Time Frame – 40 minutes

Materials

• Spreadsheet of data on planktonic foraminifera

• Chart for graphing data

Advanced Preparation

Students should have an understanding of planktonic foraminifera.  They should have a concept that our planet’s climate has not always been as it is today.  A review of the use of Neogloboquadrina pachyderma coiling ratios as a proxy for paleoclimate would be useful.  Neogloboquadrina pachyderma is an excellent recorder of climatic temperatures through geologic time.  When the earth experiences periods of relatively cold temperatures, ocean waters are cooler and Neogloboquadrina pachyderma forms its test (shell) such that it coils to the left.  Alternatively, during periods of relatively warm temperatures when ocean waters are warmer, Neogloboquadrina pachyderma constructs its test with a coiling direction to the right.  Students should be able to perform simple arithmetic procedures, namely, adding and formulation of percentage data. In addition, the students should know how to plot scientific data on graph paper.

Procedure

1. You have been given a series of samples containing planktonic foraminifera representing time from the present to 160,000 years ago.  After your analysis of the material, you decide to look at the climatic signal from these samples.  You are aware that a particular species of foraminifera, Neogloboquadrina pachyderma, is an excellent recorder of water temperature through geologic time.  When the earth experiences periods of relatively cold temperatures, ocean waters are cooler and Neogloboquadrina pachyderma forms its test (shell) such that it coils to the left.  Alternatively, during periods of relatively warm temperatures when ocean waters are warmer, Neogloboquadrina pachyderma constructs its test with a coiling direction to the right.  Therefore, you have separated out the specimens of Neogloboquadrina pachyderma from your samples.  For each sample you have counted how many of this species coil to the left and how many coil to the right.  Your data is recorded in Figure 1.  Your next step is to calculate the percentage data for each sample.  You must calculate percentage data so that your information is not biased by the total amount of foraminifera present in the sample.  Complete the worksheet in Figure 1 by calculating the total number of Neogloboquadrina pachyderma for each sample and the percentages of right- and left-coiling forms of the species.  The first sample is done for you on the worksheet. 

2. Next, use graph paper to plot your results.  On the vertical axis you should plot the age of the samples with “0” at the top and “-160,000” at the bottom.  On the horizontal axis, plot the percentage of right-coiling Neogloboquadrina pachyderma with “0%” on the left side and “100%” on the right side.  You should now have a graph representing the climatic signal derived from the coiling ratios of Neogloboquadrina pachyderma.

3. Analyze your graph and make an interpretation of the climatic history on our planet during the last 160,000 years.  Describe this history and provide evidence for this interpretation.

Extensions

This activity could be followed by a discussion of the causes for climate change, past, present and future.  This exercise can foster discussions on current climate change.  The class could discuss current evidence for climate change and what might be the potential causes, both natural and man-made, for this change.

Formative Assessment

The presenter/teacher may follow this activity with a discussion of the causes for climate change, past, present and future. This exercise can foster discussions on current climate change. Participants/students could discuss current evidence for climate change and what might be the potential causes, both natural and man-made, for this change.