Life Time Line
Students complete a time line showing the appearance and extinction of major types of fauna. Students also make forecasts into the future using time lines (see The People's Time Line in the History section).
Of the millions, perhaps billions, of species that have lived on Earth, only a tiny fraction are alive today. Many (but not all) scientists think that mass extinctions were caused by asteroids crashing into Earth. The age of dinosaurs passed 65 million years ago and growing evidence shows that it coincided with an asteroid that struck the Earth in what is now the West Indies. Other extinctions were caused by changing weather regimes and competition with species that occupied similar niches. In all cases, however, a species becomes extinct because it cannot adapt to changing circumstances.
The Earth is currently undergoing one of its most accelerated periods of extinction. Unlike all other known extinction phases, a single species, humans, is responsible. Species which are not able to adapt to human-caused changes are becoming extinct daily.
Perhaps if we become more knowledgeable about our evolutionary history, our concern for the species with which we share the Earth will grow.
We recommend that you first conduct the People's Time Line activity in the Cultural History section.
Part I - Life Time Line
Have the students make a time line showing the major biological features of several geologic periods.
Part 2 - Craters Life Labels
Have the students make and illustrate the following labels and attach them to the People's Time Line.
Part 3 - Future Time Line
Give each student about one or two feet of time line and instruct them to make a time line into the future using whichever time scale they want. For example, their time line could go from "Present" to "2 million years from now" or only "10 years from now." Students illustrate their time line with words and pictures explaining their predictions of the future.
Part 4 - Link Time Lines
Link the four time lines on your wall with string or yarn to show the temporal relationships between them. For example,
Did You Know?
Searing lava flows that initially destroyed everything in their path today protect the last refuges of intact sagebrush steppe communities on the Snake River Plain. These islands of vegetation, known as kipukas, provide important examples of what is "natural".