Eras
Which era are we living in today?
Cenozoic
A radioactive element has a half-life of 10 years. If you start with 100 grams, how much will remain after 10 years?
50 g
What does one tree ring generally represent?
1 year
What is the the amount of time it takes for half of a radioactive sample to decay
Half Life
500 grams = _____ decagrams
50
Which geologic era is known as the “Age of Reptiles”?
Mesozoic
A radioactive sample starts with 100 grams. How much remains after TWO half-lives?
What is dendrochronology?
The study of tree rings to learn about the past
This mineral is used to help date really old rocks.
Zircon
.0087 kilometers = ____ decimeters
87
Which era is the oldest?
Precambrian
A radioactive sample starts with 160 grams. Its half-life is 10 years. How much remains after 30 years?
20 grams
A very wide tree ring usually means the tree experienced...
Good growing conditions
We used _________ and __________ to help date the Earth to 4.6 billion years old
This type of heat transfer is made through direct contact
Conduction
Which era is known for the rapid development and diversification of many early life forms, including the development of many marine organisms?
Paleozoic
A sample has 25% of its original radioactive material remaining. How many half-lives have passed?
2
Which factor could cause a tree to produce a narrow ring?
Drought, extreme temperatures, etc
What are the two types of absolute dating we talked about in class?
Radiometric Dating
Dendrochronology
This type of heat transfer is made through emitting energy through space
radiation
Put the four eras in order from oldest to youngest.
Precambrian → Paleozoic → Mesozoic → Cenozoic
Scientists find a rock containing a radioactive element. The sample has 12.5% of the original radioactive material remaining. How many half-lives have passed?
3
Daily Double:
How old is this tree?
51 years old
Evidence of the oldest rock on Earth shows it is about ____ years old
4.37
Lava lamps are a good example of this type of heat transfer
Convection