Paleontologists, geologists, biologists, and others use the fossil record to learn about the past history of the Earth. Using this knowledge, we have gained an understanding of geologic processes that continue today, biodiversity past and present, species extinction, past and present climates, oceans, and atmospheres among others.
In this activity you will compare a fossil mold and cast.
Material:
Procedure:
Part I: The Mold
Make a "bowl" out of a sheet of aluminum foil, about 2-3 inches deep and 8 inches across.
Mix Plaster of Paris and fill the bowl about 1/2 of the way full.
Grease a shell with some lubricant like cooking spray, oil, or shortening.
Press the sea shell or another small object into the plaster of Paris.
Wait 20-30 minutes and then carefully remove the object and foil, and you have a fossil!
Part II: The Cast
Note: Before doing this second part you want to make sure that your mold is completely dry.
Enclose your mold with a foil bowl again. This time make the edge of the bowl go well above the mold so that you can pour another layer of Plaster of Paris.
Now grease the "fossil" mold you just made with the lubricant.
Pour another layer of Plaster of Paris.
Wait 20-30 minutes and remove the aluminum foil.
Separate the two layers. Now you have a cast of your fossil.
In this activity you used a sea shell. What other types of organic (parts of living things) objects would be good to use in the activity? Name at least two.
Compare the mold and cast.
Now that you have done a comparison of your cast and mold, does the mold or cast give you more information about the shell? Explain.
Extra Credit: (3 points) Attach a picture of your fossils.