Geologic and Biologic Scaled Time-Line
Integrated Science 2
Name:
Date:
Pd:
 Background
The Earth solidified 4.6 billion years ago. Life has been evolving on Earth for more than 3.5 billion years.
These are time spans that are difficult to comprehend. Our limited experience with time involves years grouped into
decades and centuries – not millions or billions of years! To understand geologic and biologic origins we can try to
represent time concretely by converting time into a linear dimension with a scale that is more manageable. Scaled
time lines can be used to represent changes in a more usable context. In this activity, you will construct a scale
model of the major geologic and biologic events in Earth’s history. This will help give you a sense of when critical
events happened in the history of life and of the earth.
 Pre-Lab Questions
1. On a timeline of the Earth’s history, put an “X” where you think the age of dinosaurs would first
appear.
< Earth Formed
Present Day >
2. On a timeline of the Earth’s history, put an “X” where you think humans would first appear.
< Earth Formed
Present Day >
3. On a timeline of Earth’s history, put an “X” where you think the continents formed.
< Earth Formed
Present Day >
 Procedures
Remember:
109 = 1,000,000,000 one billion
106 = 1,000,000 one million
105 = 100,000 one hundred
thousand
104 = 10,000
ten thousand
1. Review the data tables that accompany this activity. You will notice that the “Distance on Timeline
(centimeters)” column is blank. This must be filled in before you can begin creating your scaled model.
2.
a.) Your model will be 11 meters. This distance equals 1,100 cm. Therefore, every meter of space on your
timeline is equal to 420 million years.
]
b.) To begin you must convert the data found in the “Approximate Age” column to a unit of distance. The
formula for this conversion is as follows:
Value to be converted (in millions of years) x
1m
= Distance on Field (m)
420 million years
c. ) Subtract your “Distance From Present” from 11 to find out where you will stop and plant your flag.
Record this value in the “Distance on Timeline” column in your data table.
Example: the third conversion on the Geologic Time Scale (first Single-celled organism) requires you to
convert 4000 million years to distance. Using the formula above the conversion would look like this:
4000 millions of years x
1 cm
4000
=
= 9.52 m
420 million years
420
11m - 9.52m =1.48m
therefore, you would plant your flag 1 meter and 48 centimeters from the beginning to represent the point
where the first single-celled organisms appeared.
 Data Table
Event
Approximate Age
A
Formation of the Earth
4600 million years
B
Oldest known rock
4300 million years
C
First single-celled organism
4000 million years
D
Age of most continental crust
3700 million years
E
First viruses appear
Blue-green algae
(First oxygen-producers)
First fungi appear
3500 million years
First multi-celled organism
Precambrian Extinction
(70% of all life wiped out)
First shellfish appear
700 million years
K
First fish appear
510 million years
L
First true plants appear
498 million years
M
First sharks appear
390 million years
N
First amphibian appear
375 million years
O
325 million years
R
First reptile appears
Permian-Triassic Extinction
(99% of all life wiped out)
Mesozoic Era begins
(Age of the dinosaurs)
First mammal appears
S
Age of most oceanic crust
180 million years
T
First known bird appears
160 million years
U
Rocky Mountains formed
80 million years
V
Extinction of the dinosaurs
65 million years
W
First proto-humans appear
3.5 million years
X
Earliest modern humans appear
2 million years
Y
Last Ice Age
0.02 million years
Z
Recorded human history begins
0.01 million years
F
G
H
I
J
P
Q
Distance in Classroom (cm)
3000 million years
1000 million years
650 million years
570 million years
250 million years
245 million years
200 million years
2
Scaled Time Line
Analysis Questions
1. Revisit your pre-lab questions. How close were you to predicting the timing of each event? Which one
were you closest to?
2. Which event’s position on the timeline was the most surprising to you? Why? (what preconceived
notions did you have about this event?)
3. How many events involving living organisms are in the first half of earth’s history?
How many events involving living organisms are in the second half of earth’s history?
4. How long did dinosaurs exist on earth?
How long have humans (including proto-humans) lived on earth?
5. Which organisms would have gone extinct at the Permian-Triassic extinction 250 million years ago?
6. For how many billions of years, did earth exist with nothing more sophisticated than single-celled organisms?
What percent of earth’s history is this? (divide your answer by 4.6 and multiply by 100).
3
Scaled Time Line
7. Using your data table, create a timeline below organism evolution from single-celled organisms to
modern humans by listing them in order of appearance on earth (you may want to turn your paper
sideways)
4
Scaled Time Line
Formation of the Earth
A.
4.6 Billion Years Ago
Oldest Known Rock
B.
4.3 Billion Years Ago
5
Scaled Time Line
6
Scaled Time Line
First Single-Celled
C. Organism
4 Billion Years Ago
Age of Most Continental
D. Crust
3.7 Billion Years
7
Scaled Time Line
First Viruses Appear
E.
3.5 Billion Years Ago
F.
Blue-Green Algae
(First oxygen-producers)
3 Billion Years Ago
8
Scaled Time Line
First Fungi Appear
G.
1 Billion Years Ago
First Multi-Celled
H.
Organisms
9
Scaled Time Line
700 Million Years Ago
I.
Precambrian Extinction
(70% of all life wiped out)
650 Million Years Ago
10
Scaled Time Line
J.
First Shellfish Appear
570 Million Years Ago
First Fish Appear
K.
510 Million Years Ago
11
Scaled Time Line
First True Plants Appear
L.
498 Million Years Ago
First Sharks Appear
M.
390 Million Years Ago
12
Scaled Time Line
First Amphibian
N. Appears
375 Million Years Ago
First Reptile Appears
O.
325 Million Years Ago
13
Scaled Time Line
Permian-Triassic
(99% of all life wiped
P. Extinction
out)
250 Million Years Ago
14
Scaled Time Line
Q.
Mesozoic Era Begins
(The Age of the Dinosaurs)
245 Million Years Ago
First Mammal Appears
R.
200 Million Years Ago
15
Scaled Time Line
Age of Most Oceanic
S. Crust
180 Million Years
First Known Bird
T. Appears
160 Million Years Ago
16
Scaled Time Line
Rocky Mountains
U. Formed
80 Million Years Ago
V. Extinction of the
17
Scaled Time Line
Dinosaurs
65 Million Years Ago
First Proto-Humans
W. Appear
3.5 Million Years Ago
18
Scaled Time Line
Earliest Modern
X. Humans Appear
2 Million Years Ago
Last Ice Age
Y.
20 Thousand Years Ago
19
Scaled Time Line
Recorded Human
Z. History Beings
10 Thousand Years Ago
20
Scaled Time Line