Making and Dating Fossils and a Geologic Time Line

INTRODUCTION

Fossils are something every student has heard about or seen, but few have actually touched or examined them. In this experiment, students may do just that! In addition, students will make their own fossils, and learn about where and when certain fossilized animals lived in the past.

MATERIALS

Learning About Fossils
Cards with fossil diagrams for "determining age of cards"
Common Ohio fossils obtained from OSU Orton Museum:

• 3 Oysters (Cretaceous)
• 14 brachiopods, approximate identifications (Devonian)
• 7 Paraspifera
• 3 Mucrospifera
• 4 Rafinesquina
• 1 snail (Devonian)
• 3 corals (Devonian)
• 1 Belemnite (Jurassic)
• 4 Crinoid (Devonian)
• 1 shark's tooth age =?

Making a Fossil
• Modeling clay
• Plastic bowl (small disposable)
• Plaster of Paris
• Water
• Mixing bowl
• Measuring cup
• Chalk or string
• Meter stick

Geologic Time Line
• Geologic events on cards for time line
• Sheet of paper (possibly use a 6' long sheet of brown wrapping paper

WHAT TO DO

Learning About Fossils

1. Take bag full of office supplies, all mixed together.
2. Dump contents in front of students and ask how they might classify, or organize, the different supplies.
3. Let the students sort the supplies. Suggest sorting by size, shape, color, use, etc.
4. Explain that geologists have to sort rocks in much the same way. There are several different ways to classify, and geologists, like the students, must decide which way is best to sort first.
5. Show students the sandstone, shale, conglomerate, and other rocks. Explain that these are part of a classification called sedimentary rocks. Sedimentary rocks are most often formed in the presence of water.Ask students what kinds of water might be used. Suggest answers like rivers, lakes, and oceans.

Making a Fossil

1. Make the modeling clay into a round ball, then semi-flatten the ball to make a good mold.
2. Press the fossil into the modeling clay.
3. Mix Plaster of Paris (1 cup) with water (1/2 cup).
4. Remove the fossil from the mold.
5. Pour the Plaster of Paris into the mold.
6. Mark the small plastic bowl with the student's initials and place the mold with the Plaster of Paris in the bowl. Allow to dry approximately 30 minutes, then separate the mold from the "fossil."

Goelogic Time Line

1. Measure 12 meters on the floor (hallway, using water-soluble ink) or on the playground (using chalk).
2. Place the geologic events in the appropriate spot according to the length that represents the period of time, or use string with knots every meter placed on the ground or held by students.
3. Tie, or hang with clips, cards that record the events in history on the "time line" or place beside it. The string could be marked with a pen for the proper locations for each event or fossil.
4. Let every 1meter represent 50 million years in Geologic Time.
5. Mark the Era and the Periods along the time line.
6. Ask students to place pictures of various plants and animals in the generally appropriate region of the time line.

QUESTIONS

1. How are fossils preserved? (Fossils are the remains of prehistoric life or other direct evidence that prehistoric life existed. Typically animals or plants that become fossils have hard parts, such as bones or shells, are buried quickly to prevent disruption of the parts and must be undisturbed for a very long time. The biological material from the dead organism is slowly replaced with other chemicals that interact with the biological material. The shape is retained but the material is replaced.)
2. Do all animals become fossils? Why or why not? (As mentioned earlier mostly animals or plants with hard parts become fossils.)
3. How much is a million billion? (1,000,000 x 1,000,000,000)
4. Which fossil could have been in the movie Jurassic Park?
5. What is the time when the Jurassic began: ____________ millions of years?
6. What is the time when the Jurassic ended: ____________ millions of years?
7. Some fossil groups existed on earth for longer than one geologic period. The armadillo has been around for a long time. How many million years ago did an armadillo first become a fossil? In what periods did it live?
8. Do we find dinosaur fossils in Ohio? Why? (There are no fossils in Ohio because biological material decomposed due to the swampy conditions of the area more fuels formed than fossils.)

SUMMARY

Fossils are the well-preserved remains of prehistoric creatures or representatives of prehistoric life. There are many different kinds of fossils. Some are formed from plants or animals that were buried quickly and left undisturbed throughout the long fossilization process. Other fossils are not actually preserved plant or animal remains, but they are shaped like them. Some plants and animals formed molds of their exact shape as they decomposed while covered by sand or mud. As the biological material was dissolved away and the sand or mud turned into rock an empty space was left in the shape of the plant or animal remains. Over time dissolved chemicals filled the mold and hardened into a cast, forming a replica of the original plant or animal. Most fossils are made up of chemical material rather than the biological material because the biological material was decomposed and replaced by chemicals that interact with the biological material.
In Ohio few fossils are found because the conditions for fossil formation were not ideal in this area. The swampy conditions of prehistoric Ohio decomposed most plant and animal remains before they could be fossilized. In Ohio far more fossil fuels are found than fossils.

EXTENSIONS

1. Place mud in a tray and make impressions in the mud with fossils or leaves. Pour additional mud on the surface. Let dry, then break open the mud to discover fossils.
2. Place sand on the bottom of a plastic tray. Place fossils on the sand. Pour plaster of paris over the sand and let dry. Remove from tray, turn over, clean sand away from the fossils.
3. Sketch fossils.
4. Draw your own fossil animal.

VOCABULARY

• Fossil
• Cast
• Preservation and fossilization
• Geologic Time
• Millions and billions
• Relative Age

Names of Periods

• Generally, geologic formations and periods/systems are named according to the geologic feature where they were described.
• The Cambrian Period is named for Wales - Cambria is the Latin word for Wales.
• The Ordovician Period is named for the Ordiovices, an ancient Celtic tribe in North Wales.
• The Silurian Period is named for Silures, an ancient tribe in South Wales.
• The Devonian Period is named for Devonshire in the United Kingdom.
• The Mississippian Sub-Period is named for the many outcrops present on the limestone bluffs along the Mississippi River.
• The Pennsylvanian Sub-Period is named after the coal-bearing strata of Pennsylvania.
• Both the Mississippian and Pennsylvanian Sub-Periods are under the title Carboniferous Period, which is the only name used in the United Kingdom. This is in reference to the rich deposits of coal there.
• The Permian Period is named after the Perm Province of Russia.
• The Triassic Period is named from a three-fold subdivision of its rock in Germany.
• The Jurassic Period is named for the Jura Alps.
• The Cretaceous Period is named for chalk, which is its most characteristic deposit.
• The Tertiary Period is named for the third group of rocks. Geologists used to think there were four groups of rocks, and tertiary means "third."
• The Quaternary Period is named after the fourth group of rocks - from the Latin word for "four." The Quaternary Period includes the time we live in now.

SOURCES

"The Best of Wonder Science: Elementary Activities: Fabricate Some Fabulous Fossils." (p. 319) Delmar Publishers, ITP, Cincinnati, p 531.
"Science Is." Susan Bosak, Scholastic Canada Ltd, ISBN 0590-74070-99, p. 515 (Making Fossils, p. 230).
"Fossils, A Golden Guide." Frank Rhoads, H.S. Zim, and Paul R. Schaffer, St. Martin's Press, 2000.
Fossils of Ohio.
GEOEDGROUP-The Ohio State University (Amanda Cavin, Alison Laughbaum, Garry McKenzie, Christina Millan, Rachel Tayse).

© S. Olesik, WOW Project, Ohio State University, 2000.