At the tectonically rising terraced coast of Huon Peninsula, Papua New Guinea, a Holocene reef is emerging by as much as 12 m. A clean seacliff section 8 m high provides detailed evidence of the relationship between reef development and early Holocene sea-level changes, relative to the rising coast. The section shows a shallow-water reef-crest facies that grew steadily upward while relative sea level rose approximately 7 m. Reef growth terminated with emplacement of a fluvial gravel cap, which was followed by emergence. Twelve C14 dates and six Th230/U234 dates put the base of the cliff section at 8200 C14 yr B.P. and the crest at 6600 C14 yr B.P. Four Th230/U234 dates from near the base average 9,400 yr old, but C14 ages from the same samples average 7,600 yr old; the cause of the discrepancy is not known. Uplift of the section is known from previous studies of the Pleistocene reefs in the area to be approximately 1.9 m/1,000 yr. If uplift has been at a uniform rate, then the position of sea level at 6,000 C14 yr ago (around northeast Papua New Guinea) was about −4 m; 8,000 yr ago it was about −14 m. Mean upward growth rate of the reef was 4.7 m/1,000 yr, and the maximum rate was about 8 m/1,000 yr.

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