Unit 9 Guide: Foundations of Earth Science
Clues to Earth’s Past
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.
Assessments
Formal Lab Report: Half Life
Unit 9 Test
Date: _____________
Date: _____________
Reading Assignments:
Students will be assigned readings from the following pages in the text book.
Chapter 13
pages 360-389
Vocabulary
fossil
permineralized remains
carbon film
mold
cast
trace fossil
index fossil
principle of superposition
relative age
unconformity
angular unconformity
disconformity
nonconformity
absolute age
radioactive decay
half life
radiometric dating
uniformitarianism
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.