I've been there. The salt is maybe 1/8 thick on mud that is peppered with very sharp selenite crystals - some measuring 6 inches long by 1 inch wide. They let the general public dig up the crystals (yes, I've done it). The whole area is laced with trash and chuckholes. Also, the military used to practice their bombing on the flats, so every once in awhile something old and metal turns up. The public is warned to call the park rangers if they happen to find vintage ordnance. Don't even THINK of racing there.