Premise: Rockcastle County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 17,056. Its county seat is Mt. Vernon. The county founded in 1810 and named for the Rockcastle River which runs through it. The river, in turn, is named for its majestic rock cliffs.
Hypothesis: Rockcastle County was named due to a huge rock in the middle of it.