Fig 6. The spreading experiment after three elapsed times.

A. Representative disc of colored sand on March 20, 2012, 20 days after emplacement. Note the haze of pink grains that has dispersed well beyond the original disc boundary. The agents of transport are probably wind and water, but possibly also animals. Note the raindrop pitting especially visible on the disc. Inset shows entire disc. B. Appearance Sept. 21, 2012. approx. 7 months after emplacement. C. A disc of fluorescent sand 2 years after emplacement, under UV light in situ. The color of the disc was no longer visible without the aid of UV fluorescence. D. Distribution of pink grains in the spreading experiment, March 11, 2013, one year after emplacement of 500 g of 100% pink sand in a disc 20 cm in diameter. Within a year, significant amounts of pink sand have spread more than 50 cm from the edge of the original disc.