What is a delta where a river meets the sea?

You're standing where a mighty river finally reaches the ocean. But instead of one clean meeting point, the river suddenly splits into dozens of smaller channels, spreading out like fingers reaching for the sea. The land between those fingers? That's a delta — and it's one of the most creative, messy, beautiful landforms on Earth.
For thousands of miles, your river has been carrying a secret cargo: dirt. Tiny particles of rock, sand, and clay, picked up from mountains and plains upstream. The river's been moving fast enough to carry all that sediment along for the ride. But now, as it reaches the calm ocean, something changes. The river slows down.
