For those who may have never heard or even heard but never really gave this idea serious consideration, please take just a few minutes to listen and see the visual demonstrations recreating the phenomenon. Both the Grand Canyon here on Earth and the great scar on Mars share this curious geological mystery of not being able to locate all the material that would have once filled the now empty gouges. The total volume of the Grand Canyon is unaccounted for at the end of the river. On Mars, the Valles Marineris it self is basically a pit with NO outflow at all. Where did all the material go?
Thank you for your consideration in this matter.