I like the way your mind works. I too think that there is no way this book survived 6 months in the woods, in almost pristine condition. I know that these laminated cardboard books do get damaged by moisture, specially when the edge of a page gets wet. The moisture seeps into the cardboard and when it swells it makes the page bubble up underneath the lamination. After 4 kids and hundreds of laminated books, and hundreds more spills, I should know. Spills don't "always" end up exactly on the page, where they can be wiped up.
6 months in the woods, surviving rain and flood, and looking like that?
Nahh..... The same goes for the photographs found. Just take a photograph, let it soak in water over night, and then let it air dry in the sun. See what happens. If it doesn't curl up enough yet, soak it for another few nights