Hanging Rock appears in the episode "Return to Hanging Rock", which Ruby can see her parents up there if getting separated from them as their safe place (meaning the rock). This is the location where Ruby's mother told her to go to if she ever got separated from them as it was a safe place to be.
In the episode, Ruby goes back here during the Flying Rocks of Many Nights to make sure her family is safe. Ruby and the rest of the gang soon go back to the Great Valley because of Red Claw, who was nearby. Ruby was singing I Feel So Happy when Red Claw cut off the song with a roar.