Dan,
Thanks for the nice comment. The dark area is where the water was seeping over the white limestone. The interesting part about this location is that it can change from what you see here to a raging torrent of flood water in the space of about 10 minutes, when a rain storm happens up stream. Sadly, a number of people have drowned at this spot because they did not heed the clearly posted warning signs and pay attention to the weather. It takes about 10 minutes from the spot where I captured this image to negotiate back to the bank of the Pedernales River bed.
