Four rivers in Kansas bear the name Beaver Creek.

One flows south along the western part of Smith County and empties into the Solomon River near Gaylord, Kansas.
The Solomon River, and one of the Beaver Creeks, rise near Mount Sunflower, western edge of the state, which is 4039 feet elevation.

The "bluffs and white rocks" may be poetic license; rocks rhyming with "flocks."
Are there white rocks exposed along any of the rivers?