By Erica ShenoiMrs. Bratcher

Science- B Block14 December 2011

FOSSILIFEROUS FOSSILS AND GEOCHRONOLOGICAL GEOLOGIC TIME

SCALE

WHAT ARE FOSSILS???Fossils are remains of past animals, humans, plants, and other historical life, that can be found impressed into rocks.

PETRIFIED FOSSILSWhen a fossil organism is subjected to mineral replacement, it is called a petrified fossil. A petrified fossil can be a rock that contains crystals or gems inside of them, like the one on the bottom left. They are formed when a mineral slowly takes the place of original, once-living material.

CAST FOSSILSA cast fossil forms when a mold fossil is filled with some form of mineral. It is a form of fossil, formed when an animal, plant, or other organism dies, its flesh decays and bones fade due to chemical reactions. Minerals gradually enter into the cavity, resulting in a cast, also called a mold fossil, which is in the general form of the original organism.

TRACE FOSSILSTrace fossils give us proof of animal life from the past. Trace fossils include things like foot prints, burrows, and other organisms. Trace fossils are formed in place and can therefore tell us about the ancient environment in which the animal lived.

WHAT DO FOSSILS SHOW???Fossils show remains of past organisms such as plants, animals, insects, etc.

WHAT CAUSES ROCK LAYERS TO CHANGE???

Huge water erosions

Natural disasters

Meteors Dynamite Human-made

objects

GEOLOGIC TIME SCALE provides a system of

chronologic measurement relating stratigraphy to time

used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth

WORKS CITED Earth Science. 2011. Wiki Spaces. Web. 14 December 2011 <http://discoversciencefun.wikispaces.com>

Fossil. 2011. Wikipedia. Web. 14 December 2011 <http://en.wikipedia.org>

Geologic Time Scale. 2011. Wikipedia. Web. 15 December 2011 <http://en.wikipedia.org>

Mold Fossils. N.d. Boscobel. Web, 15 December 2011 <http://www.boscobel.k12.wi.us>

What is a Cast Fossil? N.d. Answers. Web. 14 December 2011 <http://wiki.answers.com>