Geology Quiz Answers Chapter 10

Chapter 10: ● The four methods used to explore the topography and rocks of the seafloor include satellites; submarines and other submersibles; ______ , whereby actual sediment and rock samples are retrieved; and _____, which uses sound to make seafloor maps. ● ● ● ● ● ● ● ● ● ● ○ Drilling ○ Sonar Satellites primarily collect data regarding ______ properties. ○ sea surface What information can be determined directly by analyzing seafloor drill cores? ○ The type of rock on the seafloor ○ The rate of sediment deposition ○ The type of sediment on the seafloor What method produces images of the materials beneath the seafloor using sound waves? ○ Seismic-reflection profiling Put the processes that occur when oceanic plates spread apart at the mid-ocean ridge in order, from the first event at the top to the last event at the bottom. ○ Basaltic lava erupts from the rift. ○ Blocks of oceanic crust are downdropped in normal faults. ○ Sediment settles onto new basalt. ○ Oceanic crust has a smooth surface covered by layered sediment. Match the technique that geologists use to study the seafloor with its characteristic of being either a direct or remote method of study. ○ Direct ■ Visiting with human-operated submersibles; drilling into the seafloor ○ Remote ■ Mapping with sonar; observing with satellites Match the spreading ridge with its characteristic shape. ○ Mid-Atlantic Ridge ■ Well-defined central rift valley ○ East Pacific Rise ■ Broad and lacking a central rift True or false: Most oceanic measurements made from satellites are of ocean surface properties, rather than deep-ocean properties. ○ True Which of the following statements describe black smokers? ○ They form mineral deposits rich in copper and zinc. ○ They form along mid-ocean ridges. ○ They form sulfide-rich chimneys. Geologists can learn about past environments and climates by collecting cylinder-shaped drill ______ from the seafloor. ○ Cores Rock units beneath the seafloor can be imaged with sound waves using a method called ______ profiling. ○ Seismic-reflection ● Magma that erupts at mid-ocean ridges forms pillow _____ . These are pushed away from the ridge crest and covered with clay-rich ____. ○ Basalts ○ Sediment ● Why does a well-defined, deep rift form at some spreading ridges, such as the one featured in the image? ● ● ● ● ● ○ ○ Large, normal faults form. ○ The spreading rate is slow. Match the seafloor feature with its description. ○ Seamount ■ Isolated mountain ○ Abyssal plain ■ Deep seafloor with smooth topography ○ Oceanic trench ■ Deepest part of the ocean Hot water, metals, and sulfur discharge from _____ vents (also known as black smokers) at mid-ocean ridges. ○ Hydrothermal The volcanic rocks on oceanic islands are _____ to intermediate in composition. ○ Mafic Oceanic plateaus form from basaltic volcanism originating from ______. ○ mantle plumes The red dots that coincide with volcanically active island chains, shown on the map, are called ______. ○ ○ Hot spots ● Match the seafloor feature with the description of its formation. ○ Seamount ■ Submarine volcanic eruptions ○ Trench ● ● ● ● ● ● ■ Downwarping of an oceanic plate as it plunges beneath another plate ○ Mid-ocean ridge ■ Rifting at divergent plate boundaries Island arcs form in association with what type of tectonic setting? ○ Subduction zones The igneous rock type you are least likely to find on oceanic islands would be ______ in composition. ○ Felsic The area behind an island arc that develops a spreading center and rifts is a(n) ______. ○ back-arc basin What rock type forms oceanic plateaus? ○ Basalt ■ Plateaus are associated with mantle plumes. Island arcs have a curved shape because there is ______ surface area on the outside of the plate than at depth. ○ More ■ Recall that subduction is occurring over a spherical surface, not a flat one. What do the areas shown in red on the map have in common? ○ ○ They are all island arcs. ○ They formed adjacent to deep trenches. ● Coral ______ form in shallow, tropical seas with clear water. ○ Reefs ● Which of the following describe the formation of an island arc? ○ The magma that creates the islands is formed due to the release of water in the subducted plate. ○ An island arc forms in association with an oceanic trench. ● Order the steps in atoll formation from first on top to last on the bottom. ○ A volcanic island forms, establishing a shoreline for the construction of a fringing reef. ○ An island subsides, forming a barrier reef some distance from the shoreline. ○ A central, shallow lagoon forms surrounded by a ring of coral and other carbonate material. ● What happens to the crust behind a migrating island arc as it moves along with a subducting slab? ○ The crust thins and a rift forms. ○ A spreading center develops. ○ A back-arc basin forms. ● Coral reefs tend to occur between latitudes ______ because the water is ______. ○ 30o north and 30o south of the equator; warm and clear ● Why are island arcs curved? ○ They form next to trenches on a spherical Earth. ● In the diagram, match the letter with the name of the feature present on the continental margin. ○ ○ A ■ Continental slope ○ B ■ Submarine canyon ○ C ■ Continental shelf ○ D ■ Continental rise ● The Pacific plate is subducting around its edges, forming the _______ shown in red on the map. ○ Island arcs ● Turbidity currents can erode rock underwater and deposit ______. ○ submarine fans ○ graded beds ● Which conditions promote the growth of coral reefs? ○ Shallow water ○ Warm water ○ Clear water ● An atoll forms when a volcano with a fringing reef ______ below the sea surface, while the coral reef continues to grow. ○ Subsides or sinks ● Submarine canyons transport sediment from the continental shelf to the continental