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This Week We Will Be Learning Of Fossils : This Week We Will Be Learning Of Fossils Topics we will cover include:
What types of rock commonly house fossils?
What can fossils tell us?
What are some of the different types of fossils?
How are these different types of fossils made?
What profession looks for fossils?
First, What Are Fossils? : First, What Are Fossils? Merriam-Webster’s Dictionary defines Fossil as: a remnant, impression, or trace of an organism of past geologic ages that has been preserved in the earth's crust
In other words, a fossil is something that was once alive hundreds, thousands, and possibly even millions of years ago, but is now dead and preserved in rock.
We Can Tell A Lot From Fossils! : We Can Tell A Lot From Fossils! Fossils and fossil records are key sources of information for scientists who want to discover information on the past. Fossils can tell us:
The living things that once existed on this planet.
The living things that coexisted at the same time.
The parts of the crust that were once under the ocean.
The approximate time species became extinct.
Times when a lot of species lived in an area, and times when very few did due to catastrophic events like volcanic eruptions, ice ages, etc.
How some types of species have changed over time.
What Kinds of Rock House Fossils? : What Kinds of Rock House Fossils? Igneous rock forms at a very hot temperature that will vaporize and/or burn objects. Only on very, very rare occasions can volcanic materials that have cooled a lot before coming in contact with an organism can create fossils. When Mount Vesuvius erupted the volcanic materials were just cool enough to create human molds of the people buried by the volcanic ash. Again, fossils are not typically found in igneous rock. These casts of people were developed from the human molds created by Romans getting buried in volcanic ash.
What Kinds of Rock House Fossils? : What Kinds of Rock House Fossils? The pressure and heat used to create metamorphic rock will also change the form of fossils too into entirely new rocks. Therefore, very rarely will we find fossils in metamorphic rock if at all. Picture from www.geology.about.com
What Kinds of Rock House Fossils? : Sedimentary rock takes a long time to harden and does not require or create a lot of heat. This does not destroy the organisms trapped in sediment very quickly giving plenty of time for fossils to form. Almost all fossils are found in sedimentary rock. What Kinds of Rock House Fossils? Photo from www.geology.about.com
Some Common Types Of Fossils : Some Common Types Of Fossils Mold Fossils
When a dead or living organism settles in wet sediment or is buried for a long time in sediment under pressure, the sediment will dry and harden at the same rate the organism disintegrates. This leaves behind a mold in the shape of the former living thing.
Some common Types Of Fossils : Some common Types Of Fossils Cast Fossils
These fossils are created after the mold fossil is completed. Once the mold hardens, water carrying minerals will fill the mold and deposit the minerals inside the space left where the organism once was. These minerals will harden in the shape of the mold kind of like Jell-O does in a bowl.
Some Common Types Of Fossils : Some Common Types Of Fossils Imprint Fossil
Imprints are created by animals doing common daily activities like walking. When the animal leaves an imprint in wet sediment like a footprint from walking in mud, the sediment will harden. If the sediment gets preserved with the footprint and does not erode, it will turn into a rock with an imprint fossil.
Some Common Types Of Fossils : Some Common Types Of Fossils Petrified Fossils
Typically created by plants and bones that are buried for long periods of time. Water with minerals dissolved inside it will seep into the plant and bone material depositing the minerals inside of them. These minerals will harden and create rock in the same shape of the bone or plant.
More Photos Of Fossils : More Photos Of Fossils The top left shows a piece of petrified wood made from quartz that was deposited into the tree by water.
The top right is a mold fossil of a fish from the Green River in Wyoming.
The lower left is a cast fossil of a clam from dinosaur times!
All photos from www.geology.about.com
Who are Paleontologists : Who are Paleontologists Paleontologists are people who dig up and carefully preserve fossils. They may work in museums, teach in colleges, or work outdoors in the field digging up old fossil records to be studied later.
Paleontologists need to be good in biology, geology, history, chemistry, art and mathematics just for starters!
So if you see a dinosaur skeleton, thank a Paleontologist for his/her very hard work!