Radiometrically calibrated ages from three reef cores are used to develop a Holocene reef growth chronostratigraphy and sea-level history in the Maldives, central Indian Ocean. Last interglacial reef (U-series age 122 ± 7 ka) was encountered at 14.1 m below mean sea level. An age of ca. 8100 calibrated (cal) yr B.P. immediately overlying this Pleistocene surface records the initiation of Holocene reef growth. Massive in situ corals occur throughout the cores and the consistency of the three age-depth plots indicate that the reef grew steadily between 8100 and 6500 cal yr B.P., and at a decreasing rate for the next 2 k.y. The position of modern sea level was fi rst achieved ca. 4500 cal yr B.P. and sea level reached at least 0.50 ± 1 m higher from 4000 to 2100 cal yr B.P. before falling to present level. Emergent fossil microatolls provide evidence of this higher sea level. Results are signifi cant to two long-standing issues relating to Maldivian sealevel history. First, the ambiguity of a late Holocene highstand has been resolved with clear evidence of its existence reported here. Second, the uncertainty of the regional pattern of sea-level change in the central Indian Ocean has been clarifi ed, the Maldivian results broadly agreeing with island records in the eastern, rather than western Indian Ocean. Our results provide the fi rst fi eld evidence confi rming geophysical model projections of a highstand 4-2 k.y. ago in the central Indian Ocean, though the observed level (+0.50 ± 0.1 m) is lower than that projected.on June 8, 2015 geology.gsapubs.org Downloaded from

Pollen and sediment analysis of two Holocene cores from Awana, Great Barrier Island, shows that at 7000 calibrated yr B P the local swamp was an estuanne salt marsh dominated by Restionaceae By c 6000 yr B P the water table was lower, and a fresh water swamp (Gleichenta-Leptospermum) had replaced the salt marsh Regional coniferhardwood forest c 7000 yr B P was initially co-dominated by Libocedrus and Dacrydmm cupressinum Libocedrus declined from c 6000 yr B P During the period c 6000-c 2500 yr B P , relatively stable environmental conditions ensued with little change in local or regional vegetation Around 2500 yr B P , the swamp surface became drier and was invaded by Dacrycarpus and Laureha swamp forest This forest was subsequently repeatedly disturbed (not by fire), indicating climatic change to drier and windier conditions Ascanna lucida was periodically a major component of swamp forest Disturbance is also recorded in the clastic (mineral) sediments, where beds of sand within finer-grained sediment and peat are interpreted as wind blown material derived from partly devegetated dunes to seaward The presence of the Kaharoa Tephra allows the timing of major Polynesian deforestation at Awana to be reliably dated to c 600 calibrated yr B P In contrast, we see no evidence in the clastic sediment record of disturbance at Awana since Kaharoa time We attribute this to the maintenance of stable dunes by a herb/scrub cover despite nearby fires, or to the presence of scrub or forest buffering the swamp from ablating dunes

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A shoreline and archaeological excavations at Cook's Cove, eastern North Island, New Zealand were examined for stratigraphy and plant microfossils and results compared with previous interpretations of this site. Buried soils, distal tephras and pollen revealed evidence of pre-and post-settlement forest disturbance. Microfossil starch and calcium oxalate crystals of introduced sweet potato (Ipomoea batatas) and taro (Colocasia esculenta) were identified throughout the deposits, indicating intensive local cultivation and processing of these crops. Results are consistent with revised New Zealand geochronological models and, bearing in mind loss of evidence by erosion, differ in several respects to those of previous studies, as follows. The searafted Taupo Pumice (AD 200) and Loisel's Pumice (from multiple offshore sources) were not as widespread. Although microscopic charcoal was present to the full depth of all profiles, we did not observe macroscopic pieces below the Loisel's Pumice. The only material we found that appeared to equate to the deposit previously identified tentatively as air-fall Kaharoa Tephra (AD 1300) appeared not to be a tephra. Finally, we found little evidence for marine inundation of the site.

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