The Geologic Time Scale: Study Guide (Quiz Grade), Due Monday
Put the following items in order from oldest (1) to most recent (4) by writing a number
in the blank beside each.
___1. Mesozoic Era ____ 2. Precambrian Time _____ 3. Cenozoic Era ___ 4. Paleozoic Era
5. Why is the geologic time scale used to show Earth’s history?
6. What methods did geologists use when they first developed the geologic time scale?
7. How did geologists decide where one division of the geologic time scale ends and the next begins?
Building Vocabulary
Fill in the blank to complete each statement.
8. Geologists divide the time between Precambrian Time and the present
into three long units of time called ________________________.
9. The record of life forms and geologic events in Earth’s history is called the
________________________.
10. According to the geologic time scale, sequence the following in order of evolution. Make #1 the most
primitive life form.
_______ birds
_______ early mammals
_______ reptiles
_______ amphibians
_______ insects
_______ single-celled life forms
_______ fish
_______ flowering plants
_______ dinosaurs
_______ (more) modern humans
_______ humans
_______ early multi-celled life forms
12. Why are fossils important tools for understanding the history of life on Earth?
13. When is an organism considered extinct?
14. In the following list, circle the data about a long-dead organism that can be determined by fossils:
weight
size
odor
diet
# offspring
birthdate
height
disease history
15. What are index fossils and how are they used to determine the age of related strata?
16. If you found fossils of seashells in a rock layer near the top of a mountain, what would the fossils tell
you about the history of that area?
17. Determine which time blocks the following events occurred. Write the name of the specific time block in the
appropriate blank. All blanks will not be filled because some events are not broken down into the same time detail.
. Description
Eon
Era
Period
Epoch
Humans
Rise of
mammals
Flowering
plants
Birds
First
dinosaurs/
mammals
First
reptiles
First
amphibians
First insects
First fish
Explosion
of life
forms
Multicelled
organisms
Single
celled
organisms
18. Fossils form in different ways. Identify the type of fossil being described in the list below. Place the name of the
fossil type in the blank provided next to the description.
☺ Acids eat away the skeleton or shell and leave an impression in the rock → ______________________
☺ This is formed when a mold fills with minerals → ______________________________
☺ Minerals in plant cells crystallize; minerals enter openings or cavities in shell or bones → ____________
☺ Whole organisms locked in tar pits, asphalt, amber, etc. → ______________________________
19. Most fossils form in ____________ rock. The ____________of fossils within this type of rock layers help
scientists construct the geologic time scale.
20. Sequence the following events in the fossilization process:
_______ Over time, the surrounding material builds up and turns to rock.
_______ The rock above eventually erodes and the fossil is exposed.
_______ The remains are rapidly buried by sediment in streams.
_______ An animal dies and begins to decompose.
21. In the undisturbed rock strata illustrated below, indicate in which layer you will find the oldest and the youngest
fossils. Write the terms “oldest” and “youngest” in the appropriate strata.
______________________________________________________
A
B
C
D