I have peaks and valleys and slopes
Whose mountains and beats are such tropes,
And the prime, you will find,
Is a step back in time;
The end, you will find, is a hoax.
What am I?
It's not "music."
It's not "rhymes" or anything to do with poetry.
It's not "waves," but is the closest guess so far (a square is a rectangle).
It's not a "desert," especially since the mountains and beats portion of the limerick isn't fully satisfied.
It's not "the ocean," and is, in fact, the wrong direction to take the "waves" hint.
Some words are more literal than they first appear.
"Tropes" has a double meaning here.