Miles from any town, fishing alone on a small stream of no significance to anyone but us, we hear the first, faint rumble. I ignore it, tell myself a waterfall ahead must be sending the sound down. The sky to the east remains clear, so I look in that direction. My son Noah, conditioned from years of playing college basketball, moves confidently through pools and over boulders the size of small cars. We wade the center of the stream, focused on our casts and the curling water around us.