There’s one big thing you notice when you go down to the beach: sand, and the patterns and dunes it forms.

If you’ve ever wondered what sand actually is, and how and why it forms itself into dunes, then you’ll find this 16 minute video interesting: Sand Dunes Shouldn’t Exist (Here’s Why They Do).
How can sand, blown by the wind, form such intricate and beautiful patterns as ripples and dunes? The answer is a surprising secret of self-organization. In this video, we travel to Great Sand Dunes National Park in Colorado to climb the largest sand dunes in North America and bring you the science of how wind and sand combine to create ordered landforms out of chaos.