Gary Gilligan has an interesting article on sand at https://malagabay.wordpress.com/2016/04/26/guest-post-by-gary-gilligan/ … the purity of sand seems to belie the standard explanation. The amount of sand seems to defy the geological mainstream theory. How is sand transported to create vast dunes – and then we have something like this ….
…. The Wave, an eroded sandstone fromation on the border of Arizona and Utah. These are said to have been laid down over millions of year – yet their banded colours are as fresh as a daisy.