Xiushan's covered bridge: a crossing you can stand in

The county takes 1,341.1 millimetres of rain a year at a mean of 16 degrees, and a bridge without a roof would be unusable for much of it. The covered bridge is the answer: a timber deck under a tiled roof, walls on both sides with openings for light, and benches fixed along them, so that the crossing is also a place to stand out of the weather. The Tujia and Miao country calls the type a wind-and-rain bridge, which is a description rather than a name. In a county where forest covers 49.2 per cent and timber is the ordinary building material, the roof is cheap and the walls cheaper.

A bridge of this kind is a frame rather than a wall. Stone piers take the posts, the posts carry the beams, and the beams carry the roof; the joints are cut so that the parts hold each other, with pegs where a joint needs locking. The roof is heavy, and its weight is what keeps the frame seated, which is why a covered bridge is more stable than its slenderness suggests until the water gets under the deck. Floods are the real enemy: a river that rises above the piers can lift the whole span and carry it away, and in this country that has happened often enough that rebuilding is part of the craft.

On a market day the bridge works as a room. Loads are set down on the benches, a seller spreads a cloth on the deck, and the noise of the water comes up through the boards. Xiushan's own arts are made for that kind of gathering: the flower lantern, in its two forms, entered the first national intangible heritage list, and the county's folk songs entered the second. The county also keeps an older register of arrival. A fossil bed of the early Palaeozoic here produced two fish, Xiushanosteus mirabilis and Tujiaaspis vividus, the second named for the Tujia. A bridge is a short-lived thing by comparison, which is why the type matters more than the span.