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"From Reefs to Rocks!"

David Stauffer

Type of entry

  • Unit Outline

Type of activity:

  • Hands-on activity
  • Inquiry lab
  • Group/cooperative learning
  • Community outreach/off-site activity

Target audience:

  • Life Science
  • Biology
  • Environmental studies

Background information:

This particular unit was designed to use the unique geologic features of Iowa to teach the concepts of evolution and biodiversity. Its intention was to supplement a separate course which focuses on these concepts. The unit requires that the teacher have an extensive understanding of local geological and biological features. In addition, knowledge of geologic history and fossil evidence associated with each time period is necessary. Help from local Department of Natural Resources personnel, university researchers, and experts in related fields, has proven to be a real asset. Students involved with this program must complete 30 contact hours and a variety of individual and team projects in order to receive the maximum credit. Due to the nature of this program, students can expect to spend several Saturdays in the field doing research and developing projects.

Many more hours have gone into preparing this program than was ever expected.Since the goals are to have students become familiar with and understand the concept of evolution from a biological and geological perspective, almost all of the work they do is at various sites around the state of Iowa. Organizing field trips, locating funds, setting up transportation, and becoming familiar with all of the different resources that are available is demanding. To help free up some teacher time, a few motivated students have taken on the key role of contacting and setting up some of these experiences.The following represent the field experiences provided during this unit:

  • 3 visits to the University of Iowa Museum of Natural History
  • 1 visit to the Botanical Garden and Science Center, Des Moines
  • 1 visit to Weber Stone Co., Graff road-cut, Pike's Peak State Park
  • 1 visit to the Henry Doorly Zoo, Omaha, NE
  • 1 visit to the Devonian Gorge (produced by the flood of 1993)
  • 1 visit to Shedd Aquarium, Museum of Science and Industry, Museum of Natural History, and Brookfield Zoo, Chicago, Ill.
  • 1 canoe trip down a selected Iowa river

Since this unit was designed to provide additional opportunities for interested students to learn about evolution and biodiversity, no class time is committed to this specific unit. Instead, the unit is completely taught on Saturdays, and students volunteer to attend various activities. What is done in class is illustrated in the field, and likewise, what is done in the field is used as a relevant source of discussion.


In part one of this program, students prepare to do their actual field work by traveling from Cedar Rapids, Iowa, to the University of Iowa in Iowa City, Iowa (approx. 30 miles). There, they explore Iowa's history from both biological and geological perspectives. Utilizing the Geological Survey, the University's libraries, and select faculty, these students have the challenge of putting together a multimedia presentation demonstrating how life in Iowa evolved and changed throughout geologic time.

In part two of the program, students take what they have learned to various sites around the tri-state area (Iowa, Illinois, Wisconsin). There, they play the role of scientist by examining rock types, rock strata, and fossil evidence. They also make notes, record data, and collect samples where permitted. Ultimately, students are asked to piece together all of their evidence from each outing in order to produce an illustrated explanation for the biological history of the area. In particular, students are asked to focus on what the environment must have been like, and how life must have adapted and changed over the course of time. Finally, students are asked to explore the current flora and fauna of a given area, collect data, and then predict what the future holds for this area based on the evidence they have.



Since each location has its own unique biological and geological history, this activity should serve only as model for what might be adapted in other regions. For this experience, the following proved to be valuable resources: the University of Iowa Departments of Geology and Education, the Department of Natural Resources, the Army Corps of Engineers, and the Geological Survey.

In addition to the information these resources provided, other basic equipment is needed. These materials include:

  • geologic time scales
  • geologic maps for the state of Iowa
  • fossil identification guide
  • rock hammers (can be borrowed instead of purchased to cut costs)
  • safety glasses or goggles (rock chips are extremely dangerous)
  • markers and collection bags (zip-loc works well)

Maps and general information about the areas to be studied were acquired from the sources mentioned above.


The goal of this unit is to have the students play the role of geological investigators. In this capacity, the students search for evidence to explain how living things have adapted and changed over time, and how the environment might have influenced these changes. On each trip, the students are asked to collect evidence (where allowed), record observations, and be prepared to share their evidence with others. At the end of each experience, the students are asked to lay out their collections and produce a short presentation about how it all fits together. Essentially, they produce a three dimensional concept map showing the relationships among their pieces of evidence. Although each trip is conducted similarly, the following is a brief description of just one experience to better illustrate how the program works. This trip includes visits to a local road-cut, the Weber Stone Quarry, Guttenburg, IA (Galena formation), two selected road-cuts (St. Peter sandstone formation), and Pike's Peak State Park.

With approximately twenty students, three vans are used to transport students (vans give added flexibility - small groups can be moved to different sites at different times if necessary). The first road-cut visited is near the school. There, the students familiarize themselves with the basic properties of limestone, and establish their place on the geologic time scale using their geologic maps of the state of Iowa. In Cedar Rapids, they will find themselves on the line between Devonian and Silurian aged rock. During a previous visit to the recently exposed Devonian Gorge in Coralville, IA ( the Devonian Gorge became exposed during the flood of 1993), the students became well versed in Devonian fossil evidence. They should understand that it was during this time that the state of Iowa was covered by a shallow, warm, tropical sea and, as a result, the fossil evidence is clearly of a type associated with a reef environment.

A tour of Weber Stone Quarry provides much information about the environment in which limestone is formed. Examining the rock layers proves to be interesting since some layers are completely void of any fossil evidence, and other layers are full of evidence. In addition, the students observe for the first time the presence of small layers of shale. Students collect samples in their bags, label them with the location from which they were taken, and include any observations they deem necessary. Before leaving this site, they are asked to discuss as a group what might account for the observations they have made.

At the Guttenburg site, a placard has been erected that explains the geologic history of this area. Students use this to place themselves on their geologic time scales. At this site the question is raised about their position now in relation to where they were while in Cedar Rapids. They suddenly realize that they have literally traveled back in time, and are now standing on Ordivician rock. Now they are challenged to explain how they have gone back in time geologically when they are currently standing at a higher elevation now than when they started, and what type of fossil evidence will they find during this time period.

The two road-cuts visited were chosen because of the unique sandstone exposures. The St. Peter's sandstone formation is altogether different from the limestone they have become accustomed to seeing. Asking the students to explain the evidence for a sudden change in environment, as well as trying to account for the lack of fossil evidence in this rock layer is a real challenge. This sandstone will serve as an excellent reference point for the final site to be visited.

Pike's Peak State Park overlooks the Mississippi River where it meets with the Wisconsin River (students are not allowed to collect samples in the park; laws prohibit this). Here, the students are turned loose to locate their exact position on the geologic time scale. Using observations and evidence they have collected throughout the day, students begin to recognize fossil evidence and various rock strata along the paths, and in the large bluffs that make this park spectacular. The students are able to see the changes and adaptations that have occurred throughout time on a much larger scale.

Before leaving the park, the group discusses any questions that may have been raised during the day. Emphasis is placed upon understanding the geological concepts that made this trip possible, but more importantly, how these changes affected the living things that inhabited this area. With the fossils and other evidence the students collected, the students look for evolutionary changes that have occurred. Using their knowledge of the geological concepts that influenced this area, the students can develop a rationale for why these adaptations might have occurred.


Since this was designed to be a volunteer program for interested students, evaluation has been done primarily by peer groups. Each group evaluates the others' concept maps and looks for strengths and weaknesses. In addition, each trip is followed up by a field trip evaluation. These evaluations help determine the success of individual experiences so that they can be improved upon. Ultimately, greater understanding and appreciation for materials discussed in the more traditional classroom setting is quite obvious.

Extensions/Additional Ideas:

With a program such as this, there is ample room to be creative. Once students begin to feel comfortable with the basic concepts emphasized in this unit, students could be divided into teams and asked to plan and facilitate a similar trip. Also, teams might be assigned to produce multimedia presentations for selected trips in order to share their experiences with students who are unable to participate. All of their collections should be saved and displayed for use in the classroom. Generally, students tend to begin to ask questions that can best be answered in the field during similar trips, and these questions can form the basis of future planning.

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