Waco Gem and Mineral Club, Waco, Tx

11.3 Effects of Meteorites and Famous Craters

 

11.3: Effects of Meteorites and Famous Craters

While most meteors simply burn up on hitting the atmosphere, some meteorite, asteroid, and comet impacts have had profound effects on our earth. For instance, it‘s now commonly accepted that an immense impact off Mexico‘s Yucatan Peninsula 65 million years ago was responsible for the extinction of the dinosaurs and many other creatures. It‘s recently been postulated that a comet exploding over North America did in large Ice Age mammals like woolly mammoths, giant ground sloths, and saber-toothed cats as recently as 10,000 years ago. In 1908, in a remote spot of Siberia, an enormous explosion known as 'the Tunguska event' flattened trees in every direction over 770 square miles and could be heard over a 500 mile radius. (That‘s 800,000 square miles!) On a smaller scale of destruction, a couple of cars and a mailbox have been hit by small meteorites, and one even crashed through an Alabama woman‘s home to bounce off her hip, leaving a nasty bruise and a very surprised woman. (That meteorite is now in the Smithsonian.)

The most visible and obvious effect of a large meteorite strike is a scar or crater on the ground. As an activity to show kids how craters form, have them create small craters by dropping or tossing marbles or ball bearings into wet sand or mud or a pan of dry white flour whose surface has been dusted with dry powdered paint. See if it makes a difference in crater size and shape by how hard the marble impacts, whether it drops straight or from an angle, or whether you use a large, small, heavy, or light marble. Dennis Gertenbach, leader of the Flatirons Mineral Club Junior Geologists of Colorado encourages us to see the following web site for still more mud ball fun: http://www.astronomy.com/asy/default.aspx?c=a&id=6186%20

As a follow up to this activity, particularly with older kids in your group, the web site www.lpl.arizona.edu/impacteffects lets you calculate the destructive power of meteorites of different sizes and trajectories.

Assign craters to kids in your group to research all they can about them. Have them report back to the group and/or write articles for the club newsletter. Some include:

  • Campo del Cielo (Argentina)
  • Monturaqui Crater (Chile)
  • Chicxulub (Yucatan, Mexico)
  • Odessa Crater (Texas, USA)
  • Henbury Craters (Australia)
  • Sikhote-Alin Strewnfield (Siberia)
  • Manicouagan Crater (Canada)
  • Whitecourt Crater (Canada)
  • Meteor Crater (Arizona, USA)
  • Wolf Creek Crater (Australia)

Have kids pick a crater from this list, or let them read books or surf web sites to find craters of their own to explore. For instance, they may want to find out about a crater closest to their own homes. Dean Smith‘s brief book The Meteor Crater Story ends with a handy appendix listing known impact sites throughout the world and O. Richard Norton‘s Rocks From Space has a similar list in an appendix. In addition to books like these, here‘s a web site you might direct kids toward to find more famous meteor craters: http://geology.com/meteor-impact-craters.shtml. Using satellite images, this site includes a Meteor Crater Map of the world that allows you to click on a highlighted spot and zoom in with the + button for close-up views of 50 selected craters. The Planetary and Space Science Centre of the University of New Brunswick (Canada) manages the Earth Impact Database listing all known craters and crater fields. Finally, Wikipedia has an article all about impact craters, as well as a table of known craters on Earth. You can access these at the following web addresses:

http://en.wikipedia.org/wiki/Impact_crater

http://en.wikipedia.org/wiki/List_of_impact_craters_on_Earth

Note: Kids who write a report about a famous meteor crater can use this toward satisfying requirement toward earning their Communication badge simultaneously (Activity 7.2).