Earth History

Which best describes a fossil that helps determine the relative age of a rock layer?

• trace fossil
• index fossil
• radioactive fossil
• unconformity fossil

Which is the most accurate method scientists can use to estimate Earth's age?

• relativism
• superposition
• relative dating
• radioactive dating

The index fossil of a type of trilobite is discovered in layer A of a set of rock layers found at three different sites of a field investigation. Which conclusion can be made about the rocks in layer A at all three sites?

• The rocks are all different ages
• The rocks are all about the same age
• The rocks were formed from melting magma
• The rocks were formed during a catastrophic event

Which statement is true?

• The oldest layers of rock and soil are closest to the surface of the earth
• The youngest layers of rock and soil are farther away from the surface of the earth.
• Carbon-14 dating is an example of relative dating, and the law of superposition is an example of absolute dating.
• Absolute geologic dating and relative geologic dating are two methods used by scientists to determine the age of geologic evidence.

Which type of rock replaces bone and other hard organic materials to create rock molds of fossils?

• metamorphic
• sedimentary
• extrusive igneous

What role do faults play in the Law of Superposition?

• Faults create new types of rock.
• Faults are younger than the layers they cut through.
• Faults are the same age as the layers they cut through.

The diagram below represents three bedrock outcrops. The layers have not been overturned. Letters A through E identify different rock layers. Fossils found in the rock layers are shown.

• 1
• 2
• 3
• 4

The table below shows the radioactive decay of carbon-14. Part of the table has been left blank. After 22,800 years, approximately what percentage of the original carbon-14 remains?

• 15%
• 12.5%
• 6.25%
• 3.125%

The timeline below represents time on Earth from the beginning of the Paleozoic Era (A) to the present (B). Which numbered position best represents the time when humans first appeared in the fossil record?

• 1
• 2
• 3
• 4

The cross sections below represent three outcrops, labeled I, II, and III, containing some New York State index fossils. The rock layers have not been overturned. When the rock layers in the three outcrops are correlated, the oldest layer is the

• Shale layer in outcrop I
• Siltstone layer in outcrop II
• Limestone layer in outcrop III
• Conglomerate layer in outcrop III