I stepped out of the time machine and into the Ordovician. The water came
up to my ankles — and this was the center of North America! Lying
slantwise across the tropics. A muggy inland sea. Pale colors everywhere,
eggshell, rose, citrine, hot springs bubbled in limestone cliffs. I
splashed ashore, letting the machine bob on bright orange floats In the
pastel waves. Nobody around to steal it.

After an hour, I turned a corner and came face to face with a tall man,
carrying a satchel. He greeted me waving, then did a double-take. "Oh,
hey, you're not Mr. Harrison," he said. "Dead ringer, though."

Overcome, I exclaimed, "You're not supposed to be here! This is the age
of Trilobites, Crinoids and Corals! You're about 250 million years
early!"

He laughed. "Brother, you and me, we been around the whole time. We just
pack out our trash, and leave nothing for the archaeologists to find.
Just who do you think is in charge of The evolution of this planet,
anyway?"