Principals of Geology
This law tells us older layers of the Earth are underneath younger layers
Law of Superposition
After one half life, a sample is reduced by this percentage
50%
Fossils are made of this type of material
Minerals
Carbon-14 is found in every form of this
Life
About 3.5 billion years ago, life began in this location
The ocean
Fault lines can be dated using this law
Law of Cross-Cutting Relationships
If the first half life takes 4 million years, the second half life will take this long
4 million years
We can determine the age of fossils through this process
Carbon Dating
Carbon-14 and Carbon-12 are the same element, but different types of this
Isotopes
The moon formed from rocks lost during a collision early in this planet's formation
Earth
Some events, such as pressure building underground, can cause this to occur in Earth's layers
Folding
After 4 half lives, this percent of the original sample will remain
6.25%
Zero
Carbon-14 is not useful for dating prehistoric fossils because their half life is only this long
5700 years
The Earth formed this many years ago
4.5 billion
Erosion lines can be dated using this law
Law of Original Horizontality
Decay
Animals with this feature are more likely to form fossils than other animals
Hard shells/bones
The stable, decayed form of Carbon-14
Nitrogen-14
About 65 million years ago, this family of animals went extinct
Dinosaurs
This type of rock often forms in non-horizontal layers, typically younger than surrounding rock
Igneous (Intrusion)
This element has a half life of 1.3 billion years
Potassium-40
As opposed to a body fossil made from the body of an animal, this type of fossil is formed from evidence left behind by the organism
Trace fossil
If you held a pound of Carbon, it would have these two distinct properties
On the African continent, humans evolved approximately this long ago
2-6 million years