TCI Science Unit 4 Lesson 2

What is the law of superposition?

• Igneous rock is older than nearby sedimentary rock, which is older than nearby metamorphic rock.

• A sedimentary rock layer in its original position is older that the layers above it and younger than the layers below it.

• Metamorphic rock is older than nearby sedimentary rock because sedimentary rock is deposited before metamorphic rock forms.

• The exact age of a sedimentary rock layer can be found using the layers above and below it, even if the layers are not in their original positions.

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NGSS.MS-ESS1-4

How does the law of crosscutting relationships explain the age of a fault caused by an earthquake?

• The fault is older than the rocks above it.

• The fault is younger that the rocks above it.

• The fault is older than the rocks it cuts through.

• The fault is younger than the rocks it cuts through.

Many fossils are found only during certain periods in the geologic record. Scientists use these fossils to determine the relative ages of rock layers. The diagram shows relative ages of four fossils. Which statement is true of a rock layer that contains fossil F?

• It could also contain fossil G

• It was formed in periods 1, 2, and 3.

• It is older than the rock layers that contain fossil H.

• It is younger than the rock layers formed in period 4.

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NGSS.MS-LS4-1

Which of these choices is an example of the way a geologist would use relative dating?

• determining the minerals that make up rocks

• placing rock layers in order of oldest to youngest

• classifying rocks as igneous, sedimentary or metamorphic

• using radioactive isotopes to determine the exact age of rock samples

What is a geologic column?

• a rock structure that is shaped like a column

• a body of rock that cuts through sedimentary rock layers

• a group of rock layers that are taken out of the ground to study

• a group of rock layers that are placed in order of their relative ages

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NGSS.MS-ESS1-4

A geologist is studying three layers of sedimentary rock in an area. the layers have not shifted from their original positions. The geologist records the relative ages of the rocks. The bottom layer is listed as the oldest. The top layer is listed as the youngest. What did the geologist use to determine the relative ages of the rocks?

• mineral content

• radioactive decay

• the law of superposition

• the principle of unconformity

The following diagram shows rock layers that are cut by a fault and two bodies of rock (rock 1 and rock 2). What are the relative ages of the features in order of oldest to youngest?

• fault, rock 1, rock 2, layer 1

• layer 1, rock 2, rock 1, fault

• rock 2, layer 1, rock 1, fault

• fault, rock 2, layer 1, rock 1

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NGSS.MS-ESS1-4

How do scientists use fossils to determine the relative ages of rock layers?

• by comparing all the fossils in one rock layer

• by comparing fossils in many different rock layers

• by determining the positions of fossils in many different rock layers

• by locating other areas of the world where the same fossils are found

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NGSS.MS-LS4-1

A team of geologists compared the rock layers found in Florida to those found in northwest Africa. The placed all of the rock layers from the two regions in order from youngest to oldest. What did the team make?

• a fossil record

• a geologic record

• a geologic column

• a topographic map

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NGSS.MS-ESS1-4

How does sedimentary rock usually form?

• in large crystals

• in vertical layers

• in swirling bands

• in horizontal layers

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NGSS.MS-ESS2-1