Copyright is or isn't. I am not sure what Australian law you are referring to when something is "copyrightable". It subsists with the author of the literary work upon creation.
Whether a description of a rock climb could be considered a literary work is where the argument would lie. I think that Neil was closest to the mark.
Unauthorised copying of a substantial part of the literary work with which the author owns the copyright would provide the author with a cause of action in infringement. Whether the author chooses to pursue that cause of action is another point altogether.
In non-law speak - if you describe something with some artistic flair you could enforce your rights if you wanted to against someone who you can prove has copied a substantial part of your work. I can't imagine many climbers doing that.