C05 Ocean Sediments - multiple choice PDF

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True / False 1. The rate of sediment deposition is fairly consistent throughout the ocean. a. True b. False ANSWER: False REFERENCES: 5-1 Ocean Sediments Vary Greatly in Appearance LEARNING OBJECTIVES: OCEA.GARR.16.5-1-1 - Describe the organic and inorganic components of marine sediments. OTHER: Bloom’s: Remember NOTES: A continuing rain of sediments is slowly dusting most of the ocean floor. Accumulation rates on the deep seafloor vary from a few centimeters per year to the thickness of a dime every thousand years. 2. Sediments of white or cream color tend to be of biological origin. a. True b. False ANSWER: True REFERENCES: 5-1 Ocean Sediments Vary Greatly in Appearance LEARNING OBJECTIVES: OCEA.GARR.16.5-1-2 - Recognize the colors of marine sediments. OTHER: Bloom’s: Remember NOTES: Sediments of biological origin are white or cream colored. 3. Clays can remain suspended in the water column for decades before settling due to their small size. a. True b. False ANSWER: True REFERENCES: 5-2 Sediments Are Classified by Particle Size LEARNING OBJECTIVES: OCEA.GARR.16.5-2-1 - Illustrate the grain size distribution of sediments. OTHER: Bloom’s: Understand NOTES: Clays, particles less than 0.004 millimeter in diameter, can remain suspended for very long periods and may be transported great distances by ocean currents before they are deposited. Once in suspension, the finest clays may circulate in the ocean for decades. 4. The mix of rubble at the base of a rapidly eroding shore cliff is an example of a well-sorted sediment. a. True b. False ANSWER: False REFERENCES: 5-2 Sediments Are Classified by Particle Size LEARNING OBJECTIVES: OCEA.GARR.16.5-2-2 - Compare and contrast the typical grain size distribution of sediments in near-shore environments and on the abyssal plain. OTHER: Bloom’s: Understand NOTES: Poorly sorted sediments form in environments where energy fluctuates over a wide spectrum. The mix of rubble at the base of a rapidly eroding shore cliff is a good example of poorly sorted sediment. 5. Biological sediments are the most abundant sediments in total volume in the ocean due to the high productivity of organisms along the continental shelf. a. True

b. False ANSWER: False REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-2 - Explain the areal patterns of marine sediment thickness and identify the locations of lower and greatest total volume of marine sediment. OTHER: Bloom’s: Remember NOTES: Terrigenous sediments are the most abundant sediments in the ocean. Biogenous sediments cover a larger percentage of the area of the ocean floor than terrigenous sediments do, but the terrigenous sediments dominate in total volume. 6. Neritic sediments are mainly comprised of biogenous sediments due to the proximity to the continental shelf. a. True b. False ANSWER: False REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Remember NOTES: Continental shelf sediments, or neritic sediments, consist primarily of terrigenous material. Finer sediments than those of the continental margins cover deep-ocean floors, and a greater proportion of deep-sea sediment is of biogenous origin. 7. Sediment on the continental slopes has an average thickness that is greater than sediment on the continental

shelves. a. True b. False ANSWER: True REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-2 - Explain the areal patterns of marine sediment thickness and identify the locations of lower and greatest total volume of marine sediment. OTHER: Bloom’s: Remember NOTES: Sediment on the continental shelves has an average thickness of 2.5 km, whereas sediment on the slopes has an average thickness of 9 km. 8. Neritic sediments are mostly eroded from land. a. True b. False ANSWER: True REFERENCES: 5-4 Neritic Sediments Overlie Continental Margins LEARNING OBJECTIVES: OCEA.GARR.16.5-4-1 - State the primary source of most neritic sediments. OTHER: Bloom’s: Remember NOTES: Most neritic sediments are terrigenous; they are eroded from the land and carried to streams, where they are transported to the ocean. 9. Lithification is a pressure-induced process. a. True b. False ANSWER: True REFERENCES: 5-4 Neritic Sediments Overlie Continental Margins

LEARNING OBJECTIVES: OCEA.GARR.16.5-4-2 - Describe the transport sources of large sediment particles in marine environments. OTHER: Bloom’s: Remember NOTES: During the process of lithification, neritic sediments are converted into sedimentary rock by pressure-induced compaction or by cementation. 10. The compression of small biological particles into fecal pellets increases the rate at which they sink to the bottom of the ocean. a. True b. False ANSWER: True REFERENCES: 5-5 Pelagic Sediments Vary in Composition and Thickness LEARNING OBJECTIVES: OCEA.GARR.16.5-5-2 - Demonstrate the relationship between particle size and settling velocity of sediments. OTHER: Bloom’s: Understand NOTES: While still quite small, the fecal pellets of small animals are much larger than the tiny individual skeletons of diatoms, foraminifera, and other plantlike organisms that they consumed, so they fall much faster, reaching the deep-ocean floor in about two weeks. 11. The silica from the shells of diatoms dissolves at a faster rate than the calcium carbonate of foraminifera

shells. a. True b. False ANSWER: False REFERENCES: 5-5 Pelagic Sediments Vary in Composition and Thickness LEARNING OBJECTIVES: OCEA.GARR.16.5-5-3 - Analyze the various precipitates that form from seawater and accumulate in marine sediments. OTHER: Bloom’s: Understand NOTES: After a radiolarian or diatom dies, its shell will also dissolve back into the seawater, but this dissolution occurs much more slowly than the dissolution of calcium carbonate. 12. Manganese nodules can grow to exceed 1 meter in diameter within about 100 years. a. True b. False ANSWER: False REFERENCES: 5-5 Pelagic Sediments Vary in Composition and Thickness LEARNING OBJECTIVES: OCEA.GARR.16.5-5-3 - Analyze the various precipitates that form from seawater and accumulate in marine sediments. OTHER: Bloom’s: Understand NOTES: Manganese nodules form in ways not fully understood by marine chemists, “growing” at an average rate of 1 to 10 millimeters (0.04 to 0.4 inch) per million years, one of the slowest chemical reactions in nature. 13. Calcareous oozes are common at deep-ocean depths below 4,500 m. a. True b. False ANSWER: False REFERENCES: 5-6 Researchers Have Mapped the Distribution of Deep-Ocean Sediments LEARNING OBJECTIVES: OCEA.GARR.16.5-6-1 - Label the areas of Earth's oceans where siliceous oozes are most

OTHER: NOTES:

likely to occur and propose specific reasons for why this happens. Bloom’s: Understand Because of their tendency to dissolve, calcareous oozes very rarely occur at bottom depths below 4,500 meters.

14. Past sea surface temperatures can be determined from fossils found in deep ocean sediments. a. True b. False ANSWER: True REFERENCES: 5-8 Sediments Are Historical Records of Ocean Processes LEARNING OBJECTIVES: OCEA.GARR.16.5-8-1 - Describe the techniques used by paleoceanographers to determine the past history of deep-sea sediments. OTHER: Bloom’s: Understand NOTES: Scientists can analyze very small variations in the relative abundances of the stable isotopes of oxygen preserved within the carbonate shells of microfossils found in deep-sea sediments; these instruments allow them to interpret changes in the temperature of surface and deep water over time. 15. Manganese nodules have successfully been commercially mined in the ocean. a. True b. False ANSWER: False REFERENCES: 5-9 Marine Sediments are Economically Important LEARNING OBJECTIVES: OCEA.GARR.16.5-9-1 - Outline the commercial uses for marine sedimentary deposits. OTHER: Bloom’s: Remember NOTES: The commercial mining of manganese nodules has been considered, but has not been accomplished as yet. Multiple Choice 16. Deep-ocean sediments are typically composed of ____. a. Beach sand b. Silt c. Shells d. Biological oozes e. Fine clays ANSWER: e REFERENCES: 5-1 Ocean Sediments Vary Greatly in Appearance LEARNING OBJECTIVES: OCEA.GARR.16.5-1-1 - Describe the organic and inorganic components of marine sediments. OTHER: Bloom’s: Remember NOTES: Sediments of the deep-ocean floor tend to be composed of fine clays 17. Sediments that are gray in color tend to be ____. a. biological in origin b. oxidized c. high in iron d. high in silica

e. high in manganese ANSWER: REFERENCES: LEARNING OBJECTIVES: OTHER: NOTES:

d 5-1 Ocean Sediments Vary Greatly in Appearance OCEA.GARR.16.5-1-2 - Recognize the colors of marine sediments. Bloom’s: Remember Sediments deposits high in silica tend to be gray in color.

18. Which areas of the ocean is most likely to have the least accumulation of sediment? a. Abyssal plain b. Continental shelf c. Continental slope d. Deep-sea trench e. Oceanic ridge ANSWER: e REFERENCES: 5-1 Ocean Sediments Vary Greatly in Appearance LEARNING OBJECTIVES: OCEA.GARR.16.5-1-3 - Compare and contrast the thickness of sediments at ocean ridges and abyssal plains. OTHER: Bloom’s: Understand NOTES: Oceanic ridges tend to be younger in origin and may not have had time to accumulate sediment. Ridges also have a rough texture that is not as conducive to sediment accumulation as the plains. 19. Most marine sediments are composed of what size of particles? a. boulders b. sand, silt, and clay c. cobbles d. pebbles e. cobbles or granules ANSWER: REFERENCES: LEARNING OBJECTIVES: OTHER: NOTES:

b 5-2 Sediments Are Classified by Particle Size OCEA.GARR.16.5-2-1 - Illustrate the grain size distribution of sediments. Bloom’s: Remember Although boulders, cobbles, and pebbles occur in the ocean, most marine sediments are made of finer particles: sand, silt, and clay.

20. Which particle size is transported the farthest by waves and currents? a. silt b. clay c. pebble d. cobble e. sand ANSWER: REFERENCES: LEARNING OBJECTIVES: OTHER: NOTES:

b 5-2 Sediments Are Classified by Particle Size OCEA.GARR.16.5-2-1 - Illustrate the grain size distribution of sediments. Bloom’s: Understand Generally, the smaller the particle, the more easily it can be transported by streams, waves,

and currents. As sediment is transported it tends to be sorted by size; coarser grains, which are moved only by turbulent flow, tend not to travel as far as finer grains, which are more readily moved. The clays, particles less than 0.004 millimeter in diameter, can remain suspended for very long periods and may be transported great distances by ocean currents before they are deposited. 21. Which particle size has the fastest settling velocity in still water? a. clay b. fine sand c. coarse sand d. silt e. coarse silt ANSWER: REFERENCES: LEARNING OBJECTIVES: OTHER: NOTES:

c 5-2 Sediments Are Classified by Particle Size OCEA.GARR.16.5-2-1 - Illustrate the grain size distribution of sediments. Bloom’s: Remember The greater the particle size the faster the particle settles in water. Coarse sand is the largest particle listed.

22. A poorly-sorted sediment would most likely be found in a(n) _____. a. lake bed b. eroding shore cliff c. deep-ocean basin d. oceanic ridge e. abyssal plain ANSWER: b REFERENCES: 5-2 Sediments Are Classified by Particle Size LEARNING OBJECTIVES: OCEA.GARR.16.5-2-2 - Compare and contrast the typical grain size distribution of sediments in near-shore environments and on the abyssal plain. OTHER: Bloom’s: Understand NOTES: Sorting is a function of the energy of the environment—the exposure of that area to the action of waves, tides, and currents. Well-sorted sediments occur in an environment where energy fluctuates within narrow limits. Poorly-sorted sediments form in environments where energy fluctuates over a wide spectrum. 23. What is the particle size distribution from largest to smallest? a. cobble → boulder → granule → pebble b. coarse silt → granule → fine silt → clay c. coarse sand →granule →medium sand → fine sand d. boulder → granule → coarse sand → coarse silt e. cobble → granule → pebble → coarse sand ANSWER: REFERENCES: LEARNING OBJECTIVES: OTHER: NOTES:

d 5-2 Sediments Are Classified by Particle Size OCEA.GARR.16.5-2-1 - Illustrate the grain size distribution of sediments. Bloom’s: Understand Particle size distribution (from largest to smallest): Boulder, cobble, pebble, granule, sands, silts, and clay.

24. An area that experiences a high rate of erosion, such as a near shore cliff, will have which type of sediments in the surrounding waters? a. well-sorted sediments b. poorly-sorted sediments c. one size of sediment d. mostly gravel sediment e. mostly clay sediment ANSWER: b REFERENCES: 5-2 Sediments Are Classified by Particle Size LEARNING OBJECTIVES: OCEA.GARR.16.5-2-2 - Compare and contrast the typical grain size distribution of sediments in near-shore environments and on the abyssal plain. OTHER: Bloom’s: Understand NOTES: Areas where high rates of erosion occur will produce a high-energy system that will lead to poorly-sorted sediments. 25. What type of marine sediment is derived from igneous rock? a. terrigenous b. biogenous c. hydrogenous d. cosmogenous e. calcareous ANSWER: a REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Remember NOTES: The majority of terrigenous sediments are derived directly or indirectly from the crystals of igneous rock. Granite is the source of quartz and clay, the two most common components of terrigenous marine sediments. 26. What is the most abundant marine sediment in total volume? a. cosmogenous b. authigenic c. biogenous d. hydrogenous e. terrigenous ANSWER: e REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Remember NOTES: Terrigenous sediments are the most abundant marine sediment. 27. Which statement is true of sediments in the ocean? a. Biogenous sediments comprise a larger area than terrigenous sediments. b. Terrigenous sediments comprise a larger area than biogenous sediments. c. Hydrogenous sediments cover more volume than biogenous sediments. d. Cosmogenous sediments cover more volume than biogenous sediments.

e. Terrigenous and biogenous sediments are equal in area and volume. ANSWER: a REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-2 - Explain the areal patterns of marine sediment thickness and identify the locations of lower and greatest total volume of marine sediment. OTHER: Bloom’s: Understand NOTES: Biogenous sediments cover a larger percentage of the area of the ocean floor than terrigenous sediments do, but the terrigenous sediments dominate in total volume. 28. What is the main source of terrigenous sediments to the ocean? a. volcanic eruptions b. rivers c. dust and ash d. cosmic dust e. marine snow ANSWER: b REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-2 - Explain the areal patterns of marine sediment thickness and identify the locations of lower and greatest total volume of marine sediment. OTHER: Bloom’s: Remember NOTES: Although estimates vary, it appears that about 15 billion metric tons of terrigenous sediments are transported in rivers to the sea each year, with an additional 100 million metric tons transported annually from land to ocean as fine airborne dust and volcanic ash. 29. What is an example of authigenic sediment? a. Quartz sand b. Phosphorite deposits c. Volcanic dust d. Diatomaceous ooze e. Tektite spheres ANSWER: b REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Understand NOTES: Hydrogenous sediments are also called authigenic sediments because they were formed in the place they now occupy. The most obvious hydrogenous sediments are manganese nodules, which litter some deep seabeds, and phosphorite nodules, seen along some continental margins. 30. The ____ comprise the highest percent of ocean area, but contain the lowest percent sediment volume. a. continental shelves b. continental slopes c. deep-ocean floor d. continental rises e. submarine canyons ANSWER: REFERENCES:

c 5-3 Sediments May Be Classified by Source

LEARNING OBJECTIVES: OCEA.GARR.16.5-3-2 - Explain the areal patterns of marine sediment thickness and identify the locations of lower and greatest total volume of marine sediment. OTHER: Bloom’s: Understand NOTES: The deep-ocean floor covers 78% of the total ocean's area, but only contains 13% of the total volume of marine sediments. 31. The west coast of South America is known for its seasonal upwelling. What kind of sediment is likely to be abundant in this area? a. terrigenous b. hydrogenous c. biogenous d. cosmogenous e. authigenic ANSWER: c REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Understand NOTES: Biogenous sediments are most abundant where ample nutrients encourage high biological productivity, usually near continental margins and areas of upwelling. 32. Which is classified as cosmogenous sediment? a. evaporites b. ooliths c. microtektites d. manganese nodules e. siliceous ooze ANSWER: c REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Remember NOTES: Cosmogenous sediment includes translucent oblong particles of glass known as microtektites. Tektites are thought to form from the violent impact of large meteors or small asteroids on the crust of Earth. 33. What is the primary origin of most neritic sediments? a. calcareous b. terrigenous c. hydrogenous d. cosmogenous ANSWER: REFERENCES: LEARNING OBJECTIVES: OTHER: NOTES:

b 5-4 Neritic Sediments Overlie Continental Margins OCEA.GARR.16.5-4-1 - State the primary source of most neritic sediments. Bloom’s: Remember Most neritic sediments are terrigenous; they are eroded from the land and carried to streams, where they are transported to the ocean.

34. Sediments of the slope, rise, and deep ocean floor that originate in the ocean are called ____. a. neritic sediments b. pelagic sediments c. terrigenous sediments d. well-sorted sediments e. authigenic sediments ANSWER: b REFERENCES: 5-3 Sediments May Be Classified by Source LEARNING OBJECTIVES: OCEA.GARR.16.5-3-1 - Classify sediment types according to source and illustrate with examples. OTHER: Bloom’s: Remember NOTES: Sediments of the slope, rise, and deep-ocean floor that originate in the ocean are called pelagic sediments. 35. Why is the average sediment thickness in the Pacific Ocean less than that of the Atlantic Ocean? a. The Pacific is smaller in area than the Atlantic. b. Ocean trenches trap sediments. c. More rivers feed into the Pacific. d. Lithification occurs more frequently in the Pacific. e. More areas of the Pacific have experienced glaciation. ANSWER: b REFERENCES: 5-5 Pelagic Sediments Vary in Composition and Thickness LEARNING OBJECTIVES: OCEA.GARR.16.5-5-1 - Compare and contrast the thickness of pelagic sediments in the Atlantic and Pacific Oceans. OTHER: Bloom’s: Understand NOTES: Sediments cover the Atlantic Ocean bottom to a thickness of about 1 kilometer, and the Pacific floor has an average sediment thickness of less than 0.5 kilometer. There are two reasons for this difference. First, the Atlantic Ocean is fed by a greater number of rivers laden with sediment than the Pacific, but the Atlantic is smaller in area; thus, it gets more sediment for its size than the Pacific. Second, in the Pacific Ocean many oceanic trenches trap sediments moving toward basin centers. 36. Which deposits are the result of gravity-propel...