Chapter 14: The Ocean Floor
Approximately what percentage of Earth's surface is covered by oceans?
70 percent.
Why is Earth called the "blue planet?"
About 70 percent of Earth's surface is covered by water.
Why is it uncommon to find calcareous ooze in deep-ocean basins?
As the calcium carbonate tests of organisms sink into deeper parts of the ocean they dissolve. In seawater deeper than 4500m, the tests dissolve completely before they reach the bottom.
Compare and contrast deep-ocean trenches and mid-oceanic ridges.
Deep-ocean trenches are formed at convergence sites where on plate is being pushed beneath another, descending into Earth's mantle. Mid-ocean ridges are areas of divergence where new ocean floor is formed.
What current disadvantages exist to using gas hydrates as a form of energy?
Gas hydrates evaporate quickly when brought to the surface.
Explain the process by which hydrogenous sediments are formed.
Hydrogenous sediments are formed when minerals crystallize directly from seawater through various chemical reactions.
Why is multibeam sonar more efficient than simple sonar at collecting data from the ocean floor?
It is more efficient because it has more than one sound source and listening device.
What is bathymetry? What techniques do scientists use to discover more about the bathymetry of ocean basins?
It is the measurement of ocean depths and charting the shape or topography of the ocean floor. Scientists use sonar, satellites, and submersibles.
What is the difference between terrigenous sediments and biogenous sediments?
Terrigenous sediments are formed from weathered continental rocks. Biogenous sediments are formed from the remains of marine animals and algae.
Compare and contrast the size and topography of the Atlantic Ocean basin to that of the Pacific Ocean basin.
The Pacific Ocean basin is about 2 times the size of the Atlantic Ocean basin. Both have a variety of topographic features including mid-ocean ridges, abyssal plains, and seamounts. Trenches are more prevalent in the Pacific Ocean. The continental margins of the Pacific Ocean are narrow and have more volcanic and earthquake activity than the Atlantic Ocean margins.
In which ocean basin are the most trenches found? Why?
The Pacific Ocean, because plates are converging.
What is a continental shelf? What economic significance do continental shelves have?
The continental shelf is the gently sloping submerged surface extending from shoreline to the ocean basin floor. They contain mineral deposits, large reservoirs of oil and natural gas, as well as huge sand and gravel deposits
What are the uses for sand and gravel harvested from the continental shelf?
To make concrete, landfill, and recreational beaches.
What could gas hydrates be used for?
as a source of energy.
Calcareous Ooze is an example of...
biogenous sediment.
Submarine canyons are believed to have been created by...
earthquakes.
Economically valuable materials such as diamonds, tin, and platinum are associated with which ocean floor resource?
sand and gravel.
The gently sloping submerged surface that extends from the shoreline toward the ocean basin floor is the continental...
shelf.
The use of sound waves to determine the depth of the ocean is called...
sonar.
Sediments that consist of mineral grains that were eroded from continental rocks are called...
terrigenous.
Which ocean basin is the largest?
the Pacific.
From which area of the ocean basin are the resources of oil and natural gas harvested?
the continental shelf.
Important mineral deposits, including large reservoirs of oil and natural gas, are associated with...
the ocean basin floor.
