Quaternary International

Published by Elsevier BV

Print ISSN: 1040-6182

Articles


Cyto-nuclear dissociation and the African elephant species question
  • Article

July 2007

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100 Reads

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Studies of skull morphology and of nuclear DNA have strongly concluded that African elephants comprise two species. Nonetheless, Debruyne (2005) has suggested a single-species model for Loxodonta based on the polyphyly of a single genetic locus, mitochondrial DNA (mtDNA). Discordant patterns between mitochondrial and nuclear DNA markers were subsequently reported in some African savanna elephant populations, further supporting a two-species model, and prompting us to re-examine here the geographic distribution of different elephant morphotypes and their relationship to nuclear and mtDNA phylogeographic patterns. We used exact tests to compare the distribution of forest elephant-typical and savanna elephant-typical characteristics across eight published datasets containing morphological, mtDNA or nuclear DNA data for African elephants. Among the elephants examined by Debruyne (2005), we found that patterns of forest vs. savanna characteristics were significantly different (p < 10(-5)) between mtDNA and morphology, suggesting the presence of cyto-nuclear genomic dissociation. We show that the eight African elephant continent-wide datasets compared, including that of Debruyne (2005), together support a two-species model with cyto-nuclear genomic dissociation rather than a one-species model, and together indicate that Africa harbors two species of elephant.
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Fig. 1. D/L values of Asx, Glx, Ser, Ala, Val and Phe, and [Ser]/[Ala] for the Free Amino Acid (FAA; bF; left) and Total Hydrolysable Amino Acid (THAA; bH*; right) fraction of bleached (intra-crystalline) Valvata piscinalis shells and Bithynia shells and opercula from Clacton (C), Waverley Wood (WW) and West Runton (WR). The species of Bithynia analysed from Clacton is B. tentaculata, but B. troschelii at Waverley Wood and West Runton. For each site, the base of the box indicates the 25th percentile. Within the box, the solid line plots the median and the dashed line shows the mean. The top of the box indicates the 75th percentile. Where more than 9 data points are available, the 10th and 90th percentiles can be calculated (shown by lines below and above the boxes respectively). The results of each duplicate analysis are included in order to provide a statistically significant sample size. The y-axes for the [Ser]/[Ala] data are plotted in reverse, so that the direction of
Fig. 2.
Fig. 5.
d/l values of Asx, Glx, Ser, Ala, Val and Phe, and [Ser]/[Ala] for the Free Amino Acid (FAA; bF; left) and Total Hydrolysable Amino Acid (THAA; bH*; right) fraction of bleached (intra-crystalline) Valvata piscinalis shells and Bithynia shells and opercula from Clacton (C), Waverley Wood (WW) and West Runton (WR). The species of Bithynia analysed from Clacton is B. tentaculata, but B. troschelii at Waverley Wood and West Runton. For each site, the base of the box indicates the 25th percentile. Within the box, the solid line plots the median and the dashed line shows the mean. The top of the box indicates the 75th percentile. Where more than 9 data points are available, the 10th and 90th percentiles can be calculated (shown by lines below and above the boxes respectively). The results of each duplicate analysis are included in order to provide a statistically significant sample size. The y-axes for the [Ser]/[Ala] data are plotted in reverse, so that the direction of increased protein degradation for each of the indicators remains the same. Note different scales on the y-axes.
Difference in the means and 95% confidence intervals between Clacton and West Runton for racemization and decomposition in the FAA (A) and THAA (B) fractions of Valvata piscinalis (Vp) and Bithynia (B) shell and opercula. The y-axes for the [Ser]/[Ala] data are plotted in reverse, so that the direction of increased protein degradation for each of the indicators remains the same. The dashed line (0.00) indicates that there is no difference between the mean of the two sites. If the 95% confidence intervals fall below this zero line, then it is not possible to discriminate between Clacton and West Runton. The opercula are clearly better at discriminating between the sites than the shells, because they show a greater difference in means and have much smaller error bars. The use of opercula therefore increases the statistical confidence and temporal resolution.

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Amino acid geochronology of the type Cromerian of West Runton, Norfolk, UK
  • Article
  • Full-text available

December 2010

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167 Reads

Aminostratigraphic studies of continental deposits in the UK have hitherto relied almost exclusively on data from the aragonitic shells of non-marine molluscs for dating Pleistocene sequences. This is usually based on the d/l value of a single amino acid, d-alloisoleucine/l-isoleucine (A/I), in the total shell proteins. Two genera of freshwater gastropods (Valvata and Bithynia) are used to explore the value of using multiple amino acids from the intra-crystalline fraction, which should be more protected from the effects of diagenesis than the inter-crystalline component. Results are compared from both the aragonitic shells and opercula composed of calcite, a more stable form of calcium carbonate. In order to put the amino acid data from the West Runton Freshwater Bed into perspective, statistical analyses are used to compare them with results from the Hoxnian (MIS 11) site at Clacton-on-Sea, Essex. Twelve protein decomposition indicators revealed that the results from the shells were not as clear-cut as those from the opercula. Five indicators from the Valvata shell suggest that West Runton is older than Clacton (at a 95% significance level), but two actually suggested a younger age. Seven indicators show that the Bithynia shells from West Runton are older than congeneric shells from Clacton. In marked contrast, all 12 indicators isolated from the opercula demonstrate that West Runton is significantly older than Clacton. The data are also compared with results from Waverley Wood, an important archaeological site in the English Midlands falling within the 'Cromerian Complex'. Contrary to earlier interpretations, the new amino acid data from Bithynia opercula indicate that West Runton is older than Waverley Wood, a relationship now consistent with the available biostratigraphy.
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Climate signals in sediment mineralogy of Lake Baikal and Lake Hovsgol during the LGM-Holocene transition and the 1-Ma carbonate record from the HDP-04 drill core

August 2009

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1,037 Reads

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Modeling the bulk sediment XRD patterns allows insight into the environmental and depositional histories of two neighboring rift lake basins within the Baikal watershed. Parallel 14C-dated LGM-Holocene records in Lakes Baikal and Hovsgol are used to discuss the mineralogical signatures of regional climate change. In both basins, it is possible to distinguish ‘glacial’ and ‘interglacial’ mineral associations. Clay minerals comprise in excess of 50% of layered silicates in bulk sediment.The abundance of smectite (expandable) layers in mixed-layer illite–smectites and the total illite abundance are the main paleoclimatic indices in the clay mineral assemblage. Both indices exhibit coherent responses to the Bølling–Allerød and the Younger Dryas. The smectite layer index is not equivalent to the abundance of illite–smectite, because illite–smectite tends to transform into illite. Repeated wetting–drying cycles in soils and high abundance of expandable layers in illite–smectites (>42%) favor the process of illitization. This relationship is clearly shown in both Baikal and Hovsgol records for the first time. The opposite late Holocene trends in illite abundance in Lake Baikal and Lake Hovsgol records suggest that a sensitive optimal regime may exist for illite formation in the Baikal watershed with regard to warmth and effective moisture.The Lake Hovsgol sediments of the last glacial contain carbonates, suggesting a positive trend in the lake's water budget. A progressive change towards lower Mg content in carbonates indicates lowering mineralization of lake waters. This trend is consistent with the lithologic evidence for lake-level rise in the Hovsgol basin.The pattern of mineralogical changes during the past 20 ka is used to interpret bulk sediment and carbonate mineralogy of the long 81-m Lake Hovsgol drill core (HDP-04) with a basal age of 1 Ma. The interglacial-type silicate mineral associations are confined to several thin intervals; most of the sediment record is calcareous. Carbonates are represented by six main mineral phases: calcite, low-Mg calcite, intermediate/high-Mg calcite, dolomite, excess-Ca dolomite and metastable monohydrocalcite. These mineral phases tend to form stratigraphic successions indicative of progressive changes in lake water chemistry. Five sediment layers with abundant Mg-calcites in the HDP-04 section suggest deposition in a low standing lake with high mineralization (salinity) and high Mg/Ca ratios of lake waters. Lake Hovsgol sediments contain the oldest known monohydrocalcite, found tens of meters below lake bottom in sediments as old as 800 ka. This unusual find is likely due to the conditions favorable to preservation of this metastable carbonate.

The rise and fall of Lake Bonneville between 45 and 10.5 ka

April 2011

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602 Reads

A sediment core taken from the western edge of the Bonneville Basin has provided high-resolution proxy records of relative lake-size change for the period 45.1–10.5 calendar ka (hereafter ka). Age control was provided by a paleomagnetic secular variation (PSV)-based age model for Blue Lake core BL04-4. Continuous records of δ¹⁸O and total inorganic carbon (TIC) generally match an earlier lake-level envelope based on outcrops and geomorphic features, but with differences in the timing of some hydrologic events/states. The Stansbury Oscillation was found to consist of two oscillations centered on 25 and 24 ka. Lake Bonneville appears to have reached its geomorphic highstand and began spilling at 18.5 ka. The fall from the highstand to the Provo level occurred at 17.0 ka and the lake intermittently overflowed at the Provo level until 15.2 ka, at which time the lake fell again, bottoming out at ∼14.7 ka. The lake also fell briefly below the Provo level at ∼15.9 ka. Carbonate and δ¹⁸O data indicate that between 14.7 and 13.1 ka the lake slowly rose to the Gilbert shoreline and remained at about that elevation until 11.6 ka, when it fell again. Chemical and sedimentological data indicate that a marsh formed in the Blue Lake area at 10.5 ka.

Vegetation history of the southern Loess Plateau of China during the last 100000 years based on pollen data

December 1997

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66 Reads

This paper summarizes the vegetation history of the past 100,000 years for the Loess Plateau, Central China. The report is primarily based on a recent pollen record from Weinan and on prior records from the Plateau.The pollen diagram of the loess-paleosol sequence at Weinan, in the southern part of the Plateau, displays a predominance of arid shrubs or herbs (Artemisia, Chenopodiaceae) alternating with abundant mesic herbs such as Cyperaceae, Ranuculaceae and Liliaceae indicating a succession of steppe and meadow-steppe environments during the past 100 ka. Forest vegetation developed in a few comparatively short time intervals: Ulmus forest at 95.1–90.7 ka; Corylus woodland at 25.0–21.1 ka, and Tsuga stand at 13.7–11.8 ka.Previously published pollen data with more-or-less reliable dates also indicates that there were different types of steppe vegetation dominating the last 100 ka. The present lack of forest on the Plateau has been explained by plant ecologists as being due to anthropogenic effects. However, in the context of the last 100 ka it appears that there are non-human factors which may have contributed to the treelessness of the Plateau, such as the free-draining nature of loess.

Meteoric 10Be dating of highly weathered soils from fluvial terraces in Taiwan

September 2008

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174 Reads

Stream terraces are geomorphic markers that can be used to gauge surface deformation in response to tectonic uplift. The surface deposits of the terraces form a chronosequence that indicates the rate and process of soil development. Placing a time or age constraint upon soil development has become one of the most important factors in the disciplines of soil science and fluvial geomorphology. The radiocarbon (14C) method is unable to date old terraces or soils, but the longer half-life of cosmogenic beryllium-10 (10Be) permits this isotope to be useful to determine soil ages and rates of formation. Red soils (redder than 7.5YR) are commonly distributed on old, high altitude stream terraces throughout Taiwan. In this study, three pedons of alluvium-related red soils were sampled from the Taoyang (TY-YM), Pakua (PK-1), and Chiayi terraces (CY-1), respectively located in northern, central, and southern Taiwan. According to field morphology and chemical analyses, these red soils are characterized in Soil Taxonomy as being highly weathered, and they are classified as Typic Hapludox (TY-YM and PK-1), and Typic Paleudult (CY-1). Meteoric 10Be dating shows ages of ⩾261 ka for TY-YM, ⩾124 ka for PK-1, and ⩾386 ka for CY-1. However, the trend of these ages does not agree with the degree of soil development. The former two ages are likely underestimated through loss of 10Be due to strong leaching and considerable erosion. The age obtained from CY-1 may represent the required time for soils develop into oxisols in Taiwan.

Human adaptation at the pleistocene/holocene boundary in Western Canada, 11,000 to 9000 BP

July 1998

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25 Reads

Most of western Canada was covered by ice until about 12,000 BP. Environments suitable for human habitation were established by about 11,500 BP. The earliest known human occupations date to about 10,700 BP. Para-glacial processes may have destroyed most early sites. Post-glacial colonization occurred from the south. Only 14 archaeological sites contain radiocarbon dates earlier than 9000 BP. The limited data from these sites suggest initial exploitation of big game in open environments until about 10,000 BP. Sites dating between 10,000 and 9000 BP are known mainly from the southern interior plains, and document a continuation of bison hunting. Adaptive strategies in early boreal forests are still unknown.

A 12,000 yr BP record from Andringitra Massif, (southern Madagascar): Post-glacial environmental evolution from geomorphological and sedimentary evidence

July 2002

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102 Reads

Two cores from Andringitra Massif (Madagascar), the peatbog of Andonaham Pasipotsy (2000 m a.s.l.) and Amboromena Lac (2400 m a.s.l.), have been analysed to reconstruct the late Pleistocene–Holocene (last 12,000 yr BP) evolution of the area. Andonaham Pasipotsy is a small depression, originally a glacier cirque barred by a push moraine and infilled by post-glacial sediments. Amboromena Lac is an etche depression developed across a big fracture crossing the Andringitra Massif also infilled by post-glacial sediments. This paper presents the first mention of glacier features for Madagascar.

Evolution and environmental impact of the eruption of Laacher See Volcano (Germany) 12,900 a BP

November 1999

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139 Reads

Laacher See Volcano (LSV), 40 km south of Bonn, explosively erupted ca. 6.3 km3 of chemically strongly zoned phonolite magma probably during spring, 12,900 years ago, the resulting eruption column having reached at least 20 km in height. The bulk of the Laacher See Tephra (LST) was deposited east of the volcano within the Neuwied Basin. LST ashes form the most important stratigraphic marker in Lateglacial deposits over much of Central Europe. A minimum of 2 Mt total S was calculated to have been released during the eruption by comparing pre- and posteruptive volatile concentrations in glass inclusions and pumice matrix glasses. Because a separate S-bearing vapor phase was probably present in the magma prior to eruption as indicated by the high melt-H2O contents close to saturation level, the actual amount of S released during the eruption, could have significantly exceeded 2 Mt. The sulfuric acid aerosol layer resulting from the massive stratospheric S-input probably resided in the stratosphere for years and most likely had a significant impact on climate and thus the environment. Increased precipitation in central Europe and/or impairment of the vegetation cover for several years is suggested by several proxies, especially increased sediment supply into lakes. Proximal to the eruptive center, major environmental impacts include an initial blast that felled trees up to 4 km away from vent. Fast deposition of huge tephra volumes led to the complete disruption of Rhine River within the lower Neuwied Basin and the damming up of a lake ca. 140 km2 in areal extent. Sudden collapse of the temporary tephra dam caused a catastrophic flood wave downstream whose deposits are recognized as far north as Bonn. Reworking of unconsolidated tephra deposits over several 100 km2 was widespread and extensive, generating abundant lahars and flood plain deposits. A braided-river system, established in Neuwied Basin, probably persisted up to several years. Recent reports for a second eruption of LSV are not confirmed.

Massive death of pinnipeds 1200 years ago: Taphonomic history of the “Lobos site” (Golfo Nuevo, Patagonia, Argentina)

May 2008

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71 Reads

The Lobos site was discovered in October 2000, as a result of the exposure of a stratified set of pinniped bone remains. These remains correspond to the Otaria flavescens species and were found on the walls of a ravine. Research included several samplings; an excavation according to archaeological methodology, and taphonomic, biological, archaeological, geological, and forensic studies. These studies indicate the occurrence of a massive natural death of a pinniped colony 1200 years 14C BP. Associated pupal cases remains suggest that the episode took place in summer and that the pinniped bodies were buried by mass wasting events a month later. Some of the bones were afterwards redeposited by water.

Evaluating the effects of climate change on environment, resource depletion, and culture in the Palau Islands between AD 1200 and 1600

July 2006

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959 Reads

The Palau archipelago is a sizeable and geologically diverse set of volcanic and coralline limestone islands in equatorial western Micronesia. Recent archeological fieldwork, pollen analyses, and radiocarbon assays have expanded our understanding of more than 3000 years of culture history in Palau, providing a potentially unique window on the relationship between climate, environment, human adaptation, and culture change in the tropical western Pacific. Our focus is on the period of AD 1200–1600, particularly as relates to the transition between the Medieval Warm Period and the onset of the Little Ice Age. This period encompasses the establishment of stonework villages throughout the archipelago, and ultimately their abandonment in the limestone islands. Paleoenvironmental and archeological data, including settlement pattern analyses, provide mixed but intriguing messages regarding the role of climate in Palauan culture change. Archeological deposits in Uchularois Cave contain domestic pig, Sus scrofa, large-eyed bream, Monotaxis grandoculis, parrotfish, Scarus sp., and the humped conch, Strombus gibberulus gibbosus, that together provide evidence of environmental degradation or overharvesting and the potential effects of climate change on culture. Our data suggest that a greater emphasis on high-resolution data is necessary to properly evaluate the role of climate in Pacific island culture change.

Comment on “Late Cenozoic uplift of southern Italy deduced from fluvial and marine sediments: Coupling between surface processes and lower-crustal flow” by Westaway R. and Bridgland D. (Quaternary International 175, 86–124)

August 2009

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194 Reads

We consider it opportune to comment on some of the statements proposed by Westaway R. and Bridgland D. (2007) in their paper “Late Cenozoic uplift of southern Italy deduced from fluvial and marine sediments: Coupling between surface processes and lower-crustal flow” (Quaternary International 175, 86–124), with particular reference to the first half of the paper focusing on the geomorphological analysis of the Pleistocene marine and fluvial terraces that occur along the Ionian coastal area of the Basilicata region (Southern Italy). As authors of some of the papers cited in [Westaway, R., Bridgland, D. 2007. Late Cenozoic uplift of southern Italy deduced from fluvial and marine sediments: coupling between surface processes and lower-crustal flow. Quaternary International 175, 86–124.], we wish to point out several significant inaccuracies in their paper, which are generally due to the misunderstanding or misuse of literature data and which regard (i) both the vertical distribution and the timing of the whole Ionian marine terrace sequence, (ii) the correlation between marine terraces and marine isotopic stages (MIS), (iii) the interaction between uplift and erosion processes in Basilicata, and (iv) the morphogenic model of the fluvial terraces of the Agri River. It is our opinion that the Late Cenozoic uplift magnitudes, rates and modelling proposed by the authors for this key-area of southern Italy using such unreliable data are, therefore, to say the least, questionable.

Marra AC. Pleistocene mammals of Mediterranean islands. Quatern Int 129: 5-14

December 2005

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493 Reads

This paper provides a synthesis and an integration of the current knowledge on Pleistocene mammals from the main Mediterranean islands. New evidence enables us to consider faunal complexes, paleobiodiversity, degree of endemism and ways of dispersals into a chronological frame. The Balearic Islands developed an endemic fauna from mainland ancestors spreading during the Messinian. Sardinia and Corsica have had a Pliocene–Early Pleistocene fauna spread from mainland during the Messinian. The arrivals after this time can be related to occasional spreading. During the Early Pleistocene and early Middle Pleistocene, Sicily and Malta acted as an archipelago made up of small islands. Since late Middle Pleistocene, Sicily has been a large island with frequent faunal exchanges with the mainland. During Early Pleistocene and Early Middle Pleistocene, Crete was an archipelago occasionally reached by mammals; communications with the mainland have probably been easier since the late Middle Pleistocene. Cyprus has been completely isolated and developed a strongly endemic and impoverished fauna.

A ∼13,000-year paleolimnological record from the Uinta Mountains, Utah, inferred from diatoms and loss-on-ignition analysis

April 2011

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115 Reads

Paleolimnological research in mountainous regions of the Western United States provide baseline understanding of how these lake systems will respond to ongoing climate change. Fossil diatom assemblage and loss-on-ignition data were investigated from a ∼13,000-year lake sediment core from the Uinta Mountains, northeastern Utah, USA. Results indicate the presence of three major zones of environmental change: 1) from ∼12.9–10.9 cal ka, modern lake formation began, temperatures were cool, and water was turbid; 2) from ∼10.9–3.5 cal ka conditions were warmer-than-present, and the lake stratified during the summer; and 3) beginning approximately 3.5 cal ka, temperatures decreased relative to the previous zone and the lake appears to have become increasingly alkaline. Shifts in diatom taxa relative abundances within the middle zone (ca. 8.2–6.5 and 5.0–3.5 cal ka) are probably caused by precipitation-driven decreases in alkalinity and increases in lake depth. This record reflects evolution of the lake system and suggests that currently rising temperatures will reduce ice cover and enhance lake stratification and internal nutrient cycling. Any future changes in precipitation patterns may also impact lake ecology through shifts in alkalinity and/or depth.

Diversified development of mountain mires, Bohemian Forest, Central Europe, in the last 13,000 years

May 2002

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110 Reads

Plant cover and past vegetation development of five mires were analyzed in different orographic and mesoclimatic situations along the NW–SE transect through the Bohemian Forest, Central Europe. Bogs at various altitudes (m), precipitation total (mm) and mean annual temperature (°C) were compared among: (1) wet windward cooling upslope plains at 860 m, 807 mm and 5.1°C, (2) very wet, cold and wind–exposed summit plains at 1120 and 1060 m, 1337 and 1100 mm, 3.2°C and 3.7°C, respectively, and (3) downwind rain-shadow valleys at 750 m, 757 mm, and 6.2°C. The mires of summit plains differ from the others by both present-day plant cover and past vegetation development, which began as late as the Preboreal, 10,000 years ago. Plant cover of their margins is predominated by the krummholz Pinus x pseudopumilio and open central mire expanses are noted by remarkable biodiversity and surface patterning. Mires of lower elevations are represented by domed raised-bogs forested by Pinus rotundata. According to pollen analysis, their development in the NW followed a typical sequence of the Bohemian Forest from the Late Glacial, with steppe-tundra prevailing 11,000 years ago, to the Boreal, with open Pinus and Corylus forests. Since the Atlantic period 6000 years ago, the surrounding forests were formed mainly by Picea, then by Picea and Fagus, and later by Abies, which became dominant in the whole Bohemian Forest since the Subboreal, 4000 years ago. Pinus expanded in the last 300 years. At present, herb and moss communities with scattered Betula pubescens occupy wet lagg, and closed–canopy bog-pine forest of primeval appearance covers the entire mire. In the SE bogs, the development started earlier, 13,000 years ago. Vegetation history here was slightly different; Alnus-Betula carrs have developed since the Atlantic period. At present and in spite of NE, the very centers of these SE bogs remain open, in lagg woods of Betula pubescens with the undergrowth of Phragmites australis prevail. The analysis confirmed that development, vegetation and mire types correspond to the differences in mountain mesoclimate. In extrapolations of paleoecological data from mountain areas the diversification of biotic development has to be taken into account.

Quaternary uplift of the Peruvian coast related to the subduction of the Nazca Ridge: 13.5 to 15.6 degrees south latitude

December 1992

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24 Reads

Marine terraces between 13.5 and 15.6°S. latitude on the Peruvian coast preserve a history of Quaternary sea-level fluctuations and forearc movement above the subducting Nazca Ridge. Field mapping and amino acid racemization/epimerization, electron spin resonance, radiocarbon, and uranium-series disequilibrium ages from mollusk shells from terrace deposits are used to define a marine terrace chronology. Terraces on the Peruvian coast formed during global high stands of Quaternary sea level, in a similar way to the marine terraces on the west coast of the United States, and Baja California, Mexico. A last interglacial marine terrace (125 ka) is preserved on nearly every terrace flight. Along the coast from northeast to southwest, each terrace varies in elevation because of variations in the rate of coastal uplift.Variations in uplift rate from northeast to southwest in the study area are explained by a simple geometric model in which the variables are the rate of plate convergence, morphology of the Nazca Ridge, and orientation of the ridge relative to the Peruvian coast. The oblique northeastward orientation of the ridge relative to the east-west direction of plate convergence results in a ca. 70 mm/yr southeastward migration of the zone of Nazca Ridge subduction beneath the Peruvian coast. The coastal area above the northern flank and crest of the Nazca Ridge is stable or has undergone net subsidence, while the coast above the ridge crest is rising at about 0.3 m/kyr. Above the southern flank of the Nazca Ridge, the coast is rising at a rate of ca. 0.5 m/kyr, the fastest rate determined from studies of marine terraces on the coasts of Peru and Chile. South of the influence of the Nazca Ridge, uplift rates are ⩽ 0.2 m/kyr. The pattern of faster uplift above the southern flank and slower uplift above the northern flank of the ridge is a predictable consequence of oblique ridge subduction.

Fig. 1. The Fiji Islands, showing the location of Viti Levu and other places mentioned in the text. The Sigatoka River is also shown, and the location of Fig. 2. The inset shows places mentioned along the coast of southwest Viti Levu relative to the Sigatoka Sand Dunes and Sigatoka River mouth.
Fig. 2. The Sigatoka Valley showing (a) locations of dated hilltop, cave, and other fortified sites (after Field, 2004) and (b) locations of dated alluvial charcoals (after Kumar et al., 2004).
Fig. 5. Exposed Level 3 palaeosol at site VL16/1, Sigatoka Sand Dunes, looking northwest. The palaeosol exposure shows here as a dark stripe of sticky humic sand that runs northwest and then turns west. This photo, first published in Wood et al. (1998), shows a continuous exposure of Level 3 that has been observed only on rare occasions. Arrows indicate the areas sampled for radiocarbon dating. Photo used with permission of Andrew Crosby and Yvonne Marshall. 
Fig. 6. Model of settlement-pattern evolution in the Sigatoka area (area located in Figs. 1 and 2) to show the effects of the AD 1300 Event. In all maps, closed circles represent well-established (permanent?) settlements while open circles represent temporary settlements, perhaps occupied only seasonally. Broken lines around settlements represent the area within which agriculture associated with particular settlements took place (this is not shown for modern times in (f)). All inland settlements shown in maps (b)-(e) were dated (see Fig. 5):
Radiocarbon dates for Level 3 on the Sigatoka Sand Dunes
Human Responses to Climate Change around AD 1300: A Case Study of the Sigatoka Valley, Viti Levu Island, Fiji

July 2006

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607 Reads

In the Sigatoka Valley on Viti Levu Island in Fiji, three independent studies of last-millennium environmental and human-societal changes suggest that these were driven largely by the climate and sea-level changes of the AD 1300 Event. Establishment dates for interior fortified hilltop (or cave) settlements show that a significant number were established during or shortly after the AD 1300 Event, probably in response to primarily food shortages arising from sea-level fall (affecting coastal populations) and water-table fall (affecting coastal and inland populations). Charcoal concentrations in valley-floor sediments formed as a result of largely human burning of vegetation associated with the establishment of inland hilltop settlements; radiocarbon dates from these charcoals also suggest significant numbers of such settlements being established during or shortly after the AD 1300 Event. The main dune at the Sigatoka River mouth is underlain by the ‘Level 3’ palaeosol, dated to the AD 1300 Event, which implies that thereafter an abrupt and sustained increase in suspended fluvial sediment, associated in increased inland population, began to build the high dunes visible today. This study provides a well-constrained example of the effects that the AD 1300 Event had on Pacific Islands and their people.

Vegetation and climate change in West-Java, Indonesia during the last 135,000 years

December 1997

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362 Reads

Sedimentological and palynological analyses of two sediment cores from the intramontane Bandung basin (Java, Indonesia) provide the first palaeoclimatic record for the Indonesian region covering the last 135,000 years. Our data indicate anomalously dry conditions for the penultimate glacial and very warm and humid conditions during the last interglacial. During the last glacial period, fresh water swamp forests of the Bandung plain were replaced by open swamp vegetation, dominated by grasses and sedges, indicating a change to considerably drier climatic conditions, possibly as a consequence of lower sea levels at the onset of glacial conditions. For the Last Glacial Maximum, temperatures 4–7°C lower than at present are recorded.

Some aspects of age assessment of Holocene loess colluvium: OSL and 137Cs dating of sediment from Biała agricultural area, South Poland

August 2011

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41 Reads

At the end of the Pleistocene in Central-Eastern Europe, the accumulation of periglacial loess had already finished. From the end of loess accumulation to the establishment of grass cover and forest succession in this area, a phase of active modeling of the land surface by slope processes occurred. Before the beginning of the Holocene, this activity stopped and mollisol and alfisol formation started. These soils are preserved beneath Holocene colluvia. Until the Neolithic age, the area of loess formations in Poland was uninhabited. The extensive Neolithic agriculture locally induced soil erosion, causing slopewash on farmedslopes. The scale of this process and establishing the age of the successive stages of the prehistoric soil erosion in loess deposits in Poland is a key problem in the investigations of the human–environment relationship in prehistory. Chronostratigraphy of the preserved Holocene colluvia is very helpful in the solution of these problems. Optical (OSL) dating was applied in chronostratigraphical analyses. Due to expected partial bleaching during sediment transport, a single-aliquot regenerative dose protocol (SAR) was applied. Insufficient bleaching during transport on the slope is expected to be a serious problem for luminescence dating of loess colluvia, and causes overestimation of the OSL age. Quartz from the study site was suitable for age determination by SAR. The youngest 50-year old colluvia were also studied using the 137Cs method. The reliability of the obtained results is discussed in this paper, as well as the influence of environmental processes and type of the applied methods on chronological assignments. The precise age determination of loess colluvia is important for study of the human impact on the environment. The results of OSL dating show that soil erosion started in the Neolithic, with three phases of soil erosion: Neolithic, Middle Ages, and modern.

Fig. 1. World map showing the spatio-temporal distribution of Proboscidean kill/scavenge sites for Africa, Europe, Asia, and North America. Site location is indicated by the base of the pin and site age is indicated by pin length. Ages (and pin lengths) are logarithmically scaled.  
Table 1 Clovis sites showing secure subsistence associations with Proboscideans 
Table 2 Old World sites showing evidence of subsistence use of Proboscideans
Fig. 3. The relative frequency of the occurrence of Proboscideans in faunal assemblages from various Old World spatio-temporal regions in comparison to Clovis. UP ¼ Upper Paleolithic, EUP ¼ Early Upper Paleolithic, MUP ¼ Middle Upper Paleolithic, LUP ¼ Late Upper Paleolithic, MP ¼ Middle Paleolithic.  
How many elephant kills are 14?: Clovis mammoth and mastodon kills in context

November 2008

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1,803 Reads

Recent evaluation of the use of Pleistocene megafauna by Clovis hunter-gatherers has suggested that a small number of reliable associations between Clovis artifacts and the remains of Proboscideans are documented, with perhaps as few as 14 occurrences currently known. Specifically, we ask whether 14 is a large or a small number of associations given the spatio-temporal dimensions of the Clovis period in North America. To place these 14 occurrences into context, we compare the time–space density and relative frequency of Clovis Proboscidean-bearing sites to those of Old World contexts. We develop models to identify the variables contributing to the archeological record of Proboscidean site creation, destruction, and sampling. While acknowledging potential biases in the record, comparative analysis suggests that the Clovis archeological record, with the possible exception of Lower Paleolithic of Iberia, indicates the highest frequency of subsistence exploitation of Proboscidea anywhere in the prehistoric world.

Baryshnikov G. — Late Pleistocene arctic fox (Alopex lagopus) from Crimea, Ukraine. Quaternary International 142–143

January 2006

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232 Reads

The teeth and bone fragments of Alopex lagopus of early Weichselian age from Mousterian layers of grotto Prolom 2 in Crimea have been studied. The Crimean fossil arctic fox was found to be smaller than the late Weichselian subspecies, A. l. rossicus, from the East European Plain, but it seems to be similar in dimensions to the recent insular subspecies, A. l. spitzbergenensis. From the latter, the Crimean arctic fox differs in the relatively longer carnassial teeth and relatively wider m1. In the Late Pleistocene of Europe, a progressive increase in size of A. lagopus is observed, that makes it possible to recognize two subspecies, stratigraphically replacing one another. The arctic fox from Prolom 2 is presumably referable to the subspecies A. l. meridionalis, while the animals from another Crimean Upper Paleolithic site, Siuren 1, are referred to A. l. fossilis.

AMS 14C analysis of Late Pleistocene non-analog faunal components from 21 cave deposits in southeastern North America

April 2010

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149 Reads

Late Wisconsinan micromammal faunas collected from caves in southeastern North America are characterized by nearly twice the number of species than are present in the region today. It has been proposed that this richness was achieved by paleoenvironments that permitted both the immigration and intermingling of boreal, steppe, and sub-tropical taxa with the present day deciduous forest micromammal community. Contemporaneity of component taxa cannot be assumed without ¹⁴C dating because taphonomic processes can produce similar configurations. If ‘non-analog’ specimens are contemporaneous, they represent communities with no modern analogs. If the dates on component species are disjunct, they are an artifact of time averaging and the species have a different paleoecological significance. The question remains: What is a significant interval of time to assert a community versus a time-averaging interpretation for Pleistocene faunal configurations?

Major Δ 14C excursions during the late glacial and early Holocene: Changes in ocean ventilation or solar forcing of climate change?

December 2003

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73 Reads

The atmospheric record during the Late Glacial and the early Holocene shows sharp increases simultaneous with cold climatic phases. These increases in the atmospheric content are usually explained as the effect of reduced oceanic CO2 ventilation after episodic outbursts of large meltwater reservoirs into the North Atlantic. In this hypothesis the stagnation of the thermohaline circulation is the cause of both climate change as well as an increase in atmospheric . As an alternative hypothesis we propose that changes in production give an indication for the cause of the recorded climate shifts: changes in solar activity cause fluctuations in the solar wind, which modulate the cosmic ray intensity and related production. Two possible mechanisms amplifying the changes in solar activity may result in climate change. In the case of a temporary decline in solar activity: (1) reduced solar UV intensity may cause a decline of stratospheric ozone production and cooling as a result of less absorption of sunlight. This might influence atmospheric circulation patterns (extension of Polar Cells and equatorward relocation of mid-latitude storm tracks), with effects on oceanic circulation, and (2) increased cosmic ray intensity may stimulate cloud formation and precipitation, while production increases.

Development of low-background vacuum extraction and graphitization systems for 14C dating of old (40–60ka) samples

May 2007

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120 Reads

At the University of Arizona's Desert Laboratory, we recently constructed new low-background vacuum extraction and graphitization systems that are dedicated to preparing old (40–60 ka) samples for 14C dating. These systems are designed to minimize the amount of contaminant carbon, specifically atmospheric carbon, that is introduced to a sample during laboratory processing. Excluding contaminants is particularly important for 14C dating of old samples because the impact of contamination increases with sample age. In this study, we processed 20 pretreated and 4 untreated aliquots of Ceylon graphite (a naturally-occurring geological graphite) to determine the total procedural background level, and hence the practical limit, of our systems. Samples were heated under vacuum at 240 °C for 1 h to drive off water vapor and other atmospheric gases, and then combusted in ultra-high-purity (UHP) O2 at 500 and 850 °C to monitor the removal of contaminants and to ensure complete combustion. After SOX, NOX, and halide species were removed, sample CO2 was converted to graphite via catalytic reduction of CO. Fe and Zn powders used in the graphitization process were oxidized, “scrubbed”, and reduced with UHP O2, He, and H2, respectively, to remove sorbed atmospheric C species. Graphite targets were stored in UHP Ar until measurement by accelerator mass spectrometry (AMS) to avoid potential interaction with atmospheric gases. Based on the AMS results, the background level of our system is characterized by a nonlinear inverse relationship with sample mass (adjusted R2=0.75; n=24). For a 1 mg graphite target, the total procedural blank, including chemical pretreatment, combustion, cleanup, graphitization, storage, and AMS measurement, is 0.05±0.01 pMC (2σ), equivalent to a 14C “age” of 61.1±1.8 ka. This should not be taken as the upper limit of our system, however, because if the 14C activity of a sample is statistically indistinguishable from the appropriate mass-dependent blank value at the 95% confidence level (2σ), then its age is considered to be “infinite”. Thus, for a 1 mg target, the practical limit of our system is actually ∼55 ka; for a 0.5 mg target, the practical limit is ∼50 ka. Although our extraction system can accommodate inorganic samples (e.g., calcite, aragonite), the above limits are only applicable to geological graphite, charcoal, and organic samples that are processed via combustion. Future work will be directed toward determining the appropriate background levels for inorganic materials.

Holocene aeolian morphogenetic phases in Southern Italy: Problems in 14C age determinations using terrestrial gastropods

May 2008

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18 Reads

Radiocarbon age determination is one of the most important methods for dating Holocene events. In particular, it has been used to reconstruct the sequence of aeolian morphogenetic phases along the Apulia and Basilicata coasts (Southern Italy). In these areas, three main Holocene morphogenetic phases have been recognized using radiocarbon data obtained from sub-fossil terrestrial gastropods, archaeological data and OSL analyses: those of the Middle Holocene period, of the Greek–Roman time and of the Middle Ages. Sub-fossil terrestrial gastropods have been considered suitable indicators in the detecting Holocene climate–environmental changes. However, it is well-known that they could show problems as chronological indicators mainly due to aging effects induced by: (i) micro-particles of calcite/aragonite in the shell structure, derived from the local substratum and (ii) a variation of CO2 content in the plants eaten. In order to verify these hypotheses, living terrestrial gastropods were collected from coastal areas and analysed using AMS. The results indicate that many living gastropods gave ages of 1500 years older than those expected, thus confirming the aging effect. As 14C ages of Middle and Late Holocene aeolian morphogenetic phases, obtained from terrestrial gastropods, seem to be confirmed by archaeological data and OSL analyses. The aim of this work is to verify if the age anomalies obtained from modern gastropods could be extended to the entire Holocene period.

Extreme Nile Floods and Famines in Medieval Egypt (AD 930-1500) and Their Climatic Implications

October 2007

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1,124 Reads

Nile gauge records of variations in Nile floods from the 9th century to the 15th century AD reveal pronounced episodes of low Nile and high Nile flood discharge. Historical data reveal that this period was also characterized by the worst known famines on record. Exploratory comparisons of variations in Nile flood discharge with high-resolution data on sea surface temperature of the North Atlantic climate from three case studies suggest that rainfall at the source of the Nile was influenced by the North Atlantic Oscillation. However, there are apparently flip-flop reversals from periods when variations in Nile flood discharge are positively related to North Atlantic warming to periods where the opposite takes place. The key transitions occur at∼AD 900, 1010, 1070, 1180, 1350 and 1400. The putative flip-flop junctures, which require further confirmation, appear to be quite rapid and some seem to have had dramatic effects on Nile flood discharge, especially if they recurred at short intervals, characteristic of the period from the 9th to the 14th century, coincident with the so-called Medieval Warm Period. The transition from one state to the other was characterized by incidents of low, high or a succession of both low and high extreme floods. The cluster of extreme floods was detrimental causing famines and economic disasters that are unmatched over the last 2000 years.

Paleoceanographic changes on the Farallon Escarpment off central California during the last 16,000 years

April 2011

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14 Reads

New benthic and planktic foraminiferal assemblage census data and Benthic Foraminiferal Oxygen Index (BFOI) values, previously published marine climate proxy data (stable isotopes and Ca/Cd), and unpublished results of total carbon, organic carbon, and calcium carbonate analyses of sediments recovered off central California on the Farallon Escarpment (1605 m water depth; 37°13.4′N, 123°14.6′W; core F-8-90-G21) document paleoceanographic changes during the latest Quaternary which reflect the intensity and source of North Pacific Intermediate Water (NPIW) and surface productivity. Accelerator mass spectrometry radiocarbon dates of both benthic and planktic species provide an excellent age-depth model for the last 16,000 years, covering the latest glacial, Bølling–Allerød, Younger Dryas, and early, middle, and late Holocene intervals. A Q-mode cluster analysis separated the benthic fauna into three clusters, one Pleistocene and two Holocene, whereas the planktic fauna was divided only into Pleistocene and Holocene clusters. Stable oxygen isotope values show an increase in water temperature of ∼1 °C from the late glacial to late Holocene and a change in faunal composition of the planktic assemblage implies surface waters warmed as well. A general trend of decreasing dissolved oxygen concentration from the Pleistocene (high oxic; 3.0–6.0+ ml/l O2) to the Holocene (low oxic; 1.5–3.0 ml/l O2) suggested by the BFOI and Cd/Ca data reflect decreased ventilation as the source of the NPIW shifted from the Sea of Okhotsk to the tropical east Pacific at ∼11,000 cal BP. The middle Holocene cooling reported in other central and northern California margin studies is not apparent in F-8-90-G21, which compares more favorably with studies from southern California and British Columbia. Total carbon and organic carbon values are highest in the Bølling–Allerød, early Holocene, and late Holocene. Similarly, calcium carbonate values are high in the Bølling–Allerød and peak in the early Holocene, but decrease significantly in the latest middle and late Holocene which coincides with a depauparate planktic foraminiferal fauna in the upper 60 cm (∼70000–0 cal BP) of the core and poor preservation of the benthic foraminiferal fauna at 40 cm (∼3000 cal BP). Decoupling is evident between the planktic and benthic faunal response to changing climatic conditions, with the surface-dwelling assemblage often leading the bottom-dwelling assemblage by several millennia.

Edwards AC, Scalenghe R, Freppaz M.. Changes in the seasonal snow cover of alpine regions and its effect on soil processes: a review. Quatern Int 162: 172-181

March 2007

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141 Reads

At its maximum annual development, snow can cover more than half the Northern Hemisphere land area with one-third experiencing seasonal snow cover. The precise conditions that develop during the annual pattern of snowpack development formation have implications for: (i) soil microbiological activity and nutrient transformations; (ii) the capacity of the accumulating snowpack to retain atmospheric derived solutes; (iii) preferential elution and rapid runoff of solutes from the snowpack during periods of thaw; and (iv) leaching of solutes. Long-term records of annual snow accumulation suggest that substantial, regional scale shifts in snowpack characteristics have been occurring. The accompanying changes in the frequency and timing of freeze–thaw episodes and the evidence of their disruptive and selective influence upon soil microbial processes, when human induced, suggests there are wider implications for nutrient cycling and functioning of mountain ecosystems. This review is focused on alpine landscapes.

Relationships within the Elephantinae using hyoid characters. Quaternary International, 169-170, 174-185

July 2007

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627 Reads

Results are based on ten hyoid characters of seven proboscidean taxa; four belong to the subfamily Elephantinae. Using PAUP we generated six equally parsimonious trees. The consensus tree yields two polytomies: in the basal polytomy the relationships among Mammut, gomphotheres, Stegodon, and Loxodonta are not resolved; in the other polytomy Palaeoloxodon, Mammuthus, and Elephas are grouped in a cluster. The joining of Palaeoloxodon and Mammuthus has not been suggested previously, and there are ample non-hyoid data of grouping Loxodonta, Elephas, and Mammuthus. For this reason and since a major focus of this study has been to test relationships among Loxodonta, Elephas, and Mammuthus, we relied on studies of other workers and rearranged the consensus cladogram to unite Loxodonta with other members of Elephantinae (Palaeoloxodon, Elephas, and Mammuthus). The hypothesis that Mammuthus is more closely related to Elephas than to Loxodonta is more parsimonious (by two evolutionary steps) than when Loxodonta joins Mammuthus. This finding is provisional and should be retested with additional data, especially with taxa with small sample size, and with specimens of extinct Elephantinae taxa. Results also corroborate other findings that Palaeoloxodon is a bona fide elephant genus; we classify it in the new subtribe Palaeoloxodontina Zhang and Zong [1983. Genus Palaeoloxodon of China. Vertebrata PalAsiatica 21(4), 301–312].

The ‘natural’ vegetation of the Mexican Bajío: Archival documentation of a 16th-century Savanna environment

December 1997

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82 Reads

Neo-ecologists make assumptions about a ‘natural’ or potential vegetation when they argue whether a particular landscape is in secondary and degraded condition. Similarly, paleoecologists attempt to infer a three-dimensional biotic mosaic from a core taken in a low-lying wetland. Yet with millennia of human disturbance, climatic fluctuation, biotic response to long-term climatic trends or catastrophic ‘events’, and co-evolution between Holocene vegetation and human land-use, ‘natural ecosystems’ have not been in equilibrium. While past vegetation changes can be traced, efforts to reconstruct potential vegetation are probably unrealistic. This paper assembles 16th century landscape descriptions of the Bajío of Central Mexico from archival repositories, to characterise the landscape at the time of Spanish intrusion. Attention is focused on five major landscape elements: (1) Riparian woodlands of mesquite, bald cypress and willow, with reed stands; (2) Level, vertisolic plains, with a low-tree savanna (mesquite-acacia-grass); (3) Steeper piedmont plains with stony substrates, probably favoring xeric, thorn-bush associations; (4) Rough uplands with a mix of mesquite-acacia woodland, scrub oak, and thorn bush; and (5) Mountains dominated by live and deciduous oak woodlands. The biotic mosaic of the 16th century appears similar to that of the modern spontaneous vegetation in physiognomic terms, despite changes in structure. Areas of older indigenous settlement were affected by local vegetation disturbance, with partial deforestation near lakes Cuítzeo and Yuríria. While Spanish-Criollo intrusion (1540–1640) brought new, potentially destructive landuse methods, there is no evidence of additional landscape degradation in the Bajío until well into the 18th century. Dramatic changes in hydrology and riparian vegetation are quite recent. Archival documentation provides a complementary methodology to re-examine the interplay of edaphic variation, climate and cumulative land-use in understanding contemporary vegetation, and it can assist in converting proxy data into a three-dimensional landscape.

Dynamics of the Ganga in West Bengal, India (1764–2007): Implications for science–policy interaction

November 2010

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1,224 Reads

Understanding of the fluvial dynamics of the Ganga, especially in its lower reach, is incomplete to present. Questions such as why the river changes its course so frequently, or what are the impacts of major structural intervention at Farakka, have not been addressed properly. Open scientific research is impeded by the governmental attitude to conceal water-related data. The present paper deals with the changing courses of the Ganga in West Bengal since the second half of the 18th century. The source materials of this research are maps published by different agencies since the colonial period and a recent satellite image provided by the National Remote Sensing Agency of India.The Ganga enters the Maldah district of West Bengal after touching the outlier of Rajmahal Hills, and swings across the deltaic plain. In the reach between Rajmahal and Farakka, the Ganga has been flowing through a series of distributaries alternately and those channels have now been abandoned. The sequential maps help to understand how the Ganga has changed its course during the known historical period. Since the construction of Farakka barrage, the Ganga has migrated eastward appreciably and has formed a mighty bend. Trapped sediment load above the Farakka barrage has largely induced the recent change. The continuous oscillation of the Ganga in Maldah district, and also along the Indo-Bangladesh border has posed many problems, including land reallocation, population displacement, and border disputes. There should be a paradigm shift in the governmental attitude to look into the matter, not as a purely engineering problem but also as a social issue.

Palaeoclimatic changes in the Qinghai Lake area during the last 18,000 years

July 2005

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646 Reads

Multi-proxy analysis of a sediment core from Qinghai Lake, including pollen, carbonate, TOC, TN and δ13C of organic matter, was used to document regional climatic changes during the last 18,000 years. Climate was very cold and dry before 16.9 cal. kyr BP. The warm and wet period, which began at about 14.1 cal. kyr BP, culminated at 6.5 cal. kyr BP and came to its end at about 4.5 cal. kyr BP. After that, the climate gradually became colder and drier. During the transitional period from the Late Glacial to the Holocene the climate fluctuated frequently. The short-term climatic oscillations, including the Bølling, Alleröd, Younger Dryas and the cooling event at ca. 8.2 cal. kyr BP, appear to be recorded in the Qinghai Lake sedimentary record. The climatic evolution in the Qinghai Lake area during the past 18,000 years indicates that solar insolation changes on the ten-thousand-year scale are the likely driving force of the East-Asia monsoon.

The Verny, 1887, earthquake in Central Asia: Application of the INQUA scale, based on coseismic environmental effects

October 2007

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82 Reads

The INQUA scale, based on coseismic environmental effects, appears to be a very promising tool to get long-term and reliable information on seismicity. However, it has to pass through comprehensive testing procedures. Results of the INQUA scale application to earthquake intensity calibration are presented, part of the worldwide testing of the scale. As a case study, the Verny, 1887, earthquake in Central Asia has been chosen. It was a large earthquake (felt over 2,000,000 km2) located in a region with a specific temporal and spatial organization of seismicity. Verification of magnitudes of some large past earthquakes is important for the correct understanding of regional seismotectonics and seismic hazard assessment. The work is based on the original materials collected by the expedition soon after the earthquake in the epicentral area. It is demonstrated that assessment of epicentral intensity derived from total area of secondary environmental effects is reliable. This enables evaluation of the parameters of historical earthquakes based on generalized information of observed earthquake environmental effects (EEE). The epicentral intensity I0 is assessed to be IX-X degrees; the highest observed local intensities are coherent with I0 assessment.

Heavy minerals, provenance and large scale dynamics of seabed sands in the Southern North Sea: Baak's (1936) heavy mineral study revisited

May 2005

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327 Reads

An overview of early studies on heavy minerals in the southern North Sea is presented, followed by the state of the art as regards seabed sediments mapping and (sub)recent sediment dynamics. The aim of this study is to relate the findings of Baak's (Regional petrology of the southern North Sea. Ph.D. Thesis, Leyden University, H. Veenman and Sons, Wageningen, 128pp) heavy mineral study and some later mineral studies to the results of more recent seabed sediment mapping activities and studies on sub-recent sediment dynamics. Baak's findings could not be appreciated properly at the time as knowledge in the other fields was almost non-existent. His five-fold subdivision of seabed sands and their geological significance is interpreted with the extant knowledge regarding geological mapping and seabed dynamics. Compared to the two fields last mentioned, heavy mineral studies remain useful in tracing relicts of former surface deposits no longer mappable and in tracking down the fate of material derived from eroded seabed deposits. The symbiosis between seabed mapping, (sub)-recent dynamics and mineral studies generates a very strong tool for the unravelling and reconstruction of the dynamic history of shallow shelf and coastal sands.

Precipitation variability (1956-2002) in the Dongjiang River (Zhujiang River basin, China) and associated large-scale circulation

November 2011

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143 Reads

Monthly precipitation data covering 1956–2002 at 36 rain stations are analyzed to explore the spatio-temporal variability of the seasonal precipitation in the Dongjiang River basin, south China, using a continuous wavelet transform method, Mann-Kendall trend test, and simple regressive technique. The results indicated that: (1) increasing precipitation is observed in spring and winter; while decreasing precipitation is identified in summer and autumn. The increasing/decreasing precipitation trend mostly occurred near the lower/upper parts of the Dongjiang River basin; (2) the spatial distribution of the precipitation anomaly between 1956–1989 and 1990–2002 is similar to that of precipitation trend; (3) in general, 4 time periods are identified: 1956–1961 and 1975–1985 are featured by increasing areal average annual precipitation; while 1962–1974 and 1986–2002 are characterized by decreasing areal average annual precipitation. The areal average annual maximum precipitation has a decreasing trend; (4) the precipitation changes in the Dongjiang River basin are mainly controlled by the south-east Asian monsoon activities. Intensity of the south-east Asian monsoon carrying excess moisture is the main driving factor for precipitation changes in this study. This result will be greatly helpful for further research on availability and management of the water resources in the Dongjiang River basin, the main focus of an on-going research project.

Impact of the 1960 major subduction earthquake in Northern Patagonia (Chile, Argentina)

December 2006

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378 Reads

The recent sedimentation processes in four contrasting lacustrine and marine basins of Northern Patagonia are documented by high-resolution seismic reflection profiling and short cores at selected sites in deep lacustrine basins. The regional correlation of the cores is provided by the combination of 137Cs dating in lakes Puyehue (Chile) and Frías (Argentina), and by the identification of Cordon Caulle 1921–22 and 1960 tephras in lakes Puyehue and Nahuel Huapi (Argentina) and in their catchment areas. This event stratigraphy allows correlation of the formation of striking sedimentary events in these basins with the consequences of the May–June 1960 earthquakes and the induced Cordon Caulle eruption along the Liquiñe-Ofqui Fault Zone (LOFZ) in the Andes. While this catastrophe induced a major hyperpycnal flood deposit of ca. 3×106 m3 in the proximal basin of Lago Puyehue, it only triggered an unusual organic rich layer in the proximal basin of Lago Frías, as well as destructive waves and a large sub-aqueous slide in the distal basin of Lago Nahuel Huapi. A very recent mega-turbidite in the two distal basins of Reloncavi fjord located close to the LOFZ suggests that 1960 co-seismic movements in this area may have triggered the remobilization of ca. 187×106 m3 of marine sediments.

Temperature and precipitation trends and dryness/wetness pattern in the Zhujiang River Basin, South China, 1961–2007

November 2011

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74 Reads

Spatial and temporal characteristics of temperature and precipitation in the Zhujiang River Basin, South China, are analysed in order to identify tendencies in dryness and wetness. Trend tests are applied to daily temperature and precipitation data from 1961 to 2007 of 192 weather stations. Nine indicators are applied in order to detect cycles of dryness and wetness and are compared with the drought indices Standardized Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI).Tendencies in temperature and precipitation characteristics can be observed. Significant positive trends (>90% confidence level) can be found for annual temperature, number of warm days, longest warm period, no rain days, and longest dry period. A significant increase in temperature by more than 0.7 K from 1961 to 2007 can be observed in the entire basin and the coastal and far western areas in particular. Negative trends are observed for annual cool days, cool period, wet days, and wet period. Almost no significant trends in annual mean and extreme precipitation are detected. Rain days decreased, and a tendency to longer dry periods and shorter wet periods can be observed.The magnitude of indices describing dryness has increased in the Zhujiang River Basin, and dry periods have become longer while wet periods have shortened in time. Rainfall intensity has increased along the coastline and in the far west of the catchment. This tendency can be partially explained by the weakening of the East Asian Summer Monsoon. Regarding the high temperature increases, the influences of the urban heat island effect due to urbanization and industrialization, especially along the coast and at the delta, should be considered. The high station density and data quality are very useful for describing detailed changes in wetness and dryness in the Zhujiang River basin.

Microfossil analysis of sediments representing the 1964 earthquake, exposed at Girdwood Flats, Alaska, USA

September 1999

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31 Reads

Diatom, pollen, foraminifera and thecamoebian assemblages from an outcrop of peat and silt at Girdwood Flats, in the upper Turnagain Arm of the Cook Inlet, Alaska, record four phases of relative land and sea-level changes. The first phase is the development of freshwater swamp above high marsh sediments during relative land uplift, caused by strain accumulation along the locked portion of the Alaska-Aleutian subduction zone. In second phase, the top 2 cm of the peat, all microfossil groups record pre-seismic relative sea-level rise (relative land subsidence). The third phase is rapid land subsidence, 1.7 m, during the earthquake of March 1964 that initiated intertidal silt accumulation above the peat. The final phase is the colonisation of mudflat by salt marsh communities during post-seismic land uplift. The microfossil data compare favourably with sequences from Washington, Oregon and British Columbia that record late Holocene submergence events caused by earthquakes. The comparable changes in microfossil assemblages record the different phases of relative land and sea-level changes and the magnitude of land subsidence caused by each earthquake (expressed relative to the tidal range at the site). These results raise the question whether preseismic sea-level rise represents any kind of warning of large earthquakes.

Phylogenetic relationships and biogeographic history of Paradolichopithecus sushkini Trofimov 1977, a large-bodied cercopithecine monkey from the Pliocene of Eurasia

March 2008

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146 Reads

Paradolichopithecus sushkini Trofimov 1977 is a cercopithecine monkey discovered from the late Pliocene of Kuruksay, southern Tajikistan. Despite the baboon-like appearance of the skull, detailed analysis of the inner structure of the rostrum with computed tomography revealed that P. sushkini has a maxillary sinus, which occurs only in macaques among the living cercopithecoids. This observation suggests that Paradolichopithecus may belong to the lineage of the macaques rather than to that of the baboons. This fact and the fossil records of Eurasian cercopithecines together suggest that Paradolichopithecus diverged from European Macaca as early as the early Pliocene, and then dispersed into eastern Eurasia. Although the dispersal route of the Asian cercopithecines, Macaca, has so far been discussed only in the context of South Asian geographical changes, the distribution pattern of the Paradolichopithecus fossil localities may indicate a more northern dispersal route, such as via Central Eurasia rather than a southern route, such as via South Asia.

Understanding of anomalous Indian Summer Monsoon rainfall of 2002 and 1994

February 2010

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75 Reads

This study focuses on understanding of the deficient rainfall of 2002 and excess rainfall of 1994 of the Indian Summer Monsoon and its association with large-scale circulation features. Outgoing longwave radiation (OLR) and 200 hPa flow regimes have been compared during a deficient year (2002) with those during an excess rain year (1994) for the northern summer months. The main emphasis is on the month of July (2002) when rainfall was the lowest during the past 100 years. Positive OLR anomalies of substantial magnitude are prominent over large parts of the Indian Ocean, Arabian Sea, most parts of India. Negative OLR anomalies prevailed over the north Pacific in July 2002. These positive OLR anomalies during the deficient Summer Monsoon of 2002 indicate very weak convection over the Indian subcontinent. The opposite patterns of OLR anomalies are found in the excess rain monsoon of 1994. Examination of upper tropospheric (200 hPa) circulation fields indicates significant changes in velocity potential, stream function, and geopotential height anomalies during 2002 and 1994. The field of geopotential height anomalies shows cyclonic (anticyclonic) anomalous circulation developed over the Caspian Sea near central Asia during 2002 (1994) rain years. The upper level stream function anomalies show weak (strong) upper level high in 2002 (1994) over large parts of India and surrounding areas in July.

Micromammals from the 1995 Mammoth Excavation at West Runton, Norfolk, UK: Morphometric data, biostratigraphy and taxonomic reappraisal

December 2010

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83 Reads

In this paper, the small mammals recovered from sediments associated with the West Runton Elephant have been analysed and compared with sites in other parts of Europe. Major taxonomical problems are indicated and we suggest ways of utilising such morphological complexity to refine biostratigraphical and chronostratigraphic attributions.The micromammal assemblage from the West Runton Elephant Site so far totals 16 species from the West Runton Freshwater Bed (WRFB). There are strong similarities with the arvicolid spectrum of basal layer H8 in the Koněprusy C 718 profile (Czech Republic), which accumulated under cooler conditions preceding the thermal maximum of an early Middle Pleistocene interglacial. Rare steppic indicators (e.g. Cricetus) at West Runton also imply a somewhat cooler and more continental climate than the present day, but overall the fauna is fully temperate in character. West Runton shares several stratigraphically significant small mammal taxa with Voigtstedt (Central Germany) and morphometric comparisons suggest that Voigtstedt may be slightly younger than West Runton. The presence of Mimomys savini, with a latest occurrence in the early part of Marine Isotope Stage (MIS) 15, together with the palaeomagnetic evidence suggests the WRFB may have been emplaced during the early part of MIS 17. However, given the complexity of the marine isotope curve during the early part of the Brunhes Chron and differences between global and regional climatic evolution, it is difficult to assign the normally magnetised WRFB to a particular Marine Isotope Stage (MIS).

Fig. 1. The sites mentioned in the text. 1 – Antrea (Kamennogorsk); 2 – Johannes (Sovetskiy); 3 – Kaukola (Sevast’yanovo); 4 – Koivisto (Primorsk); 5 – Kuolemaja  ̈rvi (Aleksandrovskoe); 6 – Kurkijoki; 7 – Muolaa (Pravdino); 8 – Pyha  ̈ja  ̈rvi (Plodovoe); 9 – Ra  ̈isa  ̈ la  ̈ (Mel’nikovo); 10 – Sakkola (Gromovo); 11 – Salmi; 12 – Sortavala; 13 – Sa  ̈kkija  ̈rvi (Kondrat’evo); 14 – Uusikirkko (Polyany); 15 – Viipuri (Vyborg); 16 – Vuoksenranta (Ozerskoe); 17 – V  ̈ rtsila  ̈ (Vyartsilya). 
Fig. 2. Excavation at Rä isälä Juoksemajä rvi Westend in June 2002 (photo: K. Nordqvist).
Waterways and the stone age and early metal period studies on the Karelian Isthmus – The pre-World War II studies and research carried out by the University of Helsinki in 1998–2006

July 2009

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342 Reads

The Karelian Isthmus has played a central role in understanding Finnish Stone Age and Early Metal Period. This is because of its topographic position with waterways which are connecting several large water basins – the Gulf of Finland, Lake Ladoga and Lake Saimaa. During the Stone Age and Early Metal Period several changes have taken place in the water connections and elevations of all the basins which have influenced the topographic setting of dwelling sites. The Karelian Isthmus has also been the route for people to reach each other in the large areas in the west and east.A central objective of the paper is to elucidate the long research history of the Isthmus particularly in the light of Finnish archaeology. Until the end of the World War II the area belonged to the most important research areas for Finnish archaeologists. After the long period of silence, the fieldwork has quickly increased during the 1990s and particularly in the Early 2000s. For these reasons also this latest period of research will be discussed. The position of sites in the neighbourhood of waterways is discussed, although it is not possible to do detailed examinations of their position.

Street, M. 1998: The archaeology of the Pleistocene-Holocene transition in the Northern Rhineland, Germany. Quaternary International 49-50 (1-4) (1998), 45-67 (B. V. Eriksen & L. G. Straus eds.), As the World Warmed: Human Adaptations across the Pleistocene / Holocene Boundary.

July 1998

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38 Reads

Northern Rhineland archaeological sites provide information on patterns of subsistence and settlement during the late-Pleistocene Magdalenian and Final Palaeolithic and the early-Holocene Mesolithic periods and allow a good resolution of their relative and absolute chronology. The Magdalenian is represented by two major sites in the Central Rhineland (Gönnersdorf and Andernach-Martinsberg). Exogenous lithic raw materials show intensive contact to the northwestern Meuse–Rhine drainage area. This phase of settlement existed in the context of a ‘loess-steppe’ or ‘mammoth-steppe’ and absolute dates show that this was before the late glacial interstadial climatic amelioration. Subsistence was based on the hunting of large herd animals. The Magdalenian is succeeded by lithic assemblages of the Federmessergruppen characterised by short scrapers and backed points. Raw materials suggest that the Central Rhineland population had a radius of mobility approaching that found in the Magdalenian. Sites are particularly well preserved in the Neuwied Basin, due to burial by pumice deposits of the Laacher See eruption, and show that the Allerød population inhabited a mosaic landscape of open woodland and hunted a range of ‘temperate’ species. Evidence for differing site structuration, the exploitation of a diverse fauna and seasonality suggest that Federmessergruppen settlement patterns were possibly as complex as those proposed for the Magdalenian. During the Dryas III stadial the northern Rhineland was occupied or visited by Ahrensburgian tanged-point groups. It has been suggested that exploitation of the northern fringe of the Upland Zone formed an integral part of the subsistence strategy of the Ahrensburgian population involving the spring hunting of reindeer migrating to the uplands. Whereas the Holocene Mesolithic in the northern part of the region probably developed out of the Ahrensburgian tradition, it seems that the Mesolithic to the South developed from Federmessergruppen industries present throughout Dryas III. A small number of Rhineland sites provides evidence for Mesolithic subsistence activities or site organisation.

Impact of extreme rainfall in the central Sudan during 1999 as a partial analogue for reconstructing early Holocene prehistoric environments

June 2006

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51 Reads

The year 1999 was an exceptionally wet year, with severe floods in China, India and Australia and very high flow in the Nile. In Sudan, the July rainfall was unusually early and heavy, and persistent rains throughout August and early September caused severe floods in much of central Sudan, including Khartoum.The synoptic conditions historically associated with extreme rainfall events in central Sudan include a warm equatorial Indian Ocean, a strong summer monsoon over both Africa and India, a northward shift of the Inter-tropical Convergence Zone earlier and further north than usual, and the presence of deep, well-developed westerly air masses accompanied by a strong Tropical Easterly Jet that allowed more moisture transport into Africa from the South Atlantic via the Congo basin, leading to very heavy precipitation in the Ethiopian uplands and the central Sudan.The intense late wet season rains in 1999 caused a major canal in the Gezira Irrigation Area to break its banks and filled normally dry depressions between dunes with water, providing a partial analogue of early Holocene environments in this region when small groups of Later Stone Age peoples occupied the sandy ridges seasonally. Global Circulation Models cannot provide such detailed local information.

Reconstruction of the 2.4 million km2 late Pleistocene Ice Sheet on the Tibetan Plateau and its impact on the global climate

December 1998

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34 Reads

During 20 expeditions new data were obtained on the maximum extent of glaciation in Tibet and the surrounding mountains. Evidence was found of moraines at altitudes as low as 460 m on the southern flank of the Himalayas and 2300 m on the northern slope of the Tibetan Plateau, in the Qilian Shan. On the northern slopes of the Karakorum, Aghil and Kuen Lun, moraines occurred as far down as 1900 m. In southern Tibet radiographic analyses of erratics document former ice thicknesses of at least 1200 m. Glacial polishing and knobs in the Himalayas and Karakorum are proof of glaciers as thick as 1200–2000 m. On the basis of this evidence, a 1100–1600 m lower equilibrium (ELA) line was reconstructed for the Ice Age, which would mean 2–2.4 million km2 of ice covering almost all of Tibet, since the equilibrium (ELA) line was far below the average altitude of Tibet.On Mount Everest and K2, radiation was measured up to 6650 m, yielding values of 1200–1300 W/m2. Because of the subtropical latitude and the high altitude solar radiation in Tibet is 3–4 times greater than the energy intercepted between 60 and 70°N or S.With an area of 2–2.4 million km2 and an albedo of 90%, the Tibetan ice sheet caused the same heat loss on the earth as a 6–9.6 million km2 sized ice sheet at 60–70°N. Because of its proximity to the present-day equilibrium (ELA) line Tibet must have undergone large-scale glaciation earlier than other areas. Being subject to intensive radiation, the Tibetan ice must have performed an amplifying function during the onset of the Ice Age.

Gobi dynamics in the Northern Mongolian Plateau during the past 20,000 + yr: Preliminary results

February 2001

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37 Reads

This study focuses on the Khyaraany sand/loess/soil section (50.2°N 106.7°E) in the Northern Mongolian Plateau with the aim of deciphering the paleoenvironmental records and inferring the last glacial Gobi dynamics. The main findings are as follows: (1) silt percentage (with a negligible clay percentage) is positively correlated with the organic matter content. (2) The silt (%) and frequency-dependent magnetic susceptibility (%) are negatively correlated. (3) The magnetic susceptibility is positively related to sand percentage and negatively to silt percentage. Based on 14C dates and the extrapolated ages, the following observations can be made. (1) Unlike the Marine Isotope Stage (MIS) 3 paleosols (24,500, 28,900, 30,700, 34,400 yr BP) that formed under oxidizing-dominated conditions, two MIS 2 paleosols (15,090, 13,030 yr BP) and two Holocene paleosols (8300, 4070 yr BP) were formed under dominantly reducing conditions. (2) Less windy and/or better vegetation conditions generally dominated the later part of the last glacial (15,090–8300 yr BP), during which three paleosols (incipient histosols) were formed (15,090, 13,030, 8300 yr BP). (3) Windy and/or poor-vegetation conditions generally dominated the early part of the last glacial (∼24,000–16,000 yr BP). (4) This section documents approximately thousand-year-long redox cycles. Two tentative conclusions can be drawn from this and previous (Feng et al., 1998) studies. (1) The northern boundary of the Gobi has shrunk as many as nine times during the past 40,000 yr: around 34,400, 30,700, 28,900, 24,500, 15,090, 13,030, 8300, 4070 yr BP and the recent 2000+ yr. (2) Based on the negative correlation of the susceptibility with silt percentage and organic matter content, it is proposed that the reducing conditions of incipient histosol formations have contributed to the alteration of magnetic minerals from strong forms of oxidized iron to weak forms. Therefore, the magnetic susceptibility is basically an indicator of redox cycles.

TABLE 2 . Calibrated radiocarbon dates of selected archaeological sites: mid-point in parenthesis
TABLE 3 . Climatic summary refined by calibrated radiocarbon dates
Archaeological evidence for climatic change during the last 2000 years in southern Africa

December 1996

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1,222 Reads

Shifting distributions of Iron Age villages in central and southern Africa provide independent cultural evidence for climatic change over the last 2000 years. A warm and wet period characterized the main spread of the Early Iron Age. Another wet period from about AD 900 to 1290—the Medieval Warm Epoch—permitted the build-up of large populations at K2 and Mapungubwe. The abandonment of Mapungubwe and simultaneous rise of Great Zimbabwe coincided with the beginning of the dry Little Ice Age, while a warm pulse in the 15th and 16th centuries created the conditions for mixed farming on the highveld. Another warm and wet period at the end of the 18th century contributed to the spread of maize, increased populations and military stress of the difaqane.

Moisture changes and fluctuations of the Westerlies in Mediterranean Central Chile during the last 2000 years: The Laguna Aculeo record (33°50′S)

January 2002

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250 Reads

The multi-proxy study of lacustrine sediments from Laguna Aculeo (33°50′S) provides detailed information about moisture changes in the lowlands of Mediterranean Central Chile during the last 2000 years. The lake lies just at the northern border of the strong Westerlies influence with dry summers and humid winters. Geochemical, sedimentological and diatom analyses provide evidence for an arid period between cal 200 BC and AD 200 and a subsequent increase in moisture after cal AD 200. Abundant clastic layers in the core represent flood events. Periods with a higher frequency of flood events indicate an increased intensity of the Westerlies, more winter frontal system activity and possibly ENSO-related variability, probably comparable to modern conditions in Mediterranean Central Chile. Periods of high clastic input occur around cal AD 200–400, 500–700, especially around cal AD 1300–1700, and around AD 1850–1998. During the last 50 years, at least eight flood events were detected, correlating mainly with El Niño years. A very short drier period also occurred in the late 1960s. In recent decades, human impact has resulted in a eutrophication of the lake.

Climate change over the past 2000 years in Western China

February 2009

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289 Reads

Western China, defined here as the land falling within the geographical boundaries of the People's Republic of China in the west, south and north, and the approximate eastern extent of the Tibetan and Alaxa Plateaux to the east, occupies an important climatic region, influenced by the Asian and Indian summer monsoons, the mid-latitude westerlies and the dry, cold central Asian winter monsoon. The Tibetan Plateau itself is a prominent topographic feature that exerts major control on regional atmospheric circulation. Previous compilations of meteorological data and documentary sources suggest that western China, and the Tibetan Plateau in particular, is highly sensitive to anthropogenically induced climate change. Temperature increases appear to be greatest at higher altitudes: moreover, precipitation variations seem to have been marked, although spatially complex. The region contains a wealth of information about past climate derived from instrumental, documentary and proxy sources although meteorological time series are generally too short to capture the full range of recent climatic variability. Documentary and proxy sources are therefore important. We review studies of climate change in western China for the past two millennia. Documentary records are complemented by proxy data from ice cores, tree rings, lake sediments, groundwater profiles and glacial geomorphology. Although general patterns of change can be identified, proxy records of past climate are often semi-quantitative at best, open to alternative interpretations and sometimes poorly dated. Despite evidence for marked variations in climate over the past 2000 years, changes during the 20th century, especially in temperature, may have been unprecedented. The density of data points over western China is currently too low for spatial patterns to be identified, especially in precipitation variation. However, there does seem to have been an increase in warming with altitude over the most recent past.

Palynology of hyrax middens: 2000 years of palaeoenvironmental history in Namibia

December 1996

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97 Reads

Well-preserved and dateable faunal middens in rock shelters of dry areas in southern Africa occur as desiccated urine-rich masses. Under local conditions, which exclude microbial decomposition and oxidation, urine cements together faecal pellets and other inclusions. Nine radiocarbon dated hyrax (Procavia capensis) dung middens from the Kuiseb River Basin of the Namib Desert were sub-sampled and analysed for fossil pollen. Some contain small proportions of rat droppings, but not many macro-fossils. Comparative modern pollen in faecal samples were also studied. Most plant macro-fossils are severely digested, but seeds are well-preserved. Some insect inclusions were identified. Small scale changes in vegetation over the last two millennia were observed, representing environmental fluctuations in cycles of ca. 100–200 years. The fluctuations partly agree with other palynological data from southern Africa and with geomorphologic evidence for environmental changes in the desert region.

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