Unit 9 Guide: Foundations of Earth Science
Clues to Earth’s Past and Geologic History
Key Concepts and Questions to Be Able to Explain and Answer:
1. What is the law of superposition? How can it be used to determine the relative age of rock layers?
2. What is an unconformity? Describe the formation and draw a picture of each of the following
unconformities: angular unconformity, disconformity, nonconformity.
3. What is the principle of uniformitarianism? How was it used to make a more accurate prediction of
Earth’s age?
4. What is a fossil? Name and describe the 2 conditions that are necessary for fossil formation.
5. What are the three characteristics of all index fossils? How are index fossils helpful in determining the
age of rock layers?
6. What is the difference between absolute and relative age.
7. Describe how knowing the half life of an isotope that undergoes radiometric decay can be used to
determine the absolute age of a rock. Be able to solve half life calculation problems.
8. What are the characteristics of eons, eras, periods and epochs?
9. Which era(s) are divided into periods? Which era(s) are divided into epochs?
10. Write the names of eons, eras and periods in order from the beginning of Earth’s history through the
present.
11. Describe the process of natural selection. How can natural selection cause species to evolve?
12. What is the leading hypothesis for the extinction of the dinosaurs? Explain this theory.
13. During what period did the first human beings exist? Have humans been around for much of geologic
history?
14. Match the following major geologic events) with the appropriate era/period:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Mass extinction (3)
First dinosaurs appear
First gymnosperms appear
First evidence of cyanobacteria
Widespread coal swamps
First angiosperms
First large mammals
Supercontinent Pangaea
First fish
“Cambrian Explosion”
Homo sapiens evolve
First birds appear
Oldest rocks
First amphibians
First reptiles
Vocabulary
fossil
permineralized remains
carbon film
mold
cast
nonconformity
natural selection
eon
era
period
epoch
evolution
Assessments
Quiz
Date: __________
Formal Lab Report: Half Life Date: __________
Unit 9 Test
Date: _________
Reading Assignments:
Students will be assigned readings from the following pages in
the text book.
Chapter 13
pages 360-389
Chapter 14
pages 390-421
principle of superposition
relative age
unconformity
angular unconformity
disconformity
absolute age
mammals
gymnosperms
trilobites
cyanobacteria
radioactive decay
half life
radiometric dating
uniformitarianism
geologic time scale
trace fossil
index fossil
angiosperms
species
How to Receive up to 5 Bonus Points for Completing the Unit Guide:
1. Type or handwrite an answer to each Unit Objective Question. Unless stated in the question, all
answers must be given in complete sentences.
2. Define each of the vocabulary terms. Do not just copy the definition out of the book’s glossary. Use
and add on to the definition we developed in class by giving additional information and examples of
each word.
3. Unit Guides must be turned in on test day and will NOT be accepted late. You must answer ALL unit
objective questions and define ALL terms.
4. Mrs. Froehlich will review your Unit Guide and determine the number of bonus points to be added to
your test. Bonus points will be granted based on correctness and completeness of answers and
definitions.