A Cross-country Trip in the Old Days
Author: Mark Terry
Overview: The PaleoPortal is an interactive encyclopedia of paleontology across the United States. Its design can promote a sweeping view of time and space with very few clicks of the mouse. One way to build an understanding of our paleontological past is to view a transect across the United States, east/west, from the vantage point of your state, during a single time period. In this lesson, students will draw on the information within The PaleoPortal to create a transect across the United States during a single period of time. By examining the evidence, they make inferences as to the paleoenvironment of that time and predict what additional evidence they might find in neighboring states.
Grade Span: 612. Younger students may be satisfied just to list fossils and environments for each state in a past geologic period. The emphasis for them could be on the fossil images. Older students could pursue the Extensions (hypothesis-building) and set the stage for a more sophisticated exploration of current paleontological research.
Predetermining the route and setting up charts with the appropriate number of cells will speed things along. It's highly recommended that you try the activity first yourself, allowing you to anticipate the questions that will be raised by the students.
Time: The information gathering necessary for one trip across the country should be possible in one class period, but careful completion of the trip charts should take longer, as would any follow up discussion.
Grouping: Students could work either alone or in pairs.
At first glance, the amount of information on The PaleoPortal site can be intimidating, but when pursued through a single time period within a single state, students will find it more manageable. Usually there is just a two- or three-sentence summary of the best current understanding of the ancient environment for the period and state in question, including references to fossils and rock types.
Students can gather brief notes from these summaries, almost as if they were field notes taken at a paleontological site. This provides an excellent opportunity to help students learn the importance of evidence, since it's the fossils and rock types discovered that have caused scientists to propose the ancient environment descriptions, not the other way round.
Sometimes students will find descriptions of environments without supporting fossil or rock types. This does not mean there is no supporting evidence, just that it wasn't mentioned in that paragraph of The PaleoPortal. This opens up a good extension activity possibility, since you can ask the students to suggest what sort of fossils and rocks must be present to have led to the paleoenvironmental description. They can follow up by digging for that information in other resources.
We encourage emphasis on the rocks and fossils. Their discovery leads to the environmental descriptions, not vice versa. This can help students understand that there's a whole lot of science going on here, first to find, prepare and accurately describe the fossil and rock specimens, then to analyze the environmental implications, and finally to publish the environmental description. All such descriptions are tentative, in that further fossil discoveries can and most likely will lead to revisions. Sometimes these revisions are subtle, sometimes they're extreme. That's paleontology!
Take a quick run-through yourself and you'll see the possibilities:
Click on "Exploring Time and Space." Look west from your state and choose the best starting position from among California, Oregon or Washington to begin your transect toward your own state.
Click on WA, OR or CA. Now that you're in your starting state, you'll see a geologic map, a time column and a fossil gallery entrance. Below, there is a summary of the paleontological history of the state. Of course students could peruse all these, but to get on with this assignment, you need to:
Click on one of the geologic time periods in the column. Each state during a single time period is similarly formatted, with a map of geologic exposures of the appropriate age, a repeat of the time column and an entrance to a more limited fossil gallery. (Some of these galleries show no specimens, either because there truly are none, or because none has yet been received for display by The PaleoPortal.)
Here is where students need to stop, read carefully, and take notes. There is a short description of what is known about this period in this state at the bottom of the display. They need to extract from it brief notes about fossils, rocks and environments, including environments mentioned without reference to supporting evidence. In some states, students may find additional links that occur below the descriptive paragraph. These are worth exploring as they link to museum collections and related paleontology websites.
If the "Fossil Gallery" is open, students should enter and explore the photographs, looking for corroboration of the statements about fossils made in the descriptive paragraph. Any fossils they don't understand or that seem to contradict what they've just read about the environment should be noted.
Up to now, the activity has not been that different from looking up this same information in an encyclopedia, but with the next step the power of The PaleoPortal begins to be realized. The state initials that surround your focus state are live links that will take you to information about the next state, within the same time period.
Click on the next state to the east and repeat the same note-taking exercise. You're on your way: repeat this all the way to the east coast.
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