Well, the lack of canyon answers his immediate question: why track what you've contained to a small enough area. In the kind of story where people wake up with mysterious tracking bracelets, they usually tracked more than location--but he still feels a little foolish, making that kind of suggestion.

"Maybe it does things like temperature and heart rate. That room--" he can't help but think of the fluorescent panel in the cave wall, coolers with red-black vials and initials. "It reminds me of the equipment there."

But that room had been in a cave, inside the vanished walls. There's no telling if they could find it now--if it even exists in this new, dust-covered village.