Earth Science 11 Learning Guide – Unit 6
Name: _______________
6.1 The Geologic Time Scale and the Paleozoic Era
1. Name the divisions of Geologic time from longest to shortest.
2. Where and when did life begin
3. What marks the end of one era and the beginning of the next?
4. Why are there no fossils from the Precambian Era?
5. Where are most Precambrian rocks found?
6. What is important about the Mississippian and Pennsylvanian period for
present day North America?
7. What may have caused the mass extinction of life on Earth at the end of
the Paleozoic Era?
6.2 The Mesozoic Era and Cenozoic Era
1. How long was the Mesozoic Era?
2. What are the periods of the Mesozoic Era? For what is each known?
3. What caused the extinction of the dinosaurs?
4. For what is the Cenozoic Era noted?
5. What are the periods of the Cenozoic Era? For what was each known?
6.3 Fossil Formation
1. What is a fossil?
2. Name the types of fossils that are found and describe each briefly.
3. What is an index fossil? What characteristics does an index fossil have?
4. What type of rocks does not have fossils? Why not?
ES11LG-Unit 6
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6.4 Relative Dating
1. What are the three laws relative dating? Explain each in your own words.
2. According to the Law of Superposition where are the youngest rocks in an
undisturbed sequence of sedimentary rock found?
3. How does the age of igneous rock compare to the layers of rock it has
intruded into?
4. How is the age of the pebbles in a conglomerate relate to the age of the
conglomerate.
5. What is the limitation of relative dating
6.5 Absolute Dating
1. What is a half-life?
2. How are isotopes of C-12 and C-14 similar and different?
3. A granite intrusion crosses a thick sandstone bed, which is older and what
law is this?
4. Pebbles of basalt are found in a conglomerate and are dated at 300
million years old, what conclusions can be made about the conglomerate?
5. The same conglomerate as above is crossed by a dike dated at 200
million years. What new conclusions can be made about the
conglomerate?
6. A mammoth is found to have 12.5% C-14 remaining, how old is it?
7. K-Ar often gives inaccurate dates. Why? Would this make the rock seem
younger or older?
8. Why would location A give a
different age than B in the
diagram?
9. What are decay curves? How are they used for absolute dating?
ES11LG-Unit 6
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