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The Earth Through Time CHAPTER 15—CENOZOIC EVENTS Multiple Choice Questions Select the best answer. 1. Expansion of the seafloor during the Cenozoic has lead to the formation of approximately __________ percent of the current ocean crust. a. 50 b. 75 c. 33 d. 66 e. 25 2. The creation of the Isthmus of Panama lead to the formation of what ocean current? a. Canary b. Gulf Stream c. South Pacific d. Labrador e. Equatorial 3. Which two southern hemisphere continents split apart in the Cenozoic? a. North and South Americas b. Europe and Asia c. Australia and Antarctica d. Africa and Asia e. Africa and Antarctica 4. North America and Pacific plates came in contact with each other during the Cenozoic forming which of the following features? a. Appalachian mountains b. Gulf of Mexico c. Cascade Range d. Yellowstone e. San Andreas Fault 5. During much of the Cenozoic the eastern margin of North America was ___________. a. active b. passive c. rifting d. subducting e. orogenic 6. Cenozoic sediment accumulation in the Gulf Coast region exceeds _____________ meters. a. 1,000 b. 6,000 c. 12,000 d. 38,000 e. 124,000 7. The Cenozoic Cordillera extended from Alaska southward to ____________. a. Florida b. California c. Chile d. Guatemala e. Panama 8. What is the name of the Paleocene Sea that was a remnant Cretaceous epeiric sea? a. Suak b. Crystalline Calm c. Sundance d. Cannonball e. Tippecanoe 9. Low sulfur coal was deposited in _____________ during the Paleogene a. forests b. swamps c. stream beds d. volcanic craters e. beaches 10. The Green River Formation is a ______________depositional environment containing varved shales. a. fast moving rivers b. mud flats c. seas shores d. saltwater lake e. fresh water lake 11. The Green River Formation is well known for its _________ fossils. a. fish b. birds c. plants d. insects e. amphibians 12. The Badlands of South Dakota are floodplain deposits belonging to which formation? a. White River Formation b. Green River Formation c. Florissant beds d. Wasatch Formation e. Ft. Union Formation 13. Paleoclimate indicators show a cooling trend in the beginning___________. a. Miocene Epoch b. Late Eocene-Oligocene c. earliest Paleogene d. Pliocene e. Holocene 14. The modern Rocky Mountains topography resulted from ___________ in the Miocene Epoch. a. deposition b. lava flows c. uplift d. normal faults e. abnormal faults 15. What is the fundamental mechanism responsible for the Basin and Range Province? a. compressing b. shearing c. collision d. stretching e. All the above 16. The Basin and Range Province is characterized by block faulting along _______. a. reverse faults b. thrust faults c. uplift d. normal fault e. abnormal fault 17. During the Miocene Epoch volcanism along the western side of the Basin and Range Province resulting in_______________. a. compression b. extensive lava flows c. flat regions d. fossil beds e. All the above 18. There are numerous reasons proposed for why the Basin and Range Province formed. Which is not a proposed cause? a. Collision of a microcontinent b. Subduction of the East Pacific rise c. Change in plate boundary style d. Upward pressing of buoyant subducted slab e. Convection currents 19. The uplift of the Colorado Plateau resulted in which of the following? a. molasse b. flysche c. glaciers d. deep canyon e. deltaics 20. The Columbia Plateau is dominated by which rock type? a. Sedimentary b. Igneous c. Metamorphic d. Fossils e. Glacial tills 21. Cascade volcanism began approximately ____________ years ago. a. 20 million b. 2 billion c. 4 million d. 40 million e. 100,000 22. Cascade volcanism is driven by the introduction of ____________ into the mantle by the descending plates? a. lava b. water c. feldspar d. quartz e. carbon dioxide 23. Which of the following Cascade volcanoes erupted most recently? a. Pompeii b. Mt. St. Helens c. Mt. Vesuvius d. Mount Lassen e. Mount Rainier 24. Which of the following is responsible for Crater Lake? a. Streams b. Rifting c. Meteorite impacts d. Caldera formation e. None of the above 25. The Sierra Nevada formed along _____________. a. thrust faults b. reverse faults c. strike slip faults d. normal fault e. Both a. and b. 26. During the Paleogene Period the style of plate boundary in California shifted to ______________. a. convergent b. transform c. divergent d. subduction e. Both a. and d. 27. Which of the following plates are remnants of the Farallon Plate? a. Pacific b. Sierra c. Juan de Fuca d. North American e. African 28. The collision between the North American and Pacific Plates resulted in the Pacific Plate changing direction from _____________ to northwest. a. north b. south c. east d. west e. southeast 29. The Pacific plate has managed to steal parts of North America including _____________. a. Oregon b. Washington c. Eastern California d. South Pacific e. Baja California 30. What is the name given to marine sediments deposited between elongated submarine banks found in the Alps? a. Molasse b. Obsidian c. Schist d. Flysh e. None of the above 31. India collision with Asia during the Miocene Epoch was marked by which of the following events? a. volcanism b. folding c. thrusting d. granitic plutons e. All of the above 32. Basaltic lavas formed in the early Cenozoic Era in Scotland, Ireland, Greenland, and other locations as a result of __________________. a. Greenland rifting off of Europe b. India colliding with Asia c. Antarctica residing on the South Pole d. North America subducting the Juan de Fuca plate e. None of the above 33. During Cenozoic time, Africa developed a ______________leading to volcanism and fault controlled lakes. a. subduction zone b. rift valley c. transform boundary d. flatland e. All but b. 34. At the beginning of the Cenozoic, Antarctica had a semitropical climate. By the Miocene Epoch, Antarctica’s climate changed and snow began to accumulate. What caused the change in climate? a. Antarctica had recently moved on top of the South Pole b. Extensive volcanism c. Reduction of volcanism d. Antarctica separated from Australia e. Antarctica collided with Australia 35. The Pleistocene Ice Age resulted in an increase in rainfall at __________. a. poles b. high latitudes c. lower latitudes d. nightfall e. Both a. and b. 36. The unsorted till deposits are formed by ________________. a. Sediments being deposited by ice b. Sediments being deposited by streams c. Sediments being deposited by lakes d. Sediments being deposited by wind e. Sediments being deposited by ocean currents 37. Currently parts of Canada’s crust are uplifting in response to the _____________. a. addition of modern continental glaciers b. removal of continental glaciers c. stream deposits in basins d. exposure of the shield e. All the above 38. Eastern Washington State has a landscape that is referred to as channeled scablands. What process produced this landscape? a. Transgression b. Regression c. Flood basalts d. Repeat failure of ice dams across a river e. Wind 39. The Ice Age appears to be related to changes in ______________. a. speed of the Earth’s spin b. appearance of vertebrate fossils c. size of the continents d. solar radiation e. All the above 40. What is the wobble of the Earth’s axis called? a. Rotation b. Orbit c. Precession d. Tides e. Projection Answers to Questions 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. a b c e b c d d b e 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. a a a c d d b a d a 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. c b b d d b c a e d 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. e a b d c a b d d c The Earth Through Time, 10th Edition by Harold L. Levin CHAPTER 15—CENOZOIC EVENTS Multiple Choice Questions 1. Freshwater lake sediments of the Green River Formation in southwestern Wyoming include what economically valuable rock? a. coal b. uranium-bearing sandstone c. rock salt d. oil shale e. iron ore Ans: d Feedback: See pages 476-477 2. As the Isthmus of Panama was formed as a result of orogenic and volcanic activity, which of the following was influenced by the presence of the Panamanian land bridge? a. migration of plants and animals b. formation of Gulf Stream c. human travel between Atlantic and Pacific Oceans d. mild climate in northern Europe e. all of the above Ans: e Feedback: See pages 470 and 500-501 3. The Oligocene deposits exposed at Florissant Fossil Beds National Monument in Colorado are well known for what type of fossil, which is found buried in volcanic ash that once settled to the bottom of an ancient lake? a. entire skeletons of mammals b. insects, leaves, and pollen c. skeletons of giant turtles d. early human remains e. snakes and lizards Ans: b Feedback: See page 477 4. The Columbia Plateau in the northwestern US is formed by this type of rock: a. shale. b. cross-bedded sandstone. c. limestone. d. granite. e. basalt. Ans: e Feedback: See pages 482-484 5. During Cenozoic, along the west coast of the U.S., the Farallon plate was being subducted at a rate faster than it was growing at its spreading center, and as a result, the North American plate was brought into contact with the Pacific plate, which led to: a. renewed subduction along the coast of California. b. collapse of Mt. Mazama to form Crater Lake. c. uplift of the Sierra Nevada mountains. d. formation of the San Andreas fault. e. formation of the volcanoes of the Cascade range. Ans: d Feedback: See pages 487-488 6. In what state is Crater Lake, a water-filled caldera that was formed from the collapse of the volcanic cone of Mount Mazama about 6000 years ago, after eruptions drained the underlying magma chamber? a. Washington b. California c. Oregon d. Nevada e. Wyoming Ans: c Feedback: See pages 485-486 7. As Cenozoic climate became cooler and drier, the tropical forests which had covered parts of North America during Cretaceous began to decline, and were replaced by the expansion of what across the plains of the midwestern part of North America? a. conifer forests b. grasslands c. fern forests d. desert plants e. tundra plants Ans: b Feedback: See page 472 8. In eastern Africa, Late Cenozoic elongate lakes formed in what kind of tectonic feature? a. subduction zones b. rift valleys c. volcanic calderas d. strike-slip fault basins e. fold and thrust belts Ans: b Feedback: See pages 490-491 9. Eight major transgressions and regressions in the Gulf of Mexico coastal plain area led to the formation of what kind of sedimentary deposits? a. oil shales b. low sulfur coals c. lacustrine rocks with fish fossils d. a great wedge of sediment that thickens seaward e. glacial tillies and related varved marine sediments Ans: d Feedback: See pages 473-474 10. Widespread glaciations occurred during what Cenozoic epoch? a. Paleocene b. Pleistocene c. Pliocene d. Miocene e. Oligocene Ans: b Feedback: See pages 491-493 11. If Earth’s albedo increased, it could cause which of these things? a. lowering of temperature and glaciation b. increase in sea level and flooding of continents c. increase in volcanism d. change in rate of tectonic plate movement e. melting of the polar ice caps Ans: a Feedback: See page 500 12. During glacial intervals, what isotope preferentially accumulates in sea water and thus in the shells of marine invertebrates? a. oxygen-18 b. oxygen-16 c. carbon-12 d. carbon-14 e. uranium-235 Ans: a Feedback: See pages 494-495 13. During Late Cenozoic ice ages, what features formed in areas that were not near the ice sheets, for example, in the northern part of the Basin and Range province? a. stratified drift b. playa lakes c. dune fields d. pluvial lakes e. calderas Ans: d Feedback: See page 496 14. What mechanism did Milutin Milankovitch propose that controls the temperature fluctuations that may have caused Late Cenozoic ice ages? a. atmospheric fluctuations b. geographic changes due to mountain building c. geographic changes due to plate movements d. e. astronomical variables f. oxygen isotope ratio changes Ans: d Feedback: See pages 497-500 15. The graph of variations in global ice volume over the past 500,000 years below shows that successive times of coldest temperatures (marked “cold”) and thus episodes of glaciation occur at an interval of approximately how many years apart? a. b. c. d. e. 26,000 years 41,000 years 10,000 years 100,000 years 20,000 years Ans: d Feedback: See pages 494-495 MULTIPLE-CHOICE QUESTIONS 1. During Cenozoic, the interiors of most continents were a. covered by epeiric seas. c. dry land with some lacustrine sedimentation. b. regions of evaporite deposition. d. regions of mountain building. (lake) 2. The Columbia Plateau formed as a result of a. block faulting and uplift. b. volcanic eruptions resulting in volcanic edifices which were later eroded to a flat-lying plateau. c. accumulation of thick successions of basaltic lavas erupted from fissures. d. glacial scouring of bedrock by Pleistocene continental glaciers. 3. The fraction of solar energy received by a planet from the sun that is reflected or reradiated back into space is called the a. albedo. c. insolation. b. ecliptic. d. refraction. 4. The location of the type section for most Cenozoic series is in the a. Ouachita Mountains. c. Michigan Basin. b. Paris Basin. d. Trans-Continental Arch. 5. During a volcanic eruption, sometimes clouds of hot gases and pyroclastic debris move rapidly down the slope of the volcano and deposit thick layers of volcanic debris. These are called a. lahars. c. debris flows. b. nuée ardente. d. ignimbrites. 6. Recent volcanic activity in the Cascade Mountains is a response to the subduction of the a. Farallon plate. c. Andean plate. b. Cocos plate. d. Juan de Fuca plate. 7. The Red Sea and the Gulf of Aden were formed when a. Arabia rifted from Africa. c. Madagascar and Australia rifted from Africa. b. Africa collided with Arabia. d. Europe collided with northern Africa. 8. Which of the following is not represent one of the Paleogene epochs? a. Paleocene c. Oligocene b. Eocene d. Pliocene 9. Freshwater limestones, fine, evenly laminated shales (varves), and oil shales are characteristic of what Eocene Formation? a. Owl Creek Formation b. Green River Formation c. White River Formation d. Fort Union Formation 10. The Pyrenees and the Atlas Mountains were formed by a. the collision of northern Africa with Europe. b. thrust faulting which displaced strata from southwestern Europe on to the northern African plate. c. sedimentation along the Tethys Seaway. d. rifting of Eurasia from Gondwana. 11. Windblown, fine-grained, quartz and silt grains that form extensive deposits in China and North America are called a. gangue. c. shale. b. loess. d. diatomite. 12. Sedimentary particles deposited by glaciers and then reworked by runoff and meltwater is called a. till. c. moraines. b. stratified drift. d. eskers. 13. Sedimentary layers deposited in ancient lakes that correspond to yearly cycles of deposition are called a. drift. c. varves. b. till. d. rills. 14. The order of glacial stages/interglacial stages in the Pleistocene from oldest to youngest is a. Nebraskan, Kansan, Illinoian, Wisconsin. c. Nebraskan, Illinoian, Kansan, Nebraskan. b. Wisconsin, Illinoian, Kansan, Wisconsin. d. Wisconsin, Kansan, Illinoian, Nebraskan. 15. Milankovich’s theory for Pleistocene glaciation, which accounts for the Earth’s movements, is based on three variables. The second variable refers to the way the axis of rotation moves slowly in a circle that is completed about every 26,000 years. It is called a. inclination. c. orbital spin. b. declination. d. precession. 16. A period of cooler and drier climatic condition from 1540 to 1890 AD was called the a. Messinian event. c. little ice age. b. Milankovich hypothesis. d. interglacial period. 17. The overall Cenozoic global temperature started to decrease during what epoch? a. Eocene c. Miocene b. Oligocene d. Pleistocene 18. The best record of Cenozoic strata in North America is found in the _______________ where eight transgressions and regressions are recorded. a. Colorado Plateau c. Gulf of Mexico Coastal Plain b. Cascade Range d. Atlantic Gulf Coast 19. The Florissant fossil beds were produced during _________________; it recorded the eruption of volcanoes that produced ash that buried countless insects, leaves, spores, pollen, fish, and some birds. a. Eocene c. Miocene b. Oligocene d. Pliocene 20. Crustal movements began during early _________________ that caused the elevation of the Sierra Nevada along a great fault producing the Basin and Range Province. a. Eocene c. Paleogene b. Oligocene d. Neogene FILL IN THE BLANK 1. The western edge of North America during much of Cenozoic was the site of an eastward-dipping subduction zone. The oceanic plate that was being fed into the subduction zone has been named . 2. The Fort Union Formation, approximately 1800 meters thick, holds immense tonnage of what ore in its lower levels? _____________________ 3. The most complete and best record of Cenozoic strata in North America is found on the . 4. The recent activity at Mount St. Helens and the older eruptions that gave rise to the volcanic peaks of the Cascades are the surface expression of the North American plate and the plate. 5. These calcareous, often star-shaped fossils believed to have been produced by golden-brown algae related to coccoliths are called . 6. The basin that is not only a sedimentary basin, but a structural basin as well and represents the type area during much of Cenozoic is called . 7. The lakes that were particularly numerous in the northern part of the Basin and Range Province of North America, where faulting produced more than 140 closed basins, were called . 8. The large scale physiographic province formed by Cenozoic faulting, which includes portions of Nevada, Arizona, New Mexico and southern California, is called and Province. 9. West of the Columbia Plateau lies an uplifted belt that was also the site of extensive volcanic activity. It was further characterized by outpourings of more viscous lavas that resulted in what mountains? 10. The interfingering of permeable sands and impermeable clays provide ideal conditions for the eventual entrapment of oil and gas in what great wedge of sediments in North America? 11. During Oligocene, explosive volcanic activity in this area of Colorado produced a great deal of ash, which settled to the bottom of a neighboring lake, burying thousands of insects, leaves, fish, few birds, and trees. This area is called the . 12. The term used in Europe to describe dark, siliceous shales, poorly sorted sandstones, and cherts that accumulated between elongated submarine banks is . 13. The best-known feature resulting from the linked processes of uplift and erosion on the Colorado Plateau is of the Colorado River. 14. The sedimentary feature which consists of a thin, dark winter layer and a light-colored summer layer representing the depositional record of a single year is . 15. Cenozoic is divided into three periods: the _________________, _________________, and the ________________. TRUE-FALSE 1. The great thickness of sediment (12,000 m) that has accumulated during Cenozoic in the Gulf Coast and Gulf of Mexico indicates that the area experienced considerable subsidence during deposition. 2. For the most part, the Lower Paleogene sediments of the Rocky Mountain region consist of gray siltstones, sandstones, carbonaceous shales, lignite, and coal. 3. The Basin and Range Province occupies a broad zone from Nevada and Western Utah southward into Central Mexico. 4. During Miocene, the Columbia Plateau formed volcanic activity. 5. Mount Kilimanjaro and Mount Kenya are isolated remnants of a great thrust sheet caused by the collision of India against eastern Africa. 6. According to the plate tectonic hypothesis, the crustal compression that resulted in the formation of the Pyrenees and Atlas Mountains was the result of a collision between northwestern Africa and southwestern Europe. 7. A branch of the Indian Ocean opened between Arabia and Africa during Cenozoic that created the Gulf of Aden and Red Sea. 8. The Mesozoic Tethys Seaway was closed by plate tectonic collisions during Cenozoic. 9. Lake Malaui and Lake Tanganyika, in eastern Africa, are the result of water accumulation in downfaulted blocks of crust formed during the current rifting activity in that region. 10. The Himalayan Mountains formed as a result of the collision of India with Eurasia during Cenozoic. ANSWER KEY Multiple Choice 1. c 2. c 3. a 4. b 5. b 6. d 7. a 8. d 9. b 10. a 11. b 12. b 13. c 14. a 15. d 16. c 17. c 18. c 19. b 20. d Fill Ins 1. Farallon plate 2. coal 3. Gulf Coastal Plain 4. Juan de Fuca 5. discoasters 6. Paris basin 7. pluvial lakes 8. Basin, Range 9. Cascade range 10. Gulf Coastal Plain 11. Florissant flora 12. flysch 13. Grand Canyon 14. varves 15. Paleogene, Neogene, Quaternary True/False 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. T T T T F T T T T T RESPONSES TO QUESTIONS ACCOMPANYING SELECTED FIGURES FIGURE 15–1 (p. 471) Although not specifically mentioned in the chapter, one would surmise that fossils would be the evidence for a milder Antarctic climate during Eocene. Such evidence includes actual spore and pollen fossils from Eocene rocks in Antarctica. Before Antarctica separated from Australia, it was warmed by currents moving toward the continent from lower latitudes. With separation, cold polar currents entered the breach between the two landmasses, resulting in frigid conditions. FIGURE 15–6 (p. 474) In order to accommodate 27,000 feet of sediment in a shallow depositional basin, the basin would have had to subside as it was being filled. FIGURE A (p. 479) Bedrock of impermeable clays and shales, the absence of a protective cover of plants, and infrequent heavy rains are the primary conditions under which badlands are formed. FIGURE 15–18 (p. 484) Careful examination of the photograph reveals that the lava flow is covered by the pyroclastics (tephra). Therefore, the lava flow occurred before the eruption of the pyroclastic material. FIGURE 15–21 (p. 484) The vertical cracks constitute columnar jointing, a feature frequently formed in cooling lava flows. FIGURE 15–32 (p. 491) The outcrop pattern shows youngest rocks in the central area and older rocks encircling the central area, as is typical of erosionally truncated basins. FIGURE 15–38 (p. 494) Ground moraine is likely to be less well sorted, as it has often not been winnowed and sorted by meltwater.