Changes

       a chemical composition which is rare on Earth.

       a chemical composition which is rare on Earth.

     - A large crater has been found on the Yucatan Peninsula in Mexico.

     - A large crater has been found on the Yucatan Peninsula in Mexico.

     - The soil near the crater contains significant amounts of chemical compounds common in

     - The Rocky underground near the crater contains significant amounts of chemical compounds common

       meteorites, but rare on Earth, especially in such concentrations.

       in meteorites, but rare on Earth, especially in such concentrations.

     - The soil near the crater shows signs of a tremendous energy release, natural glass, etc...

     - The Rocky underground near the crater shows signs of a tremendous energy release: natural

      glass, etc...

     - We can calculate the energy that would be required to create a crater that size.

     - We can calculate the energy that would be required to create a crater that size.

     - An impact of this scale has been found to be many times greater than that of a nuclear

     - An impact of this scale has been found to be many times greater than that of a nuclear