Megan will eat weird berries from a strange tree, yet does not consider to see if something tasty may have been left behind in a picnic basket? Which also makes me wonder, who would leave a picnic basket like that? Unless, they left in a hurry.
I am beginning to think that the cairn was recognizable to them. Perhaps they are familiar with it as a boundary marker of some sort, such as the people in the hills or the tent people might use to mark the edge of their territory/settlement. It could be that the "Oh!" uttered by Megan was one of surprise, not at finding a cairn, per say, but at realizing there is a settlement ahead. That may also explain why then seem to have no interest in the fence or picnic basket.
Again, what we find interesting, they don't. Very interesting. And what happened to the mountain they were climbing. This ain't it, methinks. Waiting for it, in a puzzled sort of way now.
Ah pope again. I hereby declare that no one shall post on this page but charlie_grumbles.
No No No, belay that order. I hereby declare peace on earth good will to all sentient life forms, fleshy and digital, carbon based or silicon based.
Oh, and post away to your heart's content (be it carbonish or silicon)