Fossils
Can fossils disappear from a layer of rock and reappear in a different layer?
No
What is the relative age of an object mean?
age of something compared with the age of another thing
What organism was the first to live on Earth?
Bacteria
What are the longest of the 3 ways time is measured on a geologic time scale?
Eons
What are the shortest of the 3 ways time is measured on a geologic time scale?
Periods
What are fossils?
Pieces or remains of dead animals
What does the law of superposition state?
The oldest rocks are on the bottom, the youngest on the to
What are the two laws that are used to date rocks and fossils?
Crosscutting methods and Superposition
What are the Eons before our current Eon called?
Precambrian Eons
What creatures were dominant during the "Era of Reptiles"
Dinosaurs.
What type of dating is fossil dating normally?
Relative Dating
What the difference between absolute and relative dating?
Absolute dating gives a year or range of years that something lived in.
Relative dating gives a sequence of time, what comes first, then next.
What type of animal became abundant after the extinction of dinosaurs?
mammals
The periods, eras, and eons are an example of what form of Sequencing Time (Think of the worksheet from Monday!)
Time Intervals
How do you make fossil dating more accurate?
Combine it with other dating methods
This is a type of absolute dating that is used to "Date the Earth" and cannot be used for anything older than 70,000 years old
Carbon dating
Is an intrusion older or younger than the layer below it?
younger
What is the era we live in?
Cenozoic
What would cause a period to change?
Different Weather/Ice Age
Different Continents
New Species
What is an index fossil?
A fossil of an organism that only existed for a short period of time.
How does Carbon Dating work?
Measures how much carbon has decayed, and uses this to find how much time has elapsed
How old is the Earth?
4.6 billion years old
What causes Eras to change?
A mass extinction event
What percent, approximately, of earth's history is contained in the Eon we are in?
12%