Fossils

30 minutes

1-3

Earth Science (Rocks and Minerals)

Students will understand the following:

1. How fossils were preserved.

Each group or individual will need the following materials:

Paper plate

Paper cup

Modeling clay

Seashell

Petroleum jelly

Plaster of Paris

Plastic Spoon

1. Place a piece of clay about the size of a lemon on the paper plate.
2. Rub the outside of the seashell with petroleum jelly.
3. Press the seashell into the clay.
4. Carefully remove the seashell so that a clear imprint of the shell remains in the clay.
5. Mix 4 spoons of plaster of Paris with 2 spoons of water in the paper cup.
6. Pour the plaster mixture into the imprint in the clay. Throw the paper cup and spoon away.
7. Allow the plaster to harden, about 15 to 20 minutes.
8. Separate the clay from the plaster mold.

The clay has an imprint of the outside of the shell, and the plaster looks like the outside of the shell.

The layer of clay and the plaster are both examples of fossils. The clay represents the soft mud of ancient times. Organisms made imprints in the mud. If nothing collected in the prints, the mud dried, forming what is now called a cast fossil. When sediments filled the imprint, a sedimentary rock formed with the print of the organism on the outside. This typed of fossil is called a mold fossil.

Once the students are done with their experiments/projects make sure that they are told to clean-up their areas properly. Have wet-wipes and paper towels handy during clean-up and make sure to watch the time.

The students will each get to do this experiment/project individually. This way they will each get to keep a unique sample of their "fossil." If certain students need help, they will still get to do this project individually, but they will each have a partner to refer to in case of need for help. Partners can work together by explaining to each other what to do and then they can compare results.

Make sure to tell the students never to eat any of the materials that are handed out to them. They are meant for the experiment and not for tasting or eating. They should also follow all the directions carefully and do exactly what they say.

Evaluate individuals on how well they listen and follow directions. Not only should they listen, but they should also participate.

After the student have their mold of there "fossil" they can go on by painting their formation.

Before or after making the "fossil" talk to the students about where fossils can be found, and why some fossils are in different areas of the world. Locate these different parts of the world on a map.

Fossils have come from all different time periods. Give the students different dates from fossils that have been found and ask them questions about the time difference between the dates.

Have students do research on fossils, by finding pictures of different kinds of samples. This will give them a better idea of how fossils look different and can be found in different locations.

Any hardened remains or imprints of plant or animal life of some previous geologic period, preserved in the earth's crust, including petrified wood, resin, etc.

Matter that settles to the bottom of a liquid or, matter that is deposited by water or wind.

If nothing collected in the prints, the mud dries, forming what is now called a cast fossil.

When sediments filled the imprint, a sedimentary rock formed with the print of the organism on the outside.

Sedimentary Rock Formation

20 minutes

1-3

Earth Science (Rocks and Minerals)

Students will understand the following:

1. What a sedimentary rock formation is.

MATERIALS:

Each individual will need the following materials:

2 slices of bread

Crunchy peanut butter

Jelly

Knife, for spreading

Plate

1. Lay one slice of bread on a plate.
2. Use the knife to spread a layer of peanut butter on the slice of bread.

 

3. Add a layer a jelly on top of the peanut butter layer.
4. Place the second slice of bread on top of the jelly later.
5. Eat the sandwich.

A sandwich with a series of layers has been constructed.

Sedimentary rocks are formed from loose particles that have been carried from one place to another and redeposited. These rocks usually are deposited in a series of layers similar to the layers in the sandwich. Each layer can be distinguished by differences in color, texture, and composition. The oldest layer and the lowest bed is deposited first and the youngest layer is at the top. The layers over a period of time become compacted and cemented together to form solid rock structures.

Once the students are done with their experiment/project make sure that they are told to clean-up their areas properly. Have wet-wipes and paper towels handy during clean-up and make sure to watch the time.

The students will each get to do this experiment/project individually. This way they will each get to experience the example of sedimentary rock formations. If certain students need help, they will still get to do this project individually, but they will each have a partner to refer to in case of need for help. Partners can work together by explaining to each other what to do and then they can compare results.

Never taste anything in a laboratory setting unless you are sure that there a no harmful chemicals or materials.

Evaluate individuals on how well they listen and follow directions. Not only should they listen, but they should also participate.

Make sedimentary rock structures with other materials. Wood, sand, rocks, pebbles, etc. can be used. Glue the materials together and it will be a piece of art as well as an example of a sedimentary rock structure.

Find places around the world where different sedimentary rock structures could and are formed. Talk about when and how long ago the structures were formed.

Count the number of different rock layers there are in different sedimentary rock structures. Make a table or graph of different information such as height of each layer, how many layers of each there are, etc.

Have students find a site where there is a real sedimentary rock structure. They can take samples of the different layers and see what kind of different materials are in the structure. After they have done this they can tell why they think the layers are in the order they are in.

Rock formed at or near the earth's surface by the accumulation and lithification of fragments of preexisting rocks or by precipitation from solution at normal surface temperatures. Sedimentary rocks can be formed only where sediments are deposited long enough to become compacted and cemented into hard beds or strata. They are the most common rocks exposed on the earth's surface but are only a minor constituent of the entire crust. Their defining characteristic is that they are formed in layers. Each layer has features that reflect the conditions during deposition, the nature of the source material (and, often, the organisms present), and the means of transport.

Complex process whereby loose grains of sediment are converted into rock. Lithification may occur at the time a sediment is deposited or later. Cementation is one of the main processes involved, particularly for sandstones and conglomerates. In addition, reactions take place within a sediment between various minerals and between minerals and the fluids trapped in the pores; these reactions may form new minerals or add to others already present in the sediment.

Scientific discipline concerned with the physical and chemical properties of sedimentary rocks and the processes involved in their formation, incl. transportation, deposition, and lithification of sediments. The aim of much sedimentological research is to interpret ancient environmental conditions by studying the constituents, textures, structures, and fossil content of the deposits.

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