We tend to think that rivers flow in a consistent direction: downstream. But over geologic time “downstream” can change. That’s why a place like Unaweep Canyon in western Colorado is such a good place to think about long-term time travel.
Each spring, common black hawks soar into Arizona skies from their wintering grounds in Mexico. These large, coal-black raptors, with distinctive white-banded tails, spend the warmer six months of the year here breeding, nesting and raising young.