[davem]

So maybe the world split, beginning with the Fall of Numenor. The flat, Elven, world moves further & further away from the round, human, world. While the Elven Rings retain their power they hold the worlds together at certain points, but when they fail the last 'nails' are drawn & the two worlds drift apart. Galadriel's gift draws the Shire into the Elven world & it is lost to us. Yet it was also once part of the Human world, so maybe its the nearest part of Faerie to us.

Some of Tolkien's comments on the relationship of this world & Faery are interesting in this context. (This is from his essay on Smith of Wooton Major)

The geographical relations of Wootton and Faery are inevitably, but also intentionally left vague. In such stories there must be some way or ways of access from and to Faery, available at least to Elves as to favoured mortals. But it is also necessary that Faery and the World (of Men), though in contact, should occupy a different time and space, or occupy them in different modes. Thus though it appears that the Smith can enter Faery more or less at will (being specially favoured), it is evident that it is a land, or world of unknown limits, containing seas and mountains; also it is plain that even during a brief visit (such as one on an evening walk) he can spend a great deal longer in Faery than his absence counts in the world; on his long journeys an absence from home of, say, a week is sufficient for exploration and experiences in Faery equivalent to months or even years.
As far as geography goes, Faery is situated (or its entrances are) westward. 'From Far Easton to West' denotes the bounds of the world to the villagers: from the most eastern village of people of their own kind to the Forest, yet uncultivated, immediately to the West. Wootton thus represents an earlier intrusion of men's settlements into the foreign country of Forest; Wootton Minor is [s]till a village in a clearing. The Forest is still close to the western edge of Wootton Major. The smithy is at the extreme western edge of it (if you like because of the need of wood fuel). It is at any rate thus made easier for the Smith to go into the Forest unobserved by any but his household, or to go on journeys 'on business', without his movements being the matter of gossip.
In many Fairy Tales use is made of the idea that time passes quickly in Faery, so that a man who finds his way there may come out after what seems a brief episode to find that years, even centuries have passed. Except as a mere device to bring a man out of the past into contact with a (to him) future time — that is in a tale of which this is the real point, and Faery as such is not seriously considered — I have always felt this to be a mistake: a mistake in credibility, if Faery of any kind is taken seriously. It is true that the seeming time in Faery being immensely longer than it is felt to be is usually told of mortals that intrude into Faery. It is also true that in some actual experiences the time they take may seem short, and be found to be much longer when contact is made with ordinary affairs again. This occurs especially after absorption (mainly of intense interest and also usually pleasure) in some such things as reading, seeing plays, revelry or meetings with friends. I have often said that this idea must have originated in inns: for nowhere does time 'fly' so fast compared with daily experience as when sitting and drinking and conversing with dear friends in an inn. I am sure there is some truth in this. But there are other experiences. Notably that of dreams, in which a long (or full) experience may be found to have occupied a short time in the extramental world. 'Narrative' is perhaps the only common measure. What takes a long time to relate adequately is long. (I mean: relate, if one wishes to, or has to, relate it. A diarist who enters against one day 'nothing to relate' probably means nothing that interests me, or nothing of the kind that I usually record for future reference.) 'O minutes great as years!' Dream is perhaps a better analogy for the purpose. But also this must be considered: the Faery of this tale is a particular one. If one accepts it, while 'within' the tale, then clearly the Rulers of Faery — who are presented as interested in Men (not necessarily primarily) and beneficently - must be able to arrange that the experiences in Faery of favoured human persons may be enjoyed without dislocation of their normal human life. The time of their Faery must be different, even though it may be at points contiguous. For them human time is or may be also longer than that of Faery. The King dwells in Wootton for 58 years.
As for place. Entry into the 'geographical' bounds of Faery also involves entry into Faery Time. How does a mortal 'enter' the geographical realm of Faery? Evidently not in dream or illusion. Physical objects, such as the star, the Living Flower, and the elvish toy, survive transplantation from Faery to the World. It is common in Fairy tales for the entrance to the fairy world to be presented as a journey underground, into a hill or mountain or the like. The origins of this do not concern me here. They lie largely in necrological imagination. But as used they are often mere 'rationalizations' - like the diminution in the size of 'elves' - a way of providing for a land of marvels within the same geography as that of Men. They are no more credible and no more interesting than Edgar Rice Burroughs tales dealing with a vast subterranean world. To me they kill the very kind of 'literary belief that they are supposed to produce.
My symbol is not the underground, whether necrological and Orphic or pseudo-scientific in jargon, but the Forest: the regions still immune from human activities, not yet dominated by them (dominated! not conquered!). If Faery Time is at points contiguous with ours, the contiguity will also occur in related points in space - or that is the theory for the purpose of the story. At certain points at or just within the Forest borders a human person may come across these contiguous points and there enter F. time and space - if fitted to do so or permitted to do so. Within the relatively short time of the story (or indeed of several generations of Men in its suggested 'historical' background) these points will remain recognizable and able to be revisited by those who have once found them. Going deep or far into Faery from such points represents a passing further and further away from a familiar or anthropocentric world. But in this tale Forest and Tree remain dominant symbols. They occur in three of the four 'remembered' and recorded experiences of the Smith — before his leave-taking of the Queen. They do not occur in the first, because it is at that point that he discovers that Faery is 'limitless' and is mainly involved in vast regions and events that do not concern Men and are impenetrable by them.