Ch8 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) Which rocks are most useful in unravelling Earth's geologic history? A) meteorites B) fossiliferous sedimentary rocks C) high grade metamorphic rocks D) phaneritic igneous rocks

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2) Working on fossiliferous strata in the mountains of western Italy,________ was first to work out ________, which is the fundamental way geologists know which bed is older in any sedimentary sequence. A) James Hutton, the principle of uniformitarianism B) Nicolaus Steno, the law of superposition C) Charles Lyell, the sequence of orogenies D) William Smith, the principle of fossil succession

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3) Who made the first clear statement of the law of superposition? When? A) George Dawson, 19th century B) Nicolaus Steno, 17th century C) William Smith, 18th century D) Charles Edward Stuart, 17th century

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4) What fundamental concept states that in a horizontal sequence of conformable sedimentary strata each higher bed is younger than the bed below it? A) theory of correlative supposition B) law of superposition C) theory of superstition D) law of original correlation

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5) Visualize (or draw) five, horizontal, sedimentary strata as exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are true? A) beds 1 and 3 are older than bed 4 B) bed 5 is the oldest C) bed 4 is older than bed 2 D) bed 3 is older than beds 2 and 4

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6) Which of the following geologic observations would not bear directly on working out the sequence of geologic events in an area? A) an nonconformity between a granite and sandstone B) inclusions of sandstone in a granite pluton C) the feldspar and quartz contents of a granite D) a well-exposed dyke of basalt intruding a sandstone

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7) Pieces of one rock contained within another are called ________ and give evidence that that smaller rock is ________ the main body. A) surprises, more valuable than B) inclusions, older than C) coprolites, rejects from D) xenoliths, younger than

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8) Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements concerning their relative age is geologically correct ? A) The sandstone is younger if the granite contains sandstone inclusions B) The granite is older if the sandstone contains pebbles of the granite C) They were both formed at 4004 BC but the Devil made them complicated to fool us D) The sandstone is younger if it shows evidence of contact metamorphism

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9) An unconformity is a buried ________. A) surface of erosion or non-deposition separating younger strata above from older strata below B) surface of erosion with older strata above and younger strata below C) fault or fracture with older rocks above and younger rocks below D) fault or fracture with younger strata above and older strata below

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10) An unconformity is ________. A) an erosional (or non-depositional) surface with younger strata above and older rocks below B) a fault with younger, sedimentary rocks above and older, igneous rocks below C) the contact between a cross- cutting pluton and sedimentary rocks D) the lower contact of an intrusive sill with sedimentary strata

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11) Which of the following best characterizes an angular unconformity? A) Tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity. B) The discordant boundary between older strata and an intrusive body of granite C) Horizontal lava flows lie below the unconformity and horizontal, sedimentary strata lie above.

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12) ________ is an erosional contact between tilted, older strata below and horizontal, younger strata above? A) An angular unconformity B) A disconformity C) An angular deformity D) A cross- cutting fault

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13) Which of the following statements is true, concerning sedimentary strata separated by a disconformity? A) the younger strata were tilted after the older strata were B) all strata exhibit parallel bedding or stratification, but there is a hiatus (missing record) C) all of the older strata were eroded away before the younger strata were tilted D) the older strata were tilted when the younger strata were deposited

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14) Which of the following means to recognize, identify, and describe similar- aged strata or similar lithologies in nearby areas or in widely separated, different areas? A) fossicking B) strata-titling C) correlation D) coagulation

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15) The task of matching geologic formations of the same age over vast distances (like between continents) is termed ________. A) correlation B) cross dressing C) stratification D) lithification

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16) Which of the following denotes the investigative process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas? A) strata typing B) radioactive intuition C) cross-cutting D) correlation

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17) Which English engineer and amateur geologist (his first name was William) is generally credited with first demonstrating the principle of faunal succession from his observations in building canals? A) Blake B) Tell C) Smith D) Wordsworth

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18) The ________ is the idea or concept that ancient life forms succeeded each other in a definite evolutionary pattern and that the contained assemblage of fossils can uniquely determine geologic ages of strata. A) principle of fossil succession B) law of fossil regression C) principle of cross correlation D) law of correlative indexing

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19) What geologic law/principle states that fossil organisms (fauna) changed and evolved in a definite progressive way such that strata of specific ages can be recognized by the fossils they contain? A) fossil succession B) fossil superposition C) fossil transubstantiation D) fossil exhibitionism

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20) The study of paleontology focuses on ________? A) absolute age determinations on minerals from igneous and metamorphic rocks B) palinspastic restorations of deformed strata that were once horizontal C) sedimentary rocks and their diagenetic transformations after deposition D) fossils and evidence concerning ancient life forms

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21) Which type of microfossils have tests (hard parts) made of calcium carbonate and are useful as index fossils as well as for measuring past sea temperatures and climates since the Cretaceous? A) acritarchs and dinoflagellates B) diatoms and radiolaria C) conodonts D) coccoliths and formaminifera

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22) Which of the following is an essential characteristic of an index fossil? A) the fossils are exceptionally abundant for a long time span and readily preserved B) the organism lived only in specific environments such as beaches or estuaries C) the organism only lived for a short span of geologic time but was very widespread D) the fossils occur in deep-water marine sediments, but the organism actually lived in the sunlit, surface layer of the ocean

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23) Which of the following denotes remains of particular organisms that were widely distributed, but lived for only a relatively brief interval of geologic time? A) fleeting impressions B) index fossils C) internal moulds D) eratosthenes

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24) Which type of microfossils are organic walled cysts of planktonic algae primarily used in relative dating? A) acritarchs and dinoflagellates B) diatoms and radiolaria C) conodonts D) coccoliths and formaminifera

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25) Which type of microfossils have a tooth-like shape made of apatite, are a mouth part of an extinct swimming eel- like chordate, and are useful index fossils for the Paleozoic through Triassic? A) diatoms and radiolaria B) conodonts C) acritarchs and dinoflagellates D) coccoliths and formaminifera

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26) Which organisms were free swimmers and found in a great variety of Paleozoic and Mesozoic marine habitats? A) ammonoids and conodonts B) flatclams and trilobites C) chitnozoans and graptolites D) diatoms and diatoms

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27) Which organisms were benthic (bottom dwellers) and extensively used as index fossils respectively for the Mesozoic and Lower Paleozoic? A) flatclams and trilobites B) chitnozoans and graptolites C) diatoms and diatoms D) ammonoids and conodonts

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28) Acritarchs, conodonts, graptolites and trilobites would all be useful as index fossils, environmenta indicators or relative dating tools for ________. A) Cenozoic conglomerates B) Paleozoic marine shales and carbonates C) Mesozoic coals D) Cretaceous through Eocene aeolian deposits

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29) How can fossiliferous sedimentary rock most easily be dated and correlated if they lack the mos diagnostic index fossil for that period or epoch? A) by performing radiometric dating like U- 238/Pb-206 or C- 14 on fossils B) by mapping out the intervening contacts or drilling a series of boreholes between C) by paying a geologist to tell you the answer D) by using the entire fossil assemblage and ranges for the two localities in question

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30) What is the age of the Earth accepted by most scientists today? A) about 4600 thousand years B) 4.6 million years C) 4.6 billion years D) 540 billion years

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31) Assume that human recorded history can be stretched back to 4600 years before the present. This i approximately what fraction of geologic time? A) one billionth B) one hundred- thousandth C) one ten-thousandth D) one millionth

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32) In radiometric dating, an unstable radioactive isotope is called ________. A) the parent B) a tachyon C) an alpha particle D) a red hot mama

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33) Both long-lived, naturally occurring, uranium isotopes decay through a series of intermediate, radioactive, daughter isotopes to stable isotopes of ________. A) carbon B) thorium C) lead D) radon

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34) How can yield reliable values for the ages of minerals, rocks and some fossils? A) the decay constants are fixed and well measured for isotopic decay B) one only needs to analyse for the parent isotope C) there are absolute fossil ages to compare to and test the radiometric clocks D) the physical conditions that control decay, like temperature and pressure, are always well known

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35) The radioactive isotopes uranium-238, uranium- 235, and thorium-232 eventually decay to different, stable, daughter isotopes of ________. A) iron B) strontium C) lead D) argon

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36) What gas is a radioactive daughter product of the U- 238 decay series? A) radon -226 B) xenon- 143 C) argon-40

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D) carbon-14

37) The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half-lives have elapsed since the material was 100% parent atoms? A) 1 -2 B) 2- 3 C) 3

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38) The ratio of radioactive parent to stable daughter atoms in a mineral is measured as 1:3. How many half-lives have elapsed since the mineral grain formed, assuming that only parent atoms were present when it crystallized? A) 2.0 B) 3.0 C) 0.5 D) 1.5

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39) Why is the major branch of the K- 40 decay to Ca-40 not useful in most cases for whole rock dating? A) Ca- 40 is itself unstable and further decays to more daughter product B) the Ca- 40 that is produced by decay is indistinguishable from the naturally most abundan isotope of Ca that may have been present initially C) it only works 89% of the time D) the decay to Ar- 40 is faster and has wider geologic applicability

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40) Of an original amount of many half- lives have elapsed? A) 3.0 B) 0.5

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, 25% remains and 75% has decayed. How C) 2.0

D) 1.5

41) Which of the following A) Ca; calcium B) Th; thorium C) U; uranium D) K, potassium E) Rb; rubidium

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42) What kind of materials can be reliably dated by the C- 14 method? A) Precambrian zircons in igneous and metamorphic rocks B) Paleozoic oil and gas deposits in limestones C) Recent: clams, foraminifera, and wood 1/2 C) 1/4 to 1/8 D) 1/8 to 1/16

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45) The half- life of carbon-14 is about 5730 years. Assume that a sample of charcoal formed by burning wood that lived 25,000 years ago. How much of the original carbon-14 would remain today? A) 1/16 to 1/32 B) 1/8 to 1/16 C) 1/4 to 1/8 D) 1/2 to 1/4

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46) What is the source of natural carbon-14? A) cosmic ray collisions triggering 'neutron-capture' in ordinary atmospheric nitrogen B) fusion of hydrogen and helium in the Sun and eruption of solar flares C) nuclear fission of the heavy, radioactive elements uranium and thorium D) leakage of radioactive gases from the liquid, outer core

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47) What is cross-dating? A) common social practice among close relatives in small towns B) an archeologic technique for determining the time of crucifixion C) using the cross-cutting relationships in dykes and faults to determine relative ages of strata D) matching tree ring patterns from a dated tree to an undated one

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48) Complex, invertebrate, life forms are common as fossils, beginning with marine strata of Cambrian age. How long ago did the ? A) 542 million years B) 65 million years C) 542 billion years D) 4.6 billion years

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49) A few rare times in earth history the majority of life forms disappeared "clearing the ecologic slate" for new ones. When this happens it is called ________. A) an iridium anomaly B) an ecoshift C) a mass extinction D) a half life

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50) At the end of the Cretaceous (K/T boundary) what unusual geologic phenomenon occurred that ha been linked to mass extinction and the end of the dinosaurs? A) the climate abruptly warmed and massive weathering of iridium poisoned the seas B) a 10 km diameter meteor impact occurred at Chicxulub on the Yucatan peninsula C) enormous outpourings of basaltic lavas built the Deccan plateau in northern India D) A and B are both correct

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51) Which of the following is the name of A) Cretaceous B) Phanerozoic C) Tyson D) Paleozoic E) Eocene

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52) The A) last 15%

comprises approximately the ________ of geologic time. B) last 85% C) first 85%

52) D) first 15%

53) Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time, beginning with the longest time interval and ending with the shortest? A) eon, era, epoch, period B) eon, epoch, period, era C) era, period, epoch, eon D) eon, era, period, epoch

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54) Consider the names of the A) life; living things C) ancient

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55) The name of which A) Proterozic

in the geologic time scale. What is meant by " B) animals D) rocks; lithified strata means " B) Paleozoic

"?

55) C) Phanerozoic

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D) "Geezer-cene"

56) The rare element has been implicated in which " " crisis? A) extinction of the woolly mammoths in late Pleistocene time B) disappearance of Neanderthal man during the early Cenozoic Era C) extinction of the dinosaurs at the end of the Cretaceous Period D) poisoning of primitive algae in the Hadean Eon

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57) Why are the successive periods and epochs of the geologic time scale of unequal lengths? A) they were originally all of equal duration but most of them got eroded and are full of unconformities B) the periods and epochs are based on the duration of unique environments like basins, o events in earth history like extinctions and orogenies which happen intermittently C) the passage of time has been speeding up and the length of the day is variable D) it is based on evolution and some creatures are slow learners

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58) Which A) Proterozoic

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denotes the first 800 million years of Earth history? B) Hadean C) Archean

D) Chaldean

59) While the , it is not divided into periods or epochs like the Phanerozoic because there ________. A) are no Precambrian sedimentary rocks to use for internal divisions B) were no multi-cellular organisms nor hard bodied fauna to leave much of a fossil record C) are few resources in Precambrian rocks and few geologists take an interest in them D) are few remaining Precambrian rocks to correlate or divide due to active tectonics

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TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false 60) The Earth is billions of years old and its surface and interior have changed repeatedly by the same processes still operating today.

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61) In relative dating, the principle of cross-cutting relationships allows one to infer that the rock body that does the cutting is clearly older.

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62) Pebbles of granite in sandstone and conglomerate resting on the granite suggest that the granit intruded the sedimentary beds.

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63) Unconformities often mark times of uplift and erosion.

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64) Strata above an angular unconformity were tilted before the older strata were eroded

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65) James Hutton was the very first geologist to recognize the vast amount of missing time (at least al of Silurian) represented by the angular unconformity where the gently dipping Devonian "Old Red Sandstone" overlies vertical Ordovician slates at Siccar Point, Scotland.

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66) A disconformity is an erosional unconformity with parallel beds or strata above and below.

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67) Phanerozoic, marine, sedimentary strata of the same age on different continents can usually be correlated by their fossil assemblages.

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68) Correlation of rock units between continents or widely separated areas is accomplished by using physical features such as colour, texture, and thickness of units.

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69) Paleophrenology is the study of fossils and ancient life forms

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are useful for correlation and dating of Paleozoic through Recent marine sedimentary rocks.

71) Monotids and inoceramids are planktonic microfossils useful for zoning the Cenozoic Era.

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72) An

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is equal to the sum of its protons and neutrons in its nucleus

73) The radioactive decay of U-238 to Pb-206 is slightly faster in hot magmas than in cool, solidified rock.

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74) After three half- lives, one-ninth of an original, radioactive, parent isotope remains and eight-ninths has decayed into the daughter isotope.

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76) Uranium has two, long- lived, radioactive isotopes, U-238 and U- 235.

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77) Carbon-14 is very helpful for dating geologic events from the beginning of the Paleocene Epoch until the present.

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78) Carbon-14 is produced by cosmic rays reacting with nuclei of iron atoms in the Earth's core

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79) Carbon-14 can be used to date wood and other natural organic materials used by the early Indian of North and South America.

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