Geological Time
Introduction:
Do you have any idea how old the earth is? The evidence indicates that it is at least 5 billion years old. Sometime
during those 5 billion years, a very important thing happened: life began. It is not certain exactly when this event
took place. But the remains (fossils) of ancient plants and animals give us some idea of when the most primitive
living organisms appeared.
Fossils of these primitive organisms, the bacteria and the blue-green algae, have been found in rock about 3.3 billion
years old. Evidence indicates that these were the only forms of life that existed until about 600 million years ago.
Since that time a tremendous variety of organisms have inhabited the earth, many of which are now extinct.
In this investigation you will be able to see when important events in the history of the earth took place. To see this
you will place specific events on a time line of your construction. The divisions of the meterstick represent units of
time. Your problem is to determine when these important events took place.
Materials
Meter stick
5 meters of track tape
Colored pencils
Part A
Procedure A
1. The smallest units on the meterstick are millimeters, there are 10 millimeters in a centimeter and 100
centimeters in a meter. Therefore, there are 1000 (10 X 100) millimeters in 1 meter. Use the centimeter and
millimeter to represent units of time in the life of the earth.
2.
Measure track paper to the length of 5 meters. Each meter represents one billion years.
3.
One meter is equal to one billion years, a billion is 1000 X 1 million years, therefore 1 millimeter is equal
to 1 million years and 1 centimeter is equal to 10 million years.
1mm = 1 million years
1cm = 10 million years
1 meter = 1000 million years (1 billion)
5 meters = 5 billion year
4.
Divide your paper into three sections: geological time, major geological events and major biological events
Plot the information on your timeline from the following: (See Example)
5.
The tables A, B, and C below lists some of the important events in earth history and the number of years
ago that they are believed to have occurred. Study the tables and calculate the distance to be measured back
from present day on your timeline.
6.
Use the time line you prepared in part A. Write the events, listed in the chart, in the appropriate place on
your time line
Table A
Geological Time Scale (pencil)
Table B
Major Geological Events (brown)
Table C
Biological events (green)
Table A: Geologic Time Scale
Aeon
Era
Period
Quaternary
Cenozoic
Mesozoic
Phanerozoic
Proterzoic
Archaean
Hadean
Paleozoic
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrium
Epoch
Holocene
Pleistocene
Pliocene
Miocene
Oligocene
Eocene
Paleocene
Millions of
Years Ago
Distance from
Present Day
Line
10,000 years
1.6
5.3
23.7
36.6
57.8
66.4
144
208
245
286
360
408
438
505
540
2500
3300
4600
Table B: Major Geological Events
First evidence that ….
the Pleistocene ice age began
a land bridge began to form between North and South America
the Antarctica ice cap began to form
tie Mississippi River began to form
Antarctica and Australia began to separate
India began lo collide with Asia and form the Himalayan Mountains
the present Rocky mountains began lo form
Pangaea began to break up and form the Atlantic Ocean
the supercontinent Pangaea began to form
extensive coal formations were deposited
oxygen began to reach present atmospheric levels
oxygen began to butt up m the atmosphere
the atmosphere and hydrosphere began to form
the Earth formed as a solid planet
Millions of
Years Ago
1.6
5.7
24
35
50
55
70
165
225
350
600
2500
3800
4600
Distance from
Present Day
Table C: Major Biological Events
First evidence of...
modern humans (Homo sapiens sapiens)
"Lucy" (Australopithecus afarensis)
members of the human family (hominids)
monkeys
primates
flowering plants
birds
mammals
dinosaurs
reptiles
seeds
amphibians
land animals (insects)
land plants
vertebrates (jawless fish)
animals with hard shells (marine invertebrates)
animals (soft-bodied marine invertebrates)
multicellular organisms (algae)
cells with a nucleus
life (single-celled bacteria)
Millions of
Ago
0.05
3.2
4
35
65
140
150
225
235
300
350
360
400
440
510
540
680
1000
1400
3500
Distance from Years
Present Day
Analysis:
1. During what part of the earth's history did living organisms first appear? What are they?
2.
Which appeared first animals or green plants? What characteristic of plants allow them to survive without
animals?
3.
Which of the organisms listed has been on earth the shortest period of time?