Earth Origins Review

Used to determine whether an object is older or younger than other objects

• Superposition
• Relative Dating
• Fossil
• Unconformity

States that younger rocks lie above older rocks if the layers have not been disturbed

• Law of crosscutting
• Law of superposition
• Relative Dating
• Unconformity

Analyze the seashell found in the white layer.  Which statement is true of the rock layer that contains this fossil?

• It could also contain a fossil from the bottom layer.
• It is older than the layers below it.
• It is younger than the layers above it.
• It is older than the layers above it.

How do geologists use relative dating?

• Placing rocks in order from youngest to oldest
• Placing rocks in order by minerals they contain
• Classifying rocks by different textures
• Classifying rocks by different isotopes

What are the relative ages of the features in order from oldest to youngest?

• Limestone, Basalt, Fault, Siltstone
• Siltstone, Fault, Basalt, Limestone
• Limestone, Fault, Basalt, Siltstone
• Limestone, Siltstone, Fault, Basalt

_{Which rock layer in the diagram seems to be the oldest?}

• F
• E
• B
• A

1. 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 rock, 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.

Scientists find dinosaur fossils in the bottom rock layers of a cliff and mammal fossils in the middle rock layer of the cliff. Which could best be concluded from this evidence?

• Dinosaurs ate plants.

• Dinosaurs were eaten by the mammals.

• Dinosaurs lived on Earth before the mammals.

• Dinosaurs and mammals lived at the same time.

The geologic principle that states that sedimentary rocks are deposited in horizontal layers is the principle of

• uniformitarianism

• original horizontality

• superposition

• cross-cutting relationships

How does the law of crosscutting explain the age of a fault?

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