A Little History:
Millions of years ago, this area was covered by a shallow sea. The area that you are standing on was a tropical coral reef. Ancient reefs were built primarily by tabulate and rugose corals. They built the structure, and reef dwellers, such as brachiopods, trilobites and mollusks, used it to live out their lives. We see evidence of this by the fossilized remains of the ancient sea life you can see at your feet.
The fossils that you see in the rocks underfoot are primarily corals and mollusks.
There are many different ways that an organism can become fossilized. This earthcache's lesson is to examine the ways in which fossilization occurs. Look over the list, visit the site and email me the answers to the questions. Pictures are always welcome with your log!
Methods of Fossilization:
MOLDS- We can tell that there once was an organism because it has left a mold. The mold preserves an imprint of the surface of the organism,
CASTThe cast will preserve the form of the organism, but none of the internal structures.
TRACE FOSSILS – These are the remains of what the organism left behind. These can be anything...eggs, eggshells, tracks, pathways, burrows, droppings
COMPRESSION/IMPRESSIONS- This type of fossilization usually occurs when an organism forms into a fossil, and that forms into a rock. The rock breaks apart and we find the impression on the one side, and the compression on the other. They are negative and positive imprints of one another. The difference is that the compression side contains original organic material, while the impression side does not.
PERMINERALIZATION / PETRIFICATION: The organism dies, and minerals seep into and replace the organism's tissues,and as a result a rock-like fossil is formed. An example would be 'petrified wood'
UNALTERED PRESERVATIONS The easiest way to explain this is to think of the movie Jurassic Park. Remember when they found the perfectly preserved insect in amber that started all the trouble? That was an unaltered preservation. A pretty rare fossil.
To Log this Earthcache, email me the answers to the following questions:
1) What, in your opinion, is the primary method of fossilization at the site?Is there more than one method?
2) Do you notice any evidence of trace fossils?
3) Let me know the approximate size of the largest fossil you can see at the site.
4) How is the water running today? Raging Torrent, steady, trickle or dry?
Resources/Pictures:
https://uwaterloo.ca/earth-sciences-museum/resources/fossils-ontario
http://petrifiedwoodmuseum.org/FossilTypes.htm
http://www.backyardnature.net/g/fossils.htm
http://legacy.belmont.sd62.bc.ca/teacher/geology12/fossilization.htm
http://en.wikipedia.org/wiki/Cast_fossil