Nan Madol

Why this is extraordinary

Off Temwen, on the south-east coast of Pohnpei, a ceremonial centre stands on the reef itself. Nan Madol is that centre, built as artificial islets. UNESCO describes more than 100 islets, walls of basalt and coral, and canals between them. Some walls, the nomination says, stand 6 to 7 metres. They are prismatic basalt, natural columns that look like logs, laid in a header-and-stretcher bond, alternately along and across. Header and stretcher, here, means one piece pointing into the wall and the next running along the face. The basalt was brought from quarries elsewhere on the island. The nomination estimates 2,000 tons of volcanic rock laid every year for three or four centuries, without pulleys, metal or wheels. An estimate is not a weighed cargo. It is the dossier's figure for the scale.

The dates do not start once. The public list says the palaces, temples, tombs and houses were built between 1200 and 1500 CE, the ceremonial centre of the Saudeleur dynasty. The nomination also says islets with some columnar basalt and house foundations were already there by about 500 to 600 CE, that islet building had increased by 1000, that the great tomb islet Nandowas was built around 1200 by uranium-series dates on coral, and that the residence islet Pahnkedira dates from 900 to 1000. Uranium-series dates coral, by the clock in the mineral. Ritual for the Saudeleur is placed from about 1200 to 1600. Oral history, which the nomination treats as part of the site's value, ties the centre to those chiefs and to a story of spirits of the dead offshore. Pohnpei itself was settled about 2,000 years ago in that account.

The listing compares Nan Madol with other Pacific stone centres, including the moai of Rapa Nui, as chiefly monuments of related island traditions, not as one workshop. The canals are tidal. Mangroves and silt are the threat the listing names, and the site has been on the danger list for that reason. No source used here reports a trial that moved a basalt log of this size over the reef and recorded the method.

One sky reading treats the plan as an instrument. A note on Pacific orientations proposes that the long axes meet the rising of the Southern Cross and of Orion's belt, marks in the star compass of Caroline navigators. You learn a star by the place it clears the sea horizon, and you keep that place off the bow so the canoe holds its course. The Cross rises in the south. The belt sits near the sky's equator, so it rises close to east. Pohnpei lies near 7 degrees north, and from there the Cross, a far southern group, rises well south of east. Those are two different places to learn. The note calls the fit promising rather than measured. It prints no azimuth, and it prints no horizon height. The canals also follow the reef, and a reef can point the same way a star does.

If the monumental tombs are the twelfth to sixteenth centuries, Nan Madol is a late and astonishing chiefdom capital, and the earlier islets are the foundation under it. If the oral founders are a memory of people who brought the building, the dates still have to say when. The columns do not, by themselves, require a technology from outside the reef. The early islets change the length of the story, and that changes where the astonishment sits.