An oxymoron is a figure of speech that juxtaposes elements that appear to
be contradictory, but which contain a concealed point.
But be aware that with names of geographical features there may be a reference to a seasonal feature which makes a term appear oxymoronic. Dry Falls could well be a feature on a temporary or intermittent river.
"He may be looked upon as the diamond in the rough, which may, when
properly polished, at some future day, become a bright and shining
ornament and develope its inherent lustre."
Best Answer
Oxymoron may fit
But be aware that with names of geographical features there may be a reference to a seasonal feature which makes a term appear oxymoronic. Dry Falls could well be a feature on a temporary or intermittent river.