Geologic Principles

The law of superposition helps scientists to determine what?

• The age of fossils

• The absolute age of rock layers

• The relative age of rock layers

• The origin of the universe

Which principle or law states that "the processes that shape the world today also operated in the past."

• Uniformitarianism
• Original Horizontality
• Lateral Continuity 
• Superposition 

Which principle or law states that "When layers of sediments are deposited, they settle in flat, horizontal layers due to gravity."

• Uniformitarianism

• Original Horizontality

• Lateral Continuity

• Superposition

The best index fossils have which two traits?

• widespread geographically, long lifespan
• widespread geographically, short lifespan
• specific place, long lifespan
• specific place, short lifespan

The age of a rock layer compared to the other rock layers around it is called

• Absolute Age
• Relative Age
• Comparative Age
• Layer Age

Letter "F" is a....

• inclusion
• intrusion
• fault
• unconformity 

The table 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%

If the half-life of a radioactive group of atoms is 100 years, then how old is the rock if there have been two half-lives?

• 25 years
• 200 years
• 400 years
• 800 years

You find a rock sample with radioactive atoms present.  If 25% of the original radioactive atoms were present, how many half-lives has the rock been around for? (Hint, at Half-Life = 0, you start with 100%)

• zero
• 1
• 2
• 3

The Principle of Cross-Cutting Relationships states that an igneous intrusion is 

• always younger than the layers it cuts across
• always older than the layers it cuts across
• the same age as the rock it melted
• none of the answers are correct