Every few years the equatorial Pacific Ocean warms, producing the phenomenon known as El Nino and causing a whole raft of environmental impacts around much of the world. The pattern was named by South American fishermen in the 1600's who noticed a change in fishing conditions around the Christmas season.
For decades now, puzzled birdwatchers in the southern tier of states have noticed that in some years, birds from Canada's boreal forests turn up for unexpected winter sunshine vacations in vast numbers.
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.