References

=References=

All About Frozen Ground: How Does It Form?. (n.d.). //National Snow and Ice Data//  //Center (NSIDC)//. Retrieved December 7, 2010, from  []

Earth's Structure. (n.d.). //Thinkquest//. Retrieved December 7, 2010, from []

Earth, Earth Sciences Information, Geology Facts, News, Photos -- National Geographic. (n.d.). //Science and Space Facts, Science and Space, Human Body, Health, Earth,// //Human Disease - National Geographic//. Retrieved December 7, 2010, from []

Graphic Organizers. (n.d.). //Education PlaceÂ®//. Retrieved December 7, 2010, from []

streincorp. (n.d.). YouTube - Earth's Crust - Bill Nye the Science Guy 3/3. //YouTube - Broadcast Yourself.//. Retrieved December 7, 2010, from http://www.youtube.com/watch?v=L7z3O5ZcGio&feature=related