Another photog was at the falls...

Located along the Balcones Fault line, McKinney Falls State Park borders the Hill Country and Blackland Prairie ecosystems.

100 million years ago McKinney Falls State Park lay at the bottom of a warm tropical sea which, at the time,
was located south of the equator! The neighboring Pilot Knob volcano erupted and deposited layers of volcanic ash
on the surrounding sea floor that can be observed in the park today and eventually led to the formation
of both upper and lower McKinney Falls.