The OSL chronology of eolian sand deposition in a perched dune field along the northwestern shore of Lower Michigan

Extensive coastal dunes occur in the Great Lakes region of North America, including northwestern Michigan where some are perched on high (~ 100 m) bluffs. This study focuses on such a system at Arcadia Dunes and is the first to systematically generate optical ages from stratigraphic sections containing buried soils. Dune growth began ca. 4.5 ka during the Nipissing high lake stand and continued episodically thereafter, with periods of increased sand supply at ca. 3.5 ka and ca. 1.7 ka. The most volumetrically dominant phase of dune growth began ca. 1.0 ka and continued intermittently for about 500 years. It may have begun due to the combined effects of a high lake phase, potential changes in lake hydrodynamics with final isostatic separation of Lake Superior from Lakes Michigan and Huron, and increased drought and hydrologic variability associated with the Medieval Warm Period. Thus, this latest eolian phase likely reflects multiple processes associated with Great Lakes water level and climate variability that may also explain older eolian depositional events. Comparison of Arcadia ages and calendar corrected ¹⁴C ages from previous studies indicate broad chronological agreement between events at all sites, although it appears that dune growth began later at Arcadia.     

Late Quaternary linear dune accumulation and chronostratigraphy of the southwestern Kalahari: implications for aeolian palaeoclimatic reconstructions and predictions of future dynamics

The linear dunes of the Kalahari, now largely inactive, have long been identified as having potential palaeoenvironmental significance. The application of optically stimulated luminescence (OSL) dating to these dunes in the 1990s provided the first chronology of aeolian accumulation in this region, though field methodologies and time-consuming multiple-aliquot laboratory protocols limited both the depth of sampling in dune bodies and the total number of samples dated.In order to permit a more thorough investigation of the potential of these dunes to preserve long chronological records, this intensive study presents 71 OSL ages from the linear dunes of the southwestern Kalahari at Witpan, South Africa, sampled with coring equipment at regular and frequent intervals down to bedrock.The earliest sand accumulation recorded at Witpan is at 104 ka, and in spatially discrete locations, other evidence of dune activity is recorded at 77–76, 57–52 and 35–27 ka. Although an inherently discontinuous archive, the linear dunes of the southwestern Kalahari have the potential to record multiple phases of dune construction. Following the Last Glacial Maximum there is near continuous evidence of dune-building, with a peak of accumulation recorded from 15 to 9 ka at five individual sites. This latter period is generally recognised from other proxy evidence as being unusually arid in this region, and such periods of dune activity are likely to be related to intensification of the continental anticyclone. During the Holocene, accumulation has continued at most sites sampled, albeit at a lesser intensity. This may imply that these dunes are presently not far from thresholds of activation.     

Landscape evolution of the Ulan Buh Desert in northern China during the late Quaternary

The evolution of arid environments in northern China was a major environmental change during the Quaternary. Here we present the dating and environmental proxy results from a 35 m long core (A-WL10ZK-1) collected from the Ulan Buh Desert (UBD), along with supplemental data from four other cores. The UBD is one of the main desert dune fields in China and our results indicate the UBD has undergone complex evolution during the late Quaternary. Most of the present UBD was covered by a Jilantai-Hetao Mega-paleolake lasting until ~ 90 ka ago. A sandy desert environment prevailed throughout the UBD during the last glacial period and early Holocene. A wetland environment characterized by the formation of numerous interdunal ponds in the northern UBD occurred at ~ 8–7 ka, although a dune field persisted in the southern UBD. The modern UBD landscape formed after these wetlands dried up. During the last 2000 years, eolian sand from the Badain Jaran Desert has invaded the northern UBD, while farming and overgrazing resulted in the formation of the eastern UBD. We suggest that the formation of UBD landforms is related to the disintegration of the megalake Jilantai-Hetao and to summer monsoon changes during the last glaciation and Holocene.     

The onset of dune formation in the Strzelecki Desert,South Australia

This study is concerned with the Late Quaternary climatic chronology of the Strzelecki Desert dunefields in central Australia. The sand ridges comprise layers of quartz sand, some of which include palaeosol horizons with carbonated rootlets providing excellent opportunity for dating of alternations of dune building and stability by using optically stimulated luminescence (OSL). Deduced from the OSL age of the oldest aeolian layer dated, we conclude that the onset of aridity dates back to at least ∼65 ka. Older phases of aeolian activity though, following a fluvial depositional phase 160 ka ago, cannot be excluded, although no aeolian layers giving evidence for this have been found in the two dunes dated here. Unconsolidated dune sands in the upper part of one section with Late Holocene (4 ka to modern) depositional ages indicate a reactivation of the dunefield in recent times.From the crosscheck of ¹⁴C ages of the carbonated rootlets with OSL results it is concluded that under the given environmental conditions radiocarbon dating of the calcareous rootlets is not able to provide reliable ages for the phase of soil development.     

Chronology of the impact of Quaternary climate change on continental environments in the Arabian Peninsula

The remains of former lakes show that in the past the Arabian Peninsula experienced much wetter conditions than today. The last of these humid periods dates to about 10 to 5.5 ka ago. The chronological framework for an earlier humid phase, radiocarbon dated to some 35–20 ka, is inconsistent with evidence from other records from the region. Possibly, these ages are significantly underestimating the true depositional age due to methodological problems. The earliest phase of dune accumulation known so far is dated to the penultimate glaciation maximum of the mid latitudes (ca. 150 ka). Subsequently, dune accumulation occurred around 110 ka, 65 ka and 20 ka ago. All these phases concur with rapid drops in global sea level that caused a drying out of the Persian Gulf basin and of the shelf of the Oman coast. In contrast to some previous interpretations, it is concluded here that aeolian deposition has been limited by sediment supply and not by preservation potential.     

Evidence for prolonged El Nino-like conditions in the Pacific during the Late Pleistocene: a 43 ka noble gas record from California groundwaters

Information on the ocean/atmosphere state over the period spanning the Last Glacial Maximum – from the Late Pleistocene to the Holocene – provides crucial constraints on the relationship between orbital forcing and global climate change. The Pacific Ocean is particularly important in this respect because of its dominant role in exporting heat and moisture from the tropics to higher latitudes. Through targeting groundwaters in the Mojave Desert, California, we show that noble gas derived temperatures in California averaged 4.2 ± 1.1 °C cooler in the Late Pleistocene (from ～43 to ～12 ka) compared to the Holocene (from ～10 to ～5 ka). Furthermore, the older groundwaters contain higher concentrations of excess air (entrained air bubbles) and have elevated oxygen-18/oxygen-16 ratios (δ¹⁸O) – indicators of vigorous aquifer recharge, and greater rainfall amounts and/or more intense precipitation events, respectively. Together, these paleoclimate indicators reveal that cooler and wetter conditions prevailed in the Mojave Desert from ～43 to ～12 ka. We suggest that during the Late Pleistocene, the Pacific ocean/atmosphere state was similar to present-day El Nino-like patterns, and was characterized by prolonged periods of weak trade winds, weak upwelling along the eastern Pacific margin, and increased precipitation in the southwestern U.S.     

A luminescence dating study of the sediment stratigraphy of the Lajia Ruins in the upper Yellow River valley,China

Pedo-sedimentological fieldwork were carried out in the Lajia Ruins within the Guanting Basin along the upper Yellow River valley. In the eolian loess-soil sections on the second river terrace in the Lajia Ruins, we find that the land of the Qijia Culture (4.20–3.95 ka BP) are fractured by several sets of earthquake fissures. A conglomerated red clay covers the ground of the Qijia Culture and also fills in the earthquake fissures. The clay was deposited by enormous mudflows in association with catastrophic earthquakes and rainstorms. The aim of this study is to provide a luminescence chronology of the sediment stratigraphy of the Lajia Ruins. Eight samples were taken from an eolian loess-soil section (Xialajia section) in the ruins for optically stimulated luminescence (OSL) dating. The OSL ages are in stratigraphic order and range from (31.94 ± 1.99) ka to (0.76 ± 0.02) ka. Combined OSL and ¹⁴C ages with additional stratigraphic correlations, a chronological framework is established. We conclude that: (1) the second terrace of the upper part of Yellow River formed 35.00 ka ago, which was followed by the accumulation of the eolian loess-soil section; and (2) the eolian loess-soil section is composed of the Malan Loess of the late last glacial (MIS-2) and Holocene loess-soil sequences.     

Luminescence dating of fluvial and coastal red sediments in the SE coast,India, and implications for paleoenvironmental changes and dune reddening

The Holocene and late Pleistocene environmental history of the teri (‘sandy waste’ in local parlance) red sands in the southeast coastal Tamil Nadu was examined using remote sensing, stratigraphy, and optically stimulated luminescence (OSL) dating. Geomorphological surveys enabled the classification of the teri red sands as, 1) inland fluvial teri, 2) coastal teri and, 3) near-coastal teri dunes. The inland teri sediments have higher clay and silty-sand component than the coastal and near-coastal teri, suggesting that these sediments were deposited by the fluvial process during a stronger winter monsoon around > 15 ka. The coastal teri dunes were deposited prior to 11.4 ± 0.9 ka, and the near-coastal dunes aggraded at around 5.6 ± 0.4 ka. We interpret that the coastal dunes were formed during a period of lower relative sea level and the near-coastal dunes formed during a period of higher sea level. Dune reddening is post deposition occurred after 11.4 ± 0.9 ka for the coastal teri dunes and after 5.6 ± 0.4 ka for the near-coastal teri dunes. Presence of microlithic sites associated with the coastal dunes suggest that the cultures existed in the region during 11.4 ± 0.9 ka and 5.6 ± 0.4 ka.     

Chronologies for Late Quaternary barchan dune reactivation in the southeastern Arabian Peninsula

The Liwa region of the United Arab Emirates contains some of the largest and most areally extensive megabarchanoid sand dunes on a global scale. Here we present optical dating results on samples of aeolian sediment from deep drill cores extracted from the largest dune field of the Liwa area. Optical dating of these core sediments using the single aliquot regeneration protocol indicates Mid–Late Holocene phases of rapid dune deposition, the most recent period of reactivation began at ca 2.8 ka. This event was preceded by a period of deposition at ca 5 ka. These results suggest that the dune systems of the southeastern Arabian Peninsula are closely linked to changes in Late Quaternary global climate, particularly linked to the intensity and spatial extent of palaeomonsoon rainfall. Since the last precessional maxima at ca 9 ka, at which time a peak in monsoonal rainfall has been recognised, a significant environmental transition to widespread desert conditions occurred in an apparently abrupt fashion. During the initial period of aridification, large quantities of sand were transported and deposited in the form of large and very large (up to 160 m high) scale aeolian bedforms. Following the initial phase of aeolian accumulation, the system appears to have remained in stasis.     

The timing of linear dune activity in the Strzelecki and Tirari Deserts,Australia

Linear dunes occupy more than one-third of the Australian continent, but the timing of their formation is poorly understood. In this study, we collected 82 samples from 26 sites across the Strzelecki and Tirari Deserts in the driest part of central Australia to provide an optically stimulated luminescence chronology for these dunefields. The dunes preserve up to four stratigraphic horizons, bounded by palaeosols, which represent evidence for multiple periods of reactivation punctuated by episodes of increased environmental stability. Dune activity took place in episodes around 73–66, 35–32, 22–18 and 14–10 ka. Intermittent partial mobilisation persisted at other times throughout the last 75 ka and dune activity appears to have intensified during the late Holocene. Dune construction occurred when sediment was available for aeolian transport; in the Strzelecki and Tirari Deserts, this coincided with cold, arid conditions during Marine Isotope Stage (MIS) 4, late MIS 3 and MIS 2, and the warm, dry climates of the late Pleistocene–Holocene transition period and late Holocene. Localised influxes of sediment on active floodplains and lake floors during the relatively more humid periods of MIS 5 also resulted in dune formation. The timing of widespread dune reactivation coincided with glaciation in southeastern Australia, along with cooler temperatures in the adjacent oceans and Antarctica.     

Aeolian–fluvial interaction and climate change: source-bordering dune development over the past ∼100 ka on Cooper Creek,central Australia

This study provides an interpretation of interrelated Quaternary fluvial and aeolian activity related to climate change on Cooper Creek in the Lake Eyre Basin in southwestern Queensland, central Australia. The extensive muddy floodplain is characterised by buried sandy palaeochannels now almost entirely invisible but stratigraphically connected to source-bordering dunes that emerge as distinctive sandy islands through the floodplain surface. Luminescence dating has identified pronounced periods of fluvial activity represented by abundant sandy alluvium from Marine Isotope Stages (MIS) 8–3. While all these sandy fluvial episodes on Cooper Creek were much more powerful than anything subsequent, they appear to be ranked in order of declining activity. MIS 8–6 saw reworking of almost the entire floodplain whereas subsequent phases of reworking were far less extensive. Source-bordering dunes were derived from active sandy channels in late MIS 5 (∼85–80 ka) and mid MIS 3 (50–40 ka). After ∼40 ka sand-channel activity largely ceased and the floodplains and channels were inundated with mud, isolating the dunes as emergent features. Although aeolian reworking of the upper parts of some dunes has continued to the present, they show remarkable resilience, having survived without appreciable migration for at least 40 ka. Whilst the channels once determined the location of source-bordering dunes, in an interesting role reversal the remnant dunes now determine the position of many contemporary flood-channels and waterholes by deflection and confinement of overbank flows.     

OSL chronology and possible forcing mechanisms of dune evolution in the Horqin dunefield in northern China since the Last Glacial Maximum

The evolution processes and forcing mechanisms of the Horqin dunefield in northern China are poorly understood. In this study, systematic OSL dating of multiple sites is used together with pollen analysis of a representative section in order to reconstruct the evolution of the dunefield since the Last Glacial Maximum (LGM). Our results show that there was extensive dune mobilization 25–10 ka, transition to stabilization 10–8 ka, considerable dune stabilization 8–3 ka, and multiple episodes of stabilization and mobilization after 3 ka. Comparison of dune evolution of the dunefields in northern China during the Holocene showed that Asian monsoon and resultant effective moisture have played an important role in the evolution of dunefields at the millennial time scale. Further analysis indicated that the dune evolution in the Horqin dunefield before 3 ka was synchronous with climatic changes. However, increasing human activity has impacted dune evolution during the last 3 ka.     

The evolution of coastal barrier systems: a case study of the Middle-Late Pleistocene Wilderness barriers,South Africa

Barrier systems contain lengthy, but complex, records of long-term environmental fluctuations. The Wilderness embayment, South Africa, contains a system of shore-parallel barriers reaching up to 200 m above modern sea level. This study reports the results of chronological, topographical (both on- and off-shore), sedimentological and micromorphological analyses within the Wilderness embayment. Sixty-one new luminescence ages from sixteen sites in unconsolidated dunes and three separate barriers are presented which, when combined with previously published luminescence ages from the area, provide a high-resolution chronological framework for the emplacement and evolution of the barrier system. The preserved barriers have been constructed within at least the last two glacial–interglacial cycles with notable phases between 241–221 ka, 159–143 ka, 130–120 ka, 92–87 ka and post 6 ka. Multiple phases of barrier construction occurred during sea-level highstands, with sediment deposition on each individual barrier occurring over at least two interglacials. Holocene evolution of the system sheds light on earlier events, with dune preservation occurring only during early regression from the Mid-Holocene highstand. Tectonic stability at Wilderness allowed glacio-eustatically formed shorelines to occupy similar positions on multiple occasions. This, in conjunction with a relatively humid climate and a well-vegetated landscape, enabled deflated sediment from beaches to form dunes which stacked upon each other to form an extensive and complex vertical accretionary sequence. Repeated erosion and recycling of pre-existing barriers as well as barrier construction on what is currently the off-shore platform during still-stands in sea-level regressional cycles, when sea levels dropped below ca ?50 m from the present day, has added to the complexity of the preserved terrestrial barrier record. The Wilderness barrier system contrasts with barriers developed elsewhere in the world where higher rates of crustal uplift have allowed preservation of a more complete and more widely spaced palaeorecord. This research also shows the utility of integrating off-shore topography as revealed by bathymetry, with terrestrial topographic data for the better understanding of the evolution of palaeo-coastlines and the preserved dune record found on present-day coastal plains. Local variation in the topography of the continental shelf at Wilderness has generated spatial and temporal complexity within the sedimentary records of individual barriers as well as having a significant influence on preservation.     

Postglacial climates inferred from a lake at treeline,southwest Yukon Territory,Canada

Pollen, chironomid, and ostracode records from a lake located at alpine treeline provide regional paleoclimate reconstructions from the southwest Yukon Territory, Canada. The pollen spectra indicate herbaceous tundra existed on the landscape from 13.6–11 ka followed by birch shrub tundra until 10 ka. Although Picea pollen dominated the assemblages after 10 ka, low pollen accumulation rates and Picea percentages indicate minimal treeline movement through the Holocene. Chironomid accumulation rates provide evidence of millennial-scale climate variability, and the chironomid community responded to rapid climate changes. Ostracodes were found in the late glacial and early Holocene, but disappeared due to chemical changes of the lake associated with changes in vegetation on the landscape. Inferred mean July air temperature, total annual precipitation, and water depth indicate a long-term cooling with increasing moisture from the late glacial through the Holocene. During the Younger Dryas (12.9–11.2 ka), cold and dry conditions prevailed. The early and mid-Holocene were warm and dry, with cool, wet conditions after 4 ka, and warm, dry conditions since the end of the Little Ice Age.     

The morphodynamics and internal structure of intertidal fine-gravel dunes: Hills Flats,Severn Estuary,UK

In the macrotidal Severn estuary, UK, the dynamics of intertidal fine-gravel dunes were investigated. These dunes are migrating across a bedrock platform. Systematic observations were made of hydraulic climate, geometry, migration rates and internal sedimentary structures of the dunes. During spring tides, the ebb flow is dominant, dunes grow in height and have ebb orientated geometry with bedrock floors in the troughs. During neap tides, a weak flood flow may dominate. Dunes then are flood orientated or symmetrical. Neap dune heights decrease and the eroded sediment is stored in the dune troughs where the bedrock becomes blanketed by muddy gravel. During spring tides, instantaneous bed shear stresses reach 8 N m^− 2, sufficient to disrupt a 9 mm-gravel armour layer. However, a sustained bed shear stress of 4 N m^− 2 is required to initiate dune migration at which time the critical depth-mean velocity is 1 m s^− 1. Ebb and flood inequalities in the bed shear stress explain the changes in dune asymmetry and internal structures. During flood tides, the crests of the dunes reverse such that very mobile sedimentary ‘caps’ overlie a more stable dune ‘core’. Because ebb tides dominate, internal structures of the caps often are characterised by ebb orientated steep open-work foresets developed by strong tidal currents and some lower angle crossbeds deposited as weaker currents degrade foresets. The foresets forming the caps may be grouped into cosets (tidal bundles) and are separated from mud-infused cores of crossbeds that lie below, by reactivation and erosion surfaces blanketed by discontinuous mud drapes. The cores often exhibit distinctive muddy toe sets that define the spacing of tidal cosets.     

Geochemical signatures of Late Holocene paleo-hydrological changes from Phulera and Pokharan saline playas near the eastern and western margins of the Thar Desert,India

Stratigraphical, mineralogical, geochemical and optical dating methods were used to reconstruct paleo-hydrological changes in two playas (Phulera, 500 mm/a and Pokharan, 200 mm/a) in near extremum climatic regions of the Thar Desert. Sediment successions in shallow profiles from Phulera and Pokharan contain three and four stratigraphic units, respectively, each with characteristic geochemical properties. These units reflect changes in chemical weathering, detrital input, salinity and provide a measure of the changes in precipitation (i.e. monsoon) through time.Sediments from Pokharan suggest short rainfall events during ca. 6.6–4 ka, relatively stable fresh water (higher and persistent rainfall) regime during 4–2.3 ka, and a hyper saline (low rainfall) condition during 2.3–1.1 ka. Sediments at Phulera, record hyper saline (low rainfall) lacustrine conditions during <2.3 ka to >1.4 ka. Higher abundance of gypsum in Pokharan (2.3–1.1 ka) and proto-dolomite in Phulera (2.3–1.4 ka) are nearly synchronous and reflect enhancement of salinity. Selenite crystals in Pokharan and large desiccation cracks in buried horizons at Phulera reflect desiccation of playas at ca. 2 ka. Both playas progressively became less saline after 1.4 ka. Given the regional nature of this record, these changes are attributed to fluctuation of the monsoon over the Indian sub continent.     

Last Glacial Maximum dune activity in the Kalahari Desert of southern Africa: observations and simulations

It has long been understood that as ephemeral landscape features sand dunes are highly sensitive to environmental change, and thus their distribution and the timing of their development may provide clues to past climate dynamics. The relationship between climate and dune activity, however, is neither simple nor straightforward, with a range of controls affecting the balance between erodibility (the availability of sediment for deflation) and erosivity (the potential for sediment transport). To explore such complex systems over large spatial and temporal scales, a number of dune activity indices (DAI) have been created that incorporate wind speed and moisture balances to calculate the potential for, and degree of dune mobilisation. Using modern weather station data, these indices have generally been shown to provide reasonable indications of dune activity potential. Until recently, however, the detailed quantitative data required to inform these equations has not been available for past climate scenarios, and attempts to determine the relative importance of the various controls of dune activity have relied on rough estimations of climatic parameters. This paper combines data from monthly general circulation model (GCM) outputs from the coupled Ocean-Atmosphere GCMs for 21 ka with the most detailed DAI equation presently available to calculate the potential for dune reactivation in southern Africa during the Last Glacial Maximum (LGM, 18–24 ka). Based on these data and calculations it is indicated that there was significantly less potential for dune activity across southern Africa at 21 ka. When compared to the aeolian sediment records from the region, this study poses serious and fundamental questions about: 1) the reliability of the model outputs, 2) the degree to which DAIs are able to account for the complexity and dynamics of aeolian systems, and/or 3) the interpretation of dune records as palaeoclimatic proxies at millennial time scales.     

Late Quaternary erosion events in lowland and mid-altitude Tasmania in relation to climate change and first human arrival

The establishment of a chronology of landscape-forming events in lowland and mid-altitude Tasmania, essential for assessing the relative importance of climatic and human influences on erosion, and for assessing present erosion risk, has been limited by the small number of ages obtained and limitations of dating methods. In this paper we critically assess previous Tasmanian studies, list published radiocarbon ages considered to be dependable, present new radiocarbon and thermoluminescence (TL) ages for 25 sites around Tasmania, and consider the evidence for the hypotheses that erosion processes at low and mid altitudes have been: (1) purely climatically controlled; and (2) influenced both by climatic and anthropogenic (increased fire frequency) effects. A total of 94 dependable finite ages (calibrated for radiocarbon and ‘as measured’ for TL and optically stimulated luminescence (OSL) determinations) are listed for deposits comprising dunes, colluvium, alluvium and loess-like aeolian deposits. Two fall in the >100 ka period, 15 fall in the period 65–35 ka, and 77 fall in the period 35–0.3 ka. There was a sustained increase in erosion recorded in the period 35–15 ka, as reflected by a greater number of dated aeolian deposits during this period.We considered three possible biases that may have affected the age distribution obtained: the limitations of radiocarbon dating, sampling bias, and preservation bias. Sampling bias may have favoured more recent dune strata, but radiocarbon dating and preservation biases are unlikely to have significantly distorted the age distribution obtained.Long but intermittent aeolian deposition is recorded at two sites (Southwood B; c. 59–28 ka and Dunlin Dune; c. 29–14 ka) but there is no evidence of regional loess deposits such as found in New Zealand. The timing of increased erosion in Tasmania between 35 and 30 ka approximately coincides with the intermittent ten-fold increase of dust accumulation between 33 and 30 ka in the Antarctic Dome C ice core. The absence of widespread erosion before 35 ka, the abrupt increase of erosion around this time, the frequent association of erosion products with charcoal, the arrival of people in Tasmania at c. 40 cal ka, and the known use of fires by Aborigines to maintain areas of non-climax vegetation suggest that ecosystem disturbance by anthropogenic fires, in a drier climate than that presently prevailing, may have contributed to erosion in lowland and mid-altitude Tasmania after 35 ka. Thus the Tasmanian erosion record provides circumstantial support for the proposition that human dispersal in southeast Australia was accompanied by significant ecological change.     

Reconstruction of Last Glacial to early Holocene monsoon variability from relict lake sediments of the Higher Central Himalaya,Uttrakhand, India

Proglacial lake sediments at Goting in the Higher Central Himalaya were analyzed to reconstruct the summer monsoon variability during the Last Glacial to early Holocene. Sedimentary structures, high resolution mineral magnetic and geochemical data suggest that the lacustrine environment experienced fluctuating monsoonal conditions. Optically stimulated luminescence (OSL) dating indicates that the lake sedimentation occurred before 25 ka and continued after 13 ka. During this period, Goting basin witnessed moderate to strengthened monsoon conditions around 25 ka, 23.5 ka–22.5 ka, 22 ka–18 ka, 17 ka–16.5 ka and after14.5–13 ka. The Last Glacial phase ended with the deposition of outwash gravel dated at ～11 ka indicating glacial retreat and the onset of Holocene condition. Additionally, centennial scale fluctuations between 16.5 ka and 12.7 ka in the magnetic and geochemical data are seen.A close correspondence at the millennial scale between our data and that of continental and marine records from the Indian sub-continent suggests that Goting basin responded to periods of strengthened monsoon during the Last Glacial to early Holocene. We attribute the millennial scale monsoon variability to climatic instability in higher northern latitudes. However, centennial scale abrupt changes are attributed to the result of albedo changes on the Himalaya and Tibetan plateau.     

Middle and Late Weichselian (Devensian) glaciation history of south-western Norway,North Sea and eastern UK

Data from eastern England, Scotland, the northern North Sea and western Norway have been compiled in order to outline our current knowledge of the Middle and Late Weichselian glacial history of this region. Radiometric dates and their geological context from key sites in the region are presented and discussed. Based on the available information the following conclusions can be made: (i) Prior to 39 cal ka and most likely after ca 50 cal ka Scotland and southern Norway were extensively glaciated. Most likely the central North Sea was not glaciated at this time and grounded ice did not reach the shelf edge. (ii) During the time interval between 29 and 39 ka periods with ameliorated climate (including the Ålesund, Sandnes and Tolsta Interstadials) alternated with periods of restricted glaciation in Scotland and western Norway. (iii) Between 29 and 25 ka maximum Weichselian glaciation of the region occurred, with the Fennoscandian and British ice sheets coalescing in the central North Sea. (iv) Decoupling of the ice sheets had occurred at 25 ka, with development of a marine embayment in the northern North Sea (v) Between 22 and 19 ka glacial ice expanded westwards from Scandinavia onto the North Sea Plateau in the Tampen readvance. (vi) The last major expansion of glacial ice in the offshore areas was between 17.5 and 15.5 ka. At this time ice expanded in the north-western part of the region onto the Måløy Plateau from Norway and across Caithness and Orkney and to east of Shetland from the Moray Firth. The Norwegian Channel Ice Stream (NCIS), which drained major parts of the south-western Fennoscandian Ice Sheet, was active at several occasions between 29 and 18 ka.