Trace fossils

The Rock RecordThe questions will be read automatically, if you want to hear it again click on the speaker.0Trace fossilsa.fossilized animal tracks b.c.a fossil used to date rock layers d.

1disconformitya.sedimentary rock layers are younger than layers below b.a layer of sedimentary rock over an older, eroded layer of rock c.

2varvea.an interruption in the geologic record b.a layer of sediment deposited annually c.d.

3unconformitya.an interruption in the geologic record

b.a layer of sediment deposited annually c.d.

4index fossilsa.a fossil used to date rock layers

b.sedimentary rock layers are younger than layers below c.d.

5nonconformitya.a fossil used to date rock layers

b.c. a layer of sedimentary rock over an older, eroded layer of rock d.

6Absolute agea.b.c.numeric age of an object d.the age of an object in relation to other objects

7uniformitarianismA.B.the age of an object in relation to other objectsC.D.the principle that geologic processes that occurred in the past can be explained by current geologic processes

8Relative agea.b.c.numeric age of an object d.the age of an object in relation to other objects

9Law of superpositionA.B.sedimentary rock layers are younger than layers below C.a layer of sedimentary rock over an older, eroded layer of rock D.

10A varve is most like a(n) a.b.c.tree ring.d.glacial lake.

11The way fossils are formed in very dry places is called

a.mummification. b.petrification.c.d.

12What is amber?a.b.c.tar that fossilizes insectsd.tree sap that fossilizes insects

13What is a coprolite?a.fossilized fish b.fossilized dung or wastec.d.

14If an igneous intrusion is observed through a layer of sedimentary rock, what geological law or principle applies?a.b.c.law of crosscutting relationshipsd.law of thermodynamics

15Using rates of erosion to determine the absolute age of a geologic feature is practical only for features formed within the past

a.b.c.10,000 to 20,000 years.d.10,000 years.

16Why is radioactive decay used to determine the absolute age of rocks?a.b.Radioactive decay happens very quickly.c.d.Radioactive decay happens at a relatively constant rate.

17How is radioactive decay used to determine the absolute age of rocks?

a.Parent isotopes are compared to daughter isotopes. b.Isotopes of different compounds are compared.c.d.

18What is a gastrolith?a.a stone inside a fishb.a stone that was inside a dinosaurc.d.

19Carbon films are a.carbonized trace fossils.b.c.carbonized residue of plants or fish.d.

20moldA. fossils of shells within hardened sedimentB.C.D.stone from a dinosaurs digestive system, used to help grind food

21isotopesA.a fossil used to estimate the age of rock layersB.atoms of the same element that have different numbers of neutronsC.D.

22paleontologyA.a fossil used to estimate the age of rock layersB.C.D.the scientific study of fossils

23half-lifea.b.the time it takes half the mass of a given amount of a radioactive isotope to decay into its daughter isotopesc.d.atoms of the same element that have different numbers of neutrons

24Which of the following are all ways that organisms can be fossilized?

a.freezing, petrification, desiccation, amber

b.amber, petrification, mummification, freezingc.d.

25In radiometric dating, scientists compare the proportion of a radioactive parent isotope to a stablea.b.c.daughter isotope.d.child isotope.

26One method used to estimate the absolute age of a stream is toa.measure the amount of sediment.

b.measure the rate at which the stream erodes its bed.c.d.

27When mineral solutions replace original organic materials to create a fossil, the process is called A. B. C. PetrificationD. Casting

28A break or crack in Earths crust along which rocks shift their position is called a(n) a.intrusion.b.fault.c.d.

29A varve consists of a a.b.c.coarse summer layer of sediment overlaid with a fine winter layer. d.layer of coarse sediment deposited annually.

30In general, sedimentary rock is deposited at the rate of a.30 cm over 1,000 years.b.30 cm over 100 years.c.d.

31Almost all fossils are discovered in a.b.metamorphic rock.c.sedimentary rock. d.

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original horizontalitya.b.c.horizontal layers of old sedimentary rock erode, then get covered by new layersd.undisturbed sedimentary rock remains in horizontal layers

33angular unconformitya.folded or tilted rock comes to the surface, erodes, and new sediment is depositedb.c.horizontal layers of old sedimentary rock erode, then get covered by new layersd.

34Carbon-14 is an isotopea.formed by radioactive decay.b.used to date objects less than 70,000 years old.c.d.

35A frozen organism does not decay becausea.most bacteria cant survive freezing temperatures.b.c.it needs water to decay.d.

36Layers of rock are calleda. strata.b. data.c. d.

37What can scientists assume when sedimentary rock layers are not horizontal?

a. The rock layers have been tilted or deformed

b. The rock layers are not actually sedimentary.

c.

d.

38Which geologic feature can be given an absolute age using rates of erosion?

a.Mt. Saint Helensb.c.Niagara Fallsd.

39Small amounts of what type of materials in rocks can act as natural clocks?a.b.c.radioactived.igneous

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