Unit 6 Review

The processes of weathering and erosion remove rock material from the surface of rocks. If the eroded surface gets buried during deposition of sediment, a specific geologic feature is formed. This feature marks a gap in time. What is it called?

• half-life

• correlation

• index fossil

• unconformity

Tags

NGSS.MS-ESS1-4

Index fossils are used to help correct rock layers. They are also used to help determine the relative age of rock layers. What makes index fossils useful to geologists?

• the species lived over a short period of geologic time

• few in number

• not easily recognized

• distributed over a small geographic area

Suppose that this figure represents the Miccosukee Formation.

Where is the oldest layer of the Miccosukee Formation?

• 1

• 2

• 3

• 4

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NGSS.MS-ESS1-4

Geologists have determined that while the Miccosukee Formation was being deposited, some of the layers were eroded away by wave action. The eroded surface was later covered by more sediment. The layers of the Miccosukee Formation are all horizontal. Suppose that this figure represents the Miccosukee Formation.

In what type of environment did the Miccosukee Formation form?

• in a desert

• on a glacier

• along a coastline

• at the bottom of a lake

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NGSS.MS-ESS1-4

NGSS.MS-ESS2-1

NGSS.MS-ESS2-2

What characteristic of radioactive decay makes it useful for determining the absolute age of samples?

• occurs at a constant rate

• changes based on temperature

• slows down in very dense samples

• speeds up based on the amount of the sample

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NGSS.HS-PS1-8

Radiocarbon dating is used to determine the age of materials that contain the isotope carbon-14. Which choice below can be dated using radiocarbon dating?

• lava flows

• igneous rock

• organic matter

• living organisms

When using radiometric dating, what are we determining?

• the relative date that a fossil lifeform died

• the time of crystallization of an igneous rock

• the degree of foliation in a metamorphic rock

• the rate of sedimentation of a sedimentary rock

Tags

NGSS.MS-ESS1-4

Angel and Ramona are studying relative time in their Earth science class. They have taken a day trip to Gadsden County, in Florida’s panhandle. They want to study the layers of sand and gravel that make up a rock unit called the Miccosukee Formation.
Geologists have determined that while the Miccosukee Formation was being deposited, some of the layers were eroded away by wave action. The eroded surface was later covered by more sediment. The layers of the Miccosukee Formation are all horizontal.

When Angel and Ramona returned home from the field trip, they wanted to determine the numerical ages of their sandstone samples they collected. Their professor told them that it would not be possible to do. Why not?

• The samples are poorly sorted and only grain sizes that are the same can be used in radioactive dating.

• The pieces of rock in the sandstone are too old for radioactive dating to work correctly.

• The grains that make up the sandstone are from older rocks that were broken apart and deposited as sandstone.

• The cement that glues the sandstone together is made of a different material which will interfere with the testing.

The figure shows a newly discovered index fossil. What happened that helped this fish become a fossil?

• It was buried quickly.

• It was eaten by scavengers.

• It got exposed at the surface.

• It got subjected to high temperatures.

Tags

NGSS.MS-ESS1-4

NGSS.MS-LS4-1

In a recent science magazine, a scientist reported the discovery of a new variety of fossil. It is very different from other fossils in the area. It is only present in rock layers at the bottom of a small lake area. The organism seems to have been very rare, and the fossil records indicate that this species existed for a short period of time. Would this make a good index fossil?

• Yes because a rare fossil is very distinct and index fossils are distinct.

• Yes because the lifeform lived for a short period of time and the fossil is rare.

• No because index fossil species must be both abundant and have lived for a short period of time.

• No because index fossils must be abundant, have lived for a short period of time and be distinct in appearance.