Im a huge fan of surfing, here in FL, we actually do a lot of river surfing.
Cool I've never heard of river surfing.  Does that involve a sail?
No basically the water flows over a rock in high volumes causing a wave behind it.
Interesting.  What rivers in Florida have the best river surfing conditions?
The Hillsborough River is very good for river surfing. Oddly enough, in Germany is where you can find the worlds largest urban river surfing spot.
Are there river surfing competitions?
Not at the Hillsborough River, it's amazing how old it is though, geological surveys indicate its around 27000 years old.
That's incredible.  How do they calculate the geological age?
Monazite geochronology
Monazite geochronology is a dating technique to study geological history using the mineral monazite. It is a powerful tool in studying the complex history of metamorphic rocks particularly, as well as igneous, sedimentary and hydrothermal rocks. The dating uses the radioactive processes in monazite as a clock.
The uniqueness of monazite geochronology comes from the high thermal resistance of monazite, which allows age information to be retained during the geological history. As monazite grows, it forms successive generations of different compositions and ages, commonly without erasing the
over a rock and creating a wave behind. It is a form of hydraulic jump. A river surfer can face up-stream and catch this wave and have the feeling of traveling fast over water while not actually moving.
River surfing conditions are created by a combination of underlying rock formations and specific water levels, i.e. not too much or too little water. Water flow is usually is measured in the SI-unit cubic meters per second (m/s) (alternatively in liters per second or cubic feet per