Geologic History Name__________________________

Base your answers to questions 1 through 3 on the geologic cross section in your answer booklet.Rock units A through H are shown. Several rock units contain fossils. Rock unit G was formed in azone of contact metamorphism.

1. Identify the letter of the rock unit that was formed at the same time as igneous rock unit H.

2. Identify two possible geologic periods during which the sediments that formed rock unit E could havebeen deposited.

3. Explain why the absolute age of the fossils shown in the cross section can not be determined by usingradioactive carbon-14.

A) A B) B C) C D) D

4. The graph below shows the extinction rate of organisms on Earth during the last 600 million years.Letters A through D represent mass extinctions.

Which letter indicates when dinosaurs became extinct?

A) organic origin B) constant half-lifeC) common occurrence in sediments D) resistance to weathering and erosion

5. The characteristic of the radioactive isotope uranium-238 that makes this isotope useful for accuratelydating the age of a rock is the isotope’s

A) 1.3 × 109 B) 2.6 × 109 C) 3.9 × 109 D) 5.2 × 109

6. The table below shows how the radioactive decay of potassium-40 can be used to determine the age ofa rock.

How old is a sample of granite that contains 8 grams of radioactive potassium-40 and 56 grams of itsnonradioactive decay products?

7. Base your answer to the following question on the geologic cross section below of a region of Earth'scrust. Rock layers A through E have been labeled. Two index fossils are shown and their locationswithin the rock layers are indicated.

A) folding and tilting of the rock layersB) faulting and movement of the rock layersC) igneous intrusion into the rock layersD) collision of crustal plate boundaries in the rock layers

Evidence of tectonic activity in this cross section is provided by the

A) Tug Hill Plateau B) Allegheny PlateauC) Adirondack Mountains D) Newark Lowlands

8. The diagram below shows an index fossil found in surface bedrock in some parts of New York State.

In which New York State landscape region is this gastropod fossil most likely found in the surfacebedrock?

9. Base your answer to the following question on Base your answers to questions 26 and 27 on thediagram below, which shows specific events in the history of Earth from the beginning of the universeto the present.

A) Middle Archean B) PaleozoicC) Middle Proterozoic D) Cenozoic

During which geologic era did life first appear on land?

10. Base your answer to the following question on the cross sections below, which show widely separatedoutcrops labeled I, II, and III. Index fossils are found in some of the rock layers in the three outcrops.In outcrop III, layers A, B, C, and D are labeled. Line XY represents an unconformity. Line GH represents a fault.

On outcrop II below, place the symbol ~~ for an unconformity between the two rock layers where theSilurian-age bedrock has been removed by erosion.

A) 41° N 72° W B) 43° N 77° W C) 44° N 74° W D) 44° N 76° W

11. At which latitude and longitude in New York State would a salt mine in Silurian-age bedrock mostlikely be located?

A) potassium-40 B) carbon-14 C) uranium-238 D) rubidium-87

12. Samples of plant pollen are preserved in sediment deposited by the last glacial ice sheet. Whichradioactive isotope is best for determining the age of the samples?

A) Middle Archean Era B) Early Proterozoic EraC) Early Jurassic Period D) Late Cretaceous Period

13. The largest meteorite impact crater in North America formed approximately 1,850 million years ago,which was during the

A) decrease B) increaseC) remain the same

14. If a sample of a radioactive substance is crushed the half-life of the substance will

15. Base your answer to the following question on the diagram below, which represents a model of aradioactive sample with a half-life of 5000 years. The white boxes represent undecayed radioactivematerial and the shaded boxes represent the decayed material after the first half-life.

A) carbon-14 B) potassium-40 C) uranium-238 D) rubidium-87

Which radioactive isotope has a half-life closest in duration to this radioactive sample?

A) B)

C) D)

16. The geologic cross section below shows an unconformity in New York State bedrock layers that havenot been overturned. Index fossils found throughout some rock layers are shown.

Which New York State index fossil may have been present in a rock layer that is missing due to theunconformity?

A) 1,400 years B) 2,800 years C) 5,600 years D) 11,000 years

17. An ancient bone was analyzed and found to contain carbon-14 that had decayed for nearly twohalf-lives. Approximately how old is the bone?

A) A B) B C) C D) D

18. The block diagram below of a portion of Earth's crust shows four zones labeled A, B, C, and D outlined with dashed lines.

In which zone is a younger rock unit on top of an older rock unit?

19. Base your answer to the following question on the geologic cross section below of the Grand Canyon.The numbers 1 through 10 represent Paleozoic sedimentary rock layers.

A) 1 B) 10 C) 5 D) 4

Which Paleozoic rock layer is the oldest?

A) Cambrian B) Pleistocene C) Devonian D) Triassic

20. During which period of geologic history was the surface bedrock of the Catskills deposited?

A) uranium-238 B) rubidium-87 C) potassium-40 D) carbon-14

21. The diagram below represents the skull of a saber-toothed tiger that died 30,000 years ago.

The age of the skull could be determined most accurately by using

22. Base your answer to the following question on the geologic cross section of bedrock shown below. A through G identify rock layers and Q represents a fault. Lines W, X, Y, and Z are locations ofunconformities. The rocks have not been overturned.

A) obsidian B) slateC) metaconglomerate D) sandstone

Which rock most likely formed in the zone of contact between rock E and rock F?

A) Adirondack Highlands B) Erie-Ontario LowlandsC) St. Lawrence Lowlands D) Newark Lowlands

23. Which New York State landscape region could have surface bedrock containing dinosaur fossils?

A) Cambrian B) Ordovician C) Silurian D) Devonian

24. During which geologic period would fossils in the exposed bedrock of New York State at 43º N, 77ºW most likely have been deposited?

A) variations within a species can be observed, measured, and describedB) variations within a species have had little effect upon the survival of the speciesC) few of the species of plants and animals that existed have become extinctD) there is no evidence for evolutionary development among the different fossil species

25. Studies of the fossil record found in Utah indicate that

A) A B) B C) C D) D

26. The cross section below shows undisturbed sedimentary bedrock. The ages of various layers areindicated, and reference points within the rocks are labeled A through D.

The remains of an early dinosaur could be found at reference point

27. Base your answer to the following question on the cross sections below, which show widely separatedoutcrops at locations X, Y, and Z.

A) beginning of the Cenozoic Era B) beginning of the Mesozoic EraC) end of the Cenozoic Era D) end of the Mesozoic Era

At location Y, the boundary between the red sandstone and the black shale marks the

A) B) C) D)

28. Which column best represents the relative duration of the major intervals of geologic history?

A) deposition of sediments for rock layer AB) formation of the faultC) intrusion of the igneous material ED) cementation of sediments for rock layer D

29. The geologic cross section below shows sedimentary rock layers A, B, C, and D, which have notbeen overturned. E is an igneous intrusion. Line XY represents a fault.

Which geologic event occurred most recently?

30. Base your answer to the following question on the geologic cross section below. The cross sectionshows an outcrop in which the layers have not been overturned. Rock units are labeled A through E.

State the name of the sediment that was compacted to form rock unit A.

31. Base your answer to the following question on the diagram, which shows the evolutionarydevelopment of the horse, as supported by the fossil record.

A) The horse evolved due to the influence of humans.B) The horse evolved from a complex life-form to a simpler life-form.C) The horse evolved into a life-form better able to survive.D) The horse evolved from larger ancestors without forelimbs.

Which statement best explains the changing appearance of the horse, as supported by the fossilrecord?

A) Cambrian B) Precambrian C) Permian D) Silurian

32. The diagram below shows a geologic cross section of a portion of a landscape region.

What is the probable geologic age of sedimentary rock unit X?

Base your answers to questions 33 and 34 on the graph below which shows the decay rates of fourradioactive substances, A, B, C, and D.

A) 10% B) 22% C) 63% D) 90%

33. When 90 percent of the original mass of isotope D remains, what total percent of the original mass ofisotope B remains?

A) pressure acting on the material B) amount of the materialC) temperature of the material D) composition of the material

34. The half-life of these radioactive substances depends on the

A) When the environment changed, this type of plant also changed, allowing it to survive.B) When uplifting occurred, the fossils of this type of plant were deformed.C) The processes which form fossils today differ from those of the past.D) The fossils have changed as a result of weathering and erosion.

35. Earth scientists studied fossils of a certain type of plant. They noted slight differences in the plantthroughout geologic time. What inference is best made from this evidence?

36. Base your answer to the following question on the graph below which shows the rate of radioactivedecay of element A and the rate at which decay product B is formed.

A) Precambrian B) Devonian C) Mississippian D) Pleistocene

If the half-life of radioactive element A is 10,000 years, for which time interval would this element bemost useful in determining the age of rock?

37. Base your answer to the following question on the diagram below which represents a cross section ofan eroded fold that has not been overturned.

A) Triassic Age B) Carboniferous AgeC) Cambrian Age D) Tertiary Age

If rock layer A is of Devonian Age, rock layer E could be of

A) 0 B) 1/8 C) 1/4 D) 1/2

38. A rock sample containing the radioactive isotope potassium-40 is calculated to be 4.2 × 109 years old.How much of the original potassium-40 would be left in this rock sample?

A) Present life forms have always existed.B) The Earth's environment has always been the same.C) Many life forms have become extinct.D) All life forms will remain the same in the future.

39. Which conclusion can be made based on existing fossil evidence?

40. Base your answer to the following question on the diagrams below, which represent two bedrockoutcrops, I and II, found several kilometers apart in New York State. Rock layers are lettered A through F. Drawings represent specific index fossils.

Explain why carbon-14 can not be used to find the geologic age of these index fossils.

A) before the appearance of dinosaursB) before the appearance of terrestrial plantsC) after the appearance of reptilesD) after the appearance of birds

41. When did armored fishes become extinct?

42. Base your answer to the following question on the date table below, which shows the radioactivedecay of carbon-14. The number of years required to complete four half-lives has been left blank.

How long does it take for radioactive carbon-14 to complete four half-lives?

43. Base your answer to the following question on the paragraph below, which provides backgroundinformation regarding recent fossil discoveries in Canada.

Scientific evidence indicates that the earliest mammals may have evolvedapproximately 225 million years ago from an ancient reptile group called thetherapsids. For millions of years afterward, early mammals and therapsids coexisteduntil the therapsids apparently became extinct 165 million years ago. However,geologists have recently found a fossil they believe to be a therapsid that is only 60million years old. They found the fossil, which they have named Chronoperatesparadoxus (paradoxical time-wanderer), near Calgary in Canada. This find suggeststhat for 105 million years after the apparent extinction of the therapsids, a few of thereptiles continued to live in a narrow geographic range in Canada.

According to fossil evidence, during which geologic period did the earliest mammals appear onEarth?

Base your answers to questions 44 and 45 on the diagram and information below about fossil snails.

Snails have lived in most of the world's oceans over a period of hundreds of millions of years.Paleontologists discovered that in warm, tropical waters more snails have shells that, when viewedfrom the top, spiral outward in a clockwise direction. In cool or cold waters, more snails haveshells that spiral outward in a counterclockwise direction. Both clockwise- andcounterclockwise-spiraled snail fossils have been found in New York State bedrock.

44. In a slab of rock that contains many fossil snails, what evidence would lead geologists to concludethat the slab was formed in a tropical climate?

45. State one reason bedrock that formed in tropical regions is found in New York State.

Answer KeyGeologic History Regents Review

1. G2. — Devonian Period

or MississippianPeriod —CarboniferousPeriod or DevonianPeriod

3. — The fossils aretoo old for 14Cdating. —Carbon-14 has avery short half-life.

4. D5. B6. C7. A8. A9. B10.

11. B12. B13. B14. C15. A16. B17. D18. A19. A20. C

21. D22. C23. D24. C25. A26. A27. B28. A29. C30. clay31. C32. D33. B34. D35. A36. D37. C38. B39. C40. Examples: —

Carbon-14’shalf-life is too short.— Not enoughcarbon-14 is left tomeasure. — Thefossils are too old.

41. A42. 22,800 yr.43. Triassic Period.44. Example: –

Clockwise spiralsnail shells arefound in greaternumbers.

45. Examples: –NewYork Stateexperienced awarmer climatewhen it was locatedcloser to theEquator. – TheNorth AmericanPlate has driftednorthward from theequator region overtime.