Calling all co-contributors...
Thanks to Eldest, I stumbled upon this post, and felt that it was cool enough I just had to give it some thought. I'm now pondering how to apply it.
I've already considered doing something like the Hedge with mirrors, inspired by Suzanna Clark's Jonathan Strange and Mr Norrell, in which the first English Magician, the Raven King (Yes, I liked that name enough to steal it), created a series of roads by which he and his followers could travel through mirrors, entering one with the proper spells to go into a giant house sort of thing, with the odd tree growing in it, or a creek running through it, and lots of odd bridges. Think an Escher-style house, where the geometry is odd and the angles all seem wrong. That's sorta similar to the concept above, but it's different and complex enough to warrant an entirely separate post and discussion.
As for the Mythic Geography, I was thinking about something beyond the little Fey-Paths, which a mortal can stumble along for short distances and with great risk.
Y'know that moment when a story just starts writing itself? Yeah, that just happened.
The Fogbound River? The First People didn't just block off the Western Lands. They actually moved them. The Fog is a barrier between the Spirit Realm and the Mortal Lands. The magic of the first people carried their lands away, and the Veil swelled in the fill the gap. Spirits get lost sometimes around the edge of the barrier, so the deep forest seems haunted.
When a person's soul departs, they leave for the Spirit Realm, across the river. They may leave an imprint, a piece of themselves in the hearts and souls of their family and those who share the same values and dreams (A great hunter may be called upon by other hunters, a mother by other mothers), but they, themselves, depart. They may keep an eye on their kids, and be able to give them a hand if they help on their end (A binder using pact magic to contact an ancestral or other spirit), but maintaining a strong connection is something only the most powerful can do alone.
This has been boiling around the edge of my consciousness for a while, thanks to Eldest's link I finally figured it out.