Astronomy Department, Box 351580
University of Washington
Seattle, WA 98195
The History of the Earth and the
Evolution of Life:
Creating a scale model of the Geologic Column with a focus on theevolution
of life on Earth
Geologic Column took many years and much debate to develop in the 19th
and 20th centuries. The end result is a chronological progression
of life’s evolutionary milestones through all of geologic time from Earth’s
origins to the present. Major divisions in the column are based upon either
the rise to prominence of some new form of life, or a mass extinction of
many forms of life. For example, the mass extinction we know best, the
extinction of the dinosaurs (and 50% of all other species), took place 65
million years ago, at the end of the Cretaceous and the beginning of the
Tertiary Periods. Thus a major event in the evolution of life has become a
major delineator of time in the geologic record.
activity, students will create a scale model of the Geologic Column,
including the major events in the evolution of life on Earth. It can easily
be adapted for any level within grades 4-12. Older students can work out the
math, do research, and be more creative in designing the scaled time line,
whereas it is more of a demonstration for younger students. In either case
students will come away with an appreciation for the vast expanse of time
covered by the Earth’s history relative to what we think of in our lives as
a “long time”.
scaled timeline is based on a simple scale -- 4.56 billion years of Earth
history will be condensed to a distance of 4.56 meters of adding machine
tape. This can be done in a classroom using the tops of desks that are
pushed together, or a length of classroom or hallway floor. Upon this record
we will place time markers at certain intervals, as well as objects and
images that represent major developments in the evolution of life. When all
of this is laid out before us, we will come to a startling visual
conclusion, namely how little of the Earth’s history has been involved with
complex life (organisms with more than one cell).
The Geologic Column and
Evolution of Life (provided with this
Roll(s) of adding machine
Meter sticks and metric rulers
Pencils and erasers
Items such as fossils, plants, and
small toys to illustrate the major events in the history of the earth and
the evolution of life (use The Geologic Column & Evolution of Life
as an initial reference, explore other resources for more). Bacterial
life can be represented by images from textbooks or websites.
1. Tape together lengthwise, the 3 pages of
The Geologic Column & Evolution of Life provided with this activity.
This is the source of the information to make your scaled timeline.
2. Measure out a strip of
adding machine tape 4.56 meters long.
3. Select one end of the tape to represent the
Present. Beginning at that end, mark off each billion years according to
the scale below, then subdivide and mark each billion years into 10-million
billion years = 4.56 meters
years = 1 meter
million years = 1 cm
years = 1 mm
4. Move to the opposite end of the tape.
Beginning with the oldest event, mark off all of the important events in
Earth’s history and the evolution of life as shown Geologic Time Scale &
Evolution of Life.
5. Place the appropriate items and images on the
scaled timeline to graphically illustrate the major events in the history of
the earth and the evolution of life.
Variations on this Activity:
scale can also be easily adapted for outdoor use, for example letting 4.56
billion years be represented by 456 meters (6-8 city blocks). This is an
even more startling scale, and further allows one to actually “see” 1000
years, which is 0.1 mm!
also add to the timeline a few astronomical and cosmological milestones in
the history of the Universe, which extends back to the Big Bang at 13.7
billion years ago, three times longer than the Earth’s age.
Other Methods of scaling the
History of the Earth and the Evolution of Life:
is but one method of producing a “scale model” of geologic time and
evolution. Other methods to represent the 4.56 billion years involve a
24-hour clock, a one-year calendar, or a novel use of dots on a sheet of
paper combined with a tower of reams of paper.
4.56 billion years = 24
1 million years = 18.9 seconds
4.56 billion years = one year
1 million years = 1.9 hours
Stack o’ paper
1 sheet of paper = 2000 years
(assuming that the present year is the year 2000, place 2000 evenly spaced
dots on a single sheet of 11.5 x 8 inch paper. Students circle dots that
represent their birth years, important dates in their culture or country,
important milestones in human civilization, etc.)
500 sheets = 1 ream = 1 million
years (thickness of 4.5 cm)
Stack of 4560 reams = 205 meters (670 ft) = 4.56 billion years (find a local
structure that is the equivalent height of the age of the earth)
1. The 4.56 billion years
= 4.56 meters of adding machine tape activity was drawn from the exercise,
“Lab 1, The History of the Earth”, from Laboratory Manual for Physical
Geology, by Baer, Baer, and Whittington, Highline Community College,
2. The Stack o’ Paper
activity was drawn from the exercise, “As Time Goes By”, origin unknown.