Name: _______________________
Date:_______________ Period____
Lab Biology
Geological Time-line Activity
Background Information:
Fossils are the remains of organisms, which have been turned to stone over long periods of
time. There is an extensive fossil record for many organisms which provides direct evidence of
organic evolution and also indicates the phylogeny (the evolutionary relationships) of these
organisms. These fossil records depict the changes, which have occurred over the generations
in the development if life on our planet. It must be recognized that the fossil record is
incomplete considering the fact that extremely few organisms become fossilized, that only a
few such fossils survive the normal geological processes and that the discovery of fossils is
limited at best. It is surprising that the fossil record is so good.
Fossils that are almost 4 billion years old have been discovered. The age of fossils is determined
by establishing the age of the rock in which they are found. Age dating methods using the
normal decay of radioactive elements have been especially useful.
Paleontologists have used knowledge of geology and fossils to develop a picture of past events
and life forms on our planet. The current age of the earth is estimated at approximately 4.6
billion years. Fossils of the first living organisms (bacteria) date back 3.5 billion years.
Purpose:
To construct a linear time-line depicting the main geological eras and periods and showing the
main life forms living during each time period.
Procedure:
1. Examine the geological time-scale in your text (page 298) which shows the major Eras,
Periods and Epochs of the earth’s history.
2. Working as a team, produce a time-ordered sequence of events naming the major
geological Eras, Periods and Epochs and listing the significant evolutionary events of
each time period. You must include drawings or pictures to show the life forms of each
era. Use your text as a reference.
3. Each team of 2 students will turn in 1 time-line for their group.
Lab Hints:
Use the following scale in constructing your time-line.
1 billion years = 1000 million years
1 meter = 1000 millimeters
1 meter = 1,000,000,000 years
Discussion: *Answer these questions on a separate piece of paper.*
1. During the history of the Earth there have been five mass extinctions. One of those mass
extinctions eliminated the dinosaurs. Discuss what catastrophic events occurred to
cause such a mass extinction.
2. Absolute geologic dating and relative geologic dating are two methods by which
scientists try to determine the age of geologic evidence. Carbon-14 dating is an example
of absolute dating, and the law of superposition is an example of relative dating. Discuss
the differences between absolute and relative geologic dating methods and how they
can be used together.
3. Piece by piece, geologists put together evidence to begin to tell a story of what
happened and is happening to create our dynamic Earth. Discuss how a geologist is like
a detective.