I'm certified that there is no such word as "crestling". You may have typed it wrong or so. Maybe you mean cresting (crest).
Cresting (Crest)
(n) peak, summit; top line of a mountain
(v) reach a high point; top out
Sample sentences:
(n) Robert headed to the nearby crest.
(v) The snow crested yesterday evening.
-KookEin
