chapter 14 assessment part 2
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 4,500 m, 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 one plate is being pushed beneath another, descending in 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?
Multibeam sonar uses more than one sound source and listening device. This allows scientists to obtain a profile of a narrow strip of floor and from that build a swath of detailed coverage.
What are the uses for sand and gravel harvested from the continental shelf?
Sand and gravel are used to make concrete, for landfill, and to fill recreational beaches.
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 twice 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 than the Atlantic Ocean. The continental margins of the Pacific Ocean are narrow and have more volcanic and earthquake activity than Atlantic Ocean margins. Plates in the Pacific Ocean 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. Continental shelves contain mineral deposits, large reservoirs of oil and natural gas, as well as huge sand and gravel deposits.
What is bathymetry? What techniques do scientists use to discover more about the bathymetry of ocean basins?
bathymetry is the measurement of ocean depths and charting the shape or topography of the ocean floor; sonar, satellites, submersibles
In which ocean basin are most trenches found? Why?
the Pacific Ocean; plates in the Pacific Ocean are converging
From which area of the ocean basin are the resources of oil and natural gas harvested?
the continental shelf