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FOSSILS

FOSSILS. 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 .

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FOSSILS

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  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.

  4. 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.

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

  6. How do fossils form? • Death • Burial • Sediments harden

  7. http://www.discoveringfossils.co.uk/whatisafossil.htm

  8. Geological forces distort the sediment

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

  10. http://www.discoveringfossils.co.uk/whatisafossil_stage_9.jpghttp://www.discoveringfossils.co.uk/whatisafossil_stage_9.jpg http://www.discoveringfossils.co.uk/whatisafossil_stage_9.jpg Roy Shepherd extracts the fossil fish

  11. Sept.19 • Set up a paper for Cornell notes • Topic: Types of Fossils • EQ: Back board

  12. Turn in comics • Notes • Look at fossils

  13. Types of Fossils

  14. the different types of fossils based on how they were formed • Carbonized fossil – forms when organisms or parts, like leaves, stems, flowers, fish, are pressed between layers of soft mud or clay that hardens squeezing almost all the decaying organism away leaving the carbon imprint in the rock. • Trace fossil – forms when the mud or sand hardens to stone where a footprint, trail, or burrow of an organism was left behind. • Mold fossil – forms when sediments bury an organism and the sediments change into rock; the organism decays leaving a cavity in the shape of the organism.

  15. the different types of fossils based on how they were formed • Cast fossil – forms when a mold is filled with sand or mud that hardens into the shape of the organism. • Petrified fossil (permineralized fossil) – forms when minerals soak into the buried remains, replacing the remains, and changing them into rock. • Preserved fossil – forms when entire organisms or parts of organisms are prevented from decaying by being trapped in rock, ice, tar, or amber.

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

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

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

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

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

  21. Mold fossil – forms when sediments bury an organism and the sediments change into rock; the organism decays leaving a cavity in the shape of the organism.

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

  23. Cast fossil – forms when a mold is filled with sand or mud that hardens into the shape of the organism.

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

  25. http://www.salem.k12.va.us/staff/jwright/vocabulary/fossil_cast&mold.jpghttp://www.salem.k12.va.us/staff/jwright/vocabulary/fossil_cast&mold.jpg Cast&Mold

  26. Amber

  27. http://www.salem.k12.va.us/staff/jwright/vocabulary/image2PV.JPGhttp://www.salem.k12.va.us/staff/jwright/vocabulary/image2PV.JPG http://www.salem.k12.va.us/staff/jwright/vocabulary/image2PV.JPG http://www.salem.k12.va.us/staff/jwright/vocabulary/image2PV.JP Imprint

  28. BILL NYE FOSSIL VIDEO

  29. Warm-up: September 10, 2013 Write the history of the place represented in the sedimentary column below. Be specific!

  30. Topic: Absolute Dating Carbon-14 & Uranium

  31. What is Absolute dating? • It is the age of a rock unit, fossil or geologic event expressed in units of time, such as years. • A good example is your birthday. You were born at a specific time on a specific day of the year.

  32. What is an example ofabsolute dating? • Carbon-14 dating is an example of __________(relative/absolute) dating.

  33. How does absolute (radioactive decay) work? • it will break down naturally into a lighter element called a decay product. This process occurs at a predictable rate and can be used to determine how old an object is.

  34. How does carbon-14 work? • When animals eat, they ingest radioactive Carbon-14 • organism grows, more Carbon 14 is added to it. • When the organism dies, the Carbon 14 starts to decay into Nitrogen 14 (stable element). Unit 4 : Chapter 16 : Section 2

  35. Potassium Potassium 1.3 billion years ROCK ROCK (half-life) Argon

  36. How fast do elements decay? • A certain element will decay at a constant speed. The speed never changes. • This rate of decay is known as the element’s HALF-LIFE. • HALF-LIFE = the time it takes for half of the radioactive element to decay into the new element.

  37. What is a Half-life? • A half-life is the time required for half of an element's atoms in a sample to change to the decay product. • In each half-life only half of the remaining radioactive atoms decay, no matter how large the sample is.

  38. What does a graph for radioactive decay look like?g Exponential Unit 4 : Chapter 16 : Section 2

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

  40. Easiest way to calculate half-life? • Chart the half-lives, radioactive element (or decay product) and the age of the sample are related.

  41. What is another method other than C-14? • Uranium (U-238) is used for Radioactive dating 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.

  42. How to calculate half life? Example. • A piece of granite is determine to contain 50 grams of U-238. After one half-life, how much material is left? After 2 half-lives? After 3 half-lives? After 4- lives?

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