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Earth’s Beginnings

The Story from before time. Earth’s Beginnings . 3. The earth and life on earth have been changing over billions of years 4. The earth and life on earth have remained much the same since the beginning of time 5.I have mixed ideas, and am not sure what to think.

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Earth’s Beginnings

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  1. The Story from before time Earth’s Beginnings

  2. 3. The earth and life on earth have been changing over billions of years 4. The earth and life on earth have remained much the same since the beginning of time 5.I have mixed ideas, and am not sure what to think. 1. The early earth and life forms changed over time initially, but now are stable 2. Creation of certain features of the universe and living things can best be explained by a directed process (intelligent design) Select one statement. Support your selection with evidence.

  3. Theories • Traditional view based on review of historic literature placed the age of earth at ~ 10000 years • Geologic formation does not fit into 10000 year time frame • Fossil and sediment layers suggest an earth that has undergone a series of changes over a long period of time

  4. New Technology brought new theories • Radioactivity discovered by Madame Curie in late 1800’s • Early in 1900’s scientists discovered how radioactivity could be used to determine the age of rocks and carbon based organisms • In the late 1960’s the age of meteorites found on earth was found to match the rocks from the moon • This opened the way for accepting new theories

  5. The Universe • Thought to have begun 10-20 billion years ago • This is called the Big Bang Theory • Billion Years Ago ~ bya

  6. The Earth - 4.6 BYA • 4.6 bya the earth is thought to have coalesced from interstellar matter • The first atmosphere is thought to have been heated hydrogen gas. • This atmosphere was very thin as heated Hydrogen would rise and escape

  7. Formation of Modern Earth • 4.1 bya the molten earth cooled and solidified into layers ~Nickel and Iron sunk to center (Core) ~Less dense material settled in middle (Mantle) ~Least dense material, silicon and oxygen, formed on the surface (Crust) (The Crust and Mantle and connected by flexible layer called Asthenosphere)

  8. Milky Way Geology • We can understand the top layers (lithosphere) of the earth by examining a Milky Way Bar • Unwrap your chilled Milky Way Bar • Carefully hold each end by the sides of the bar • Now slowly pull the bar apart 1-2 cm. to expose the caramel filling. • Now push the candy bar back together. Watch the chocolate layer • Pull the bar apart and push it back together several times • Now divide it in half to look at the three layers inside

  9. Milky Way Geology Response • Describe the texture and consistency of each of the three layers. • What happens to the chocolate crust where your earth is pulled apart? • What happens to the chocolate crust where your earth is pushed together? • How does this model the action of the earth’s crust? • Draw a cross section of your Milky Way, and label each layer with its corresponding layer of the earth.

  10. The Earth 4.1 BYA • Early volcanoes emitted water vapor, carbon monoxide, carbon dioxide and nitrogen • Cooling caused water vapor to condense and form seas and rivers • The climate was dominated by intense lightening

  11. The Earth 4 BYA • Inorganic Molecules combined to form organic material (contains carbon) • Organic material linked (polymerized) to form organic molecules • First simple cells (Archea Bacteria)

  12. 3.5 BYA • First Modern Prokaryotes (Bacteria) arose • lack a membrane bound nucleus (pre-nucleus) • Then came photosynthetic prokaryotes (3.2 bya) • Bluegreen Algae or Cyanobacteria • Still exist today in very similar form • Provide Oxygen for the atmosphere

  13. 1.5 Billion Years Ago • First Eukaryote Organisms • Cells contain a membrane bound nucleus • Allowed for cell specialization • Some reproduce sexually • Opened the door for emergence of diverse life forms

  14. 400 MYA -Explosion of life forms • Progressively more complex life forms appeared • Most modern plant and animal groups present on earth

  15. 100,000 - 200,00 years ago • First homonids appeared • 35,000 - Homo sapiens

  16. Evidence • What kind of evidence do people use to determine the history of the earth? • Is there more evidence for current of distant events?

  17. Cosmic rays activate atoms in the atmosphere creating neutrons • This activated neutrons collide with Nitrogen 14, knocking out one proton, adding one neutron, making Carbon 14 • Over time, the activated neutron, breaks down, releasing a proton and an electron to reform Nitrogen 14

  18. Definitions • Radioisotopes – elements that contain atoms in an unstable state. To become stable, these atoms ‘decay’ into other elements. • Radioactive decay – The process by which radioactive elements release energy, and change into new elements • Half-life – The length of time for half of the radioisotopes in a radioactive element to decay

  19. In this activity: • Pennies will represent a new radioactive element called Headsium that decays to Tailsium • Make sure that all pennies in your element are heads up! This represents the radioisotope. • Make a table to record data

  20. Procedures • Shake box vigorously - 4 times • Now remove all ‘Tailsium’ • Record data, and shake again. Repeat until data table is full. • Record data for class average • Make a graph that records both the number of Headsium, and the number of Tailsium.

  21. Graph 50 50 Headsium Tailsium 0 0 2 4 Half Life

  22. Questions • Describe 2 ways that this activity models the process of radioactive decay. • A student changes this experiment by using 2400 dimes. If 75 heads remain in the box, how many half lives do you think have occurred? Show your math. • If each half life in the problem above is 50 years, how much time has passed since the headsium was formed?

  23. Works Cited • Campbell, Concepts and Connections, Kendall Hunt, 2000 • Ford, Brent A.Project Earth Science, Geology, NSTA Press, 1996 • Pictures of Protists from Picture PerfectProtista files, Oct. 2002 • Skehan S.J.The Creation Controversy, National Science Teachers Assn., 2000.24 • National Geographic, photo gallery

  24. Make a time line • Make a time line for your own life. • Put your birth at one end, and today at the other • Record important events in your life • What evidence do you have for the events? • Do you have more evidence for recent or distant events? Today Birth

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