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FINDING THE AGES OF ROCKS & FOSSILS
by Larry Flammer
|NOTICE: If a student ever challenges you with criticisms of the reliability or validity of geological age-dating methods, CLICK HERE|
|This lesson should effectively and accurately
inform students about the high level of confidence we have in
the geological ages of an old Earth. At the same time, it should
reveal an example of pseudoscience which should be part of any
effort to improve science literacy and critical thinking.
Students are taken through a combination of some background information and interactive experiences, and checked frequently by questions to confirm understanding. The narrative includes concepts of isotopes, radioactive decay, half-life, mineral formation, age analyses, Fair Test questions, and isochrons. The lesson can be used as a one-day team activity, individually in class, or as a self-teaching homework assignment. It is intended to either stand by itself, or to serve as a useful introduction to the very effective online interactive Virtual Age Dating Tutorial. This lesson would be helpful in Biology, Earth Science, Physical Science, Physics, Chemistry, or Geology classes.
|1. Several independent
lines of evidence confirm that the Earth is billions of years
2. A Fair Test analysis confirms that the Earth is billions of years old.
3. Half-life is a fundamental property of radioactive material, enabling accurate age-dating.
4. Methods exist for age-dating which are internally self-checking.
5. Efforts to overturn a massive body of work must be equally compelling.
6. Anything presented as scientific, yet clearly ignores the rules of science, is pseudoscience.
However, some of those preferring the "young Earth" idea have attempted to seek "proof" of their position by presenting "scientific studies" which seem to undercut the established scientific conclusions. In addition, this position is widely publicized, suggesting there is (untrue) widespread uncertainty in the science community about the validity of those ancient ages. As a result, the general public, even those not particularly committed to the Young Earth position, are often not aware of the clear status of geological ages, and the diverse body of evidence pointing to such deep time.
It turns out, upon closer scrutiny, that the "scientific evidence" for a young Earth is nothing more than selective reporting of a handful of samples which were either poorly analyzed, or notable exceptions to the huge body of data pointing to a very old Earth. Such exceptions can be variously explained in ways that do not require a young Earth solution.
This lesson should effectively and accurately inform students about the high level of confidence we have in the geological ages of an old Earth. At the same time, it should reveal an example of pseudoscience which should be part of any effort to improve science literacy and critical thinking.
STRATEGY AND PREPARATION:
5. Run off enough copies of the Deep Time Activity #15
Cutouts sheet so that you (or lab assistant, or students
in class) can cut apart the right hand column of 17 strips, shuffle
them, and place them along with the intact left hand column in
an envelope or small zip-lock bag, so there will be one set (bag)
for each team of 4 (or team of 2, if preferred) in your largest
class. Use the intact sheet to make an overhead showing these
as All Known Original Radioisotopes With Half-Lives
of 1 Million Years or More, properly sequenced
8. When each team has completed activity #15, and answered
questions 16-19, collect that team's envelope.
12. Try to get class consensus that the studies of Deep Time are very reliable and well-established, based on an overwhelming amount of quality science and very compelling work. The few discrepancies found can easily be attributed to factors which do not destroy the general picture, and in any case are generally very minor. Also point out that any statement to the contrary would have to explain away this huge body of evidence. You might also point out (especially if you can reference some of the alleged "science" which attempts to "disprove" the ancient Earth consensus), how either poor science was used (e.g. selecting favored data, and ignoring all the other data), or they are examples of pseudoscience.
EPILOG AND COMMENTS:
2. Encourage students (especially those who find it difficult to let go of the young Earth idea) to explore the issue further. Suggest they carefully read the material suggested in the references (some of it online), and perhaps prepare a report of their careful comparison of the ideas. Be sure they include a fair balance of "Young Earth" "evidence" and the ancient Earth evidence, what each side criticizes about the other, and what the counter-arguments are. Encourage the use of Fair Test questions wherever possible, along with the answers to those questions, and how they affect the conclusions.
BETA TESTING: Since this lesson has not been extensively classroom tested, if you like the idea, try it as a "Beta Tester", and please get back to us. Let us know how it goes, any problems, questions, suggestions for improving it, etc. We will share your experiences with other teachers. Contact us through the webmaster.
EXTENSIONS & VARIATIONS:
2. In addition, be sure to install a geological timeline in your classroom, something students can view throughout the year, and to which you can often point when talking about or showing something in prehistoric time. Some excellent ideas for this can be found in the "Time Machine" lesson.
3. To help students gain a more realistic personal sense of deep time (especially in middle school life science or earth science), try our Patterns in Time lesson. In that lesson, students also come to realize that the different vertebrate classes emerged separately over several 100s of millions of years, and did not exist prior to their emergence (as revealed in the fossil record). That lesson also demonstrates the accumulation of modified traits on top of the accumulated traits found in the previously emerged group, showing gradual, additive and mosaic changes over time. All of this provides a strong implication that each group descended from the earlier antecedents through gradual change over time.
4. We now have (2004) a nice lesson which provides a simulated rock-dating experience. Try it: "Date-a-Rock!"
Some of the ideas in this lesson may have been adapted from earlier, unacknowledged sources without our knowledge. If the reader believes this to be the case, please let us know, and appropriate corrections will be made. Thanks.
|Lesson created by: Larry Flammer, September 2002. Based mainly on material presented in Miller's Finding Darwin's God, chapter 3. This lesson was intended primarily to serve as an introduction to the interactive online Virtual Age Dating Tutorial, but can also be used as a stand-alone lesson.|