Which of the following methods are currently used to measure the depth to the ocean floor?
The most common and fastest way of measuring ocean depth uses sound. Ships using technology called sonar which stands for sound navigation and ranging can map the topography of the ocean floor. The device sends sound waves to the bottom of the ocean and measures how long it takes for an echo to return.
Which one of the following is part of the passive continental margin?
The Atlantic and Gulf coasts show the classic form of a passive continental margin: a low-lying coastal plain broad continental shelf then a steep continental slope gentle continental rise and flat abyssal plain. This topography is a consequence of the transition from thick continental to thin oceanic crust.
Which of the following describes an active continental margin?
An active continental margin is found on the leading edge of the continent where it is crashing into an oceanic plate. An excellent example is the west coast of South America. Active margins are commonly the sites of tectonic activity: earthquakes volcanoes mountain building and the formation of new igneous rock.
Which of the following statements accurately describes deep ocean trenches quizlet?
Which of the following statements accurately describes deep-ocean trenches? All active continental margins are adjacent to deep-ocean trenches. With which type of plate boundary or zone is the Mariana Trench associated? Which of the following is an erosional feature on the abyssal plain?
Which of the following processes would decrease the amount of salinity in seawater?
Processes that decrease seawater salinity include evaporation and sea ice formation. A rapid change in ocean temperature with a change in depth occurs in the: pycnocline.
What is the name of the process that recycles the ocean floor?
How are abyssal plains formed?
Do active margins have continental rise?
Active continental margins are those that are tectonically active such as along much of the Pacific coast. Active margins are marked by earthquakes volcanoes and mountain belts. Unlike passive margins they lack a continental rise and abyssal plain.
How does hydrothermal metamorphism alter saltwater and the basaltic rocks that make up the seafloor?
How does hydrothermal metamorphism alter saltwater and the basaltic rocks that make up the seafloor? … It also dissolves various ions in the hot seawater which eventually rise along fractures and spew out on the ocean floor.
Which three parts make up the continental margin?
The continental margins consist of three portions: (1) the continental shelf which has shallow water depths rarely deeper than 650 ft) and extends seaward from the shoreline to distances ranging from 12.3 miles to 249 miles (2) the continental slope where the bottom drops off to depths of up to 3.1 miles and (3) the …
Which of the following are ways in which local mountains are generally created?
A local mountain is created if overthrust block is uplifted faster than it is eroded or it is composed of erosion-resistant rocks. Match the situation with how it may form local mountains. One block slips down forming a basin the other remains high or is moved upward and can form a local mountain.
What transports most of the sediment that forms the continental rise?
They are carved by undersea erosion processes associated with “turbidity currents.” Turbidity currents transport sediment into deep ocean basins via submarine canyons. Turbidity currents moving down submarine canyons eventually slow down and deposit sediments on the continental rise as deep-sea fans.
What is salinity and how is it usually expressed what is the average salinity of seawater?
Salinity of seawater is usually expressed as the grams of salt per kilogram (1000 g) of seawater. On average about 35 g of salt is present in each 1 kg of seawater so we say that the average salinity of the ocean salinity is 35 parts per thousand (ppt). Note that 35 ppt is equivalent to 3.5% (parts per hundred).
What is the primary reason that the oceanic ridge system is higher in elevation and rises above the deep ocean floor?
In brief the oceanic ridges rise about 2 km (1.2 miles) above the seafloor because the plates near these spreading centres are warm and thermally expanded. In contrast plates in the subduction zones are generally cooler.
What process gives trenches their unique arc shaped depressions?
Trenches are formed by subduction a geophysical process in which two or more of Earth’s tectonic plates converge and the older denser plate is pushed beneath the lighter plate and deep into the mantle causing the seafloor and outermost crust (the lithosphere) to bend and form a steep V-shaped depression.
Is the salinity of seawater increases its?
As the salinity of seawater increases its: density increases.
Which of the following processes increases the salinity of seawater quizlet?
When sea ice forms the water molecules preferentially exclude any salt in the water resulting in ice that is mostly fresh. Sea ice formation increases the salinity of remaining seawater.
What are the factors affecting the salinity of the seawater?
Salinity of seawater is affected by evaporation precipitation ice formation and ice melting. Evaporation increases the salinity of seawater because when seawater evaporates the salts are left behind thus increasing their concentration.
What processes are involved in seafloor spreading?
How is it possible for a new crust to be formed without increasing the surface area of the Earth?
New crust is continually being pushed away from divergent boundaries (where sea-floor spreading occurs) increasing Earth’s surface. But the Earth isn’t getting any bigger. What happens then to keep the Earth the same size? The answer is subduction.
How does the observed change in sea floor age support the theory of sea floor spreading?
The ages of rocks helps to prove the theory of the sea floor spreading by hot less dense liquids below earth’s crust rising toward the surface of the mid ocean ridges. … As it would then move away from the mid ocean ridge and become cooler and denser.
What directly underlies the abyssal plain?
Geology. An average of 1.1 kilometers (0.68 mi) of exclusively deep-sea sediments resting upon oceanic crust underlies the Madeira Abyssal Plain. … Immediately overlying the oceanic crust is a layer of hemipelagic sediments.
How are abyssal plains formed quizlet?
How are abyssal plains formed? Abyssal plains are deep extremely flat features of the ocean floor. They are formed as sediments from coastal regions are transported far out to sea and settle to the ocean floor and as materials from the water column above settle to the bottom.
How does most abyssal clay form?
Lithogenous sediments (lithos = rock generare = to produce) are sediments derived from erosion of rocks on the continents. … When these tiny particles settle in areas where little other material is being deposited (usually in the deep-ocean basins far from land) they form a sediment called abyssal clay.
Where is Continental Rise found?
…the ocean floor called the continental rise at a depth of roughly 4 000 to 5 000 metres (13 000 to 16 500……
Why are most oceanic trenches in the Pacific?
Why are most oceanic trenches found in the Pacific Ocean? The Pacific Ocean is shrinking and plates are descending below surrounding plates along its edges hence the creation of trenches.
Why are abyssal plains more extensive on the floor of the Atlantic than on the floor of the Pacific?
The Atlantic Ocean has the most extensive abyssal plains because it has few trenches to catch sediment carried down the continental slope. The sediments that make up abyssal plains are carried there by turbidity currents or deposited as a result of suspended sediments settling.
How do plate tectonics affect ocean basins?
Active ocean basins undergo changes mainly due to plate tectonics. … When plates spread apart they create gaps where magma from the earth’s mantle can rise up and cool to form structures such as oceanic ridges which are continuous mountain chains located under the surface of the sea.
What happens at an oceanic ridge?
Mid-ocean ridges occur along divergent plate boundaries where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate molten rock rises to the seafloor producing enormous volcanic eruptions of basalt.
What makes up the deep ocean basin?
What geographic features make up the continental margin?
What do turbidity currents produce?
Which has larger changes in elevation and depth the continents or oceans?
An estimated average continental elevation increase relative to average ocean floor depth of about 54 m and sea level decrease relative to the ocean floor of about 102 m add up to a 156-m increase of continent elevation over sea level since 65 Ma.
How are mountains formed step by step?
The world’s tallest mountain ranges form when pieces of Earth’s crust—called plates—smash against each other in a process called plate tectonics and buckle up like the hood of a car in a head-on collision. The Himalaya in Asia formed from one such massive wreck that started about 55 million years ago.
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