1. A trip through geologic time: Fossils

2. Uniformitarianism The present is the key to the past. The same geologic processes that operate today operated in the past Fossil fish- not a goldfish

3. Fossils: evidence of past life Fossil Formation: 1. organism dies 2. organism buried in sediment 3. sediments slowly harden into rock preserving the parts of the organism

4. Most important conditions for fossil formation Rapid burial Hard parts

5. Types of Fossils Mold and Cast 1.organism dies, gets buried, decomposes – leaves behind a hole the shape of the original organism ( the mold) 2.Water washes in sediments which fill in the mold and solidify to form a rock with the same external structure as the organism had (the cast) Trilobite fossil

6. Petrified: (mineralized) fossils- organism dies, every molecule of the organism is replaced by a molecule of a mineral This shows the internal structure as well as the external structure. Petrified Wood

7. Actual Fossils The actual organism frozen in ice or amber (tree sap) Termites in amber Frog in amber Baby mammoth frozen in ice

8. Trace Fossils:evidence that an organism has been there coprolyte Dinosaur footprint gastroliths Dinosaur tracks Worm casings

9. Carbon films: an extremely thin coating of carbon on rock Leaf fossil

10. Index Fossil: fossils of widely distributed organisms that lived during only one short period.

11. http://cartage.org.lb/en/themes/sciences/Paleontology/Foss ilsAndFossilisation/AmberFossils/AmberFossils/AmberFossils. htm http://news.bbc.co.uk/2/hi/6284214.stm http://www.envs.emory.edu/faculty/MARTIN/ichnology/tf- eggs.htm http://en.wikipedia.org/wiki/Gastrolith http://www.clas.ufl.edu/users/pciesiel/gly3603c/fossils.html http://pubs.usgs.gov/gip/geotime/fossils.html Picture bibliography