Flandrian sea-level changes in the Fenland. I: The geographical setting and evidence of relative sea-level changes

The Flandrian sediments of the Fenland record the infilling of the Wash embayment on the east coast of England, UK. Since at least 6500 BP changes in sea level have been a major control on the rate and pattern of sediment accumulation. New data are presented from the area which together with published information allow the reconstruction of palaeoenvironments from 6500 to 2500 BP. The major environmental changes involved alternations between freshwater fen and intertidal marine sedimentation. Each episode was characterised by transitional changes as vegetation and sediment zones shifted over large areas. Marine/brackish sediments are found up to 45 km inland of the present coast. Radiocarbon dated sea-level index points, with relevant stratigraphic and micropalaeontological data, ranging from 6415 BP at ?8.17m OD to 2595 BP at +1.45m OD, are described.     

Late Holocene sea levels in Ireland

The course of Irish sea levels during the late-Holocene is not well-known, yet it is an understanding of this period that will prove crucial in the definition and management of future sea-level changes. The coastline of Ireland embraces wide environmental and glacio-isostatic contrasts, which serve and, to some extent, control sea-level events at both local and regional scales, making definitive resolution of relative sea-level changes difficult. In the southwest, the picture is of inexorable relative sea-level rise. Studies in Co. Kerry show a gradual submergence of terrestrial facies, by estuarine and, in places, marine materials. Pollen and diatom studies, together with ¹⁴C dates, suggest a decreasing rate of relative sea-level rise in the last 2500 years, often associated with geomorphological changes. Sites on the south coast of Ireland confirm the evidence from the southwest. In Cork Harbour, recent relative sea-level rise since 2100 BP was responsible for marginal land submergence, while elsewhere rising water levels appear to have caused rapid barrier migrations and coast erosion. Palaeoenvironmental evidence from this region suggests a distinctive pattern of sea-level change, associated with sedimentary and/or crustal dynamics, which is not encountered elsewhere in northwest Europe. The overall rate of relative sea-level change on the south and southwest coasts falls between 0.6 and 1.1 mm/year over the last 5000 years. In the north, there is a clear east to west variation in relative sea-level trends, following an isostatically-controlled peak (+3 to ?1 m OD) between 6500 BP (east) and 3500 BP (west). Falling sea levels from 3500 to 1500 BP have been followed by a general slow rise, although there are still local anomalies to this pattern, most noticeably at Malin Head, where sea level is currently falling at 2.4mm/year. Relative sea-level signatures in Ireland differ markedly between the north and south coasts. Furthermore geomorphological and ecological contexts of this rise vary from east to west, providing a complex all-Ireland framework for future investigations.     

Relative sea-level changes during the Holocene in Bangladesh

This paper presents a reconstruction of the Holocene paleo-environment in the central part of Bangladesh in relation to relative sea-level changes 200 km north of the present coastline. Lithofacies characteristics, mangal peat, diatoms and paleophysiographical evidence were considered to reconstruct the past position and C-14 ages were used to determine the time of formation of the relative sea level during the Holocene. With standard reference datum, the required m.s.l. at the surface of five sections was calculated. The relative sea-level (RSL) curve suggests that Bangladesh experienced two mid-Holocene RSL transgressions punctuated by regressions. The curve shows an RSL highstand at approximately 7500 cal BP, although the height of this highstand could not be determined because the transgressive phase was observed in a bioturbated sand flat facies. The curve shows a regression of approximately 6500 cal BP, and the RSL was considerably lower, perhaps 1–2 m, than the present m.s.l. The abundant marine diatoms and mangrove pollens indicate the highest RSL transgression in Bangladesh at approximately 6000 cal BP, being at least 4.5 to 5 m higher than the modern m.s.l. After this phase, the relative sea level started to fall, and consequently, a freshwater peat developed at approximately 5980–5700 cal BP. The abundant mangrove pollens in the salt-marsh succession shows the regression at approximately 5500 cal BP, when it was 1–2 m higher than the modern sea level. The curve indicates that at approximately 5000 cal BP and onwards, the RSL started to fall towards its present position, and the present shoreline of Bangladesh was established at approximately 1500 cal BP and has not noticeably migrated inland since.     

Holocene relative sea-level changes in the Qaqortoq area, southern Greenland

We present results from an investigation of relative sea-level changes in the Qaqortoq area in south Greenland from c. 11 000 cal. yr BP to the present. Isolation and transgression sequences from six lakes and two tidal basins have been identified using stratigraphical analyses, magnetic susceptibility, XRF and macrofossil analyses. Macrofossils and bulk sediments have been dated by AMS radiocarbon dating. Maximum and minimum altitudes for relative sea level are provided from two deglaciation and marine lagoon sequences. Initially, relative sea level fell rapidly and reached present-day level at ∼9000 cal. yr BP and continued falling until at least 8800 cal. yr BP. Between 8000 and 6000 cal. yr BP, sea level reached its lowest level of around 6-8 m below highest astronomical tide (h.a.t.). At around 3750 cal. yr BP, sea level has reached above 2.7 m below h.a.t. and continued to rise slowly, reaching the present-day level between ∼2000 cal. yr BP and the present. As in the Nanortalik area further south, initial isostatic rebound caused rapid isolation of low elevation basins in the Qaqortoq area. Distinct isolation contacts in the sediments are observed. The late Holocene transgression is less well defined and occurred over a longer time interval. The late Holocene sea-level rise implies reloading by advancing glaciers superimposed on the isostatic signal from the North American Ice Sheet. One consequence of this transgression is that settlements of Palaeo-Eskimo cultures from ∼4000 cal. yr BP may have been transgressed by the sea.     

Relative sea-level change in the Beauly Firth, Scotland

Relative sea-level changes in the Beauly Firth have been inferred from stratigraphy, pollen and diatom analyses and by radiocarbon dating of former coastal reedswamp deposits. Using lithostratigraphic and biostratigraphic arguments for establishing the changes in coastal environment at the site, a preliminary scheme of positive and negative tendencies of sea-level is produced. This may be related to changes in relative sea-level. Two periods of falling relative sea-level have been identified: (1) between c . 9,600 B.P. and c . 8,800 B.P. and (2) post c . 6,400 B.P. The period of rising relative sea-level between c . 8,800 B.P. and c . 6,400 B.P. was interrupted briefly by a possible storm surge event which took place between c . 7,200 B.P. and c . 7,300 B.P.     

Holocene sedimentation on the North Norfolk barrier coast in relation to relative sea-level change

Fourteen distinct sedimentary environments have been recognised in the surface sediments of the intertidal zone of the North Norfolk coast. Nine of these can be distinguished in borehole samples on the basis of sedimentological and micro-palaeontological characteristics. They comprise: gravel; channel sand; intertidal sand; intertidal silty sand; intertidal mud and marsh creek; lower salt marsh; upper salt marsh; dune sand; and peat. Sediment accumulations have been penetrated to a depth of ?8 m OD and basal peats dated by ¹⁴C back to 8410 ± 50 years BP. An overall rate of sediment accumulation (and subsidence) of about 1 m per thousand years is indicated. There is considerable persistence of sedimentary environments in the same areas during up-building, but some erosion and roll-over of the coastal barrier system has occurred. Evidence of positive and negative sea-level tendencies are present in the record, but the main development of the tract is determined by sediment supply to the beach and marshes; positive sea-level tendencies occur at c. 6610, 5970, 4630 and 2790 BP, negative sea-level tendencies occur at 4520 to 4450 and (possibly) 3470 BP.     

渤海湾西岸CZ01钻孔沉积物粒度端元分析及其气候—海平面变化响应*

沧州地区位于海陆交互的渤海湾西岸,易受到海平面变化和极端气候事件的影响,对于全球气候变化的响应十分敏感。应用非参数化端元分析模型将沧州地区CZ01钻孔中更新世晚期以来的沉积物粒度划分出6个端元并分析其物源,结合已有地质记录,揭示不同时间尺度下各端元对气候—海平面变化的响应。结果表明: (1)EM1(5.01 μm)主要为远源的风尘输入,EM2(13.18 μm)和EM3(39.81 μm)为古黄河所携带的沉积物,EM4(69.18 μm)和EM5(138.04 μm)为海相沉积物,EM6(275.42 μm)可能指示古洪水等极端气候事件。(2)深海氧同位素(MIS)Ⅰ 阶段,气候温暖湿润,EM4+5含量指示渤海海平面整体呈波动上升的趋势并逐渐接近现代海平面。该阶段内由于11.5 ka BP左右的新仙女木事件以及5.1 ka BP左右冷干事件的发生,渤海海平面在稳定上升状态后出现停滞或小幅下降的现象; 而在9.5 ka BP、7.5 ka BP、5.8 ka BP和1.7 ka BP左右,东亚夏季风增强导致降水增加,渤海海平面升高。(3)MIS Ⅵ 阶段北半球气候冷干,150~132 ka BP左右因喜马拉雅运动减弱造成的区域沉降中心转移致使渤海海面升高。MIS Ⅴ 阶段气候波动剧烈: 在间冰期暖期(5a、5c和5e)气候暖湿,渤海海平面上升; 而MIS5b和5d时期渤海海面高度较低。MIS Ⅳ 阶段较MIS5a末期海平面突然下降后趋于稳定,期间出现若干次小规模海侵事件,可能与东亚夏季风频繁变化有关。MIS Ⅲ 阶段至末次冰盛期海平面大幅度下降且存在周期性升降变化,并在46 ka BP左右出现大规模海侵事件。MIS Ⅱ 阶段较MIS Ⅲ 阶段海平面出现小幅度下降,为低海平面时期; 伴随15 ka BP左右冰盛期的结束,东亚夏季风增强,海平面开始上升。渤海海平面180 ka BP以来的变化记录与北半球乃至全球范围内的地质记录存在一致性,与太阳辐射波动引起的冰川消融及东亚夏季风变化密切相关。     

Late Holocene sea-level changes and isostasy in western Denmark

Cores and exposed cliff sections in salt marshes around Ho Bugt, a tidal embayment in the northernmost part of the Danish Wadden Sea, were subjected to ¹⁴C dating and litho- and biostratigraphical analyses to reconstruct paleoenvironmental changes and to establish a late Holocene relative sea-level history. Four stages in the late Holocene development of Ho Bugt can be identified: (1) groundwater-table rise and growth of basal peat (from at least 2300 BC to AD 0); (2) salt-marsh formation (0 to AD 250); (3) a freshening phase (AD 250 to AD 1600?), culminating in the drying out of the marshes and producing a distinct black horizon followed by an aeolian phase with sand deposition; and (4) renewed salt-marsh deposition (AD 1600? to present). From 16 calibrated AMS radiocarbon ages on fossil plant fragments and 4 calibrated conventional radiocarbon ages on peat, we reconstructed a local relative sea-level history that shows a steady sea-level rise of 4 m since 4000 cal yr BP. Contrary to suggestions made in the literature, the relative sea-level record of Ho Bugt does not contain a late Holocene highstand. Relative sea-level changes at Ho Bugt are controlled by glacio-isostatic subsidence and can be duplicated by a glacial isostatic adjustment model in which no water is added to the world's oceans after ca. 5000 cal yr BP.     

利用盐沼泥炭重建长江三角洲北部全新世中期海平面

根据对长江三角洲北部海安地区4个钻孔标志性沉积物(潮上带盐沼泥炭、高潮滩沉积)的年龄测定和高程测量,以及沉积物压实沉降量的分析研究,重建了本研究区全新世中期8.1～7.3 cal kyr BP和5.6～5.4 cal kyr BP的相对海平面位置。结果显示,8.1～7.3 cal kyr BP海平面缓慢上升1.46m,上升速率仅为0.2cm/yr, 与三角洲南部全新世早期海平面的快速上升(2cm/yr)形成鲜明对比,验证了冰盖控制下的全球海平面阶段性波动上升模式。对比长江三角洲地区海平面曲线发现,三角洲北部海平面曲线较南部低5～6m,长江三角洲海平面曲线与世界各地海平面曲线也存在明显差异,分析认为主要是由长江口地区的差异性沉降和中国东部边缘海的水均衡作用两个因素引起的。     

Relative sea-level trends during the early–middle Holocene along the eastern coast of mainland Scotland, UK

Previously published radiocarbon-dated horizons relating to early and middle Holocene relative sea-level change along the eastern coast of mainland Scotland are examined and trends determined. The data are modified to ensure comparability and are compared against the pattern of glacio-isostatic uplift in the area. Results show that the rate of relative sea-level rise during the Main Postglacial Transgression in the middle Holocene becomes greater towards the edge of the uplifted area, whilst the age of the Main Postglacial Shoreline becomes younger in the same direction. Linear and quadratic regression analyses disclose trends which indicate that at the 0 m HWMOST isobase of the Main Postglacial Shoreline the rate of relative sea level rise between c. 8400 and c . 7000 14 C years BP ( c . 9500 to c . 7900 cal. BP) was 5-11 mm/radiocarbon year or 6-11 mm/calibrated year, whilst at the same isobase the Main Postglacial Shoreline was reached between 5500 and 6100 14 C years BP (between 6300 and 7000 cal. BP). The relative sea-level changes identified are compatible with a rising sea surface level offshore, which may have involved three episodes, possibly related to regional and wider deglaciation.     

A hypothesis for the sawlike pattern of world sea-level fluctuations

A theory of the world's sea-level fluctuations during late Pleistocene time, based on the analysis of the general equation of the mass balance between ocean water and inland water, suggests that the exchange of water masses between the ocean and the land, where at continental glaciation periods water is stored as ice, occurs only as a result of global climatic changes. The tectonic effect is considered insignificant for late Pleistocene time. The proposed theory explains the asymmetric character and the sawlike shape of the curve of the main cycles of sea-level fluctuations. The theory also makes it possible to construct a diagram of sea-level fluctuations from the last glacial maximum to the present time. This diagram is governed by two parameters, the amount of the average “effective” evaporation from the world's ocean surface (evaporation minus rainfall) and the rate of the sea-level rise at the present time. The resulting theoretical curve agrees well with known estimates of sea level within the time span being considered. The comparison of the theoretical curve with these estimates eliminates the apparent discrepancy between data obtained by different methods: measurements of old coastline and the isotopic composition of bottom sediments.     

全球海平面变化与中国珊瑚礁

本文以政府间气候变化专业委员会（IPCC）于2001年专门报告中关于21世纪内全球气候变化的温度和海平面变化的预估为前提。简要介绍了中国珊瑚礁的定位、类型和分布,对其进行了成熟度分类,评估了全球海平面变化对中国珊瑚礁的影响。据预测,21世纪我国各海域海平面上升以南海最大,为32 ~ 98cm,其平均上升速率为0.32 ~ 0.98cm/a。从海平面上升速率与珊瑚礁生长速率的理论对比分析,中国珊瑚礁基本上能与前者同步生长,即使海平面以预估高值上升,也不会威胁其生存。从中国珊瑚礁成熟度较高、其生长趋势以侧向生长为主的现实状况出发,未来全球海平面上升能为其创造向上生长的有利条件。从古地理学“将古论今”观点出发,自全新世6000aBP以来曾存在过的高海平面和较高表层海水温度的历史,也可以佐证,21世纪的全球海平面上升不会对中国珊瑚礁的存在和发育造成威胁。现存的珊瑚礁岛应对于全球海平面上升,可以做到“水涨岛高”,它们能够屹立于上升了的未来海平面之上;但对于岛上的人工建筑物则会被浸、被淹,或被淘蚀和破坏,因此必须根据海平面上升的幅度和速率,采取相应的防御措施。     

Holocene evolution of an estuary on a tectonically rising coast: the Pakarae River locality, eastern North Island, New Zealand

Estuarine and beach deposits in the vicinity of the present coastline at Pakarae River record the infilling of an estuary and subsequent development of a sequence of seven marine terraces during Holocene time.

At the maximum of the last glaciation about 18,000 years ago the shoreline at the ancestral Pakarae River was approximately 20 km east of the present shoreline. By about 9000 years BP the sea had transgressed across most of that coastal plain to lie within a few hundred metres of the base of the present coastal hills. Seventeen radiocarbon ages from estuarine deposits record the overall rise in post-glacial sea level, but in the period c. 9500-7000 yrs BP there are reversals to the overall rising trend. Between 9500 and 8500 yrs BP there appears to have been a eustatic fall in sea level of at least 4 m. This observation is supported by data from several other localities around New Zealand. Maximum transgression occurred about 6500–7000 yrs BP when the sea reached the base of hillslopes and an extensive estuary existed behind a barrier bar.

Since that time the barrier bar disappeared, probably due to stranding in an uplift event, and the coastline advanced progressively outward toward its present position. Coastal progradation (sea level regression) and subsequent erosion have occurred in association with episodic large earthquakes at about 6700, 5400, 3910, 2450, 1570, 1000 and 600 yrs BP. The present distribution of terraces has been influenced by coastal erosion, which has removed all trace of some terraces from some areas, and river erosion has modified the marine terraces near the river.     

Late Quaternary sea-level changes and palaeoseismology of the Bering Glacier region,Alaska

Glacial isostatic adjustment and multiple earthquake deformation cycles produce temporal and spatial variability in the records of relative sea-level change across south-central Alaska. Bering Glacier had retreated inland of the present coast by 16 ka BP and north of its present terminus by ～14 ka BP. Reconnaissance investigations in remote terrain provide new but limited insights of post-glacial relative sea-level change and the palaeoseismology of the region. Relative sea-level was above present ～9.2 ka BP to at least 5 ka BP before falling to below present. It was above present by the early 20th century, before land uplift in the 1964 M 9.2 earthquake. The pattern of relative sea-level change differs what may be expected in comparison with model predictions for other seismic and non-seismic locations. Buried mud–peat couplets show a great earthquake ～900 cal BP, including evidence of a tsunami. Correlation with other sites suggest simultaneous rupture of adjacent segments of the Aleutian megathrust and the Yakutat microplate.     

Neotectonics, sea-level changes and biological evolution in the Fennoscandian Border Zone of the southern Kattegat Sea

Shallow seismic data and vibrocore information, sequence stratigraphic and faunal evidence have been used for documentation of Late Weichselian reactivation of faulting in the south central Kattegat, southern Scandinavia. The study area is situated on the Fennoscandian Border Zone, where tectonic activity has been recurrent since Early Palaeozoic time and still occurs, as shown by present earthquake activity. New data from the area south of the island of Anholt show that after deglaciation fast isostatic rebound resulted in reactivation of a NW-SE striking normal fault system. This tectonic episode is dated to a period starting shortly before 15.0 cal. ka BP and ending around 13.5 cal. ka BP, after regression had already reached a level of about 30 m b.s.l. The vertical displacement associated with the faulting was in the order of 20 m. More generally, the results support the previously reported late Weichselian sea-level highstand, which was followed by forced regression until the eustatic sea-level rise surpassed the rate of glacio-isostatic rebound in early Preboreal. Our findings further imply that drainage of the Baltic Ice Lake through the Øresund at c. 15 cal. ka BP (Bergsten & Nordberg 1992) may have been triggered by tectonic activity in this region.     

Song Hong (Red River) delta evolution related to millennium-scale Holocene sea-level changes

The Song Hong (Red River) delta occurs on the northwest coast of the South China Sea. Its evolution in response to Holocene sea-level changes was clarified on the basis of sedimentary facies and 14 radiocarbon dates from the 40 m long Duy Tien core from the delta plain, and using previously reported geological, geomorphological, and archaeological data. The delta prograded into the drowned valley as a result of early Holocene inundation from 9 to 6 cal. kyr BP, as sea-level rise decelerated. The sea-level highstand at +2–3 m from 6 to 4 cal. kyr BP allowed widespread mangrove development on the delta plain and the formation of marine notches in the Ha Long Bay and Ninh Binh areas. During sea-level lowering after 4 cal. kyr BP, the former delta plain emerged as a marine terrace, and the delta changed into the present tide- and wave-influenced delta with accompanying beach ridges. Delta morphology, depositional pattern, and sedimentary facies are closely related to Holocene sea-level changes. In particular, falling sea level at 4 cal. kyr BP had a major impact on the evolution of the Song Hong delta, and is considered to be linked to climate changes.     

Little Ice Age subsidence and post Little Ice Age uplift at Juneau, Alaska, inferred from dendrochronology and geomorphology

Application of dendrochronology and geomorphology to a recently emerged coastal area near Juneau, Alaska, has documented a Little Ice Age (LIA) sea-level transgression to 6.2 m above current sea level. The rise in relative sea level is attributed to regional subsidence and appears to have stabilized by the mid 16th century, based on a sea-cliff eroded into late-Pleistocene glaciomarine sediments. Land began emerging between A.D. 1770 and 1790, coincident with retreat of regional glaciers from their LIA maximums. This emergence has continued since then, paralleling regional glacier retreat. Total Juneau uplift since the late 18th century is estimated to be 3.2 m. The rate of downward colonization of newly emergent coastline by Sitka spruce during the 20th century closely parallels the rate of sea-level fall documented by analysis of local tide-gauge records (1.3 cm/yr). Regional and Glacier Bay LIA loading and unloading are inferred to be the primary mechanisms driving subsidence and uplift in the Juneau area. Climate change rather then regional tectonics has forced relative sea-level change over the last several hundred years.     

The mid-Holocene sea-level highstand at Bogenfels Pan on the southwest coast of Namibia

The radiocarbon ages of mollusc shells from the Bogenfels Pan on the hyper arid southern coast of Namibia provide constraints on the Holocene evolution of sea level and, in particular, the mid-Holocene highstand. The Bogenfels Pan was flooded to depths of 3 m above mean sea level (amsl) to form a large subtidal lagoon from 7300 to 6500 calibrated radiocarbon years before present (cal yr BP). The mollusc assemblage of the wave sheltered lagoon includes Nassarius plicatellus, Lutraria lutraria, and the bivalves Solen capensis and Gastrana matadoa, both of which no longer live along the wave-dominated southern Namibian coast. The radiocarbon ages of mollusc shell from a gravely beach deposit exposed in a diamond exploration trench indicate that sea level fell to near or 1 m below its present-day position between 6500 and 4900 cal yr BP. The rapid emergence of the pan between 6500 and 4900 cal yr BP exceeds that predicted by glacio-isostatic models and may indicate a 3-m eustatic lowering of sea level. The beach deposits at Bogenfels indicate that sea level rose to 1 m amsl between 4800 and 4600 cal yr BP and then fell briefly between 4600 and 4200 cal yr BP before returning to 1 m amsl. Since 4200 cal yr BP sea level has remained within one meter of the present-day level and the beach at Bogenfels has prograded seaward from the delayed arrival of sand by longshore drift from the Orange River. A 6200 cal yr BP coastal midden and a 600 cal yr BP midden 1.7 km from the coast indicate sporadic human utilization of the area. The results of this study are consistent with previous studies and help to refine the Holocene sea-level record for southern Africa.     

Holocene relative sea-level changes in the inner Solway Firth

Bio- and lithostratigraphic data from four sites from the inner Solway Firth allow an accurate reconstruction of Holocene RSL changes in the estuary. Radiocarbon assays give eleven new sea-level index points providing a total of 24 reliable index points for the inner Solway Firth. These data show a consistent pattern of rapid RSL rise during the early Holocene culminating in a mid-Holocene sea-level maximum, then a gradual fall to the present day level. Detailed analysis of this dataset quantifies for the first time differential crustal movement between the north and south shores of the Solway Firth. These data are used to test the accuracy of quantitative isostatic rebound models of Lambeck and Peltier, and show there is good general agreement between the data and the models, especially during the early Holocene. The models predict the mid-Holocene sea-level peak slightly later than shown by the data (c. 500 and c. 2000 yr), this may be partly due to lack of resolution in the models, and for the south Solway the maximum altitude at this peak is 1 and 2.5 m too high in the two models. The data are also compared to the isobase models of the Main Postglacial Shoreline, showing slight diachroneity between the north and south shore but otherwise general agreement with the postulated age, and indicating that the altitude of this feature is 1–3 m higher than suggested by the models.     

New relative sea-level curves for the southern Scott Coast,Antarctica: evidence for Holocene deglaciation of the western Ross Sea

Here we present new relative sea-level (RSL) curves developed from Holocene-aged raised beaches along the southern Scott Coast of the western Ross Sea, Antarctica. Fifty-four dates of marine shells, seal skin and elephant seal remains incorporated within raised beaches during storms afford a chronology for these curves. All of the curves show the same pattern and timing of RSL change within a small range of error. The best-dated curve suggests that final unloading of grounded Ross Sea ice from the southern Scott Coast and McMurdo Sound region occurred shortly before 6500 ¹⁴C yr BP. This age is consistent with glacial geological evidence that places deglaciation between 5730 and 8340 ¹⁴C yr BP. Our data strongly suggest that grounding-line retreat of the Ross Sea ice sheet southward through the McMurdo Sound region occurred in mid- and late Holocene time. If this is correct, then rising sea level could not have driven ice recession to the present-day grounding line on the Siple Coast, because global deglacial sea-level rise was essentially accomplished by mid-Holocene time. Copyright © 1999 John Wiley & Sons, Ltd.