Correlation Practice

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

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

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

Fossil remains of a trilobite are most likely to be found in which type of rock?

• igneous
• volcanic
• sedimentary
• metamorphic

Which statement best describes the Law of Superposition?

• Each sedimentary layer of rock represents 1,000 years of Earth's age, much like the rings of a tree.
• In undisturbed layers of sedimentary rocks, the upper rock layers are older than the lower rock layers.
• In undisturbed layers of sedimentary rock, the lowest layers contain the older rocks.
• Rocks that form near volcanoes are older than surrounding rock.

Which statement best supports the inference that most of Earth's present-day land surfaces have, at one time, been covered by water?

• Volcanic eruptions contain large amounts of water vapor

• Coral reefs formed, in the past, along the edges of many continents

• Seafloor spreading has pulled landmasses apart and pushed them together.

• Sedimentary bedrock of marine origin covers large areas of Earth's continents.

Volcanic ash can be used as a time marker to correlate rock layers because the ash

• is deposited rapidly over a large area

• represents a buried erosional surface

• forms intrusive igneous rock

• cuts across rock layers

During the late Silurian epoch, very salty seas extended from New York State to Michigan. These environmental conditions resulted in the formation of halite layers. At the same time, Eurypterus remipes lived in nearby environments. Both the halite layers and Eurypterus remipes fossils can now be used to identify a specific geologic time interval because both formed over a

• large geographic area and in a short geologic time

• large geographic area and in a long geologic time

• small geographic area and in a short geologic time

• small geographic area and in a long geologic time

What lettered rock layer is the youngest?

• A

• B

• C

• D

Volcanic ash deposits such as these are usually excellent geologic time markers because they

• occur at regular time intervals

• spread over a large area in a short amount of time

• represent a time gap in the rock record

• contain index fossils from different time periods

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