How Old is the Earth?











     Have you ever heard the expression, "It's Older than Dirt?"  It's a funny way of saying something is very old but you really don't know the exact age.  Some people use it as a way of saying that something is nearly as old as 
the Earth itself.

     How old is the earth?  At one time scientists thought it was only a few thousand years old.  Is it possible for today's scientists to accurately determine the age?  What evidence leads them to believe that the Earth is a certain age?  What discoveries have been made that have helped scientists to estimate the age of the Earth?  If the Earth is very old, how does the interior stay hot?

     People have asked questions like these for a long time.  You will discover how scientists have answered these questions as you complete this WebQuest. 

 The Earth Today

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      Imagine that you and your partner are writers for a well known science magazine.  Your editor has assigned you to research the facts and details about the age of the earth.  When you have completed your research you will write articles to be published in your magazine.

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Part 1:  Research

     You will be given 5 writing prompts.  These prompts will be the topic for 5 articles that you will publish in your magazine.  You will research the facts related to each prompt.  Use the websites listed for your research.  Don't forget to find the, who, what , where, when, why and how  for your topics.

Part 2:  Write

     After you have finished your research you will write your articles.  Each article must be 3 to 5 paragraphs in length.  Remember to include as much detail as possible.  DO NOT PLAGIARIZE! (COPYING SOMEONE ELSE'S WRITING)  WRITE IN YOUR OWN WORDS.  You may include mock interviews with important scientists  or include other "reporting"  techniques as long as it adds to the historical content of the article.  (Example: Pretend you are traveling back in time to investigate an event.) 

Part 3:  Publish

     Using Microsoft Publisher  create a magazine of your own design and special style.  Be creative!  (You will use the Newsletter feature on Publisher)  You may add graphics, pictures or any other visual aids to give your magazine Pizzazz!

Special Note:  You will be given a lesson on how to use Microsoft Publisher before you begin.

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     It is important that you discuss the scientific discoveries and technological advances that have helped us to understand the age of the earth.   Below you will find your writing prompts.  You will also see questions and statements that may help you conduct your research.  Use the websites listed below each writing prompt for your research.


This shows heat rising in convection currents from the outer boundary of the core and cooling at the surface.


1.  Lord Kelvin (William Thomson Kelvin) estimates the age of the
(What did Kelvin say about the age of the Earth?  How did
    he do it?  Was he right?)

      Understanding Science:  Lord Kelvin
       Engines of our Ingenuity
       StarrySkies:  Age of the Earth
       Today in Science History:  Lord Kelvin
       Geologic Time

2.  Geologist Charles Lyell studies geologic processes.  (What
     is "Uniformitarianism"?  What does this process tell us about the
     age of the Earth?)

        History:  Uniformitarianism
        How Old is that Rock?
        Sir Charles Lyell
        Strange Science:  Charles Lyell

3.  Discovery!  Radioactivity!  (Write about the who, what, where,
     when and how of the discovery of radioactivity.)

     How Does Radioactive Decay Work?
        Radioactivity:  The Unstable Nucleus and it's Uses
        Access Excellence: The Discovery of Radioactivity
        Cruising Chemistry: The Discovery of Radioactivity

4.  How do radioactive elements produce their own energy?
(What ability do radioactive elements have that other elements
    do not?  How do radioactive elements help us to estimate the age
    of the Earth?)

     Clocks in the Rocks
        ABC' s of Nuclear Science
        USGS:  The Age of the Earth
        Uranium and Other Radioactive Elements
        Wikepedia:  Radioactive Decay

5.  Scientists explain the Earth is several billion years old
     and is still hot!
 (What evidence do we have that the Earth has
    an internal source of heat?  What keeps it hot after
    all of this time?)

   The Age of the Earth
     What Definitive Proof is there for the Age of the Earth
     Online Minerals:  Age of the Earth
     Restless Earth:  A Geologic Planner
     The Earth's Internal Heat Energy
     Earth Interior
     Earth Interior (Chapter Summary)

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Remember!  Your  five articles should address the writing prompts.  Please write the articles in the order listed above. You may create your own title or headline for each article.



     Your grade will be based on a special grading rubric.  You should thoroughly review the grading rubric before you begin.  Be sure you and your partner understand what criteria will be used to determine your grade.

Click to view or print "Older than Dirt" Grading Rubric

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     You are now ready to begin.  Be sure to check back to this page often to review the project requirements.  Be creative!  Work together as a team.  Most of all - have fun while completing this project!

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Last updated by Paul Elliott on Thursday, March 25, 2010