Student Activities

Leafy Thermometers and Rain Gauges

Grade Level:: High School: Ninth Grade through Twelfth Grade
Subject:: Science

During this six-part activity, students investigate climate and climate change. Using fossil leaves from southwestern Wyoming and modern leaves from their area, students classify leaves, determine mean annual temperature and precipitation using leaf margin and leaf area analysis, analyze climate data (temperature and precipitation), and make statements about climate change. The lesson mirrors an ongoing research project at Fossil Butte National Monument so the students are doing real science!

One of the fundamental principles of geology is "the present is the key to the past." This means the processes we observe happening on Earth today also happened in Earth's past. This allows scientists to use knowledge of the present to make inferences about Earth's history.

Rocks and fossils serve as indicators, called proxies, which open windows into deep time. For example, rock types and sedimentary features offer clues about depositional environments. Comparing fossils with their closest living relatives provides information about biological diversity, climate, and ecosystem.

Scientists studying flowering trees and shrubs noticed relationships between certain leaf characteristics and climate. In areas with higher average temperatures, more untoothed leaves were found. In places receiving abundant annual rainfall, more large leaves were present. Formulas to estimate mean annual temperature (MAT) and precipitation (MAP) were developed and tested on modern leaves. Today the same methods are applied to fossil leaves providing quantitative information about ancient climates.

Materials

· Photographs of fossil leaves from Fossil Basin, Wyoming (provided)

· Copies of Seven Simple Steps to Binning Leaves (provided)

· Copies of Binning Chart (provided)

· Copies of Leaf Classification Worksheet (provided)

· Copies of Climate Analysis Worksheet (provided)

· Copies of Climate Change Worksheet (provided)

· Modern leaves from your area

· Rulers with millimeter scale

· Calculators

· Scrap paper for leaf labels

· Paper clips

· Index cards (3"x5")

Procedure

Part One
Classroom-Teacher-lead demonstrations of binning process, leaf surface area computation and size classification. Each student will need three fossil leaf photographs, Seven Simple Steps to Binning Leaves, Binning Chart, Leaf Classification Worksheet, ruler and calculator. Students begin work on Leaf Classification Worksheet.

Homework-Students complete Leaf Classification Worksheet.

Part Two
Classroom-Sort fossil leaves from homework into bins. Divide students into teams, assign each team 1-3 bins, provide each student with a copy of Climate Analysis Worksheet and have teams complete Part A for assigned bin. Teacher may wish to use projection equipment to display all student data collected in Table 1. Students begin work on Climate Analysis Worksheet Parts B thru D.

Homework-Students complete Climate Analysis Worksheet.

Part Three
Classroom-Students discuss findings from Climate Analysis Worksheet. Students begin work on Climate Change Worksheet.

Homework-Students complete Climate Change Worksheet.

Part Four
Classroom-Students discuss Climate Change Worksheet.

Part Five +
Assessment-Students demonstrate understanding by applying learned skills to modern leaves from your area.

Assessment

1. Students collect and classify (margin type and size class only) a suite of modern woody dicot leaves from your area.

2. Students use leaf margin (LMA) and leaf area analysis (LAA) to determine mean annual temperature (MAT) and mean annual precipitation (MAP) for the modern leaves.

3. Students compare the results of the analysis with an observation-based meteorological database. Find historical data summaries by visiting the National Climate Data Center web site at and clicking on the appropriate regional climate center for your area.

4. Discuss student findings. If significant discrepancies exist between the analysis of modern leaves and the observation-based meteorological database brainstorm possible explanations.

Extensions

Using the internet, students find examples of modern places with similar mean annual temperature and precipitation data as those estimated from the fossil leaves.

Visit and click on the Photos & Multimedia link to see what types of plants and animals lived in southwestern Wyoming during the Early Eocene.

Do any modern places with similar temperature and precipitation have the same types of plants and animals?

What are the implications for the Eocene climate based on evidence from Fossil Basin?