Ch11 Question Bank With Solutions PDF

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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question 1) In the 1870s, the ________ was involved in the first far- reaching, comprehensive study of Earth's oceans. A) U.S.S. Enterprise B) H.M.S. Beagle D) H.M.S. Endeavour H.M.S. Challenger

1)

2) How were water depths and seafloor bathymetry (submarine topography) determined by the Challenger surveys? A) timing the descent of heavy bricks with sand glasses and listening for the echos with early hydrophones B) multi-beam, towed echo sounders C) by early deep sea divers hand thrown and retrieved weighted lead- lines

2)

3) Water depths and seafloor bathymetry (submarine topography) are now routinely determined by ________. ship-mounted or towed echo sounders B) ship-mounted radar with fiber-optical satellite uplink systems C) computerized, satellite-mounted, weighted lead-lines D) by satellite -linked, laser reflector systems

3)

4) An echo sounder operates by measuring the time required for a ________. A) radar beam to travel from a harbour patrol boat to a fuzz-buster on a speeding yacht sound pulse to travel from a ship or survey towfish to the seafloor and back C) light beam to travel from a satellite at a known altitude to the sea bottom and back D) radar beam to travel from a ship to the seafloor and back

4)

5) If you are sailing across the continental shelf in Queen Charlotte Sound and your echo sounde reported the bottom at 200 milliseconds (0.200 sec) at the maximum depth crossing the axis of Mitchell Trough, how deep is the seabed in the middle of this drowned submarine valley? Use the equation: depth (m) = 0.5 * (1500 m/s * total 2- way travel time in sec) A) 1500 m B) 15 m C) 50 0 m 150 m

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6) If your ship is out in the middle of the North Pacific Ocean on the edge of the abyssal plain south o 6) the Aleutian trench, how deep is the seabed if it took 6 seconds to get a bottom return from your 3500 kilohertz echo sounder? Use the equation: depth (m) = 0.5 * (1500 m/s * total 2-way travel time in sec) A) 6000 m B) 2625 m C) 1286 m 4500 m 7) You are doing a hydrographic survey by the Sand Heads Light, off the mouth of the Fraser River in very silty green water. You lower a bar to check its reflection and calibrate your sounder. You find that the fresh river water has dropped the speed of sound to 1483 m/sec. If the bottom registers at 15 milliseconds (0.015 sec), how deep is the top of the Fraser delta? Use the equation: depth (m) = 0.5 * (1500 m/s * total 2 - way travel time in sec) 11.12 m B) 22.25 m C) 11.25 m D) 2250 m

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7)

8) What was the latest technological addition to seafloor mapping, developed in response to mapping the ocean floor for national security, resource development, and directing seabed cable and pipeline crossings? swath echo sounding by mechanical multi-beam sonar B) fleets of remotely telemetered, miniature drifter buoys C) airborne sounding methods, by overflying the oceans D) walking it off one step at a time by the "Pirates of the Caribbean

8)

9) Which one of the following would typically have the narrowest continental shelf? a tectonically active continental margin next to a deep ocean trench B) a tectonically passive, trailing continental margin C) a tectonically passive, mid-ocean ridge and trench system D) an atoll

9)

10) Satellites like SEASAT can observe the ocean using ________ to measure sealevel to + /- 2 cm and infer the seabed bathymetry from the ________ exerted by the variable elevation and mass of seabed features. A) surveying telescopes, tidal pull B) accelerometers, magnetism C) infrared radiation, temperature and heat effects microwave beams, gravitational pull

10)

11) Which one of the following would typically have the widest continental shelf? A) a tectonically active continental margin next to a deep ocean trench B) an atoll a tectonically passive, trailing continental margin D) a tectonically passive, mid-ocean ridge and trench system

11)

12) Geologically, ________ are actually submerged parts of the continents continental shelves B) coastal guyots C) abyssal plains D) continental trenches

12)

13) On average, the continental shelf is about ________ kilometres wide and ________ metres deep. 80; 130 B) 400; 2000 C) 1800; 80 D) 20; 50

13)

14) On average, the slope across a continental shelf is about ________. A) 5 ° B) 1.5° 1°

14) D) 0.001°

15) The geologic process responsible for the most rugged relief on the seabed of a passive continenta margin is ________. glacial erosion and deposition modified by rising sea levels. B) active explosive submarine volcanism C) dredging and bottom dragging in shelf fisheries for scallops and groundfish D) deposits of major river deltas

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15)

16) The geologic process responsible for the most rugged relief to be found on a passive margin's continental shelf is ________. A) earthquake induced submarine landslides B) turbidity currents C) eustatic sea level changes glacial erosion and deposition

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17) How thick are the accumulations of shallow water sediments on passive continental margins like the Scotian Shelf? several kilometres B) several metres C) several tens of metres D) several hundred metres

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18) ________ is the oceanward edge of a continental shelf. The top of the continental slope B) The base of the continental rise C) The top of the abyssal plain D) The deepest portion of a deep- ocean trench

18)

19) ________ marks the edge of a continent. A) The highest part of the continental shelf The lowest part of the continental slope

19) B) An offshore, barrier island system D) The centre of an abyssal plain

20) The ________ lies at the base of the continental slope. A) continental rift B) offshore shelf

20) continental rise

D) off-slope reef

21) The continental rise is located ________. A) at the seaward edge of a deep ocean trench between an abyssal plain and continental slope C) at the top of the continental slope D) at the top of a mid-ocean ridge

21)

22) How does the continental rise form? coalescing deep-sea fans built from turbidites B) tectonic uplift and tilting of the edge of the continental margin C) outbuilding of major river deltas D) deep sea pelagic oozes that drape guyots and seamounts

22)

23) Which one of the following statements concerning submarine canyons is not true? A) They generally connect across the continental shelf to specific river valleys on land B) They channel turbidity currents down the continental slope to deeper waters C) They extend from the continental shelf to the base of the continental slope They were cut by streams and rivers during the Pleistocene when sea level had dropped to the base of the continental slope.

23)

24) Which one of the following would most likely be covered with thick turbidite layers? A) axial rift zone of an active mid-ocean spreading centre B) lagoon floor inside an atoll C) upper flanks of a steep, narrow, submarine canyon deep- sea fan at the base of a continental slope

24)

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25) Which one of the following statements regarding turbidity currents is generally true? A) The moving sediment-laden waters are less dense than the surrounding seawater B) They are shaken loose by earthquakes and move from abyssal plains to the continental shelf C) They flow down submarine canyons to estuaries at the edge of the continental shelf They form on the continental shelf and flow down submarine canyons to deeper water

25)

26) Which one of the following is not typical of sandy turbidite deposits? A) They contain land-derived and shallow-water fossil materials, even deposited in deep waters. B) Within a depositional layer, they show graded bedding but little stratification C) They form very gently sloping deep-sea fans at the mouths of submarine canyons They occur on the continental shelf in cross-stratified dunes with very low silt and clay contents.

26)

27) Graded bedding is ________. A) the layering in coral limestone produced by the combined chemical action of living coral animals and submarine, hot spring emissions an upwards decrease in clastic particle size within a single sediment layer C) an accumulation of sedimentary beds beginning with sandy beds at the bottom and ending with clayey beds at the top D) a Canadian quality-rating scale for different brands of mattresses

27)

28) What is meant by graded bedding? 28) A) Muddy and silty strata grade upward into sandy and pebbly strata Particle sizes in a single, sedimentary bed change from pebbles and coarse sands at the base to silt and mud at the top. C) Thin, laminated, storm-beds slope gently back towards the land D) Strata have the same thicknesses and bedding contacts are smooth and flat 29) What was the original cause of the 1929 turbidity currents that cut submarine cables off o Newfoundland? A) a submarine landslide a M L 7.2 earthquake

29)

C) a tsunami D) the grounding of a massive iceberg that caused the seafloor to fail 30) Which one of the following did not accompany the 1929 Newfoundland ML 7.2 earthquake?

30)

A) Submarine telegraph cables were broken on the floor of the North Atlantic B) Submarine landslides moved down the continental slope at the time of the earthquake C) A tsunami struck the Burin Peninsula of Newfoundland. D) Turbidity currents moved down the continental rise to the edges of the North Atlantic abyssa plain. Explosive volcanic eruption of pillow basalts occurred on the west edge of the Grand Banks 31) How broad an area of seafloor was covered by the 1929 Grand Banks turbidite deposit? A) 2,500 km3 B) 2,500,000 km3 250,000 km3 D) 25,000 km3

31)

32) Active continental margins are found ________. A) surrounding Africa C) underneath passive continental margins

32) mainly around the Pacific Ocean D) around the Arctic Ocean

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33) The largest regions underlain by deformed marine sediments occur on ________. A) deep ocean basins active continental margins C) passive continental margins D) mid-ocean ridges

33)

34) The chaotic accumulation of deformed sediments and tectonic slices of oceanic crust plastered onto the edge of a continent is called ________. A) a guyot an accretionary wedge C) an agglutinated foram D) a deep sea fan

34)

35) How much of the Earth's surface is covered by the deep ocean basins? 30% B) 65% C) 50%

35) D) 15%

36) Which of the following is NOT true of deep ocean trenches? A) They may act as sediment traps. B) They are sites where plates plunge back into the mantle They are geologically very stable. D) They are long and narrow depressions.

36)

37) Where are the greatest number of deep ocean trenches found? A) around the rim of the Arctic B) along the western edge of North America C) along the eastern margins of the Atlantic along the western edge of the Pacific

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38) How deep is the deepest portion of the ocean floor and what are these regions called? >10,000 m, trenches A) 2500 m, rift zones C) 4000 m, abyssal plains D) 2000 m, submarine canyons

38)

39) Which is the deepest ocean trench? A) Kurile- Kamchatka C) Aleutian

39) Marianas D) Peru-Chile

40) ________ develop where oceanic lithosphere bends downward and sinks into the mantle A) Rift valleys on mid -ocean ridges B) Abyssal seamounts Deep ocean trenches D) Submarine canyons

40)

41) Trenches are often parallel to, and genetically related to ________. A) mid- ocean ridges B) oceanic transform faults volcanic island arcs or continental margin mountain belts with active volcanism D) hotspot volcanic island chains

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42) What are the flattest and most level places on Earth? A) mid- ocean ridges abyssal plains C) oceanic volcanic plateaus D) continental shelves

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43) For its size, which ocean has the largest proportion of abyssal plains? A) Arctic B) Pacific Atlantic 44) The ________ is the Ocean Drilling Program's Drill Ship. JOIDES Resolution B) H.M.S. Resolution C) C.S.S. Viagra D) Exxon Valdez 5

43) D) Indian 44)

45) Which is the longest ocean trench? A) Kurile- Kamchatka C) Aleutian

45) B) Java Peru-Chile

46) Seamounts ________. are volcanoes that form on the ocean floor B) are a special type of oceanic trench C) form only in the Pacific Ocean basin D) are submarine canyons found near Australia

46)

47) ________ are highly detrimental to healthy growth of coral reefs. A) Warm water temperatures B) Clear, sunlit waters C) Vigorous wave action and water circulation Nutrient -rich waters, cloudy with luxuriant plankton growth

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48) As a result of the 1831 expedition of the H.M.S. Beagle, ________ proposed the correct theory of how atolls formed. Charles Darwin B) James Hutton C) Charles Lyell D) Isaac Newton

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49) A(n) ________ is a low lying, coral reef island perched above a sunken, truncated volcano A) guyot B) re- entry cone atoll D) seamount

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50) Geologically, what is the best way to explain the thousands of metres of coral limestone beneath most atolls? The eroded volcano slowly sank as sea level remained steady or rose gradually B) The volcano never reached the surface, but built a very thick cap of coral limestones from its deep submarine hotsprings emissions. C) An eroded volcanic seamount rose thousands of metres after the limestone formed D) Sea level has fallen thousands of metres since the reef began to grow

50)

51) What geologic studies finally confirmed Darwin's hypothesis that coral atolls all had a volcanic substrate underneath that formed the original platform for corals to colonize? A) seismic imaging of the West Pembina Pinnacle Reefs in the Alberta Basin by Amoco scientific drilling of Eniwetok and Bikini Atolls by the U.S. government in preparation for nuclear weapons tests C) submersible traverses down the flanks of North Atlantic atolls by the C.S.S. Hudson D) exploration drilling of the Great Barrier Reef by Petro Canada for offshore oil production

51)

52) Below the coral limestone, surface rocks of an atoll, what would you find? A) a magma chamber of an active shield volcano B) a slab of rifted, continental crust extending down to ocean floor depths C) an upraised, abyssal plain covered with turbidites basaltic volcanic rocks of a truncated seamount

52)

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53) What sedimentary process is dominantly responsible for the accumulation of up to 9 kilometres of sediment in deep ocean trenches? A) sunken or subsided coral reefs B) offshore dumping of unending bargeloads of garbage from major cities turbidity currents and submarine landslides from the continental slope and trench walls D) pelagic, biogenous ooze slowly settling from the top of the water column

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54) What thicknesses of unconsolidated sediment typically covers the deep abyssal plains? A) about 1500 to 4500 metres about 500 to 1000 metres C) about 5000 to 9000 metres D) 5 metres per year

59)

60) Which ocean floor sediment type includes abyssal plain clay? terrigenous B) hydrogenous C) biogenous

60) D) orogenous

61) Why are the deep sea clays mostly red or brown? Slow settling of fine clay-sized mineral particles allows for complete oxidation of their iron by dissolved oxygen. B) They are eroded mostly from desert areas and carried to the sea by winds or rainstorms C) These are the residues of red algae blooms, dispersed by ocean currents to settle ou everywhere. D) They are mostly volcanic ash particles erupted onto the seafloor; this is their colour

61)

62) Which ocean floor sediment type includes calcareous ooze? A) orogenous B) hydrogenous C) terrigenous

62)

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biogenous

63) How do calcareous oozes form? The particles are biogenically or chemically precipitated in warm, surface waters and sink to the bottom. B) The particles are precipitated in the water column below the depth of sunlight penetration and then sink to the bottom. C) The particles are precipitated by deep- ocean, bottom-dwelling, carbon- fixing bacteria. D) The particles settle out from calcite-rich turbidity currents at depths greater than 4,500 metres.

63)

64) Calcareous ooze is composed of ________ sediment. biogenous B) androgynous

64) C) terrigenous

D) hydrogenous

65) ________ is/are most soluble in cold seawater at ocean depths in excess of 4500 metres Calcite B) Quartz C) Clay minerals D) Manganese oxides

65)

66) ________ consists of diatom and radiolarian remains. A) Calcareous ooze B) Terrigenous ooze Siliceous ooze D) Reddish clay ooze

66)

67) Which ocean floor sediment type includes diatom ooze? A) hydrogenous B) orogenous C) terrigenous

67) biogenous

68) What kinds of materials account for the phosphate rich sediments? A) calcareous ooze hard residues of teeth, scales, bones, and fecal pellets of fish and other marine animals C) mineral rich turbidites D) diatoms and radiolarians

68)

69) Manganese nodules represent ________ sediment on the seafloor. hydrogenous B) terrigenous C) androgynous

69)

70) Which ocean floor sediment type includes manganese nodules? A) orogenous B) terrigenous C) biogenous

D) biogenous 70) hydrogenous

71) Which method did not contribute significant geologic knowledge about the rocks, structures, and mineral deposits of the mid- ocean ridges? A) mapping of slices of ocean crust added to the continents by tectonic activity B) geophysical surveys and soundings of the ocean floor C) deep diving submersibles traverses by manned and unmanned subs D) deep sea drilling by the Deep Sea Drilling Project or Ocean Drilling Program ships remote sensing and mapping of mineral deposits by satellites

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71)

72) Which is the best description of a mid-ocean ridge? A) thick sequences of folded and faulted sedimentary rocks pushed up 500-1000 metres above the regional seafloor B) narrow ridges 5-10 km wide, 3-4 kilometres high, and 10- 50 km long with active erupting volcanoes every 1- 2 kilometres of ridge length C) 50-200 metre- wide rough mounds of metal sulphides that encircle the globe continuously for more than 70,000 kilometres 1000 to 4000 kilometre wide, block faulted regions of sparsely sedimented, basaltic seafloor raised 2- 3 kilometres above the regional abyssal plains

72)

73) ________ are not associated with a mid-ocean ridges. A) Shallower depths than abyssal plains B) Submarine basaltic lava eruptions C) Very thin, ocean floor sediment layer Deep ocean trenches

73)

74) Which one of the following statements concerning actively spreading mid-ocean ridges is false? Sediments include thick siliceous ooze deposits and sandy turbidite beds B) Terrigenous sediment coverings are very thin or absent. C) They are sites for submarine eruptions of basaltic lava. D) They are places where young lithosphere is added to the edges of spreading, oceanic plates

74)

75) What is the most active, long term, deep diving, manned submersible used for studying t...