In my understanding when I hear the words "Deep, Dusk, and black" I think of a dark tone in the mood as some would call it "Emo" *although that's somewhat offensive to some* the word deep has me thinking of a deep pond at dusk as it looks black because of the day time all those words used in the sentence mean something deep and dark almost as if it leave suspense for the "Reader" although i'm not sure if you were looking for a writing term