Literally a polder – the word derives from Old Dutch – is a tract of low-lying land reclaimed from a body of water and generally surrounded by dykes; to ensure its continued existence, these dykes must be maintained. The protagonist of Gustav Meyrink's Das grüne Gesicht (1916; trans as The Green Face 1992 UK) leaves Amsterdam after the end of World War I for the safety of a polder from which he watches an apocalyptic wind scour the rest of the world. This may be the only Dutch polder in fantasy.
Here we use the word analogously: polders are defined as enclaves of toughened Reality, demarcated by boundaries (> Thresholds) from the surrounding world. It is central to our definition of the polder that these boundaries are maintained; some significant figure within the tale almost certainly comprehends and has acted upon (in the back-story, or during the course of the ongoing plot) the need to maintain them. A polder, in other words, is an active Microcosm, armed against the potential Wrongness of that which surrounds it, an anachronism consciously opposed to wrong time. In fantasy terms, pacific enclaves become polders only when a liminal threshold must be passed to enter them, for only then are they defended.
Within the threshold that marks the outer boundary of a polder, a Portal may exist; its presence may, indeed, explain the existence of the polder itself, and this points to the polder's central role in many Crosshatches. The size of the polder may vary widely. At its smallest it may be co-extensive with a Garden (>>> Pastoral); examples include: Tom Bombadil's realm within the malign Old Forest in J R R Tolkien's The Lord of the Rings (1954-1955); Medwyn's undiscoverable Arcadian valley, which dates from the time of the Flood, in Lloyd Alexander's The Book of Three (1964); the Time Island which demurely protects the village of Barly in Robert Nathan's Autumn (1921) and The Fiddler in Barly (1926); the secret valley in Tibet inhabited by The Masters in H P Blavatsky's The Secret Doctrine (1888), a location used also by James Hilton in Lost Horizon (1933) for Shangri-La; and the poisonous Eden and Time Abyss which the god Thasaidon, in Clark Ashton Smith's "Xeethra" (1934), uses to embroil victims with irretrievably belated (> Belatedness) former selves, of whom they become doomed Reincarnations. Alternatively, the polder may be an extremely large and complex Edifice, the kind whose roots, like the banyan tree's, are extensive but linked to a single heart – an example is the House Absolute in Gene Wolfe's The Book of the New Sun (1980-1981). Or the polder may occupy a secreted portion of a City, like Toontown in Who Framed Roger Rabbit (1988). At its largest, a polder may be a landlocked Otherworld like Oz, or a Ruritania.
Surrounding the polder is a world whose effects may – all unconsciously – be inimical: the secular nation state whose presence threatens any Ruritania; the winds of Time which blow a Brigadoon onwards; the state of Chaos which threatens the land ruled by Earl Aubec in Michael Moorcock's Count Brass sequence; the vacuum of space which stresses the walls of any pocket universe; the Thinning which eats at the boundaries of Faerie; the pressure of time which surrounds the wild wood (> Forest; Into the Woods) with suburbs ...
Successful polders do not change. Polders change only when they are being devoured from without. [JC]