Relative Dating and Index Fossils

Which fossil organism is best represented in the Paleozoic Era?

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Tags

NGSS.MS-LS4-1

NGSS.MS-LS4-2

The diagram shows a cross section of the layers of a sedimentary rock with some fossils in it.

Assume that the rock layers have been preserved in their original sequence, which fossil is the oldest?

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Tags

NGSS.MS-ESS1-4

NGSS.MS-LS4-1

The geologic cross section diagram shows undisturbed rock layers with index fossils from two regions (A and B). The two index species are identified in the index fossil key.

Which answer option correctly describes the relative ages of the rock layers in the diagram?

• • Layer 6 is older than Layer 3.
  • Layer 2 is younger than Layer 4.

• • Layer 6 is older than Layer 3.
  • Layers 2 and 4 are the same age.

• • Layer 6 is younger than layer 3.
  • Layers 2 and 4 are the same age.

• • Layer is younger than layer 3.
  • Layer 2 is older than layer 4.

Tags

NGSS.MS-ESS1-4

A scientist studies a geologic cross section of rock layers in a region. The rock layers have not been disturbed by any faulting, folding, or tilting.

Which statement is a correct inference?

• Each rock layer is older than the one below it.

• The youngest rock layer is found at the bottom.

• Each rock layer is younger than the one below it.

• The oldest rock layer will contain the most fossils.

Tags

NGSS.MS-ESS1-4

A researcher is studying undisturbed, horizontal, sedimentary rock layers in a region. The rock layers have no igneous intrusions. He observes that some of the rock layers contain various kinds of fossils.

How can the researcher use the fossil evidence to help determine the ages of the rock layers?

• He can list the number of fossils present in each rock layer and then use the geologic law of uniformitarianism.

• He can compare the complexity of index fossils within the rock layers and then use the geologic principle of original horizontality.

• He can analyze the depth at which different fossils are present and then use the geologic principle of cross-cutting relationships.

• He can research the age of any index fossils found in the rock layers and then use the geologic law of superposition.

Tags

NGSS.MS-ESS1-4

The diagram shows Fossil A and Fossil B. Assume that Fossil A is typically found in rock layers that are far above the rock layers containing Fossil B.

Based upon the positions of Fossils A and B, which inference is best ?

• Fossil A must have evolved from Fossil B.

• Fossil B existed in greater numbers than Fossil A.

• Fossils A and B lived during the same period of geologic time.

• Fossils A and B lived during different periods of geologic time.

Tags

NGSS.MS-LS4-1

Examine the geologic cross section.

Geologists can use different kinds of dating methods to determine the ages of rocks and rock layers. If geologists are only observing the layers as shown in the diagram (and no further lab testing is performed), which kind of dating method is being used to learn about Earth's history in this example?

• absolute dating

• radiometric dating

• relative dating

• carbon dating

Tags

NGSS.MS-ESS1-4

The diagram is a geologic cross section showing sedimentary rock layers with an igneous intrusion.

Which layer of rock is the youngest ?

• layer W

• layer X

• layer Y

• layer Z

Tags

NGSS.MS-ESS1-4

The diagram shows three sedimentary rock layers and an igneous intrusion.

What is the relative age of igneous intrusion W?

• Igneous intrusion W is younger than sedimentary rock layers Z and X, but its relative age to layer Y cannot be determined.

• Igneous intrusion W is younger than sedimentary rock layers Y and Z but older than layer X.

• Igneous intrusion W is older than sedimentary rock layers Z and X, but its relative age to layer Y cannot be determined.

• Igneous intrusion W is older than sedimentary rock layers Y and X but younger than layer Z.

Tags

NGSS.MS-ESS1-4

The diagram shows the same rock layers in 1938 and in 2013.

What could have caused the change in position of layer X?

• Deposition added layers of material under layer X.

• Volcanic activity added layers of material on top of layer X.

• Erosion removed material from the layers above layer X.

• Organisms removed material from under layer X.

Tags

NGSS.MS-ESS2-2