Wet early to middle Holocene conditions on the upper Coastal Plain of North Carolina, USA

A peat core from a cutoff paleochannel of Little River on the upper Coastal Plain of North Carolina provides a continuous pollen record of environmental change for the past 10,500 years and includes a sedimentary record of overbank floods. Palynological and sedimentary data indicate that the early to middle Holocene was wetter than previously suggested from lake sites in the southeastern United States. The period from 9000 to 6100 cal yr B.P. is characterized by high pollen percentages of Nyssa and Quercus, but low percentages of Pinus. Fifteen large overbank flood events are present within this period (5 floods/1000 yr). In contrast, only 6 large overbank flood events occurred since 6100 cal yr B.P. (1 flood/1000 yr). The increases in moisture and flood events probably were controlled by changes in atmospheric circulation related to shifts in the position of the Bermuda High, sea surface temperatures, and El Niño activity that together may have affected the frequency of large floods generated from tropical storms in the region.     

Late-Quaternary vegetation history at White Pond on the inner Coastal Plain of South Carolina

At White Pond near Columbia, South Carolina, a pollen assemblage of Pinus banksiana (jack pine), Picea (spruce), and herbs is dated between 19,100 and 12,800 ¹⁴C yr B.P. Plants of sandhill habitats are more prominent than at other sites of similar age, and pollen of deciduous trees is infrequent. The vegetation was probably a mosaic of pine and spruce stands with prairies and sand-dune vegetation. The climate may have been like that of the eastern boreal forest today. ¹⁴C dates of 12,800 and 9500 yr B.P. bracket a time when Quercus (oak), Carya (hickory), Fagus (beech), and Ostrya-Carpinus (ironwood) dominated the vegetation. It is estimated that beech and hickory made up at least 25% of the forest trees. Conifers were rare or absent. The environment is interpreted as hickory-rich mesic deciduous forest with a climate similar to but slightly warmer than that of the northern hardwoods region of western New York State. After 9500 yr B.P. oak and pine forest dominated the landscape, with pine becoming the most important tree genus in the later Holocene.     

Coastal landscape evolution tracked from late Holocene wave-cut benches in the Sinan Archipelago,Southwest Korea

Glacio-isostatic adjustment(GIA)and tectonic activity are important factors in the formation of marine terraces.Late Holocene wave-cut benches in the eastern part of the West Sea of Korea,also called the Yellow Sea,can be divided into two steps:531 cm above sea level(ASL)for the upper bench(T2)and 464-481 cm ASL for the lower bench(T1).Sediments on the benches a re classified into four units,and are interpreted to be beach deposits acco rding to gravel shape,textu re,and seaward inclination.The ove rlying sediment indicates that T2 was formed at approximately 530 cm ASL before 2900 yr BP,and T1 at approximately 460-480 cm ASL before 1520 yr BP.Late Holocene(4000-2000 yr BP)relative sea level(RSL)curves based on GIA models are inconsistent with the wave-cut bench elevations.Comparing T1 and T2 benches to the RSL curves of the West Sea,the upper and the lower benches were uplifted by approximately 5-8 m and 4-7 m,respectively.Although the area is several hundred kilometers away from plate boundaries,the high frequency of earthquakes in the West Sea may have induced the uplift of wave-cut benches during the last 2000 years.These indicate that the west coast of the Korean Peninsula(KP)should no longer be considered an area of subsidence,but be assigned to a regime of uplift during the late Holocene.     

Holocene geoarchaeology of the Sixteen Mile Beach barrier dunes in the Western Cape, South Africa

Holocene evolution and human occupation of the Sixteen Mile Beach barrier dunes on the southwest coast of South Africa between Yzerfontein and Saldanha Bay are inferred from the radiocarbon ages of calcareous dune sand, limpet shell (Patella spp.) manuports and gull-dropped white mussel shells (Donax serra). A series of coast-parallel dunes have prograded seaward in response to an overall marine regression since the mid-Holocene with dated shell from relict foredunes indicating periods of shoreline progradation that correspond to drops in sea level at around 5900, 4500 and 2400 calibrated years before the present (cal yr B.P.). However, the active foredune, extensively covered by a layer of gull-dropped shell, has migrated 500 m inland by the recycling of eroded dune sand in response to an approximate 1 m sea level rise over the last 700 yr. Manuported limpet shells from relict blowouts on landward vegetated dunes indicate human occupation of coastal dune sites at 6200 and 6000 cal yr B.P. and help to fill the mid-Holocene gap in the regional archaeological record. Coastal midden shells associated with small hearth sites exposed in blowouts on the active foredune are contemporaneous (1600-500 cal yr B.P.) with large midden sites on the western margin of Langebaan Lagoon and suggest an increase in marine resource utilisation associated with the arrival of pastoralism in the Western Cape.     

Late Holocene evolution of Tiber river delta and geoarchaeology of Claudius and Trajan Harbor,Rome

This study provides new information on the evolution of the Tiber delta during the late Holocene, and describes the record of sedimentation in the Port of Claudius and Trajan. The Tiber flowed into the Tyrrhenian Sea in the area of the Port of Claudius and Trajan between the 8th and 5th centuries B.C. The harbor basins excavated by the Romans during the 1st and 2nd centuries A.D. were filled with sediments containing saltwater fauna, then brackish‐water fauna, and finally by alluvial and marsh deposits. The Port of Claudius and Trajan was silted in as a consequence of episodes of alluviation that correlate with environmental events, possibly triggered by global climate changes. © 2009 Wiley Periodicals, Inc.     

杭州湾沿岸平原晚第四纪沉积特征和沉积过程

本文采用层序地层学基本原理,以海平面升降旋回为主线,根据３００口钻井,静力触探井和分析化验等资料。探讨了杭州湾地区晚第四纪地层层序,沉积特征,控制沉积的主要地质作用及沉积层的形成过程。结果表明,该区晚第四纪地层底界面为区域不整合面,是末次冰期海面下降时形成的。     

南黄海南部陆区全新世沉积研究

研究区全新统不整合超覆于上更新亚统之上,自下而上由滨海相(局部含河口海湾相)?近岸浅海相(潮成沙体相)和潮滩相构成?全新统海侵层主要受控于晚更新世末SE→NW逐渐抬高的掀斜状古地形,表现出明显的水平相交,可归纳为四种层序类型?本文通过钻孔剖面分析对比,揭示了研究区垂向相序演替和水平相变的规律及其二者间的关系,恢复了全新世沉积演化过程?     

A new chronological framework for Middle and Upper Pleistocene landscape evolution in the Sussex/Hampshire Coastal Corridor, UK

The unique Middle and Late Pleistocene sedimentary record preserved along the Sussex/Hampshire Coastal Corridor between Romsey and Brighton contains a wealth of deposits including highstand marine sediments associated with a variety of different aged beaches, fluvial sediments associated with rivers crossing the coastal plain and cold stage deposits accumulating above the marine and fluvial sediments. Although quarrying activity has been extensive across much of the area it has been undertaken in flooded workings due to the high level of the watertable. Consequently little is known in detail about the sequences except where they outcrop on the foreshore around the coast. This paper examines recent work from the lower coastal plain using a multi-disciplinary approach these deposits to elucidate the age of the sequences and their associated environments of deposition.OSL dates from two of the beaches, the Aldingbourne and Brighton/Norton Beaches, place both within MIS 7. Although these OSL dates cannot differentiate between sub-stages within MIS 7, coupling these results with inferences from local geography, lithology and contained microfossils it is clear that the beaches belong to two different phases within MIS 7. These two beaches are clearly divided by a major phase of erosion and downcutting associated with a fall in sea-level. Fluvial sediments from Solent Terrace 2 and Arun Terrace 4 also date within MIS 7 and are tentatively ascribed to the downcutting event between the beaches. Together this information allows us to propose, for the first time, a robust independently dated framework for the lower parts of the coastal plain integrating for the first time the marine and terrestrial record.     

New data on the Holocene evolution of the Dvina Bay (White Sea)

Doklady Earth Sciences - The Holocene sediments from the inner part of the Dvina Bay of the White Sea (core no. 6042) were analyzed with multidisciplinary methods for the first time. The age of the...     

Holocene climate and landscape evolution East of the Pechora Delta, East-European Russian Arctic

This study presents a multiproxy record of Holocene environmental change in the region East of the Pechora Delta. A peat plateau profile (Ortino II) is analyzed for plant macrofossils, sediment type, loss on ignition, and radiocarbon dating. A paleosol profile (Ortino III) is described and radiocarbon dated. A previously published peat plateau profile (Ortino I) was analyzed for pollen and conifer stomata, loss on ignition, and radiocarbon dating. The interpretation of the latter site is reassessed in view of new evidence. Spruce immigrated to the study area at about 8900 ¹⁴C yr B.P. Peatland development started at approximately the same time. During the Early Holocene Hypsithermal taiga forests occupied most of the present East-European tundra and peatlands were permafrost free. Cooling started after 5000 ¹⁴C yr B.P., resulting in a retreat of forests and permafrost aggradation. Remaining forests disappeared from the study area around 3000 ¹⁴C yr B.P., coinciding with more permafrost aggradation. The retreat of forests resulted in landscape instability and the redistribution of sand by eolian activity. The displacement of the Arctic forest line and permafrost zones indicates a warming of at least 2–3°C in mean July and annual temperatures during the Early Holocene. At least two cooling periods can be recognized for the second half of the Holocene, starting at about 4800 and 3000 ¹⁴C yr B.P.     

Alluvial geoarchaeology of an ephemeral stream: Implications for Holocene landscape change in the central part of the Ebro Depression,northeast Spain

La Virgen is an ephemeral tributary of the Ebro River in northeast Spain with a complex alluvial sequence. We analyzed alluvial stratigraphy to develop a model of Holocene fluvial evolution for La Virgen and infer causes of floodplain dynamics. Three alluvial terraces were mapped and described using a combination of geoarchaeological and geomorphological techniques. Stratigraphic ages were estimated using ¹⁴C dating and archaeological remains. Sedimentation in the valley floor commenced in the Neolithic period ca. 6000 BC and continued during the Bronze and Iron ages (ca. 1800–500 BC), the Iberian and Roman periods (ca. 500 BC–AD 500), and the Middle Ages (ca. AD 500–1500). The main terrace (N3) is 14m thick and predominantly composed of sand, silt, and clay that we believe are derived from local hillslopes and represent a long period of human‐induced soil erosion that intensified during the Bronze and Iron ages until the Late Roman period. © 2010 Wiley Periodicals, Inc.     

Multiple-method estimation of recharge rates at diverse locations in the North Carolina Coastal Plain, USA

Recharge rates determined at diverse study sites in a shallow, unconfined aquifer differed from one another depending on the analytical method used and on each method’s applicability and limitations. Total recharge was quantified with saturated-zone methods using water-table fluctuations at seven sites in North Carolina, USA and using groundwater-age dating at three of the seven sites; at two of the sites, potential recharge was quantified with an unsaturated-zone method using Darcy’s law; and at five of the sites, net recharge was quantified with a stream hydrograph-separation method using streamflow-recession curves. Historical mean net recharge was 25 to 69% of the historical total recharge rates. The large disparity is attributed to groundwater losses between recharge and discharge areas, primarily by evapotranspiration and seepage to underlying aquifers. The spatial distribution of historical mean annual total recharge did not vary between landscape units, as suggested in a previous study. Similarly, total recharge did not correlate significantly with mean annual rainfall, mean annual water table depth, or the surficial soil properties of percent clay and bulk density. Total recharge did correlate significantly with the surficial soil properties of percent sand and percent silt.

---

Résumé Les taux de recharge déterminés sur divers sites d’études dans un aquifère phréatique libre, varient les uns par rapport aux autres selon la méthode analytique utilisée et les limites et l’applicabilité de chaque méthode. La recharge totale a été quantifiée avec des méthodes en zone saturée utilisant les fluctuations des nappes sur sept sites de la Caroline du Nord, USA, et en utilisant les datations des eaux souterraines sur trois des sept sites ; sur deux des sites, la recharge potentielle a été quantifiée avec une méthode en zone non-saturée utilisant la loi de Darcy, et sur deux sites, la recharge nette a été quantifiée suivant une méthode de séparation des hydrographes de cours d’eau utilisant les courbes de récession du débit. La moyenne historique de la recharge nette est comprise entre 25 et 69% des taux historiques de recharge totale. L’importante disparité est attribuée aux pertes en eaux souterraines entre les zones de recharge et les zones d’exutoire, d’abord par évapotranspiration et ensuite par infiltration vers les aquifères sous-jacents. La distribution spatiale de la recharge historique moyenne annuelle et totale ne varie pas selon les unités paysagères, comme cela était suggéré dans une étude antérieure. De même, la recharge totale n’est pas corrélée significativement avec la moyenne annuelle des précipitations, la moyenne annuelle de la profondeur de la nappe, ou les propriétés de surface des sols que sont le pourcentage d’argile ou la densité apparente. La recharge totale est corrélée significativement avec les propriétés de surface du sol et les teneurs en sable et en silt.

---

Resumen Las tasas de recarga determinadas en diversos sitios de estudio en un acuífero somero no confinado difieren entre sí dependiendo del método analítico usado y de las limitaciones y aplicabilidad de cada método. Se cuantificó la recarga total con métodos de zona saturada usando fluctuaciones del nivel freático en siete sitios en Carolina del Norte, Estados Unidos, y usando datación de edades de agua subterránea en tres de los siete sitios; en dos de los sitios se cuantificó la recarga potencial con un método de zona no saturada usando la Ley de Darcy y en cinco de los sitios se cuantificó la recarga neta con el método de separación hidrográfica usando curvas de recesión de flujo en arroyos. La recarga neta media histórica varió entre 25 y 69% de las tasas de recarga total histórica. La diferencia tan grande se atribuye a pérdidas de agua subterránea entre áreas de descarga y recarga, principalmente por evapotranspiración y escurrimiento hacia acuíferos subyacentes. La distribución espacial de la recarga total anual media histórica no varió entre las unidades de paisaje, como ya se había sugerido en un estudio previo. De modo similar, la recarga total no guarda correlación significativa con la lluvia media anual, la profundidad media anual del nivel freático, o las propiedades superficiales del suelo, particularmente porcentaje de arcilla y densidad volumétrica. La recarga total si tuvo una correlación significativa con las propiedades superficiales del suelo tal como porcentaje de arena y porcentaje de limo.

     

Geological evolution of the Holocene Yarra Delta and its relationship with Port Phillip Bay

The Holocene and pre-Holocene sediments and stratigraphy of the Yarra Delta have been examined using nearly 600 geotechnical bores. The oldest Holocene unit is the Coode Island Silt that has two depocentres, each up to 20.0–25.0 m thick, separated by a NW–SE belt of older pre-Holocene units. The northern depocentre represents estuarine infill to the Yarra and Maribyrnong, a river system, whereas the southern depocentre appears to be an offshore bay facies. The youngest unit is the Port Melbourne Sand, which is largely restricted to the area south of the present Yarra River. It is between 5.0 and 28.0 m thick, and is diachronous with the underlying Coode Island Silt. New ¹⁴C shell dates from the Coode Island Silt and Port Melbourne Sand have shown an age range between 8341 and 2760 yrs BP. These sediments infill former swamplands covering low-stand river valleys of the Yarra and Maribyrnong rivers across West Melbourne, Fishermans Bend and South Melbourne. After ca 2760 yrs BP active sedimentation in the delta ceased as base-levels fell, and Yarra and Maribyrnong river sediments bypassed the delta because of falling bay levels. The Yarra and Maribyrnong river courses also shifted progressively westwards behind growing beach barriers of the Port Melbourne Sand. A comparable stratigraphy exists between the Yarra Delta and the adjacent Port Phillip Bay, i.e. marine and lagoonal shelly sediments of the Coode Island Silt and barrier sands of the Port Melbourne Sand infill last-glacial channels cut into the middle Pleistocene Fishermans Bend Silt.     

Geomorphic evolution and stratigraphy of Price and Capers Inlets, South Carolina

A three-dimensional model for a tidal inlet-barrier island depositional system was constructed through examination of 37 vibracores and 10 auger drill holes on Capers and Dewees Islands, South Carolina. Two cycles of southerly inlet migration and subsequent abandonment resulted in beach ridge truncation on the northern ends of both barriers. Historical evidence indicates that these tidal inlets migrated 1.5 km to the south owing to a dominant north-south longshore transport direction. The hydraulic inefficiency of these over-extended inlet channels caused shorter, more northerly-oriented channels to breach through the ebbtidal deltas. After inlet reorientation, large wave-formed swash bars migrated landward closing former inlet channels. Weakened tidal currents through the abandoned channels permitted clay plugs to form thick impermeable seals over active channel-fill sand and shell. Price and Capers Inlets formed during the onset of the Holocene transgression following submergence of the ancestral Plio-Pleistocene Santee River drainage system. Coarse, poorly sorted inlet-deposited sand disconformably overlies Pleistocene estuarine clay and is capped by a dense clay plug. Shoreline reorientation and landward retreat of a primary barrier island chain occurred between the first and second cycles of inlet-channel migration and abandonment. Beach ridges prograded seaward over the first inlet sequence. A second cycle of inlet migration truncated the northernmost portion of these beach ridges and scoured into the clay plug of the earlier inlet deposit. Abandonment of this channel resulted in deposition of a second abandoned inlet-channel clay plug. Abandoned tidal inlet channels exhibit U-shaped strike and crescentic- to wedge-shaped dip geometries. Basal, poorly sorted inlet sands are sealed beneath impermeable, abandoned-channel silt and clay, washover deposits, and salt marsh. Multiple episodes of inlet migration and abandonment during a rising sea-level deposited stacked inlet-fill sequences within the barrier islands. The resultant stratigraphy consists of interlayered, fining-upward, active inlet-fill sand overlain by thicker abandoned inlet-fill clay plugs. These clay plugs form impermeable zones between adjacent barrier island sand bodies. Shoreline transgression would remove the uppermost barrier island deposits, sealing the inlet-fill sequences between Pleistocene estuarine clay and shoreface to shelf silt and clay.     

渤海湾西岸滨海平原晚第四纪以来的沉积间断

渤海湾西岸滨海平原1:50 000区域地质调查发现晚第四纪地层多次出现沉积间断.深入的岩石与生物地层、年代地层、磁性地层和气候地层等多重地层学研究及与深海氧同位素曲线的对比表明,这些间断均与寒冷气候有关.氧同位素曲线证实,全球相对寒冷气候时期几乎占过去180万年时间的一半[1],这为本区的寒冷导致间断的推断提供了依据.这些间断可以分为两类,一类即通常为人们熟知的具明显侵蚀面的间断;另一类为极缓慢的沉积(即在空间上占有一定的厚度,并非象第一类那样仅占一个侵蚀面)的层段.作为地层划分重要组成因素,对间断的重视与深入研究,在重建第四纪地质环境演变历史和地层划分中具有重要意义.     

Reconstruction of a Civil War landscape: Little Folly Island,South Carolina

The inlet dividing Little Folly Island and Big Folly Island was relocated through the use of Union Navy and Army maps and a global positioning system device. Identification of the inlet was confirmed through foraminiferal analysis of marsh sediments retrieved with gouge‐auger cores. The inlet was 1.8 km closer to Confederate batteries on Morris Island than previously believed. In addition to identifying the inlet, sedimentary structures were used to differentiate anthropogenic and natural sand mounds and dunes, resulting in the identification of four previously undocumented Union gun parapets. The results of this study suggest foraminifers are a useful tool for reconstructing coastal military landscapes from the Civil War and potentially earlier conflicts. © 2008 Wiley Periodicals, Inc.     

苏北滨海平原全新世沉积物物源研究--元素地球化学与重矿物方法比较

运用元素地球化学与重矿物方法对苏北滨海平原全新世沉积物物源进行的比较研究表明,沉积物形成主要由长江与黄河提供物质来源,且又以黄河物源为主。全新世早期长江物质对本区影响范围大于黄河,黄河供给泥沙量较少,对本区影响主要在北部、中部地区。全新世最大海侵之后,黄河曾由苏北入海并携带了大量泥沙,其影响范围明显大于长江,长江仅由狭窄的汊道提供有限的物质而影响范围较小。最近2000年来本区沉积物物源主要由黄河提供。分析表明元素地球化学方法在沉积物物源判别时,可有效的避免水动力因素影响,而相对重矿物方法取得较好的效果。     

The effects of Holocene barrier-island evolution on water-table elevations, Hatteras Island, North Carolina, USA

 On Hatteras Island, North Carolina, USA, complex stratigraphy results from surficial sediments being superimposed on an inherited Pleistocene platform. Numerical simulations used to simulate water-table profiles on the island illustrate the influence that the complex stratigraphy has on water-table elevations. Field data consist of water-table profiles collected from a cross-island transect of wells. These profiles show unusually high water-table elevations in the south-central portion of Hatteras Island. Geophysical data are used to constrain the subsurface stratigraphy. Simple analytical solutions to the groundwater flow equation using laterally varying recharge rates cannot match mean water-table profiles. More complex numerical simulations, which do match the profiles, indicate that the elevated water levels result from a low-permeability unit that extends several kilometers along the longitudinal axis of the island. Island geomorphology and ground-penetrating radar (GPR) data suggest that this unit is a former interdunal wetland that has been buried by a series of parabolic dunes. Received, September 1999 / Revised, March 2000 / Accepted, March 2000     

Upper Maastrichtian ammonite biostratigraphy of the Gulf Coastal Plain (Mississippi Embayment,southern USA)

The Cretaceous outcrop belt of the Mississippi Embayment in the Gulf Coastal Plain (GCP) spans the Cretaceous/Paleogene (K/Pg) boundary. A detailed reconstruction of this time interval is critical for understanding the nature of biotic and environmental changes preceding the end-Cretaceous Mass Extinction event and for deciphering the likely extinction mechanism (i.e., bolide impact versus volcanism). Eight sections encompassing the K/Pg succession across the Mississippi Embayment were analyzed using biostratigraphic sampling of ammonites, dinoflagellates, and nannofossils. An upper Maastrichtian ammonite zonation is proposed as follows, from oldest to youngest: Discoscaphites conradi Zone, D. minardi Zone, and D. iris Zone. Our study documents that the ammonite zonation established in the Atlantic Coastal Plain (ACP) extends to the GCP. This zonation is integrated with nannofossil and dinoflagellate biostratigraphy to provide a framework to more accurately determine the age relationships in this region. We demonstrate that ammonites and dinoflagellates are more reliable stratigraphic indicators in this area than nannofossils because age-diagnostic nannofossils are not consistently present within the upper Maastrichtian in the GCP. This biostratigraphic framework has the potential to become a useful tool for correlation of strata both within the GCP and between the GCP, Western Interior, and ACP. The presence of the uppermost Maastrichtian ammonite D. iris, calcareous nannofossil Micula prinsii, and dinoflagellates Palynodinium grallator and Disphaerogena carposphaeropsis suggests that the K/Pg succession in the GCP is nearly complete. Consequently, the GCP is an excellent setting for investigating fine scale temporal changes across the K/Pg boundary and ultimately elucidating the mechanisms causing extinction.