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FOSSILS

This article explores how fossils help geologists study the Earth's past, including determining when life began, identifying the first plants and animals on land, and tracking the appearance and disappearance of organisms. It covers different types of fossils, such as remains, imprints, bones, teeth, and traces, and explains how fossils form in sedimentary rocks. The article also highlights index fossils and provides examples of state fossils. English.

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FOSSILS

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  1. FOSSILS

  2. Fossils help geologists study Earth’s past & determine… • Approximately when life began • What plants & animals were 1st to live on land • When organisms appeared/disappeared • How organisms live

  3. Fossils Can be in the form of: REMAINS IMPRINTS BONES TEETH TRACES

  4. How Fossils form • The body must be protected from scavengers & bacteria • Hard parts have a better chance of becoming fossils • Fossils are found in sedimentary rocks

  5. Types of Fossils • Original remains • Petrified remains • Molds/Casts • Trace fossils • Carbonaceous film

  6. Original Remains An actual organism or part of an organism Usually forms in amber or ice – must be preserved quickly

  7. Carbonaceous Film Carbon residue left by an organism Coal is a carbon residue left by millions of organisms together – a fossil fuel!

  8. ReplacedorPetrified remains Some or all of the original material has been replaced by minerals, such as when silica seeps into buried trees & creates a replica of the tree called petrified wood

  9. Molds & Casts • Impressions of an organism left in clay, sand or mud • Mold: organism decays inside rock, leaving a cavity that is an impression of the outside • Cast: mold fills in with sediments, making a replica of the organism Watch them form! Cast Mold

  10. Trace Fossils Fossilized tracks, tools, burrows or other traces left of ancient organisms

  11. INDEX FOSSILS Since each organism comes from a specific time period, we can use a fossil to determine the age of the rock it is found in. The shorter the time a certain organism lived, the better we know when the rock formed. These special fossils are called index fossils.

  12. Index Fossils - Requirements • Existing for a short period of time • Abundant over a wide area • So it is more useful for comparing rocks in different places http://seedmagazine.com/content/article/the_evolution_of_life_in_60_seconds/ http://www.johnkyrk.com/evolution.html

  13. Which of the following do you think is most likely to preserve a fossil safely, & why?

  14. State Fossils • Delaware: Belemnitella americana • Virginia: Chesapecten jeffersonius • Maryland: Ecphora gardnerae

  15. Bibliography • http://wrgis.wr.usgs.gov/docs/parks/gtime/ • http://www.cr.nps.gov/museum/exhibits/dino/geotime/geotime2.html • http://denali.gsfc.nasa.gov/sci_hi/sci_hi_2004_05/2004_05b.html • http://maritime.haifa.ac.il/departm/lessons/ocean/lect03.htm • http://www2.worldbook.com/wc/popup?path=features/dinosaurs&page=html/trilobite.htm&direct=yes • http://www.intelligentdesign.org/menu/evolution/fossils/fishes.htm • http://www2.worldbook.com/wc/popup?path=features/dinosaurs&page=html/mesozoic.htm&direct=yes • http://skullduggery.com/extinct.htm • http://www.lpi.usra.edu/education/timeline/gallery/images/063.jpg • http://library.thinkquest.org/11922/extinct/mammoth.htm • http://www.hmag.gla.ac.uk/Neil/Amber/ant.jpg • http://www.paleozoic.org/shows/tucson-2003/images/fs/petrified-stumps.jpg • http://www.gpc.edu/~pgore/myphotos/fossils/cast&mold.jpg • http://www.baystatereplicas.com/images/dino_multi_tracks2.jpg • http://www.humboldt.edu/~natmus/Case_indexes/Case_jpgs/MakeFossil.web/368.jpg • http://upload.wikimedia.org/wikipedia/commons/a/a5/Conglomerate_Death_Valley_NP.jpg • http://www.es.ucl.ac.uk/schools/Glossary/sandstone.jpg • http://www.geology.wisc.edu/courses/g112/Images/gneiss2.jpg

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