Mr. CH 01/07/09

Making a Fossil Cast

A. Purpose:

The objective of the making a fossil cast experiment is to show how to make a fossil cast, along with being able to see how that cast will develop.  The experiment gives a keener understanding of the way casts are created.  It also demonstrates the crucial fact that every cast must be made by a mold.  In addition to these things, the experiment emphasizes the point that you must have the proper conditions to form a complete cast of the object.  This is the objective of the experiment.

Much background information can be given on the subject of fossils.  In ancient times, many people relied on myths and legends to explain fossils.  The Chinese, for example, thought that fossils of ancient mammals were dragon bones and they used the grinded remains of the fossils in medicine.  The Greek scholar Aristotle was the first to see it from a wiser point of view.  He noticed that the ancient fossils of shells and trilobites looked remarkably similar to the seashells on the beach.  Concluding that fossils were the remains of once living creatures, he left the project and moved onto his next assignment.  Another man who strongly backed Aristotle's view on Fossils was the Italian painter and problem solver, Leonardo De Vince.  Though he came a time later than Aristotle, he had the same principles on the subject as the Greek scholar before him.  An English canal engineer by the name of William Smith noticed that in canyons and other places, each different layer of rock (strata) generally contained a different type of fossil.  This led to what we now know as the Principle of Superposition.  Nowadays, with the technology we have, fossils give us a gateway into the people hundreds of years ago would never have dreamed of.  This is some information on fossils.   

The making a fossil cast experiment is designed to exemplify the way a fossil cast is made.  The goal is to demonstrate that if a shell is pushed into clay, it will form a mold. When plaster of Paris is added, the mold will be filled by "sediments" and those will hopefully harden, forming a cast coming from the mold, with the exact same design as the mold itself had.  Then it should be simple enough to pull the cast out and get a close replica of the underside of the shell.  That is, if the experiment goes as planned.  This experiment mainly hopes to show how a cast is formed and what the result of the mold being filled will be. 

As imaginable, fossils are of huge interest to science.  Fossils allow the scientists a brief glance back in history.  There is no telling how valuable fossils can be if they are the right kind.  Clam-like fossils appear so regularly, that they are used to date the ground in which they were found.  For example, if a clam was found from supposedly 300 years ago, you could date the place where you found it back to the early 1700's.  Science will forever be in debt to fossils because without them, the world would not know nearly as much as it does about the earth's past.  If the cast and mold process of fossilizing was not in existence, knowledge of earth's past would decrease significantly.  These fossils are the most common kind and make up much of what we know about fossils and earths past.  Fossils are infinitely valuable to a scientist.  These are the main reasons why fossils are of enormous interest to science.

Hypothesis: If the Plaster of Paris is mixed properly and poured carefully, then a good cast of the object will be obtained.

B.  Equipment:

1.  Modeling clay
2.  Plaster of Paris
3.  A paper plate
4.  A shell or something with a distinct shape or design
5.  Vaseline or another petroleum jelly
6.  Eye protection such as glasses or safety goggles

C. Procedure:

1.  Cover the outside of the shell, the (part you will fossilize) with Vaseline.         
2.  Roll the clay out on the paper plate so it covers an area larger than the shell.
3.  Choose the most interesting part of the shell and firmly press it into the clay, so an imprint forms in the clay.
4.  Pull the shell away, and you should see a nice impression of the shell in the clay.  At this point there will be a mold of the shell.
5.  Mix the plaster according to the directions on the package and pour the plaster into the impression.  Fill the impression so full that the plaster spills a little over the clay onto the paper plate. 
6.  Allow the plaster to harden. 
7.  Once the plaster has hardened, pull it off the paper plate and remove the clay from it.  Check how it turned out.  This is the cast of the shell.
8.  Clean up the mess.

D.  Observations:

1.  The shell being used was in the shape of a unicorn horn and it was about one inch long.  At its widest point, the shell was a bout a centimeter but then it tapered down to a point.  It was coated with Vaseline and then smoothed over so that the Vaseline would not make any extra indentions of its own. 
2.  A slab of brown clay was spread out on the paper plate just bigger than the shell.   And after a talk, it was decided that, since the shell was shaped like a screw, it was decided that it would be put in sideways.  This was done because if it had been vertical, the groves would have been ruined when it was pushed in and pulled out. 
3.  The shell was pushed into the plaster horizontally until only half was still visible.
4.  The shell was carefully pulled out and we pulled it out.  The back was pushed down in order to make the point rise.  It was observed that though the shell came out mostly smooth, there was a faint residue of brown clay on the underside.
5.  A bucket, more than large enough for its purpose, of Plaster of Paris was brought out.  The Plaster of Paris was at this point in a powder form, and the mixture was incredibly smooth to the touch. 
6.  To turn the Plaster of Paris into its real form, the powder had to have water added to it.  There was no exact amount for the mixing in measurements, it was in proportions.  The way it had to be added was this:  two parts Plaster of Paris to one part water.  In other words, you need twice as much plaster mixture as water.
7.  The Plaster of Paris was mixed with relatively cold water using teaspoon and after some persistent stirring, it was ready to be poured into the formerly made mold.
8.  The Plaster of Paris was poured into the shell mold and it was left to droop down to the plate.  When the Plaster of Paris had stopped dripping, it was almost covering the slab of clay. 
9.  The mess made had been cleaned up and the shell was placed on a lofty shelf so that it could sit without interference and dry.

E.  Conclusions:

The Making a Fossil Cast experiment was a success in demonstrating the natural process of making a fossil cast.  While it did speed up the process of a cast and mold quite a bit, it was performed so that there would be as little laboratory hindrances as possible.  The experiment did an excellent job of showing that a fossil cast will form only under the right circumstances.  For instance, the Plaster of Paris represented sediments which would naturally leak into the mold to form the cast.  If there were not proper conditions to push sediments into the mold, like water or wind, there would be no cast.  This fact was laid down bare by the experiment.  Obviously, the force which was acting as the push in the experiment was the bucket being tipped.  Also, the experiment demonstrated that if the ground is not right, no mold will form.  In the experiment, there was no one walking on top of the mold but if there had been the mold would have been squashed to a pulp.  This is another fact which was kindly pointed out by the experiment.  It was a good demonstration and one that gave a deeper understanding of the process of cast and mold.  The Making a fossil cast experiment did an outstanding job of showing how a natural cast and mold was formed and helped out even more by speeding up the process a bit.  Overall, it was a first-rate experiment.

Though the Making a Fossil Cast was a great experiment even without corrections, there was much room for improvement.  To make sure that no clay stuck to the shell, it would be a good idea to have it coated with special, nonstick material using a machine.  This would also eliminate the difficulty of having to spread the Vaseline over the shell just right so that the Vaseline would make no blotchy marks of its own in the mold.  Another good idea would be to attain some type of nonstick clay meant especially for experiments and other scientific purposes.  A further improvement would be to have a standardized type of Plaster of Paris.  The results would be dramatically different between a runny type of plaster, and a thick, gooey type.  Both might dry into the same material, but there will be large differences and neither one will come out remotely like the other.  A standardized type of shell and clay would also be a welcomed edition.  You will get much different results between a flat shell and one with more depth.  Of course, many of these things would require lab equipment but they are all in the sake of improvement.  To get a better grasp of cast and mold it would be worthwhile to do the same experiment with different types of shells, leaves, and more.  There are many things that this experiment can be done with. 

Like mentioned earlier, more practical research could be done in a lab with the appropriate tools, but even without a lab, much more studying could be done on the subject of cast and mold fossils.  It would be a good idea to do experiments similar to the Making a Fossil Cast experiment.  Maybe, to give more realism, the place of clay could be taken by cement and the place of the plaster could be taken by mud or some other self-hardening substance.  Other substances would work too.  The main point in this experiment was to help understand the forming of cast and mold, but just the way it draws one's mind to the past and to fossils, it's impossible not to think of how incredible God is and what an amazing world he's blessed us with.  With the knowledge of fossils, it is possible to look into the past of the some of the greatest gifts God has bestowed upon mankind.  That gift is the earth, and everything on it.

F.  Bibliography:

Domain:  http://en.wikipedia.org
Document:  /wiki/Fossil

Rosenoff. Steve.  Class Lecture.  January 5, 2009

Wile. Dr. Jay.  Exploring Creation with General Science, 2nd Edition.  Apologia Educational Ministries.  2008.