Unit 9 Guide: Concepts of Earth Science
The Rock Record and a View of Earth’s Past
Key Concepts and Questions to Be Able to Explain and Answer:
1. What is the principle of uniformitarianism? How can it be used to understand the past?
2. What is the law of superposition? How can it be used to determine the relative age of rock
layers?
3. What is an unconformity? Be able to identify and describe the formation of the following
unconformities: angular unconformity, disconformity, nonconformity.
4. How can cross cutting features be used to determine the relative age of a rock layer?
5. Be able to look at a diagram of rock layers with various unconformities/cross cutting features
and use your knowledge of relative dating procedures to make predictions about the past.
6. What is a fossil? What conditions are necessary for a fossil to form?
7. Be able to name and describe the possible types of preservation: mummification, amber, tar
seeps, freezing, etc. Be able to name and describe fossil types: imprints, molds and casts, etc.
8. What makes an index fossil unique? Be able to use the concept of index fossils to identify the
age of a rock layer.
9. Describe how relative age is different from absolute age.
10. What is radiometric decay? What is half life? Be able to determine the absolute age of a
sample given half life data.
11. What are the characteristics of eons, eras, periods, epochs and ages?
12. Be able to complete a geologic time scale with the names of eons, eras, periods and epochs.
13. Be able to describe the process of natural selection. How can natural selection cause species to
change over time?
14. What is the leading hypothesis for the extinction of the dinosaurs? Be able to explain evidence
for this theory.
15. During what period did the first human beings exist? Have humans been around for much of
geologic history?
16. Identify important events in geologic history with the appropriate era/period/epoch.
Assessments
Half Life Formal Lab
Unit 9 Test
Date: ______________
Date:_______________
Reading Assignments:
Students will be assigned readings from the following pages in the text book.
Chapter 8
pages 184-209
Chapter 9
pages 210-235
Vocabulary
Uniformitarianism
Relative age
Law of superposition
Unconformity
Angular unconformity
Nonconformity
Disconformity
gymnosperms
eon
era
period
epoch
law of crosscutting relationships
fossil
paleontology
trace fossil
index fossil
absolute age
geologic time scale
ammonite
rhipidistians
stromatolites
angiosperms
trilobites
graptolites
homo sapiens
eurypterids
radiometric dating
parent isotope
daughter isotope
half-life
carbon dating
Pangaea
natural selection
age (geo time scale)
evolution
species