay on top of
Float over a layer of molten rock called magma
How do two plates push apart
When the magma heats up it rises
What are the two type of tectonic plates?
Oceanic and continental
Are oceanic of continental plates denser?
Oceanic
Oceanic plates?
They lie under oceans
Continental plates?
Lie under continent
What happens when two plates r pushed apart? What does this create?
The underlying magma oozes up into the empty spaces which creates a mid one a ridge
What is the largest example of a mid ocean ridge and where is this found?
Mid Atlantic ridge in the Atlantic Ocean
What two continents have been getting pushed about and for how long from the mid Atlantic ridge?
North America and Europe for the last 200 million years
What happens when the magma cools after creating a mid ocean ridge?
It becomes the newest Rock on the planet
What does the rising no hardening of magma cause?
Forces the plates to continually move apart, making the ocean for grow wider and wider
How fast do the oceans grow per year?
2.5cm
What is subduction? And what does it form?
When an Oceanic plate Comes in contact with a continental plate and the denser oceanic plate is forced to slip underneath the continental Plate. This forms a trench
Trench?
A long v shaped groove that marks the boundary between an oceanic plate and a continental plate
Where do trenches develop?
Near the outer edges of the ocean
Where do mid ovens ridges develop?
Middle of ocean basins
abyssal plains?
Wide flat areas Stretching between the areas of trenches and mid ocean ridges
What percent do abyssal plains make up in the Pacific ocean?
75%
What percent do abyssal plains make up of the Atlantic ocean?
30%
Seamount?
An old Inactive volcano that once developed near a mid ocean ridge, but have been shifted away as the plates move apart
Continental margins?
Regins of the ocean floor that lie underwater on the edge of the continents
Continental shelf?
A flat area that extends from the continents floor line to the ocean basin
Continental slope?
A steep area that drops off rapidly to the ocean basin from the edge of the continental shelf
The depth of continental shelf ranges..
30m to 600m
What is the average width of continental shelves?
480 km wide
What happened during the last ice age?
Continental shelves in the northern hemisphere were not underwater. As more ocean water became locked up as ice, The water level fell, leaving the shelf exposed
How are sediments carried into the ocean?
By rivers flowing off the continent
How is turbidity current caused?
The sediments build up along The steep continental slope. When the build up becomes too great, gravity suddenly causes the build up to give away
Continental rise?where is it
Gently sloping piles of sediment. Between the continental slope and the abyssal plains.
Submarine canyons?
Steep sided valley cut into the sea floor of the continental slope
Where else are submarine canyons found?
Regions where large rivers reach the ocean
What is the result when a living organism dies in the ocean?
A thick layer of material on the ocean floor made of these biological sediments, particles produced from the remains of a living substance
When an organism dies in the ocean, what chemically reacts in the water?
Shells, teeth, skeleton, and scales
