Built on Sand: “Wherever we go, we’re surrounded by sand. It’s in the floors beneath us, walls around us and ceilings above us, plus the sidewalks and roads we use to get from place to place. Sand is a key ingredient in concrete, asphalt, and glass, not to mention the silicon chips inside our phones and computers. It is an essential component of modern life as we know it, yet, strangely enough, we are starting to run out.” 99percentinvisible.org/episode/b…