Ch05 The Sedimentary Archives Test.docx

CHAPTER 5 The Sedimentary Archives Select the best answer. 1. A continental platform is part of a (an) a. Depositional environment. b. Orogenic belt. c. Continental shelf. d. Craton. e. Shield. 2. Thick sequence of sedimentary rocks can accumulate when ________. a. A basin subsides with the accumulation of sediments. b. A basin uplifts with the accumulation of sediments. c. A glacier advances. d. The elevation of the basin does not changed. e. Both a. and b. 3. What part of the continent has not been disturbed since the Precambrian? a. Shield. b. Orogenic belt. c. Platform. d. Craton. e. All but b. 4. The continental shelf environment is generally restricted to waters less than ___deep. a. 2,000 meter. b. 10,000 feet. c. 200 meters. d. 5,000 meters. e. 25,000 meters. 5. Which marine depositional environment tends to host the coarsest sediments? a. Continental shelf. b. Continental slope. c. Deep marine. d. Streams. e. Lake. 6. What continental depositional environment is produced by flowing water? a. Lacustrine. b. Eolian. c. Glacial. d. Stream. e. Both a. and b. 7. What transitional depositional environmental lies immediately inland of a barrier island? a. Tidal flats. b. Lagoons. c. Barrier island. d. Continental shelf. e. Streams. 8. What element is responsible for red beds? a. Organics. b. Silica. c. Manganese. d. Iron. e. Copper. 9. What is the term that refers to the uniformity of grain sizes? a. Sorting b. Roundness c. Grain size d. Shape e. Sphericity 10. A clastic particle less that 1/256 mm across is called (or named) a. Boulder. b. Gravel. c. Coarse sand. d. Clay. e. Sand. 11. A sedimentary rock that is poorly sorted with large angular grains was likely deposited in which one of the following environments? a. Deep marine. b. Lagoon. c. Mountain glacier. d. Lacustrine. e. Barrier Island. 12. A sedimentary structure characteristic of tidal flats is _________. a. Mud cracks. b. Cross-bedding. c. Asymmetric ripple marks. d. Sole marks. e. Graded bedding. 13. What is the name of the sedimentary structure developed on the top of bedding plain by an oscillatory motion of water? a. Graded bedding. b. Cross-bedding. c. Symmetric ripple marks. d. Asymmetric ripple marks. e. Sole marks. 14. What is the name of the structure where the size of sediment grains fine upwards? a. graded bedding b. asymmetric form c. symmetric form d. cross-bedding e. way-up structures 15. What additional information can be obtained from shape of the cracks in mud cracks? a. Thickness of the unit. b. Lateral extent of the unit. c. Flow direction of water. d. The original orientation of the beds. e. Flow direction of the wind. 16. In what environment of deposition would arkose sandstone most likely be found? a. A river delta and river channels. b. Barrier island and beach. c. Alluvial fans. d. Continental slopes (turbidity deposits). e. Glacial deposits. 17. Mature sandstones will contain which of the following characteristics? a. Well sorted b. Angular grains c. Clay d. Feldspars and pyroxenes e. Both a. and c. 18. Modern carbonate sediments forming in the Bahama Banks results primarily from the presents of ______________. a. Penicillus. b. Large invertebrate shells. c. Öoids. d. Cold water. e. Fish skeletons. 19. Modern environments for carbonate deposition are less common than in the past. Which of the following helps to explain this difference? a. Extensive glaciation. b. Higher global sea level in the past. c. Extensive shallow seas covering the continents. d. Generally warmer climates in the past. e. All but a. 20. Which of the following is not always true about a formation? a. Consistent lithology. b. Distinctive form the units above and below it. c. Deposited during the same time interval. d. Can be traced form outcrop to outcrop. 21. The term facies refers to the part of the rock body that indentifies the _________. a. Lithofacies. b. Biofacies. c. Lithostratigraphic units. d. Depositional environment. e. Age of the rock. 22. An example of a lithofacies is a. Arkose sandstone. b. Bioclastic limestone. c. Micritic limestone. d. Greywacke sanstone. e. All the above. 23. If sandstone directly underlies shale in a vertical sequence, this is an example of: a. Biofacies. b. Offlap sequence. c. Onlap sequence. d. Member. e. Formation. 24. Walther’s Law states that ___________. a. Older units are always below younger units. b. Younger units are always under older units. c. Onlap and offlap sequences occur. d. Vertical sequences can be used to predict lateral sequences in the region. e. Biofacies are equivalent to lithofacies. 25. Select the vertical sequence that indicates transgression. a. Sandstone over shale b. Limestone over conglomerate c. Conglomerate over sandstone d. Shale over limestone e. Conglomerate over limestone 26. During the maximum glacial advance of the Pleistocene, the Atlantic shoreline moved _________ seaward. a. 1 to 2 miles. b. 100 to 200 kilometers. c. 1 to 2 kilometers. d. 500 to 1,000 kilometers. e. None of the above. 27. The study of layered rocks is called ___________. a. Walther’s Law. b. Lateral continuity. c. Stratigraphy. d. Lithofacies and biofacies. e. Epeiric. 28. Matching rock bodies by composition, texture, and color is called __________. a. Chronostratigraphic correlation. b. Chemotratigraphic correlation. c. Biostratigraphic correlation. d. Rhybostratigraphic correlation. e. Lithostratigraphic correlation. 29. Which of the following needs to be consistent between outcrops in order for a chronostratigraphic correlation to exist? a. Texture, color, and stratigraphic position. b. Lithofacies. c. Plant and animal fossils. d. Sedimentary structures and textures. e. Orientation of grains in clastic rocks. 30. Unconformities are characterized by ______________. a. Continuous rock record. b. Gap in the geologic record. c. Continuous fossil record. d. Plutonic magma emplacement. e. Both a. and c. 31. A nonconformity is defined by _____________________. a. Younger igneous rocks in contact with older sedimentary rocks. b. Older tilted sedimentary rocks below younger flat laying sedimentary rocks. c. Flat lying sedimentary rocks with a significant age difference in the fossils. d. Younger metamorphic rocks in contact with older sedimentary rocks. e. Older igneous rocks in contact with younger sedimentary rocks. 32. The vertical sequence of strata showing structural changes at a given locality is shown by a ___________. a. Geologic map. b. Geologic column. c. Stratigraphic cross section. d. Structural cross section. e. Geologic datum. 33. What is the name of a map view showing the change in thickness of a geologic unit? a. Geologic cross-section b. Stratigraphic cross-section c. Structural cross-section d. Isopack map e. Paleogeographic map 34. Geologist measure __________ in the field in order to understand the structure of a region. a. Geologic cross-section b. Strike and dip. c. Thickness. d. Age e. Lithology 35. What is the name of the feature that sits between the continental slope and the deep marine environment? a. Angular unconformity. b. Continental rise. c. Continental shelf. d. Abyssal plain. e. Turbidite. 36. Streams are complex systems that have the type and amount of deposition controlled by which of the following processes? a. Discharge. b. Water velocity. c. Shape of stream channel d. Type sediment being transported. e. All the above 37. You pick up a sedimentary rock containing pebble size grains. Which of the following depositional environments is not likely? a. Stream. b. Sand dune. c. Alluvial fan. d. Delta. e. Glacial drift. 38. When sediment removal exceeds sediment accumulation ____________. a. The delta will build seaward. b. The delta will be stationary. c. The delta will not form. d. A barrier island will form. e. Both a. and d. 39. What interpretation can be made from black colored shale? a. Deposited in an Alluvial fan. b. Deposited as glacial drift. c. Deposited in anaerobic quiet water of lake. d. Iron is common in the shale e. It is from the Mesozoic Era 40. Which of the following forms after deposition? a. Cement. b. Matrix. c. Clasts. d. Cross-bedding. e. Both a. and b. Answers to Questions 1. d 11. c 21. d 31. e 2. a 12. a 22. e 32. d 3. e 13. c 23. c 33. d 4. c 14. a 24. d 34. b 5. a 15. d 25. b 35. b 6. d 16. c 26. b 36. e 7. b 17. e 27. c 37. b 8. d 18. a 28. e 38. c 9. a 19. e 29. c 39. c 10. d 20. c 30. b 40. a TEST 2 1. Deformation or structural activity of a large area of the Earth's lithosphere over a long period of time is called: facies. tectonics. subsidence. unconformities. stratigraphy. Ans: b Feedback: See page 82 2. What is the whole stable interior of a continent called? platform craton continental shelf shield continental rise Ans: b Feedback: See page 82 3. A turbidity current is most likely to be found in this depositional environment: continental slope and rise. floodplains along rivers. tidal flats at the coast. playa lakes in desert areas. alluvial fans at the base of mountains. Ans: a Feedback: See pages 85-86 4. Regarding the figure below, which of these types of ripples forms in a current, and in which direction did the current flow? 0-213677500 A; from left to right A; from right to left B; from left to right B; from right to left Ans: c Feedback: See pages 95 and 98 5. Black coloration in sedimentary rocks generally implies what about the character of the sedimentary environment? presence of iron and abundant oxygen presence of iron and lack of oxygen abundance of organic matter and lack of oxygen lack of organic matter and abundant oxygen lack of iron and abundant oxygen Ans: c Feedback: See pages 89-90 6. If you found layers of sedimentary rock that are red (what are sometimes called red beds), you would interpret them as having been deposited in what type of sedimentary environment? oxygen-deficient environment, such as a lake or swamp nonmarine environment, such as a floodplain or alluvial fan reef continental slope barrier island Ans: b 7. Which type of sandstone is most likely to be deposited in the setting or location marked A in the figure below? 0-107759500 arkose lithic sandstone quartz sandstone graywacke shale Ans: b Feedback: See pages 99-100 8. Clastic sediments are categorized into groups such as sand, silt, or clay, on the basis of: sorting. grain size. minerals present. grain shape. arrangement of grains. Ans: b Feedback: See page 91-92 9. Sandstones are classified into groups such as quartz sandstone, arkose, and lithic sandstone on the basis of: sedimentary structures. grain size. grain shape. composition. arrangement of grains. Ans: d Feedback: See page 99 10. Carbonate sediments are most abundant in this depositional environment: swamps. floodplains. river deltas. deep sea fans. warm shallow seas. Ans: e Feedback: See pages 99 and 101-102 11. Gaps in the geologic record where strata have been lost due to erosion, or where deposition did not occur for long intervals of geologic time, are called: lithofacies. greywackes. unconformities. onlap sequences. offlap sequences. . Ans: c Feedback: See pages 109-110 12. Which of the following types of unconformity involves sedimentary rocks overlying igneous and/or metamorphic rocks (as shown in the figure below)? 0-153860500 angular unconformity nonconformity disconformity paraconformity uniform unconformity Ans: b Feedback: See page 110 13. The principle of sedimentary geology that says the lateral succession of facies is also seen in the vertical succession is called: Steno’s axiom. Walther’s law. Bowen’s series. Lyell’s rules. Ans: b Feedback: See pages 105-106 14. Sea level rise can be caused by: melting of the polar ice sheets. growth of extensive mid-oceanic ridges. tectonic subsidence of the land along the coast. d).all of the above. none of the above. Ans: d Feedback: See pages 106-107 15. A fundamental unit in geology that is lithologically-distinctive, that has recognizable contacts with other units above and below, and that can be traced across the countryside from exposure to exposure is called this: sedimentary structure. formation. sedimentary environment. unconformity. lithofacies. Ans: b Feedback: See page 103 TEST 3 1. The term used for the central, topographically subdued region of a continent is a. orogenic syncline. c. craton. b. crustal trench. d. tectonic subduction zone. 2. What is the proper order of these clastic rocks from coarsest to finest texture? a. sandstone, shale, siltstone, claystone b. sandstone, siltstone, shale, claystone c. shale, sandstone, siltstone, claystone d. siltstone, claystone, sandstone, shale 3. What is the smallest particle size found in sedimentary rocks? a. silt c. fine sand b. clay d. granules 4. Which of the following sedimentary rock types does not fit within the clastic grouping? a. shale c. limestone b. sandstone d. conglomerate 5. Which of the following is not a primary sedimentary structure? a. mud cracks c. folds b. cross bedding d. ripple marks 6. The three major types of environments of deposition are a. continental slopes, rises, shelves. b. continental slopes, marine, nonmarine. c. transitional, marine, nonmarine. d. continental slopes, marine, lagoonal. 7. The characteristic appearance or aspect of a rock from which its environment of deposition can be determined is a. biolithic zone. c. facies. b. isopach zone. d. paleoclimatic zone. 8. Transitional sandstone in which feldspars are relatively scarce and quartz muscovite and chert are abundant; the quartz grains that are more rounded and abundant are called a. arkoses. c. graywackes. b. orthoquartzites. d. subgraywackes (lithic sandstone). 9. What are immature sandstones consisting of significant quantities of dark, very fine-grained materials with a fine matrix that consists of clay, chorite, micas and silt? a. arkoses c. graywackes b. orthoquartzites d. subgraywackes 10. A type of sandstone that may develop as a basal sandstone derived from the erosion of granitic coastal area experiencing an advance of the sea or in adjacent areas adjacent to granite mountains is a. arkoses. c. orthoquartzite. b. subgraywacke. d. graywacke. 11. A map showing the geography of a region or area at some specific time in the geologic past is a. a paleogeographic map. c. an isopach map. b. a geologic interval map. d. a lithofacies map. 12. Lithofacies maps are useful in determining changes mostly in which of the following areas? a. sea floor spreading b. geosyncline formation c. zones of tectonic instability d. aerial variation in the overall lithologic character of a given stratigraphic unit 13. A map prepared by geologists to illustrate changes in the thickness of a formation or time rock unit is a (an) a. paleoclimatic map. c. lithofacies map. b. paleogeographic map. d. isopach map. 14. This method of correlation links rock units by age equivalences, determined by fossils or radioactive dating. a. lithostratigraphic c. chronostratigraphic b. biostratigraphic d. paleostratigraphic 15. Spherical grains of concentric laminated calcium carbonate which are formed in shallow, saline marine conditions are called a. crinoids. c. blastoids. b. ooid. d. septarian nodules. 16. This type of unconformity is characterized by stratified sedimentary rocks resting on older igneous or metamorphic rocks. a. angular unconformity c. disconformity b. nonconformity d. paraconformity 17. A ferric mineral that tends to color rock red, brown, or purple and are dubbed “red beds.” a. hematite c. graywacke b. micrite d. orthoclase feldspar 18. Lithostratigraphic units are bodies of rock having distinctive features without regard to time boundaries. a. time-rock unit c. rock units b. formation d. lithofacies unit 19. Four sedimentary structures are formed during or after deposition, but before lithification. Which one of the following would not be included? a. mud cracks c. graded-bedding b. cross-bedding d. scour marks 20. A body of rock that can be recognized wherever it occurs by the characteristics of composition, texture, or color is a. time rock. c. formation. b. rock interval. d. rock unit. Fill in the Blank 1. The study of the deformation or structural behavior of a large area of the Earth’s crust over a long period of time is . 2. Hues of brown, red, and green often occur in sedimentary rocks as a result of their ________ content. 3. Geologists designate strata colored in shades of red, brown, or purple by ferric iron as _____ . 4. The size, shape, and arrangement of mineral and rock grains in a rock constitute its . One category of bonding material that consists of finer clastic particles (often clay) that were deposited at the same time as the larger grains and that fill the crevices between them is called . 6. An expression of the range of particle sizes deviating from the average size is . 7. The sandstones that are clastic rocks characterized by a dominance of quartz with little or no feldspar, mica, or fine clastic matrix are . 8. The immature sandstones that consist of significant quantities of dark, very fine-grained material are . 9. Quartz sandstone, arkose, and graywacke are rather distinct kinds of sandstones. A rock that has a more transitional composition and texture is termed a . 10. The general appearance or aspect of a rock from which its environment of deposition can be inferred is a sedimentary . 11. A map showing the geography of a region or area at some specific time in the geologic past is termed a map. 12. Maps prepared by geologists to illustrate changes in the thickness of a formation or time-stratigraphic unit are called maps. 13. _____________________ ____________________ form a shallow ocean environment near the shore. 14. During an __________ ___________ world temperatures drop and more of the planet’s water becomes frozen in glaciers and polar ice caps. 15. _____________ ______________ form when fast-moving currents begin to slow, dropping larger particles (cobbles then pebbles) followed by progressively finer grains (sand, then salt, then clay). True/False 1. The three major environments of deposition are marine, continental, and fluvial. 2. Small-scale, wave-like structures on bedding planes produced by running water are called flute casts. 3. A rock unit deposited during a marine transgression becomes younger in a seaward direction. 4. Sedimentary rocks represent the material record of environments that once existed on the earth. 5. Alluvial fans occur when streams enter bodies of standing water, undergo an abrupt loss of velocity, and drop their load of sediment. 6. A time-rock unit differs from a rock unit in that the time-rock unit is an assemblage of strata deposited within a particular interval of time. 7. Lacustrine deposits are accumulations of sediment that form where a stream flows into relatively quiet water. 8. On the landward side of lagoons are almost featureless, low-lying plains called tidal flats. 9. Deltas are the seaward mouths of rivers drowned by the sea. 10. Sorting is a geologic term for the degree to which sediment and particles in sedimentary rocks are uniform by particle size. AnswerS Multiple Choice c b b c c c c d c a a d d c b b a c d d Fill Ins tectonics iron oxide red beds texture matrix sorting quartz graywacke lithic (subgraywacke) facies Paleogeographic isopach Continental shelves Ice Age Graded beds True/False F F F T F T F T F T RESPONSES TO QUESTIONS ACCOMPANYING SELECTED FIGURES FIGURE 5–2 (p. 84) Fossils would be the most diagnostic feature. One would look for fossils of non-marine crustaceans, mollusks, freshwater fish, and insects. There would be an absence of marine invertebrates. Other clues might be desiccation features such as mudcracks and finely laminated (varved) shales. FIGURE 5–5 (p. 86) Graywacke (immature sandstone) is characteristic of deep-sea fan deposits. FIGURE 5–6 (p. 87) Quartz and feldspar would be abundant in the debris produced by the weathering of granite. Clay, which also is silicate mineral, is another product of the weathering of granite. FIGURE 5–9 (p. 88) A delta would cease to prograde if wave current action removed sediment faster than it could be supplied by the stream. Progradation also might cease if the supply of sediment from the stream diminished. FIGURE 5–10 (p. 89) Coarser sediments occur along the windward side of the barrier island because wave action removes finer particles, leaving the heavier material to accumulate. FIGURE 5–12 (p. 92) Graywacke is an immature sandstone. FIGURE 5–15 (p. 94) Multiple impacts during transport cause feldspar grains to break along cleavage planes, imparting angularity. Quartz has no cleavage and is harder. FIGURE 5–17 (p. 95) The walls of mudcracks converge downward so as to form a V profile, and the point of the V indicates the downward direction. FIGURE 5–18 (p. 96) Current flowed from right to left, as indicated by the flattening of the inclined laminae at the bottom of the beds. FIGURE 5–21 (p. 97) Asymmetric ripple marks are formed by currents. They are commonly formed in shallow near-shore sandy deposits worked by currents, but they also may occur in deep parts of the ocean as a consequence of turbidity current deposition. FIGURE 5–23 (p. 98) Overturned beds are common in orogenic belts around the world. FIGURE 5–25 (p.101) As a result of wave action, the sands are likely to exhibit ripple marks in addition to having such textural features as good sorting and good rounding. FIGURE 5–25 (p. 101) Arkose has poor sorting. Because of the clay and other fine particles between the larger grains, fluids would not pass through this rock readily, and it is unlikely to have good permeability. FIGURE 5–44 (p. 112) An onlap or marine transgression is indicated by the fining upward sequence of quartzite (formerly sandstone), followed upward by shale, siltstone, and finally limestone. FIGURE 5–46 (p. 114) The oldest rock unit seen at the surface along A-A’ is the sandstone. The siltstone is the youngest rock unit. FIGURE 5–51 (p. 117) Ash from volcanic eruption may be spread across a wide area in what amounts to a “geologic instant.” As a result, it is the same age wherever it occurs, and its age can be ascertained through the use of isotopic radioactive dating methods.