Which of the following is a reason why rock units may

Problem 96MCQ This figure has rock units and geologic features that are assigned letters that are not in any particular order. From the geologic relations, what is the oldest unit or feature of those listed below? A. the canyon (feature N) B. lava flow (unit L) C. dike (unit D) D. fault (feature F) E. old river channels (feature R)

Problem 97MCQ Using the data in this table, calculate the number of half-lives that have passed for the granite (unit G on this table)? A. 1 B. 2 C. 3 D. 4 E. 5

Problem 98MCQ Using the data in this table, determine the age of the granite (unit G on this table). A. 500 B. 750 C. 50,000,000 D. 1,000,000,000 E. 1,500,000,000

Problem 94MCQ This figure has rock units and geologic features that are assigned letters that are not in any particular order. From the geologic relations, what is the oldest unit? A. limestone in the far right (unit K) B. dike (unit D) C. conglomerate (unit C) D. lava flow (unit L) E. granite (unit G)

Problem 93MCQ From this cross section of the Grand Canyon, what is the boundary between the various Precambrian rocks and the Paleozoic sedimentary units? A. it is a depositional contact, probably representing only a short period of geologic time B. it is an angular unconformity in most places and a nonconformity where it overlies granite C. it generally is an unconformity and represents more time in the right part of the diagram than in the left part of the diagram D. all of these

Problem 95MCQ This figure has rock units and geologic features that are assigned letters that are not in any particular order. From the geologic relations, what is the youngest unit or feature of those listed below? A. limestone in the far right (unit K) B. dike (unit D) C. conglomerate (unit C) D. lava flow (unit L) E. granite (unit G)

Problem 99MCQ Using the data in this table, calculate the number of half-lives that have passed for the dike (unit D on this table). A. 1 B. 2 C. 3 D. 4 E. 5

Problem 100MCQ Using the data in this table, determine the age of the dike. A. 500 B. 1,000 C. 40,000,000 D. 500,000,000 E. 1,000,000,000

Problem 2MCQ What is the main geologic feature for which Siccar Point in Scotland is famous? A. a boundary between steep gray layers below and gently dipping red layer above B. an unconformity C. an ancient erosion surface D. all of these E. none of these

Problem 3MCQ Which numbered layer in this photograph represents the oldest layer? A. 1 B. 2 C. 3 D. 4

Problem 1MCQ What type of feature is shown in this photograph of Siccar Point, Scotland? A. monocline B. thrust fault C. normal fault D. unconformity

Problem 7MCQ This photograph shows an upper unit with fragments and a lower unit with tilted layers. Which of the following statements is true? A. the upper unit is younger because it is on top B. the upper unit is younger because it contains pieces of the underlying unit C. the lower unit is older because it was tilted and eroded before deposition of the upper unit D. all of these

Problem 5MCQ Which sequence of numbers reflects the order in which the layers were deposited? A. 1, 2, 3, 4 B. 1, 3, 4, 2 C. 4, 3, 2, 1 D. 4, 3, 1, 2 E. none of these

Problem 8MCQ This photograph shows an upper light-colored conglomerate and a lower dark basalt. Which of the following statements is true? A. the conglomerate is older because it overlies the dark basalt B. the conglomerate is younger because it contains clasts of the dark basalt C. the basalt is younger because it is crosscut by fractures filled with conglomerate D. none of these

Problem 6MCQ Where is the oldest layer in this tilted sequence of sedimentary rocks? A. at the top of the hill in the center of the photograph B. the darkest layers will be the oldest C. the layers on the lower left part of the photograph D. the layers on the right of the photograph

Problem 9MCQ Which of the four sedimentary layers in this figure is the oldest? A. the layer on top B. the layers in the middle C. the layer on bottom D. there is not enough information to tell

Problem 4MCQ Which numbered layer in this photograph represents the youngest layer? A. 1 B. 2 C. 3 D. 4

Problem 10MCQ This photograph shows light-colored granite and darker diorite (both igneous rocks). Which of the following statements is true? A. the light-colored unit is younger because granite is more continental than diorite B. the diorite is older because its weathered surfaces are darker C. the granite is younger because it crosscuts the diorite D. all of these

Problem 11MCQ Which of the four numbered features on this figure is the oldest? A. 1 B. 2 C. 3 D. 4 Step-by-step solution

Problem 12MCQ Which of the four numbered features on this figure is the youngest? A. 1 B. 2 C. 3 D. 4

Problem 14MCQ The geologic relationships in this figure indicate that the lava flow: A. pushed the trees over B. overlies an angular unconformity C. is younger than the landscape surface partially covered by the lava flow D. that materials beneath the lava flow were uplifted from great depth

Problem 15MCQ The highest surface on this figure is a river terrace. This terrace: A. is older than the modern river channel B. formed sometime in the past C. predates erosion down to the present level D. all of these

Problem 16MCQ What kind of geologic feature is shown in this photograph? A. contact metamorphism B. unconformity C. desert varnish D. desert pavement E. none of these

Problem 13MCQ What type of feature is represented by the boundary between geologic units 2 and 3? A. cleavage B. unconformity C. anticline D. joint

Problem 18MCQ What is a principle we use to determine the age of a landscape surface? A. A landscape surface must be older than any rocks onto which it is carved. B. A landscape surface is younger than any rock that is deposited on top of the surface. C. The highest river terrace is probably the youngest in age. D. A surface with a well-developed soil is probably older than a surface with no soil.

Problem 21MCQ This figure shows a disconformity between an upper dark layer (being deposited by the sea) and a lower light-colored layer. What happened to form this disconformity? A. The lower layers were tilted and untilted before deposition of the upper layers. B. The boundary between the two units indicates that for a time there was either erosion or no deposition. C. The lower limestones were converted into another rock type by seawater. D. The upper layer must have been deposited by volcanic eruptions.

Problem 19MCQ What is the youngest event represented in this block diagram? A. formation of the lowest layer B. deposition of the top layer C. erosion of a canyon by a river D. retreat of the seas

Problem 17MCQ What kind of geologic feature is shown in this photograph? A. contact metamorphism B. unconformity C. desert varnish D. desert pavement E. none of these

Problem 22MCQ How does an angular unconformity form? A. rocks are folded into an angle and the top is removed by faulting B. older rocks are tilted, eroded, and overlain by younger rocks C. rock layers are turned upside down at an angle D. angular rocks are deposited on top of flat-lying layers E. any of these

Problem 20MCQ In this photograph, Paleozoic sandstone rests depositionally on Precambrian granite. What events must have occurred before deposition of the sandstone? A. uplift of granite to the surface B. solidification of granite at depth C. formation of an erosion surface D. all of these E. none of these

Problem 24MCQ The term half life represents the time it takes: A. to dissolve half of the atoms in the lattice B. for the parent atoms to decay into atoms half their original size C. for half of the parent atoms to decay into daughter atoms D. for the Sun to decrease its size by 50 percent

Problem 25MCQ If a rock started with 1,000 atoms of a parent but now contains 250 atoms, how many half lives have passed? A. .25 half lives B. .5 half lives C. 1 half life D. 2 half lives E. there is no way to tell

Problem 26MCQ Which of the following is NOT something we can learn by determining isotopic ages? A. the age of a volcanic eruption B. the age when a rock is uplifted toward the surface C. the age of material from which clasts in a sedimentary rock were derived D. the cooling history by using different types of isotopic ages E. we can determine all of these

Problem 23MCQ If the contact between the upper light-colored sedimentary layers and the lower dark-colored metamorphic rocks is a depositional contact, what type of feature is present? A. a surface representing missing geologic time B. an angular unconformity C. an ancient erosion surface D. all of these

Problem 27MCQ The impressions of fossil shells in this photograph probably indicate that the rock was deposited: A. by the wind B. in the sea C. in a dry climate D. in a forest

Problem 28MCQ The fossil fern in this photograph probably indicate that the rock was deposited: A. by the wind B. in the deep ocean C. in the shallow ocean D. on land

Problem 29MCQ Which of the following is NOT a way in which fossils can be preserved? A. They can be replaced by hard materials, such as silica. B. They can be buried and decay, leaving a cavity in the rock. C. They can be preserved in ancient tree sap. D. They can be too small to see but can build diagnostic features in the rocks. E. All of these are ways a fossil can be preserved.

Problem 30MCQ What factors are the most critical in determining whether a fossil is preserved? A. the age of the fossil and the age of sediments in which it is preserved B. the temperature of the granite and how fast it cooled C. whether the creature had hard parts and how fast it was buried D. the color of the original organism compared to the color of the sediments in which it is found E. whether the creature was a predator or was prey

Problem 31MCQ Which of the following features look like fossils but are not? A. footprints from dinosaurs and other creatures B. burrows excavated by worms and other creatures and filled by other sediment C. leaves and other plants formed on land D. dark minerals that grow in branching patterns E. all of these are fossils

Problem 32MCQ This figure shows the main subdivisions of the geologic timescale. Which of these is the Cenozoic? A. A B. B C. C D. D

Problem 35MCQ This figure shows the main subdivisions of the geologic timescale. Which of these is the Precambrian? A. A B. B C. C D. D

Problem 34MCQ This figure shows the main subdivisions of the geologic timescale. Which of these is the Paleozoic? A. A B. B C. C D. D

Problem 33MCQ This figure shows the main subdivisions of the geologic timescale. Which of these is the Mesozoic? A. A B. B C. C D. D

Problem 36MCQ Which of the following time periods were dinosaurs the dominant creatures? A. Cenozoic B. Mesozoic C. Paleozoic D. Precambrian

Problem 37MCQ To what does the term evolution refer? A. observed changes in the fossil record B. to one or more theories that help explain observed changes C. as a general term to describe how something, such as a landscape, has changed over time D. all of these

Problem 38MCQ Which of the following is the earliest (oldest) chapter of geologic time? A. Cenozoic B. Mesozoic C. Paleozoic D. Precambrian

Problem 39MCQ In which of the following time periods did coral, clams, fish, plants and insects become abundant? A. Cenozoic B. Mesozoic C. Paleozoic D. Precambrian

Problem 42MCQ The contact at the base of unit F in both columns: A. is a disconformity B. represents erosion or no deposition C. represents some missing time D. all of these

Problem 41MCQ Which of the following chapters in geologic time occurred before there were abundant animals with hard parts? A. Cenozoic B. Mesozoic C. Paleozoic D. Precambrian

Problem 40MCQ In which of the following time periods were mammals the dominant type of life? A. Cenozoic B. Mesozoic C. Paleozoic D. Precambrian

Problem 44MCQ Why don't these two sequences of fossil-bearing rocks match exactly? A. they represent different parts of geologic time B. one section was tilted but not the other C. they have different histories of erosion and deposition D. one represents a transgression whereas the other represents a regression

Problem 43MCQ Unit C is present in the left column but not the right column because: A. rocks in the right column were tilted and eroded B. it was not deposited or was eroded away C. it has different kinds of fossils than rocks in the right column D. all of these

Problem 45MCQ This figure shows two sections that represent the same age range and contain some of the same fossils. If you compare the two sections, what conclusions do you come to? A. Some of the fossils must have had a limited geographic distribution. B. Some units were deposited in the left section but not in the right one or were eroded away. C. The thickness of the units are consistent between the two sections. D. All of these. E. None of these.

Problem 46MCQ This figure shows two sections of rocks. What is the youngest unit? A. unit 1 B. unit 4 C. unit 6 D. unit 9 E. none of these

Problem 49MCQ This figure shows the geologic timescale. Which period listed below would be part of the Cenozoic? A. Neogene B. Jurassic C. Triassic D. Pennsylvanian E. Cambrian

Problem 47MCQ This figure shows two sections that partially overlap in age. Dashed lines show how the two sections correlate. What can you conclude from these correlations? A. the oldest unit is unit 4 B. the youngest unit is unit 6 C. the rate at which unit 5 was deposited was constant across the area D. the left section represents older rocks than the right section E. none of these

Problem 51MCQ This figure shows the geologic timescale. Which period listed below would be part of the Paleozoic? A. Neogene B. Paleogene C. Jurassic D. Triassic E. Cambrian

Problem 50MCQ This figure shows the geologic timescale. Which period listed below would be part of the Mesozoic? A. Neogene B. Jurassic C. Pennsylvanian D. Mississippian E. Cambrian

Problem 48MCQ Which of the following collection of fossils would be LEAST useful for determining the age of a section of rocks? A. fossils that are large and distinctive B. fossils that are widely distributed across different parts of Earth C. the fossil of a family of creatures that lived unchanged for a very long time D. index fossils

Problem 52MCQ This figure shows the geologic timescale. Which period listed below would be part of the Paleozoic? A. Permian B. Pennsylvanian C. Mississippian D. Cambrian E. all of these

Problem 53MCQ How would we use isotopic ages to infer the ages of the upper and lower unit in this diagram? A. The lower unit would be younger than an age on the crosscutting dike. B. The upper unit would be older than an age determined on pebbles of the dike in that unit. C. The dike is younger than the lower unit but older than the upper unit. D. An age on the dike would not help us because it is an igneous rock.

Problem 55MCQ Upon what basis were the upper and lower boundaries of the Mesozoic Era defined? A. dramatic changes in the color of the rocks from green to tan B. major episodes of mountain building C. abrupt changes in the types of fossils, representing mass extinctions D. the discovery that a meteoroid impact may have killed the dinosaurs

Problem 54MCQ What would fossil ages from the geologic timescale and an isotopic age on the granite tell us about the age of the unconformity? A. The unconformity is older than the isotopic age of the granite. B. The unconformity is older than the age assigned to the fossils. C. The granite is younger than the unconformity. D. It is not possible to have fossils preserved so close to granite. E. None of these.

Problem 57MCQ Which of the following is evidence that Earth’s history is not short? A. millions of layers of light- and dark-colored sediment that record yearly cycles B. rates of seafloor spreading compared to the width of the Atlantic Ocean C. a 4-billion-year age on a rock in Canada D. thousands of isotopic ages measured by different methods E. all of these

Problem 58MCQ Which of the following forms different layers from season to season and can be used to determine how many years the layers represent? A. tree rings B. layers in ice cores C. varves D. all of these

Problem 59MCQ Which of the following is NOT accurately dated at between 4 and 4.6 billion years old? A. the oldest dates on mineral grains on Earth B. age of the oldest meteorites C. age of moon rocks returned to Earth and dated D. isotopic ages on Earth’s oldest known fossil shell

Problem 56MCQ What would fossil ages from the geologic timescale tell us about the age of this unconformity? A. The unconformity is younger than the fossil ages on the tilted bed. B. The unconformity is older than the fossil ages in layers above the unconformity. C. The amount of time represented by the unconformity can be approximately bracketed by the ages of the fossils above and below. D. All of these.

Problem 61MCQ What were some of the earliest forms of life on Earth? A. land plants and insects B. corals and other bottom-dwelling sea creatures C. microscopic creatures that built mound-shaped structures called stromatolites D. sharks

Problem 64MCQ What is a possible cause of the extinction event called the Great Dying? A. a meteorite impact that killed the dinosaurs B. a great outpouring of lava at the end of the Paleozoic C. a sudden increase in the oxygen content of the atmosphere during the Precambrian D. a new kind of super predator that devoured nearly all of the life in the oceans

Problem 63MCQ What types of life developed during the Paleozoic? A. corals, crinoids, and other creatures with shells B. trilobites C. fish and amphibians D. plants and insects E. all of these -

Problem 60MCQ This art work shows life on the sea bottom, at a time when fishes and creatures with shells appeared on Earth. What time period is represented? A. Mesozoic B. Cenozoic C. Precambrian D. Paleozoic

Problem 65MCQ What time period is represented by this scene? A. Mesozoic B. Cenozoic C. Precambrian D. Paleozoic

Problem 66MCQ What time period is represented by this scene? A. Mesozoic B. Cenozoic C. Precambrian D. Paleozoic

Problem 67MCQ Which of the following did NOT live during the Mesozoic era? A. dinosaurs that had a bird-like hip B. dinosaurs with a hip structure similar to lizards C. large flying reptiles D. large marine reptiles E. all of these lived during the Mesozoic

Problem 68MCQ What marks the boundary between the Mesozoic and the Cenozoic (called the K-P boundary)? A. the extinction of the dinosaurs B. the start of a rise to dominance of mammals C. a meteorite impact in Mexico D. all of these E. none of these

Problem 70MCQ Which of the following would be LEAST useful in correlating the ages of these two sequences of rocks? A. numeric ages on the volcanic rocks on top B. the pattern of magnetic reversals (R and N) C. the overall sequence of the upper three layers D. the type of material present in the landslide at the bottom of the right column

Problem 69MCQ If you were trying to correlate these two sequences of rocks, what would probably be the most straightforward strategy to use? A. determine numeric ages on pieces of rock in the landslide on top B. compare the fossils of the middle layers C. compare the thicknesses of the middle layer D. compare the thicknesses of the lower layer

Problem 71MCQ This figure shows two sections of rocks. Which of the following is NOT a valid way to correlate one of the numbered units from one section to another? A. Units at the top of two sections will automatically be correlative. B. A distinctive rock type (breccia in unit 4) is probably equivalent to the same rock type in the other section. C. Match units that contain the same types of index fossils (as in unit 3). D. The shale in unit 2 is part of a distinctive sequence that is overlain by the same type of fossils.

Problem 72MCQ Which of the numbered units is the oldest? A. unit 4 B. unit 6 C. unit 8 D. unit 9 E. unit 10

Problem 76MCQ Which of the following is a reason why rock units may change from one section to another? A. facies change B. restricted aerial distribution C. removed along an unconformity or disconformity D. eroded away E. all of these

Problem 74MCQ Of the following numbered units, which is the youngest? A. a sedimentary layer (2) B. the fault and fault scarp (3) C. a sedimentary layer (5) D. the volcano and lava flow (9) E. the highest sedimentary layer (11)

Problem 75MCQ Of the following numbered units, which is the oldest? A. a sedimentary layer (2) B. the granite (4) C. gravels along the river (7) D. the volcano and lava flow (9) E. the highest sedimentary layer (11)

Problem 73MCQ Of the following numbered units, which is the youngest? A. unit 4 B. unit 5 C. unit 6 D. unit 9 E. unit 11

Problem 77MCQ This figure shows two sections of rocks. What is the surest way to correlate a unit in one section to a unit in the other section? A. match the similar sequence of rocks B. find a distinctive unit in both sections C. find two layers that both contain fossils D. physically trace a unit through the landscape from one section to another

Problem 80MCQ Which of the following might help determine the age of the volcanic features in this figure? A. numeric ages B. how well the shapes of the volcanoes are preserved C. how well developed soil is on the lava flows D. all of these

Problem 81MCQ Which numbered feature in this figure is the oldest? A. the upper volcanic unit (1) B. limestone (2) C. sandstone (3) D. metamorphic rocks (4) E. granite (5)

Problem 79MCQ In this diagram, the contact between the granite (unit 1) and the lowest layer (unit 2) is depositional and the dike (unit 6) cuts across both units. What is the oldest unit? A. the lava flow (unit 11) B. the fault (unit 10) C. the dike (unit 6) D. lowest layer (unit 2) E. granite (unit 1)

Problem 78MCQ In this diagram the contact between the granite (unit 1) and the lowest layer (unit 2) is depositional. What is the youngest unit? A. the lava flow (unit 11) B. the fault (unit 10) C. highest layer (unit 5) D. lowest layer (unit 2) E. granite (unit 1)

Problem 82MCQ Which numbered feature in this figure is the youngest? A. the upper volcanic unit (1) B. limestone (2) C. sandstone (3) D. metamorphic rocks (4) E. granite (5)

Problem 84MCQ Which of the numbered features is the oldest? A. conglomerate (1) B. unconformity (2) C. shale layer (3) D. lower sedimentary units (4) E. formation of the fold (5)

Problem 83MCQ What happened between deposition of units 1 and 2? A. erosion and weathering B. mineralization as expressed by the zone around the granite C. solidification of magma into granite D. all of these

Problem 85MCQ Which of the numbered features is the youngest? A. conglomerate (1) B. unconformity (2) C. shale layer (3) D. lower sedimentary units (4) E. formation of the fold (5)

Problem 87MCQ This figure shows two fault scarps, a lava flow, and erosion along one of the scarps. What is probably the oldest feature of those listed below? A. the scarp on the left B. the scarp on the right C. the lava flow D. erosion of the scarp on the right

Problem 86MCQ Which of following geologic events is the youngest? A. deposition of the shale (3) B. deposition of the lower units (4) C. formation of the fold (5) D. accumulation of the oil and gas

Problem 88MCQ What strategies do we use to investigate human origins? A. the same relative-dating principles we apply to older rocks B. finding pieces of an older wall in younger deposits C. determining carbon-14 ages on bones, wood, and charcoal D. dating interbedded volcanic rocks E. all of these

Problem 89MCQ For which of the following resources do geologic ages help us explore? A. mineral deposits related to granites B. oil and gas C. groundwater D. all of these

Problem 90MCQ From this cross section of the Grand Canyon, what are the oldest rocks or structures? A. Late Cenozoic basalts B. Mesozoic sedimentary rocks C. Precambrian sedimentary and igneous rocks D. Precambrian metamorphic rocks and granite E. Hurricane fault and faults along the Grand Wash Cliffs

Problem 91MCQ From this cross section of the Grand Canyon, what occurred between the formation of the Precambrian metamorphic rocks and the deposition of the lowest Paleozoic rocks? A. uplift B. erosion C. deposition and tilting of the Precambrian sedimentary and igneous rocks D. all of these E. a and b only

Problem 92MCQ From this cross section of the Grand Canyon, what is the youngest rock or structure of the ones listed below? A. Late Cenozoic basalts B. Mesozoic sedimentary rocks C. Precambrian sedimentary and igneous rocks D. Precambrian metamorphic rocks and granite E. Hurricane fault and faults along the Grand Wash Cliffs

Problem 62MCQ What was the Cambrian explosion? A. a large volcano that went off in Wales, which the Romans called Cambria B. a meteorite impact that struck the north coast of the Yucatan Peninsula of Mexico C. a time when a meteorite collided with the center of a supercontinent, melting all the glaciers D. a time when many different types of creatures appeared on Earth