Earth Science

Q: Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. Choose the option which does not fit the pattern. Paleozoic Mesozoic Phanerozoic Cenozoic

Q: Which method best describes how the geologic time scale, which was developed through fossil successions in sedimentary rocks, was tied to absolute time even though sedimentary rocks cannot usually be dated directly by geochronology? A) Geologists estimated time through sedimentation rates, then using those rates together with maximum ages of underlying rocks that are datable, to extract a time interval and rate for deposition of the sedimentary rocks. B) Geologist used things like volcanic ash beds, interbedded volcanic rocks, cross-cutting intrusive igneous rocks, etc. in sedimentary sections with a known fossil succession, and this age was extrapolated globally. C) Geologists recently developed a technique to directly date sedimentary rocks, solving the problem. D) Geologists realized that there were many other cosmogenic isotopes besides Carbon 14 that allow the dating of sediments, and this has allowed the dating of sedimentary rocks.

Q: In the last few years improvements in technology have allowed geologists to date single grains of some minerals in rocks. A geologist separates 5 grains of the mineral zircon, which can be dated by the Uranium-lead method, and the crystal retains parent and daughter through weathering, erosion, and deposition. Thus, dating each mineral grain only gives the age of the source rock that was eroded, to produce that sand, from which the zircon grain is derived. The 5 grains yield ages of 160, 110, 2020, 66, and 162 million years. What do these ages tell you about the age of the sedimentary strata? A) They are Precambrian rocks, older than 2020 million years. B) They are between 160 and 162 million years. C) They are younger than 66 million years. D) There are no age constraints from this data; sedimentary rocks cannot be dated by geochronology.

Q: Different periods of the geologic time scale are different in length. Why? A) Early geologists made mistakes, but it was easier to retain the terminology in the time scale. B) The time scale was developed ad hoc, as a relative time scale based on rocks and fossil succession with no reference to absolute time when it was developed. C) The geologists who developed the time scale did not care about absolute ages. D) None of the above

Q: The era known as the "age of mammals" is the ________ era. A) Precambrian B) Paleozoic C) Mesozoic D) Cenozoic

Q: 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) era, period, epoch, eon C) eon, epoch, period, era D) eon, era, period, epoch

Q: About 88 percent of geologic time is represented by the time span called the ________ era. A) Paleozoic B) Precambrian C) Mesozoic D) Phanerozoic

Q: The era of "ancient life" is the ________ era. A) Cenozoic B) Paleozoic C) Mesozoic D) Precambrian

Q: Consider the names of the eras in the geologic time scale. What is meant by "zoic"? A) life; living things B) rocks; lithified strata C) time; recording of events D) places; geographic references

Q: The subdivision of the geologic time scale that represents the longest time span is called a(n) ________. A) epoch B) era C) period D) eon

Q: Assume that man's recorded history can be stretched back to 4600 years before the present. This is approximately what fraction of geologic time? A) one ten-thousandth B) one millionth C) one billionth D) one hundred-thousandth

Q: What is the age of the Earth accepted by most scientists today? A) 6.4 billion years B) 4.5 million years C) 4.5 billion years D) 6.4 million years

Q: The half-life of carbon-14 is about 6000 years. Assume that a sample of charcoal formed by burning of living wood 15,000 years ago. How much of the original carbon-14 would remain today? A) more than one-half B) between one-fourth and one-eighth C) between one-half and one-fourth D) between one-half and one-third

Q: In the last 20 years geologists have begun measuring accumulation of Helium (He) in some minerals because these minerals can retain He at temperatures up 100-200C. The "date" gives a time when the material cooled below the temperature where the helium began to be retained, which is related to the depth of the material. Where do you think the He comes from that allows this technique to work? A) the atmosphere, like carbon-14 B) the sun C) beta decay of some radioactive element D) alpha decay of some radioactive element

Q: The decay of 40K has a half of 1.3 x 109 years. The age of the earth is estimated at 4.6 x 109 years. The decay of 40K is a major heat source for the earth's interior. Relative to today, how much more heat was produced by 40K in the early Archaeon era or 3.9 x 109 years ago? A) 2x B) 4x C) 6x D) 8x

Q: Which radioactive decay used for radiometric dating is not an isotope that was generated during nuclear synthesis in the star that went supernova and its products became our solar system? A) 238U B) 147Sm C) 40K D) 14C

Q: An important geochronometer is the decay of 147Sm to 143Nd. What type of radioactive decay is involved in this parent-daughter pair? A) beta decay B) electron capture C) alpha decay D) a positron capture

Q: 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) less than l B) more than 3 C) between l and 2 D) between 2 and 3

Q: When a radioactive isotope decays by electron capture, the electron ________. A) combines with a neutron in the nucleus, raising the mass number of the daughter isotope by one B) combines with a proton in the nucleus; the atomic number of the daughter is one less than the parent C) makes the parent isotope into an ion with a charge of negative one D) makes the daughter isotope into an ion with a charge of positive one

Q: Which of the following describes radioactive decay by beta particle emission? A) The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same. B) The mass number of the daughter isotope is one more than the parent, and both isotopes have the same atomic number. C) The daughter isotope has an atomic number two less than the parent and a mass number four less. D) The daughter isotope has an atomic number one less than the parent and a mass number two less.

Q: Which of the following is not a very long-lived, radioactive isotope? A) U-238 B) K-40 C) Rb-87 D) C-14

Q: A geologist observes abundant fossils of a distinctive trilobite species in a shale, but this trilobite disappears as she walks through the shale. In younger rocks, just above the horizon where the fossil disappears another species of trilobite becomes the prominent fossil in similar shales. Which conclusion is most logical for this observation? A) The organisms whose remains form the first fossil moved from the area for unknown reasons. B) A hurricane or other catastrophe killed all of the early species so the other species could move in. C) The second, trilobite group in the upper section went extinct where the change in fossils is seen. D) The first trilobite species went extinct and its ecological niche was occupied by another species, which may have evolved from the first.

Q: Which of the following is an essential characteristic of an index fossil? A) The organism lived only in specific environments such as beaches or estuaries. B) The organism only lived for a short period of geologic time. C) The fossils are exceptionally abundant and well preserved. D) The fossils occur in deep-water marine sediments, but the organism actually lived in the sunlit, surface layer of the ocean.

Q: Oysters are an invertebrate the lives today in brackish waters along coastal zones. When a geologist working in stratified rocks observes a limestone bed with oyster fossils overlain by beds with clam and echinoderm fossils indicative of marine conditions, the fossils probably indicate ________. A) the oysters went extinct while these rocks were being deposited B) the oysters evolved into clams and echinoderms C) the environment changed as sea level rose, displacing the oysters environment with marine conditions represented by the clams and echinoderms D) There is not sufficient information to reach any conclusion from these observations.

Q: You observe a distinct, red sandstone rock body about 50 m thick that is depositionally overlain by a red shale with interbedded gypsum and you follow this boundary in the rock bodies for 1 km until you cross a fault which has displaced the boundary between the two rock bodies. You walk along the fault and see a boundary between a 50 m thick red sandstone and overlying red shale interbedded with gypsum. You conclude ________. A) this is impossibly complex; the fault broke up all the rocks B) this new exposure of sandstone, shale and gypsum must be a different age rock unit C) the stratigraphic section must have been inverted by the deformation; the rocks are upside down D) the second exposure of sandstone, shale and gypsum correlates to the first, and the boundary between the sandstone and shale is the same stratigraphic horizon

Q: A geologist is working in an area with exposed sedimentary rocks and finds a well exposed sequence of stratified rocks. As he works through a thick sequence of limestone, he sees abundant large clam fossils that produce an interlocking texture suggesting a reef, but within the limestone section these clams disappear and the overlying limestone is made up primarily of fragments of corals. He now moves 50 km away and finds limestones interbedded with shales, and the limestones contain the same clam fossils he had seen previously 50 km away. As he continues through this section, the rocks become entirely limestone, and the clams disappear again with coral fossils above forming a reef structure. He concludes ________. A) this is impossible; the rocks are different at the same place the fossils change B) the horizon where the clams disappear occurred at the same time in the two sections when the clams went extinct C) clams have nothing to do with reefs, so he needs to go back to the first section to determine what he missed D) sea level must have risen abruptly in a great catastrophe to produce the coral fragments scattered over 50 km

Q: Faunal succession recognized in the sequence of fossils in stratified sedimentary rocks was a key concept that led to ________. A) the concept of evolution of life on Earth B) continental drift C) sea floor spreading D) Catastrophism and evidence the world was once covered with water

Q: 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 determine geologic ages of strata. A) principle of cross correlation B) law of fossil regression C) law of correlative indexing D) principle of fossil succession

Q: Which of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks of the same ages in different areas? A) super matching B) correlation C) strata indexing D) cross-access dating

Q: Which of the following organisms would be most likely to be preserved in the geologic record? A) the bones of a dinosaur that lived on semi-arid plains B) a clam with a thick calcite shell that lived on a mudflat C) a tree D) a mussel that clings to rock outcrops in the surf zone

Q: Little Johnnie from down the street from your house brings an object that looks like a bone, and Johnnie says "look, I found a dinosaur bone." Which of the following would not be useful in evaluating Johnnie's claim? A) Examine the object for hardness to determine if the sample is permineralized. B) Ask if the object was found embedded in rock. C) Evaluate the object for fine textures indicative of bone material or replaced bone material. D) Extract charcoal from the object and use carbon-14 dating

Q: The Morrison Formation is exposed in the western United States and represents a nonmarine deposit with abundant dinosaur fossils. Much of the Morrison is pure mudstone, yet it is common to find highly polished pebbles and cobbles in the mud. Which of the following do you think is the best explanation of these cobbles? A) They were placed in the mud by space aliens. B) They represent meteorites that killed the dinosaurs. C) They are impossible; people must have put them there. D) They are gastroliths, a trace fossil.

Q: You go for a hike across an outcropping of sandstone and you see large footprints in the sandstone. You have just found ________. A) Bigfoot B) a trace fossil C) proof of an ancient flood D) a mold

Q: Rare, but complete preservation of fossils occurs in ________. A) limestone B) shale C) amber D) mudstone

Q: One type of fossil that can preserve details of organic soft parts is ________. A) permineralization B) cast C) coprolites D) carbonized imprints

Q: You pick up a sandstone. In the rock sample you see an impression of a sea shell in the rock. This type of fossil is a ________. A) mold B) cast C) permineralized fossil D) pseudofossil

Q: Petrified wood is an example of a fossil formed by ________. A) direct preservation B) cast and mold preservation C) permineralization replacing original cellulose of the wood D) trace fossil imprints

Q: Which of the following is not a fossil? A) imprint of an invertebrate shell in a mudstone B) a tooth from an early man site in a lake sediment deposit C) a mummified sloth in a cave D) None of the above-these are all fossils.

Q: Paleontology is the study of ________. A) paleo meaning old, and ontology referring to philosophical study of nature, so paleontology is the study of old nature B) ancient life C) prehistoric human history D) none of the above

Q: A worm would stand a poor chance of being fossilized because ________. A) worms have been rare during the geologic past B) worms have no hard parts C) worms contain no carbon-14 D) all of these

Q: Assume that you have just examined several flat-lying sedimentary layers. After much study you determine that there is a considerable span of time for which no sedimentary rock layer exists at this site. You have just discovered a(n) ________. A) angular unconformity B) series of conformable strata C) disconformity D) example of cross-cutting relationships

Q: Visualize five horizontal sedimentary strata 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 is true? A) Bed 5 is the oldest. B) Beds l and 3 are older than bed 4. C) Bed 4 is older than bed 2. D) Bed 3 is older than beds 2 and 4.

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

Q: Which type of unconformity would generally indicate the greatest amount of erosion prior to deposition of the overlying rocks? A) nonconformity B) angular unconformity C) disconformity D) buttress unconformity

Q: Who made the first clear statement of the law of superposition? When? A) John Wesley Powell, nineteenth century B) William Smith, eighteenth century C) John Stuart Priestly, nineteenth century D) Nicolaus Steno, seventeenth century

Q: ________ is an erosional contact between tilted, older strata below and horizontal, younger strata above. A) Inverse bedding B) An angular unconformity C) A disconformity D) Cross cutting

Q: By applying the law of superposition, ________ dates can be determined. A) conventional B) radiometric C) relative D) both relative and radiometric

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

Q: 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) Horizontal lava flows lie below the unconformity and horizontal; sedimentary strata lie above. C) The discordant boundary between older strata and an intrusive body of granite. D) Tilted strata that lie below the unconformity are truncated at the unconformity, and strata above the unconformity are also tilted and truncated, but at a different angle

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

Q: In the late 1800's various principles (original horizontality, inclusions, cross cutting relations, etc. arte) were established and used to ________. A) determine the age of the earth B) determine the age of events on the earth C) organize the order in which events occurred on earth D) prove that evolution was a valid theory that could explain many geologic observations

Q: If you observe a nonconformity, you would infer that the region had experienced ________. A) deposition in shallow water, uplift or lowering of sea level enough to expose the rocks to erosion and non-deposition for a period of time, and subsequent resubmergence of the remaining sedimentary units where they experience new deposition B) uplift and tilting of sedimentary units that exposes them to erosion over a period of time with subsequent renewed deposition C) intrusion of igneous rocks into a depositional setting, forcing the sedimentary layers upward and possibly deforming them, followed by subsidence of the remaining sedimentary layers and renewed deposition D) deposition of sedimentary layers on crystalline igneous or metamorphic rocks that are exposed at the surface of the earth

Q: If you observe a disconformity, you would infer that the region had experienced ________. A) deposition in shallow water, uplift or lowering of sea level enough to expose the rocks to erosion and non-deposition for a period of time, and subsequent resubmergence of the remaining sedimentary units where they experience new deposition B) uplift and tilting of sedimentary units that exposes them to erosion over a period of time with subsequent renewed deposition C) intrusion of igneous rocks into a depositional setting, forcing the sedimentary layers upward and possibly deforming them, followed by subsidence of the remaining sedimentary layers and renewed deposition D) deposition of sedimentary layers on crystalline igneous or metamorphic rocks that are exposed at the surface of the earth.

Q: If you observe an angular unconformity, you would infer that the region had experienced ________. A) deposition in shallow water, uplift or lowering of sea level enough to expose the rocks to erosion and non-deposition for a period of time, and subsequent resubmergence of the remaining sedimentary units where they experience new deposition B) uplift and tilting of sedimentary units that exposes them to erosion over a period of time with subsequent renewed deposition C) intrusion of igneous rocks into a depositional setting, forcing the sedimentary layers upward and possibly deforming them, followed by subsidence of the remaining sedimentary layers and renewed deposition. D) deposition of sedimentary layers on crystalline igneous or metamorphic rocks that are exposed at the surface of the earth

Q: Unconformities which represent a break in the geologic record of deposition are important because ________. A) they cannot be mapped B) they represent a period of major activity C) the fossils found in the unconformities can be used to correlate global time period D) they give an indication of sea level rise within an ocean basin

Q: The principle of inclusions which states that the source of rock fragments found in a unit must be older than the unit with the fragments is important because ________. A) it provided a tool for sorting out the relative timing of various geologic events B) it provided a way to recognize if rocks had been deformed C) it showed that igneous rocks were younger than sedimentary rocks D) it allowed geologists to correlate rock units over large distances

Q: The principle of cross-cutting relationships which states that a geologic feature that cuts across another feature must be younger than the feature it cuts is important because ________. A) it provided a tool for sorting out the relative timing of various geologic events B) it provided a way to recognize if rocks had been deformed C) it showed that igneous rocks were younger than sedimentary rocks D) it allowed geologists to correlate rock units over large distances

Q: The principle of lateral continuity proposes that sedimentary rock layers continue in all directions until they grade into a different rock type or thin out on the edge of a basin is important because ________. A) it showed that catastrophism could not explain the flat layers of the earth B) it provided a way to recognize if rocks had been deformed C) it provided an explanation how rocks behave in a depositional setting D) it allowed geologists to correlate sedimentary rock units over large distances

Q: The principle of horizontality which states that sediments are usually deposited in relatively flat layers is important because ________. A) it showed that catastrophism could not explain the flat layers of the earth B) it provided a way to recognize if rocks had been deformed C) it provided an explanation how rocks behave in a depositional setting D) it allowed geologists to correlate sedimentary units over large distances

Q: The principle of superposition which states that in undeformed rocks, the younger rocks will be on top of older rocks, is particularly important because ________. A) it supports the laws of gravity which indicate that rocks must be deposited on something that already exists B) it showed that the interior of the earth is not growing outward C) it provided an order for assembling the relative ages of various rock layers D) it proved that life evolved by putting fossils in a logical order

Q: An important tool in understanding the actual numerical dates of past geologic events is ________. A) radioactivity B) fossils C) unconformities D) depositional rates E) cross-cutting relationships

Q: One of the primary goals of geology is to ________. A) identify all of the rocks on the surface of the earth B) develop a comprehensive relationship between fossils and geologic formations C) understand the role of plate tectonics in the earth's evolution D) understand the history of the earth E) determine the role of meteorites in the decline of species over time

Q: A major difference between Catastrophism and Uniformitarianism is ________. A) Uniformitarianism does not allow for catastrophic events while Catastrophism is based on the assumption that they are the major forces of change in the earth B) Catastrophism requires all changes on earth be due to unpredictable events that cannot be explained while Uniformitarianism proposes that all events are predictable C) Uniformitarianism explains the young age of the earth by suggesting that while processes have not changed over time, the rates of processes may vary significantly D) Catastrophism supports rapid changes on the earth and a young age of the earth while Uniformitarianism requires long times for changes to be significant and thus a very old earth

Q: Who is credited with formulating the doctrine of uniformitarianism? A) Aristotle B) Lyell C) Hutton D) Playfair

Q: One reason that Catastrophism was popular was ________. A) Ussher's estimated age of the earth required catastrophic events to form mountains and canyons B) Hutton's observations of great geologic time could not explain the rise of mountains or formation of deep canyons C) everyone loves a disaster and as a result, the hypothesis that supported disasters was a favorite D) there were many real catastrophes, like earthquakes and volcanic eruptions, to support the Catastrophism idea

Q: The basic concept of Uniformitarianism is ________. A) nothing has changed since the earth was formed B) geology has not changed since the earth was formed but other things do change C) geology changes constantly but the rules that control those transformations do not change D) there is a predictable way that the laws of nature change over time and we are beginning to understand them E) evolution, Plate Tectonics, and similar theories are all related and can be viewed as the grand theory of Uniformitarianism.

Q: In the late 1700s James Hutton published his important work titled ________. A) Catastrophism B) Principles of Geology C) Modern Earth Science D) Theory of the Earth

Q: In the mid-1600s, James Ussher determined that the earth was created in 4004 BC based on ________. A) ancient records from the Egyptians B) Biblical passages C) fossils D) rates of deposition and erosion of earth materials E) none of the above

Q: Modern geochronology studies recognize that most radiometric dates record a time when a mineral cools below a temperature where the mineral closes to gain or loss of parent and daughter isotopes. This "closure temperature" varies between different minerals and different isotopic systems. This has allowed the absolute dating of sedimentary rocks through dating of single crystals. For example, if a rock is heated above the closure temperature of the rocks constituent minerals, the date of that mineral provides a minimum age. In contrast, if the rock contains a mineral with a closure temperature higher than the maximum temperature reached by the rock, that mineral will retain the age from its source. The mineral zircon dated by U-Pb methods is an example. So, you look at a rock that has Cretaceous fossils in it, but your paleontologist friend looks at them and cannot determine if they are Early or Late Cretaceous in age. The rock contains the mineral apatite, which accumulates He through the decay or U and Th, but closes to He loss at temperature of around 75oC. You know from the stratigraphic section that the rocks were originally buried at least 3km. The local geothermal gradient is about 35oC/km. You obtain an apatite He date of 105 +/- 2 million years. You also date 100 grains of zircon from the rock. The zircons yield dates that range in age from 2.1 billion years to 125 million years. Three different zircon grains yield ages between 125 and 127 million years. You google "cretaceous time scale" and learn that the Cretaceous begins at about 144 million years and ends at about 65 million years ago. The Early Cretaceous ends about 100 million years ago. How old are these sedimentary rocks?

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