I would think that before the United States Army Air Corp decided to build a base for the most important military program ever in Wendover, and started flying irreplaceable B-29 bombers over the Bonneville Salt Flats training for the mission to end World War II, they made sure that those salt flats were thick enough to land those airplanes on them! It's been seventy years, where are the surveys that I'm they sure did? It's not Top Secret any more. There has to be a feasibility report on using the Bonneville Salt Flats as an emergency landing zone! And that report would list the thickness of the salt, and the date that was measured.