Earth History

Which generalization can be made about the relative age of a fossil found in a sedimentary rock bed?

• The fossil is younger than the rock layer above it
• The fossil was formed before the rock layer that contains it
• The fossil and the rock layer were formed in different environments
• The fossil was formed around the same time as the rock that contains it.

Scientists uncover mammoth bones and are able to determine the amount of carbon-14 in the bones. Whichbest explains the use of carbon-14 in studying the mammoth?

• It identifies the species of mammoth
• It identifies the diet of the mammoth
• It determines the age of the mammoth
• It determines the cause of death of the mammoth

Fossilized dinosaur eggs have been found in the third of five rock layers during a fossil dig. Based on the law of superposition, which best represents the age of the eggs?

• The eggs are older than all of the rock layers.
• The eggs are younger than all of the rock layers
• The eggs are about the sme age as the third rock layer
• The eggs are about the same age as the fifth rock layer

Which characteristic of carbon-14 dating helps scientists determine the approximate time a species became extinct?

• Carbon-14 is not present in more recent fossils
• Carbon-14 increases at a constant rate over time
• Carbon-14 decreases at a constant rate over time
• Carbon-14 can only be found in fossils of a certain period

Which is the most accurate method used in determining the age of a fossil?

• relative dating
• geologic column
• radioactive dating
• law of superposition

Why are fossils most likely found in sedimentary rock samples?

• More plants and animal species grow on sedimentary rocks.
• Sedimentary rocks preserve fossils with intense heat and pressure.
• Sedimentary rocks are formed in layers that trap the material for fossilization.

Four sedimentary rock layers are cut by an igneous rock intrusion. Which best describes the relative age of the igneous rock intrusion in comparison to the ages of the four sedimentary rock layers?

• THe igneous rock intrusion is older than sedimentary rock layers W, X, Y and Z.
• The igneous rock intrusion is younger than sedimentary rock layers W, X, Y, and Z
• The igneous rock kintrusion is older than sedimentary rock layer W and younger than sedimentary rock layers X, Y, and Z
• The igneous rock intrusion is younger than sedimentary rock layer W and older than sedimentary rock layers X, Y, and Z.

The diagram shows different layers of sedimentary rock. Each layer is labeled with a letter. Which statement correctly describes the relative ages of rock layers shown in the diagram?

• THe left part of Layber B is younger than the right part
• The left part of Layer F is the same age as Layer M
• Layer R is older than Layer M
• Layer I is older than Layer B

The half-life of a radioactive element, such as carbon-14, is the time it takes for half of the atoms of the element to decay. How many half-life periods have passed if a fossil contains 1/32 of the original amount of carbon-14?

• 3
• 4
• 5
• 6

Rock layers were found containing 30 kg of radioactive elements that had a half life of 5 million years. How old were the rock layers if scientists determined that the samples had originally contained 120 kg of the radioactive materials?

• 5 million years old
• 10 million years old
• 15 million years old
• 2.5 million years old