20 terms

Fossils and Geologic time

For 7th grade science's quiz
1. Law
Stand the test of time. An experiment confirmed it's true. It can create true predictions for different situations. It has uniformity and it's universal.
1. Hypothesis
A statement with a few observations. It's an idea based on observations without experimental evidence.
1. Theory
It has many observations and has loads of experimental evidence. It can be applied to unrelated facts and new relationships. It's flexible to be modified if new date/evidence is introduced
2. Name the laws of relative dating and what they are.
superposition- is any undisturbed sequence of strata, the oldest layer is at the bottom of the sequence, and they youngest layer is at the top of the sequence
cross cutting- any feature that cuts across a body of sediment or rock is younger than they body of sediment or rock that it cuts across.
inclusions- if one rock body contains fragments of another rock body it must be younger than the fragments of rock it contains. OR... the inclusions are older than the rocks which contain them.
succession- Fossils are found in a predictable sequence.
3. Name the major events in Earth's history and when they happened
Big bang- 13.7 BYA
Earth and solar system form- 4.6 BYA
Moon forms- 4.5 BYA
1st oceans- 4 BYA
1st signs of life- 3.8 BYA
Photosynthetic organisms- 3 BYA
Oxygen in the atmosphere- 2.6 BYA
1st ice age- 1.9 BYA
Cambrian explosion- 530 MYA
Pangea splits- 150 MYA
4.What's the fossil record?
Information that paleontologists gather in order to group similar organisms and arrange from oldest to youngest.
5. What's a paleontologist? What do they do? (How does the fossil find simulate what a paleontologist does?)
A paleontologist is a person who studies fossils. The fossil find simulates what a paleontologist does because we had to use our information the background knowledge to determine what it was. Paleontologists find bones and have to determine what it is.
5. How do scientists explain things that happened millions of years ago?
They make observations and theories through the fossil record
6. How are fossils formed? What affects fossil formation?
It could be buried in sediment, be frozen in ice, get stuck in tar pits and tree sap. (amber)
6. What percent of organisms become fossilized?
Less then 10%
7. Name and define the types of rock. What rocks do you find fossils in? Which one can you date absolutely?
Sedimentary- Where fossils are found. It's rock that formed from pieces of other rocks.
Igneous- rock that forms from magma
Metamorphic- Rocks that have changed chemically and physically because of large amounts of heat/pressure.
What's a mineral, what's our state mineral?
A solid inorganic substance of natural occurrence.
Fluorite is our state mineral.
8. Name the two types of fossils and their characteristics
Body- remains of an organism, like bones.
Trace- Evidence the organism was there, such as footprints.
9. What's an index fossil? What makes a GOOD index fossil?
Defines and identifies geologic periods; often in only one layer of rock. It's easily recognizable, short lived, found only in few layers of rock worldwide.
10. Define the dating techniques and the drawbacks of each.
Relative- Can determine the age of the fossil with respect to another rock/fossil. It's performed by comparing depth of fossils. Source is stratum to the position of a reference rock/fossil.Drawbacks: Imprecision and limitation of age date.
Absolute- It can determine the age of a fossil in years. It's performed by determining the relative amounts of a radioactive isotope in a specimen. Drawback: Difficulty of radioassy laboratory methods.
Half life- At the instance the matter is formed, it's 100% radioactive. In about 1.2 billion years, it'll only be half radioactive. In another 1.2 billion years, it'll be one fourth radioactive and so on.
11+12. Define these divisions of geologic time: Era, period and epoch. How do scientists determine divisions in time scales?
A geologic time scale is a series of time intervals that divides Earth's history.
Era- Biggest geologic time scale
Period- 2nd biggest geologic time scale
Epoch- 3rd biggest geologic time scale
13. What was early life like? What was missing from the atmosphere? When did life begin?
It was very, very uninviting and uninhabitable. It was impossible for life to live there. There was no oxygen in the atmosphere. There was only hydrogen and nitrogen in the atmosphere. The first signs of life were 3.8 BYA.
14. What are the major events in the Paleozoic era?
Cambrian explosion, many fossils and plants and animals moved to land
15. What are the major events during the Mesozoic era?
the age of reptiles, flowering plants, first birds, it ended with a mass extinction.
16. What are the major events during Cenozoic era?
Mammals came, humans appeared