1. + FOSSILS

2. + OCTOBER 9, 2012 Schedule Critique Your Thinking Essay Due Friday Quiz Friday Lab Reports and Rock layer Models TURN IN if you have not. Do your assignments some points are better than NO points

3. + More recently deposited rock layers are more likely to contain fossils resembling existing species. Fossils provide important evidence of how life and environmental conditions have changed. “Fossils” can be compared to one another and to living organisms according to their similarities and differences. Fossils can be used to help determine the relative age of rock layers are called index fossils.

5. + Fossils tell us… 1. Life forms have changed over time Extinction of organisms is apparent in the fossil record 2. Earth’s climate and surface have changed over time.

6. + By studying fossils (and rocks)…. Scientists have developed a geologic time scale which outlines the major divisions of Earth’s history.

7. + How do fossils form? Death Burial Sediments harden

8. + http://www.discoveringfossils.c o.uk/whatisafossil.htm

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13. + Geological forces distort the sediment

14. + http://www.discoveringfossils.co.uk/whatisafossil_stage_8.jpg The uplifted rock is exposed to weathering and gradually erodes away

15. + http://www.discoveringfossils.c o.uk/whatisafossil_stage_9.jpg Roy Shepherd extracts the fossil fish http://www.discoveringfossils.co.uk/what isafossil_stage_9.jpg

16. + Types of Fossils

17. + Unit 4 : Chapter 16 : Section 3 Looking at Fossils Fossil Amber with Insect Inclusions Fossilized tree sap is called amber

18. + Unit 4 : Chapter 16 : Section 3 Looking at Fossils Fossil Amber with Insect Inclusions Animals caught in amber are perfectly preserved

19. + Unit 4 : Chapter 16 : Section 3 Looking at ICE Woolly Mammoth Fossils of mammoths, extinct for 12,000 years, have been found frozen in Arctic ice

20. + Unit 4 : Chapter 16 : Section 3 Looking at Fossils Theropod Track A trace fossil is naturally preserved evidence of animal activity

21. + Unit 4 : Chapter 16 : Section 3 Looking at Fossils Theropod Track This dinosaur track is located in Glen Rose, Texas, in Dinosaur Valley State Park

22. + Unit 4 : Chapter 16 : Section 3 Looking at Fossils Ammonite Fossil A mold is a cavity in rock where a plant or animal was buried

23. + Unit 4 : Chapter 16 : Section 3 Looking at Fossils Ammonite Fossil A cast is an object made when sediment fills a mold and becomes rock

24. + Cast&Mold http://www.salem.k12.va.us/staff/jwright /vocabulary/fossil_cast&mold.jpg cast and mold

25. + Imprint http://www.salem.k12.va.us/staff/jwright /vocabulary/image2PV.JPG http://www.salem.k12.va.us/staff/jwright /vocabulary/image2PV.JP IMPRINTIMPRINT

26. + Amber AMBERAMBER

27. + BILL NYE FOSSIL VIDEO

28. + Carbon-14 & Uranium

29. + Carbon-14 Carbon-14 dating is an example of __________(relative/absolute) dating, and the law of superposition is an example of ___________(relative/absolute) dating.

30. + Unit 4 : Chapter 16 : Section 2 Absolute Dating When animals eat, they ingest radioactive Carbon-14

31. + Unit 4 : Chapter 16 : Section 2 Absolute Dating By comparing the amount of C-14, geologists can calculate the age of a fossil

32. + Since C-14 has a half-life of only 5730 years, other isotopes are used to date older rocks

33. + Unit 4 : Chapter 16 : Section 2 Absolute Dating

34. + Uranium Radioactive dating is used to study the uranium in igneous and metamorphic rocks. Uranium is a mildly radioactive substance that breaks down at a slow and steady pace which cannot be altered by temperature or pressure. By looking at different rocks and comparing the amount of uranium still in the rock to the amount of lead that has been formed, scientists can measure the age of the earth. Using this method, scientists have determined that the earth is 4-5 billion years old.