Sand has superhero qualities, as far as geological deposits go. Behaving at times like a solid, at times a liquid and at times a gas, it is a master shape-shifter. Formed by wind and water, sand allows large-scale geography to play out in miniature: settling into ripples, channels, canyons, valleys and deltas.
Sand is born as tiny pieces break away from rock. Young grains have rough edges, which smooth with time. The roundest grains are found in the desert, where the constant shifting winds rub the grains against each other, grinding them to a smooth polish. Because of this, dunes, like those of the Sahara, move in vast waves.
For a geologist, sand is any particle of a certain size. By studying rocks that were made when sand was deposited and compacted over millions of years, geologists can learn about the conditions under which the sand was laid down. And sand can be made of anything — the Huygens probe found “sand,” made of hydrocarbon ice, when it landed on Titan — and comes in many colors.
The enormous golden dunes of the world are made mostly of silicon dioxide, in the form of quartz. Bright white sands are made of limestone or gypsum, in the case of White Sands National Monument, New Mexico. Magnetite or obsidian give sands a black color. Greenish sands hold chlorite-glauconite or olivine, also called peridot, when it is of gem-like quality. Iron-bearing sands are deep yellow, red and orange. Worn coral deposits give some beaches a pink hue.
Sand goes into nearly as many materials as it comes from: glass, bricks, concrete, paint and electronics, to name a few. It is key to the workings of our natural world and a source of endless fascination for arenophiles (sand enthusiasts).
To bring out your inner arenophile, we’ve gathered some of the strangest and most impressive pictures we could find of sand patterns.