Past the dam, the river runs through a field of boulders until the falls. It splits and braids into dozens of channels, where hundreds of feet before it was a slow moving reflecting pond. Soon you are above the middle channel.
The rock is abrupt and ungainly. The water thrashes against it to make its descent down to the next pool, and no concessions are made in its path. There is no easy way down. The landscape is baked. The few plants that live on these islands of rock have been thrown there from floods, or exist in the marginal space between regular flow and flood level. Grace under Pressure.
Soon the river runs into itself and slows down. The walls of rock lift up around the riverbed and create a corridor for the tranquil Potomac to slowly move toward the sea. The float out settles the river back to the reflecting pond it was when it began, and your mind can return to contemplating what happens in congress only a few miles away...