1. What is a fossil

1. 1. What is a fossil? Fossils are any evidence of past life. many things can become fossils: standard shells, bones, petrified wood, and leaves footprints, pollen, feeding traces, worm burrows, even fossilized feces,

3. 3. Describe types of body fossils. Compression � sediment layers pile on top, compressing specimen, making a flat layer. Casts & molds � organic material decays, depression fills in w/ shape of organism Petrified wood � minerals replace organic material

4. 4. What is amber and why is it important? Amber � tree resin, preserves organic materials, insects & plant material most often captured Important � other fossils don�t preserve organics.

5. 5. Who were the early scientists who recognized the age of the earth? What did each do? Archbishop James Ussher of Ireland, (late 1600's, calculated the age of the earth based on the geneologies from Adam and Eve listed in the biblical book of Genesis. According to Ussher's calculations, the Earth formed on October 22, 4004 B.C. History of the World. The chronology he developed was taken as factual because it did not contradict anything in the bible

6. 5. Con�t Historical Scientist studying earth age. Leonardo Da Vinci (1452-1519; painter of the Last Supper, and the Mona Lisa, architect and engineer) calculated the sedimentation rates in the Po River of Italy. Da Vinci concluded it took 200,000 years to form some nearby rock deposits. Earth was thought to be only 5,000 year old at that time.

7. 5. Con�t Historical Scientist studying earth age. James Hutton - 1726-1797, Scottish physician, intellectual, and farmer, is regarded as the father of modern geology. His investigations led to his development of the Theory of uniformitarianism - the basis of modern geology and paleontology. Charles Lyll later made Hutton�s work more famous and is also sometimes called Father of Geology.

8. 5. Con�t Historical Scientist studying earth age. French physicist Antoine Henri Bequerel (1852-1908) discovered radioactivity in 1896. He shared the 1903 Nobel Prize in Physics for this work, along with Pierre and Marie Curie. Led to new method to date the earth, based on radioactive decay.

9. 5. Con�t Historical Scientist studying earth age. Carbon-14 dating, developed by 1960 Nobel laureate Willard Frank Libby (1908-1980), is based on the ratio of C-14 to C-12 in an organic sample. This technique allows us to date the fossil itself. C-14 dating.

10. How old do we think the earth is? Based on what evidence? Radiometric age assignments based on the rates of decay of radioactive isotopes, not discovered until the late 19th century, The Earth is thought older than 4.5 billion years; oldest known rocks are 3.96 billion years old.

11. 7. How was the modern geologic time scale derived? The geologic time scale was first assembled using fossils and relative dating techniques decades before the development of radiometric dating techniques. The longest duration units of the time scale are the eons. Each eon is subdivided into eras, which are in turn split into periods.

12. 8. What are 3 eons? What was occuring in each? Hadean � not an eon but before geologic time � whenever earth was created until 3.8 million years ago. Archean Eon � 3.8 to 2.5 billion years ago Proterozoic Eon covers the time span from 2.5 billion to 544 million years ago Simple, prokaryotic cells simple eukaryotes approximately 1.5-1.2 billion years ago. Iron crisis The Phanerozoic Eon represents the past 544 million years of geologic time. "time of visible life".

13. Archean Eon methane, ammonia, sulfuric acid and other toxic gases Our oldest fossils date to roughly 3.5 billion years � all bacteria microfossils Landscape starting to form Stromatolites � columns of bacteria

14. Proterozoic Eon covers the time span from 2.5 billion to 544 million years ago Simple, prokaryotic cells initially (bacteria) Iron crisis � oxygen Algae & simple celled eukaryotic 1.5 billion ya

15. Phanerozoic Eon 544 million years of geologic time "time of visible life". Start of modern plants & animals

16. 9. What is radio carbon dating?� Fill out worksheet on radio carbon dating. Carbon-14 dating, is based on the ratio of C-14 to C-12 in an organic sample less than 70,000 years old As long as the organism was alive, the ratio of carbon-12 to carbon-14 was in equilibrium with its environment. When the organism dies, the "clock" starts as the carbon-14 decays, changing the ratio

17. 9. C �14 dating con�t http://dwb.unl.edu/Teacher/NSF/C03/C03Links/www.all.mq.edu.au/online/edu/egypt/carbdate.htm

18. 10.� What was happening to continents during the history of the earth? Http://sos.noaa.gov/datasets/Land/paleo.html Pangea - Gondwana - Laurasia- Applachian mts- Himalayan mts-