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OCN 201 EXAM QUESTIONS AND
ACCURATE ANSWERS
Hydrogen and helium account for about ______of the composition of the universe. a) 2% b) 50% c) 98% d) 99.8% e) none of the above - ANSWER 98% The continental rise is: a) A type of trench found at high latitude b) Aridgecreatedbytheformationofnewcrust c) A wedge of sediment at the base of the continental slope d) Anupliftedsedimentarybasin e) None of the above - ANSWER A wedge of sediment at the base of the continental slope Free Oxygen in the Earth's atmosphere is thought to have accumulated mainly through: a) Photodissociation of water and loss of hydrogen to outer space b) Change in sea level c) Formation of the earth's core d) Photosynthesis and burial of a small fraction of the organic carbon e) Nucleosynthesis in stars - ANSWER Photosynthesis and burial of a small fraction of the organic carbon The Earth, from the center outward, is composed of the following layers: a) Inner core, outer core, mantle, crust b) Inner core, outer core, mesosphere, lithosphere c) Core, mantle, asthenosphere, crust
d) Core, mantle oceanic crust, continental crust e) Core, mantle, asthenosphere, troposphere - ANSWER Inner core, outer core, mantle, crust The Hawaiian-Emperor seamount chain is thought to have been created by: a) A subduction zone b) A mid-ocean ridge c) A hot-spot d) A transform fault e) None of the above - ANSWER A hot-spot Continents are built by: a) Basaltic volcanism at subduction zones b) Volcanism in large igneous provinces c) Accretion of terranes onto the margins of existing continental masses d) Andesitic volcanism at spreading centers e) Both b and c - ANSWER Basaltic volcanism at subduction zones We know that the outer core of the earth is liquid in part because: a) No earthquakes occur there b) The plates move c) Seismic "s" waves do not propagate through it d) Mantle plumes start there e) The increased pressure melts the rock into a liquid - ANSWER Seismic "s" waves do not propagate through it In approximately 50 My, plate tectonics is predicted to result in which of the following: a) The Atlantic Ocean will be larger than it is now b) The Mediterranean Sea will be closed (i.e., Africa will be connected to Europe) c) The Pacific Ocean will have closed d) Both a and b e) Both b and c - ANSWER Both a and b
d) John Tuzo-Wilson e) None of the above - ANSWER None of the above
The rock type associated with mid ocean ridges is a) Andesite b) Basalt c) Marble d) Pyrite e) Sandstone - ANSWER Basalt
The major forces driving the plates in the theory of plate tectonics are: a) Inertia and mass balance b) Convection currents and centrifugal force c) Slab pull and convection currents in the mantle d) Refraction and isostasy e) Diagenesis and blue shift. - ANSWER Slab pull and convection currents in the mantle
The San Andreas Fault, in California is an example of a: a) Back arc basin b) Good spot to buy real estate c) Passive margin d) Spreadingcenter e) Transform fault - ANSWER Transform fault
After the earth formed, the distribution of matter changed with: a) Andesite going to the mantle and basalt to the core b) Denser material going inward and lighter material towards the surface
c) Nickel and iron remaining in the crust, and silica and basalt sinking. d) Oxygen sinking into the mantle, to be released later through degassing. e) None of the above - ANSWER Denser material going inward and lighter material towards the surface
The element gold is thought to have formed a) During nuclear fusion in our Sun b) Duringthe"BigBang" c) During Super Nova explosions d) In the center of the Earth e) All of the above - ANSWER During Super Nova explosions
The fact that the average thickness of sediment on the ocean floor is only ~600 m implies that: a) The earth is expanding b) The ocean floor is relatively young c) The earth is heating up d) Sediments are dissolving nearly as quickly as they are being produced e) None of the above - ANSWER The ocean floor is relatively young
The Wadati-Benioff Zone: a) Is the high velocity layer between the lithosphere and the asthenosphere b) Is the "shadow area" where p waves do not appear after an earthquake c) Is the "shadow area" where s waves do not appear after an earthquake d) Is an area of earthquakes associated with a subducting lithospheric plate as it enters the asthenosphere e) Is the zone of seismic and volcanic activity that encircles the Atlantic Ocean. - ANSWER Is an area of earthquakes associated with a subducting lithospheric plate as it
b) Wind c) Glaciers d) Turbiditycurrents e) All of the above - ANSWER Rivers
Cosmogenic sediments: a) Are composed of belemnites, granite, and tektites b) Are abundant in the sedimentary record at the permo-jurassic boundary c) Are from outer space d) Are found almost exclusively in the Pacific Ocean e) A, b and c - ANSWER Are from outer space
Most atolls in the Pacific are believed to have formed by a) Coral growth on banks built up by sediments b) Coral growth on subsiding volcanic foundations c) Global Thermal Subsidence d) Nuclear testing e) All of the above - ANSWER Coral growth on subsiding volcanic foundations
Earthquakes associated with the descending plate at a convergent plate margins can occur as deep as: a) 7-10 km b) 70-100km c) 300-700 km d) Upto1000km e) All of the above - ANSWER 300-700 km
A typical depth for deep-sea abyssal plains is approximately: a) 130m b) 4000-5000ft c) 4000-5000 m d) 7km e) 35km - ANSWER 4000-5000 m
Turbidity currents lead to the formation of: a) Graded deposits b) Sedimentfans c) Submarine canyons d) All of the above e) None of the above - ANSWER All of the above
In which of the following do earthquakes not generally occur? a) At fracture zones b) Attransformfaults c) At mid ocean ridges d) AtWadati-Benioffzones e) They occur in all of the above - ANSWER At fracture zones
The transition between a continental shelf and slope is known as: a) An abyssal plain b) Abank c) The continental rise d) Theshelfbreak e) None of the above - ANSWER The shelf break
d) Waterdepth e) None of the above - ANSWER Time
The age of the universe is estimated to be about: a) 6000 years b) 4.5 million years c) 4.5 billion years d) 13.8millionyears e) 13.8 billion years - ANSWER 13.8 billion years
A seismograph mounted in a submarine would not be able to detect: a) Earthquakes b) Electromagneticwaves c) Gravity waves d) P-waves e) S-waves - ANSWER S-waves
Which of the following helped Captain Cook navigate more accurately than many of his predecessors? a) An accurate compass b) A better navigator c) A chronometer d) Bettercharts e) None of the above - ANSWER chronometer
Overall, the Pacific plate moves at approximately which speed? a) 1-2 cm/yr
b) 2-4 cm/yr c) 8-10 cm/yr d) 15-20 cm/yr e) None of the above - ANSWER 8-10 cm/yr Atlantic plate 1-2 cm/yr
Continental crust is approximately how thick? a) 6km b) 11 km c) 35 km d) 70-100 km e) None of the above - ANSWER 35 km
Scientific theories are always subject to challenge and may be overturned. - ANSWER True
Yellowstone is an example of a hot spot. - ANSWER True
Lava exits from Kilauea volcano vents at temperatures exceeding 2000 oF - ANSWER True
The bend in the Hawaii-Emperor seamount chain is due to a reversal of the magnetic field of the earth, which occurred 20 million years ago. - ANSWER False
Erosion from continents is a significant source of sediment in the oceans. - ANSWER True
Turbidity currents help carve submarine canyons and take sediment from the
Hot spots provide a measure of absolute plate motion relative to the mantle - ANSWER True
The Molokai Fracture zone is the line dividing West Molokai Volcano from East Molokai Volcano - ANSWER False
Radioactivity in the deep Earth is one potential source of heat driving mantle plumes. - ANSWER True
Charles Darwin was the principal proponent of the theory of: a. the Big Bang b. formation of atolls c. mantle plumes d. continental drift e. plate tectonics - ANSWER formation of atolls
What is the generally accepted (minimum) scientific estimate for the age of the Earth? a. ~2,000 years b. ~4.55 million years c. ~4.55 billion years d. ~13.7 million years e. ~13.7 billion years - ANSWER 4.55 billion years
The Earth's crust comes in two main varieties whose average densities are: a. 4.5 and 5.7 g/cm b. 12 and 16 g/cm c. 2.7 and 2.9 g/cm d. 3.7 and 3.9 g/cm e. none of the above. - ANSWER 2.7 and 2.9 g/cm
Reversals of the Earth's magnetic field: a. are important in understanding longitude b. were the basis for Arthur Holmes' concepts of thermal convection cells c. cause the Earth to turn on its axis d. are recorded in seafloor rocks in bands parallel to spreading centers e. never occur in Earth surface rocks - ANSWER are recorded in seafloor rocks in parallel bands to spreading centers
The region where plates collide with each other is called a: fracture zone spreading center guyot transform fault none of these - ANSWER transform fault / convergent zone/ subduction zone
The two dominant types of biogenic sediment in the deep sea are: a. glacial sediments and hydrothermal vent deposits b. hydrogenous material and sand c. terrigenous silt and manganese nodules d. calcareous ooze and siliceous ooze e. clay and ferro-manganese nodules - ANSWER calcareous ooze and siliceous
The leading theory for the origin of the Earth's Moon is: a. formation in the same manner as Earth, by accretion b. condensation from the Solar nebula c. impact by a large planetesimal, about the size of Mars, which spun off the Moon d. gravitational capture of a large planetesimal e. fission due to rapid rotation - ANSWER formation in the same manner as earth,
c. a disrupted subduction zone followed by plate motion realignment d. creation of a new mid-ocean ridge which changed plate motion e. movement of the subduction zone into which the linear trace descends - ANSWER a disrupted subduction zone followed by plate motion realinment
Earthquakes associated with the MOR system typically occur at depths of less than: - ANSWER 70 km
Which of the following produce siliceous tests that contribute to sediments on the ocean floor? - ANSWER diatoms
Which of the above terms consistently describe a subduction zone? - ANSWER shallow to deep earthquakes, andesitic volcanism, older crust, thick sediment
Which of the above terms consistently describe the mid-ocean ridge, a zone of seafloor spreading? - ANSWER shallow to deep earthquakes, basaltic volcanism, young crust,sediment absent to thin
The Earth's atmosphere is considered secondary in origin. This means that: - ANSWER cold plantsimals, which aggregated rapidly to form a hot earth, lost some of the primary atmosphere
The three main settings on Earth where active volcanism occurs are: - ANSWER mid ocean ridges, subduction zone, hotspots
The main factor causing present sea level to rise over the past 18,000 to 20,000 years is:
- ANSWER thermal expansion of sea water and melting of polar ice caps
A star such as our Sun can make elements by nucleosynthesis up to: - ANSWER carbon, oxygen
Which of the following island groups is not thought to be a Hot Spot trace? - ANSWER Hawaiian arch, society isl, line isl, emperior seamounts
Sea level changes attributable to changes in the extent of continental glaciation are manifested over - ANSWER few thousand- sevral twns of thousands
For every 1 meter of rise in sealevel there will be approximately: For every 1 meter of rise in sealevel there will be approximately: - ANSWER 100 m of horizontal loss of coastal land thru erosion
Supercontinent cycles cause - ANSWER the joining and disconnecting, in and out, of continents separating
Continental crust is composed mainly of: - ANSWER andesit and granite
During the past twenty in the past 20 years, the ground under you in Hawaii has moved approximately: - ANSWER 6 km to the NW
Planktonic animals whose silica-rich shells are abundant on the sea floor near the equator are called: - ANSWER coccolithospores
The major forces driving the plates in the theory of plate tectonics are - ANSWER slab pull and mantle drag asso w convection cells
Changes in sea level that are observed on a global scale are called: - ANSWER eustatic
Formation of large igneous provinces (LIP) such as the Ontong Java Plateau could have raised sea level changes by about 10 m and raised global temperatures 7-13oC. - ANSWER True
Our solar system does not contain elements that formed during a supernova explosion. -
The oldest rocks from the seafloor are older than the oldest rocks from the continents. - ANSWER False
The Darwin point is the temperature above which magnetic minerals in molten rock are able to align with the Earth's magnetic field. - ANSWER False, Curie
Hydrothermal vents on Loihi volcano have spewed water as hot as 200oC. - ANSWER True
The lithospheric plates include both crust and upper mantle - ANSWER False
To determine latitude, one does not need to be able to tell time. - ANSWER True
The modern atmospheres of the Earth and its neighbors, Venus and Mars, are similar. - ANSWER False
A hypsometric curve shows one surface elevation on Earth and two on Venus. - ANSWER False
