Madagascar is characterized by high climatic heterogeneity and its topography plays a key role in modulating the regional hydroclimate variability in South and East Africa. However, knowledge on past climate of Madagascar very limited, in line with the general scarcity of paleoclimate records from the southern tropics and subtropics. We generated a 26 kyr paleoclimate record from Madagascar, located in the southwestern Indian Ocean spanning the Last Glacial Maximum (LGM) to the late Holocene. In particular, we present a deuterium/hydrogen isotopic ratio of terrestrial leaf waxes (δ2Hwax) from a sediment core taken from the central eastern part of the island near the capital Antananarivo. The δ2H records of both the aquatic and terrestrial plant derived n-alkanes exhibit similar long-term trends implying that they all record changes in the isotopic composition of source water, namely meteoric water that recharges soil and lake waters. In this tropical region, the δ2H variability of precipitation recorded by n-alkanes δ2H is mainly influenced by the amount effect resulting in lower values for periods with high rainfall. We observe five long-term trends: (i) stable and relatively dry conditions during the Last Glacial Maximum (LGM) (ii) gradually wetter conditions from 17.5 ka to 11.5 ka, especially during the Heinrich stadial 1 (HS1) and the Younger Dryas (YD) (iii) an arid interval from 11.5 ka to 8.5 ka, and (iv) a general trend to more humid climate until 3.0 ka, followed by (v) a drier interval until 1.0 ka. The Madagascar climatic signal is opposite to other records from South Africa and East Africa records especially during the YD and early to middle Holocene period. This regional dipole mode is consistent with the modern rainfall anomaly pattern associated with the variability of Mozambique Channel Trough and the migration of austral summer Intertropical Convergence Zone (ITCZ) position as a response to changes in local summer insolation orbital and/or Northern Hemisphere cold events, such as the YD and HS1.
The Holocene climate history of Southern Africa remains inconclusive despite the increasing number of proxy records from the region. This might be related to the diversity of proxy records, how the proxies are interpreted, or that proxies may respond to more than one forcing (e.g. hydroclimate, fire, temperature.). Here, a 175-cm peat sequence from Free State, South Africa (28 degrees 17 & PRIME;53 & DPRIME;S, 29 degrees 25 & PRIME;10.9 & DPRIME;E), was analyzed using a comprehensive set of novel and conventional proxies, including isotopic (813C), elemental (CS-XRF), mineral (pXRD), molecular (FTIRATR and pyrolysis-GC-MS), grain size (Malvern 3000) and GSSC phytolith composition. The chronology was constructed through AMS radiocarbon dating (n = 7). The early Holocene (10,380-7000 cal yr BP) was characterized by an initial wet phase, followed by relative dryness, at least seasonally, evidenced by slow accumulation rates, low organic content and dominance of terrestrial vegetation in the organic matter matrix. From 7000 cal yr BP, decreasing temperatures, as evidenced in regional climate reconstructions, were associated at Marias Geluk with higher biogenic silica and organic matter content and an increase of moisture-adapted grasses, indicating increasingly mesic conditions. This trend was amplified after 6000 cal yr BP, co-occurring with a southward displacement of the ITCZ. Complex proxy dynamics were observed between 4300 and 2180 cal yr BP, with bulk organic proxies indicating a drier environment (lower carbon content, slow accumulation rates, enriched 813C values) but the phytolith record pointing towards relatively mesic conditions. The period was also associated with increased fire frequency, that also reached the local wetland. We suggest that the period was associated with seasonally mesic conditions together with increased fire incidence, which affected some of the organic proxies. Increased fire activity was also recorded in the region, while the hydroclimatic indications differed. The last 2000 years, during which human activity is known to have increased in the region, was characterized by lower fire incidence and variable, but relatively moist, conditions. The hydroclimatic inferences for the last 2000 years are in line with previous studies from the region, but additional studies are needed to decipher if the decline in fire incidence was associated to climate forcings, human activities, or a combination of both. The multiproxy approach applied here - in particular the inclusion of FTIR-ATR and pyrolysis GC-MS revealed a complex interplay between vegetation dynamics, hydrology and paleofire variability. This study confirms that relatively small Holocene temperature variations (compared to northern higher latitudes) were associated with major hydrological variability at Marais Geluk, and reinforces concerns from earlier studies that the hydroclimate of the region is vulnerable to climate change. The result s also show that the southward displacement of the ITCZ, and associated tropical air masses, likely had significant effects on regional hydrology and fire incidence.
Fossil diatoms and litho-stratigraphic changes in the Guern El Louläilet depressions, NW of the Great Western Erg, Algeria, were analysed to infer paleoenvironmental changes in the northern Algerian Sahara during the Early and Middle Holocene. Analysis was based on calcareous diatomite collected from four outcrops within the depressions. The diatom flora consists of brackish and epiphytic taxa, such as Epithemia argus, with percentages of some freshwater and planktonic species, mainly Cyclotella distinguenda. Results provide evidence for two Holocene lacustrine episodes related to the African Humid Period. The first episode (Early to Middle Holocene) was characterized by abrupt development of shallow-water conditions, with extensive littoral zones and evaporative periods that coincided with high salt concentrations in warm, alkaline water (swampy conditions). A second episode (Middle to Late Holocene?), with brackish water and alkaline conditions, coincided with a decline in lake water level that is attributed to drier conditions. Our findings are consistent with those of other studies from the area and demonstrate similar environmental changes occurred after 9300 cal yr BP at sites within the region. The main drivers of the African Humid Period were the northward shift of the Intertropical Convergence Zone (ITCZ) and expansion of summer monsoonal rains. Our study sites were located in the northern Sahara, where variations in the position of the Intertropical Convergence Zone (ITCZ) did not affect rainfall. Early and Middle Holocene climate fluctuations detected in this study may have been caused by intensification of winter precipitation in the south-central Mediterranean and its penetration southward.
An overview of the diatom flora of the last interglacial (Eemian) lacustrine gyttja deposit at Sokli, northeastern Finland is presented together with descriptions including photomicrographs of resting spores similar to the Aulacoseira islandica-skvortzowii group, not found in recent material from Europe. Comparisons are made with literature data on similar taxa. The morphology of the resting spores (e.g., the number of striae and areolae in 10 mu m) links them to the A. islandica-skvortzowii group, but the lack of vegetative cells in the Sokli record makes the determination of true synonymy difficult. The presence of spores similar/related to the A. islandica-skvortzowii group in the Sokli Eemian palaeolake may reflect a more widespread distribution of this group in the past.
Using diatoms, pollen, and geochemistry, we explore human habitation around Lina myr, Gotland, in relation to shore displacement. Archeological evidence has shown that Lina myr was an important area for its prehistoric human inhabitants. We investigate if and when Lina myr was connected to the sea and could therefore have been part of an inland water system useful for transport. A chronology was based on 14 C AMS dating of terrestrial macrofossils and bulk sediments with dates ranging between 9100 and 2360 cal. yr BP. The initiation of the Littorina transgression was dated to 8500 cal. yr BP. A twofold pattern for the maximum sub-phase of the Littorina Sea is suggested from 8100 to 7500 cal. yr BP and from 6500 to 6000 cal. yr BP. The onset of cultivation and grazing was indicated by the presence of Hordeum and Plantago lanceolata in the pollen record during the Late Neolithic, at about 4580 cal. yr BP. During this time sea level was relatively higher than today and the Lina myr basin was connected with the Littorina Sea, which it continued to be until isostatic uplift caused it to become isolated at about 3820 cal. yr BP. After about 3000 cal. yr BP, human-made landscape changes intensified, grasslands increased, and shrublands decreased.
Holocene relative shore level (RSL) changes and Stone Age palaeogeography of Hiiumaa Island are reconstructed using airborne LiDARelevation data, sedimentological and archaeological proxies as well asGIS‐based landscape modelling. Altogether, 38RSLindex and limiting points are used in modelling and presented in the current paper. The highest raised shorelines of the Ancylus Lake and Litorina Sea, mapped at the elevations of 47 and 26 m a.s.l., formed around 10.3 and 7.4 cal. kaBP, respectively. The reconstructedRSLcurve reveals a 20‐m drainage of Ancylus Lake followed by a land‐uplift‐driven 3‐m regression during the Initial Litorina Sea period.RSLrise during the Litorina Sea transgression remained below 4 m and its maximum was reached later than proposed previously, discarding therefore the idea of highly diachronous Litorina culmination in the eastern Baltic Sea. During the period 7.4–6.0 cal. kaBP,RSLfall was about 4.3 mm a−1, and afterwards in average at about 1 mm‐1less suggesting deceleration in isostatic rebound. suggesting deceleration in isostatic rebound. Palaeogeographical reconstructions show that during its earliest occupation at about 7.6 cal. kaBPless than 1% of the terrain of Hiiumaa was above the sea level and that wind‐protectedSEexposed shores were the most preferred campsite locations of Late Mesolithic and Neolithic settlers. These campsites are located successively at lower elevations following the shoreline retreat and show repeated use of this coastal area between 7.6 and 4.6 cal. kaBP. Due to the spread of the Corded Ware culture around 4.8–4.0 cal. kaBPthe settlements of Hiiumaa Island and many other coastal areas of the eastern Baltic moved from the coast to more suitable places for agriculture and animal husbandry.
The shore displacement and palaeogeography of the Pärnu Bay area, eastern Baltic Sea, during the Stone Age, were reconstructed using sedimentological and archaeological proxies and GIS-based landscape modelling. We discovered and studied buried palaeochannel sediments on the coastal lowland and in the shallow offshore of the Pärnu Bay and interpreted these data together with previously published shore displacement evidence. The reconstructed relative shore-level (RSL) curve is based on 78 radiocarbon dates from sediment sequences and archaeological sites in the Pärnu Bay area and reported here using the HOLSEA sea-level database format. The new RSL curve displays regressive water levels at −5.5 and −4 m a.s.l. before the Ancylus Lake and Litorina Sea transgressions, respectively. According to the curve, the total water-level rise during the Ancylus Lake transgression (10.7–10.2 cal. ka BP) was around 18 m, with the average rate of rise about 35 mm per annum, while during the Litorina Sea transgression (8.5–7.3 cal. ka BP), the water level rose around 14 m, with average rate of 12 mm per annum. During the short period around 7.8–7.6 cal. ka BP, the RSL rose in Pärnu, but probably also in Samsø (Denmark), Blekinge (Sweden) and Narva-Luga (NE Estonia–NW Russia), faster than the concurrent eustatic sea level calculated from the far-field sites. The palaeogeographic reconstructions show the settlement patterns of the coastal landscape since the Mesolithic and provide new perspective for looking Mesolithic hunter-fisher-gatherer settlement sites on the banks of the submerged ca. 9000 years old river channel in the bottom of the present-day Pärnu Bay.
In conjunction with the extensive archaeological projects conducted at the current outlet of Sweden’s second largest lake, Lake Vättern, macrofossil, pollen and diatom records have been studied from 14C-dated lake and river sediments from River Motala Ström in Motala and Lake Boren. These investigations have revealed sedimentary evidence of the Yoldia Sea regression, the Ancient Lake Vättern transgression, and the following stepwise river formation process. Around 9000 cal BC, two small kettlehole basins at Strandvägen and Kanaljorden became isolated from the Baltic basin. As the ice sheet retreated further north, the isostatic uplift isolated the Vättern basin from the Baltic basin. Due to the uneven isostatic uplift, the basin tilted toward the south, and the Ancient Lake Vättern transgression started in Motala. The threshold in Motala at 92.5 m a.s.l. was reached around 7200 cal BC, and River Motala Ström was formed. 14C-dated diatom records from Lake Boren, and shoreline deposits in Motala, confirm this event. The water level in Lake Vättern initially fell around 1.5 m, and around 5800 cal BC, a second erosional event cut down the threshold to modern day level. At this time, the Late Mesolithic settlements in Motala were established and expanded.
The coastal areas of Eastern Mediterranean have long been the subject of research, due to their rapid geomorphological changes, but also because of their archaeological interest. Our study is focused on a shallow coastal lagoon of Peloponnese, Gialova Lagoon, which for several years has attracted the scientific interest of archaeologists, geomorphologists as well as sedimentologists. Gialova lagoon is located near the ancient city of Pylos, the kingdom of king Nestor during the Mycenaean period (1600-1100 BC). The objectives of this study are: (a) to reconstruct the middle to late Holocene depositional environments of the lagoon and (b) to correlate our data to already existing publications, in order to shed new light on the Holocene evolution of the lagoon and the associated coastal palaeoenvironmental changes. An 8m deep vibracore was drilled and a multi proxy analysis was carried out on the sediment sequence, including sedimentological (grain size analysis and moment measures, total organic carbon - TOC, total nitrogen e TN and total phosphorus - TP), high resolution geochemical (XRF-scanning) and palaeontological (micro-and macro faunal) analysis. The chronological framework is based on five C-14 datings forming the basis for an age depth model, calculated using the OxCal software. The radiocarbon dates from previous studies (6 cores, similar to 20 dates) were also taken into account. The data synthesis and interpretation provided robust and coherent indications regarding the palaeoenvironment, shoreline changes and the rate of geomorphological changes of the coastal area of Gialova Lagoon, as well as useful information about the palaeonvironmental and palaeoclimatic conditions that prevailed during the Mycenaean period. The interpretation, reveal a transition from a shallow marine environment (65005800 yr B.P.) to a brackish/lagoonal (5800-3300 yr B.P.), followed by a shift towards a freshwater/marsh environment (3300 yr B.P. to present). (C) 2018 Elsevier Ltd and INQUA. All rights reserved.
Deltaic wetlands experience changes over time, with substantial impacts on the coastal ecosystems. These changes, whether they are natural or human-induced, are caused by multiple factors through complex links and interdependences, and constitute challenges for coastal management aiming to set up practical adaptation measures. In this study, we investigate a case study of Save River Delta to interpret the typical morphodynamic pattern on the deltaic plain over an interdecadal timescale and the implications of geomorphological changes for the coastal ecosystems, with emphasis on mangroves. Our results reveal the pattern of the geomorphological changes on the deltaic wetland in river and back-barrier sectors. In both sectors, erosion and accretion are mutually adjusting processes, and they result in geomorphological settings characterized by a distinctive interaction with the ecosystem; on the one hand, mangrove trees colonize new favorable settings; on the other hand, the existing mangrove trees undergo degradation related to the morphodynamic processes. Notwithstanding current episodic events that affect the deltaic wetlands (e.g. cyclones and floods), the changes observed in the study area are part of interdecadal timescale morphodynamics. These changes were consistent for the 50-year time period analyzed. If, on the one hand, some of the episodic and high magnitude weather events such as floods undermine the status of the deltaic ecosystem, on the other hand these events contribute to develop the same ecosystem over a longer timescale. Within interdecadal timescales, biogeomorphological changes in deltaic wetlands are a critical reference frame for understanding future scenarios of environmental changes caused by climate change. (C) 2018 Elsevier B.V. All rights reserved.
This study explores temporal dynamics within grassland and Miombo woodland ecosystems in southern Mozambique and their potential coupling to hydro-climate change during the late-Holocene period. Palaeo-reconstructions are based on phytolith and diatom assemblages and mineral magnetic properties in fossil sediments from Lake Chilau, southern Mozambique. Phytolith interpretation was aided by previous ecological studies on modern plants and soils. The Lake Chilau record suggests high abundance of Panicoideae and other mesophytic grasses during the AD 1200s and 1300s, followed by an increase in Chloridoideae and grasses of more xerophytic affinity between ca. AD 1400 and 1550. This vegetation transition takes place during the early phase of the so-called ‘Little Ice Age’ (LIA), when regional palaeoclimate records report a shift from warmer and wetter towards drier and cooler conditions in southern Africa. Concurrent to these shifts within the grassland biome, the Chilau record reports an increase in phytoliths associated with arboreal vegetation (ca. AD 1400–1550), probably associated with the woody component of the Miombo savanna ecosystem. This supports previous studies hypothesizing that the forest component of the Miombo savanna was favoured by LIA dryness, although at Chilau, this expansion may have been amplified by a decline in fire disturbance. These tentative responses in the woody components of the savanna biome to shifts in moisture availability in the past have implications for future management and sustainability of the Miombo ecosystem in southern Mozambique under a changing climate.
ABSTRACTWe present a 6000‐year‐long record tracing hydroclimate changes in SW Greece, based on hydrogen isotope composition of aquatic plant‐derived n‐C23 alkanes (δDC23) in a sediment core from the Messenian plain, Peloponnese. The δDC23 record co‐varies with other eastern Mediterranean records, suggesting relatively wetter conditions c. 6–4.5 ka, followed by progressively drier conditions leading up to maximum aridity c. 2.8 ka. This arid phase was interrupted by a shift in δDC23 between 3.3 and 3.1 ka inferring wetter conditions and/or tentative responses to anthropogenic water regulating activities during the Late Bronze Age. After 2.7 ka, a return to more humid conditions was followed by increased dryness and stronger seasonality contrasts from c. 2.0 ka. The δDC23 record shows three short‐lived excursions (5.7, 5.3, 2.8 ka), where isotope values dropped by >20‰ and immediately stabilized again. The events were paralleled by abrupt increases in sedimentation rates. We hypothesize that the isotopic shifts represent a response to mixing of ground water systems during tectonic events, followed by sealing of seismically derived cracks in the active fault. The outcome of the study is promising for future expansion of isotope‐based proxies on sediments in the region, to reconstruct both hydroclimate and past seismic activity.
Detailed studies on fossil remains of plants or animals in glacial lake sediments are rare. As a result, environmental conditions right at the moment of deglaciation of the large N-Hemisphere ice-sheets remain largely unknown. Here we study three deglacial phases of the Fennoscandian Ice Sheet as a unique, repeated element in a long sediment record preserved at Soldl in northern Finland. We summarize extensive multi-proxy data (diatoms, phytoliths, chironomids, pollen, spores, non-pollen palynomorphs, macrofossils, lithology, loss-on-ignition, C/N) obtained on glacial lake sediments dated to the early Holocene (ca. 10 kyr BP), early MIS 3 (ca. 50 kyr BP) and early MIS 5a (ca. 80 kyr BP). In contrast to the common view of an unproductive ice-marginal environment, our study reconstructs rich ecosystems both in the glacial lake and along the shores with forest on recently deglaciated land. Higher than present-day summer temperatures are reconstructed based on a large variety of aquatic taxa. Rich biota developed due to the insolation-induced postglacial warming and high nutrient levels, the latter resulting from erosion of fresh bedrock and sediment, leaching of surface soils, decay of plant material under shallow water conditions, and sudden decreases in lake volume. Aquatic communities responded quickly to deglaciation and warm summers and reflect boreal conditions, in contrast to the terrestrial ecosystem which responded with some delay probably due to time required for slow soil formation processes. Birch forest is reconstructed upon deglaciation of the large LGM ice-sheet and shrub tundra following the probably faster melting smaller MIS 4 and MIS 5b ice-sheets. Our study shows that glacial lake sediments can provide valuable palaeo-environmental data, that aquatic biota and terrestrial vegetation rapidly accommodated to new environmental conditions during deglaciation, and that glacial lake ecosystems, and the carbon stored in their sediments, should be included in earth system modeling.
Exposures of Middle Pleistocene lacustrine sediments at the margins of an open-cast lignite mine at Marathousa near Megalopolis, western Arcadia, Greece yielded the partial remains of a Palaeoloxodon antiquus skeleton which exhibited signs of being butchered. Sedimentation occurred between ca. 400 and 480 ka. Lithic artefacts were found in close spatial and stratigraphic association with the elephant remains. A palaeobotanical investigation (involving carpological, phytolith and wood remains) as well as diatom analysis led to a detailed reconstruction of the local environment at the time of sediment deposition. The results of this study enabled the environmental context of the butchering of the Palaeoloxodon antiquus carcass to be established. Palaeobotanical data show that sediment deposition at the Palaeoloxodon antiquus site occurred in shallow water in front of a reed swamp with trees in the immediate surroundings (particularly Alnus and Salix) on a flat plain where the water table was at or just below the ground surface. Warm conditions prevailed at the time of sediment deposition allowing aquatic plants typically recorded in the climatic optima of European interglacial assemblages to occur (e.g. Brasenia schreberi) and palms (Palmae) to live close-by. This suggests that the organic-rich sediments that contain the archaeological finds represent a transition between the underlying clastic sediments deposited during colder conditions and the overlying lignite that was deposited during warm climatic conditions as reported in previous studies.
Many mangrove wetland systems in deltaic environments are negatively affected by massive sedimentation from river inflows. In this paper we use the example of the Save River delta to assess the palaeogeographic distribution of mangrove wetlands and to analyze their dynamics. To track past occurrences of mangrove wetlands in the study area we have integrated sedimentological data with siliceous microfossil analysis combined with AMS radiocarbon and OSL dating. The results show a fine-grained deposit with an approximate thickness of 2m, present at different sampling sites. In the upper deltaic plain, the deposit is interbedded between sand layers, while in the lower deltaic plain the deposit occupies the uppermost stratigraphic position. In most of the sampling sites the deposit shows a succession with brackish-marine diatoms at the bottom of the sequence while the upper part shows only scattered occurrences. Based on sedimentological and microfossil characteristics we have interpreted the layer to represent a mangrove wetland deposit. The development of the deposit in the study area is suggested to have been initiated around 3100cal. yr BP, induced by sea-level rise. Thereafter, the development followed the combined effect of a sea-level fall and delta progradation processes. In some areas, particularly in the proximal part of the delta, the mangrove deposit has developed progressively on top of the delta-front. From around 1300years ago (OSL) onwards, massive alluvial sedimentation impacted the mangrove ecosystem. However, the retreat of mangrove wetland coincided with a regional fall of sea level. At the edges of the alluvial deposit, the current mangrove ecosystem has reclaimed the habitat in some sectors where gully erosion has exposed the once extinct mangrove habitat.
We report on late Holocene paleoenvironmental and sea-level changes in southern Mozambique, based on analysis of diatom stratigraphy, mineral magnetic susceptibility, Saturation Isothermal Remnant Magnetization (SIRM) and organic carbon content in a sediment core from Lake Lungué, located ca. 30km north of Xai Xai City in the Limpopo River floodplain. Eleven radiocarbon dates performed on terrestrial shells allowed establishment of an age-depth model. High content of brackish-marine taxa, especially Diploneis suborbicularis and Navicula yarrensis, suggests that the Lake Lungué basin was part of the Indian Ocean coastal zone between ca. 740 and 910CE, suggesting higher relative sea-level during this phase. A similar diatom distribution in older parts of the sequence, of unknown age, indicates that the site was connected to the Indian Ocean also at some stage prior to 740CE. Between ca. 910 and 1130CE the basin was under a combined effect of sporadic marine water influx and Limpopo River actions. A freshwater lake was established sometime between 1130 and 1360CE, when the basin became less affected by marine influences due to lower sea-levels. Instead, the lake system was more influenced by Limpopo River meandering dynamics and flooding events, and eventually isolated into a more or less independent lake ecosystem where diatom diversity most likely responded to lake levels fluctuations driven by shifts in relative humidity and rainfall amounts within the floodplain and also from upstream sources. During this phase, high abundance of freshwater planktonic species, i.e. Aulacoseira granulata and A. ambigua, indicates high lake levels and wetter conditions dated to ca. 1360–1560CE. From 1560CE until present, the lake has been subject to drier conditions and higher evaporation as indicated by lower lake levels, reported by a decline in freshwater planktonic taxa and increase in brackish taxa, e.g. Amphora robusta.
Here we present a palaecological reconstruction covering the last 1700yr from Lydenburg fen, located in the north-eastern grassland biome, Mpumalange, South Africa. A 300cm peat sequence was analysed for biogenic (grass phytoliths, diatoms) and geochemical proxies (δ13C, δ15N, carbon/nitrogen content) to infer past grassland dynamics and hydro-climatic changes. The Lydenburg record reports a C4 dominated grassland throughout the studied period, with more or less pronounced fluxes between C4-Chloridoideae and C4-Panicoideae grass subfamilies. The record reflects moderate to dry conditions from AD 400 to 1000; more mesic conditions until around AD 1250; followed by a significantly drier period between c. AD 1250 and c. AD 1350, when Chloridoideae grasses expand at the expense of Panicoideae grasses. During this phase, the δ13C-record reports more enriched values indicating higher influx of C4 grasses. Furthermore, lithological evidence indicates highly erosive conditions, with significant gravel input from the surrounding hills. After AD 1350, proxy indications suggest a shift towards more mesic conditions. During this increasingly mesic but also unstable period, farming communities using specialized agricultural practices (e.g. the people in Bokoni) expanded their settlements into new regions (Delius et al., 2008). This expansion was also coupled to population growth, suggesting these communities applied techniques that enabled improved food production under environmentally challenging conditions. Over the last century, Lydenburg δ13C-values indicate increased input of C3 taxa. The phytolith record shows that this increase is not coupled to an increase in Pooideae (C3) grasses, suggesting that the C3 input may be related to woody encroachment.
A 12m long lacustrine record from Sokli, N Finland, was analyzed for diatoms, non-pollen palynomorphs, macrofossils, pollen and geochemistry in order to reconstruct the development of a high-latitude Eemian lake and investigate the influence of climatic and environmental changes on the lake ecosystem. Based on this multi-proxy dataset we distinguished five major lake phases in the lake's evolution. An initial minerogenic, glacio-lacustrine phase was followed by an organic-rich early Eemian lake phase characterized by anoxic bottom waters, high seasonality and rising nutrient levels. A long open water season, pronounced summer stratification and high productivity characterized the following early mid-Eemian lake phase, corresponding to the Eemian thermal maximum. During the late mid-Eemian lake phase decreasing water depths due to infilling and extensive mixing of the water column resulted in less stable summer stratification and decreased anoxia. The late-Eemian lake phase was characterized by shallow and dynamic conditions and a cooling climate. Superimposed on these general trends are two events characterized by colder and more arid conditions, that possibly match cold and arid events registered in palaeolimnological records on the European continent. In general, the multi-proxy record reflects a nutrient rich lake, where changes in mixing regime associated with climatic forcing and lake level changes asserted a major impact on the aquatic assemblages. The changes in the aquatic assemblages reflect the major patterns of climate change that took place during the Eemian in northern Europe; i.e. a rapid warming and high seasonality during the early Eemian, decreased seasonality during the mid Eemian and a cooling late Eemian with increased seasonality. The high latitude Sokli Eemian palaeolake record lengthens the latitudinal extent of Eemian terrestrial records across Europe, adding to the understanding of climatic gradients and drivers over Europe.
Earlier work on the terraced settlements of the Bokoni area (16th to 19th century, Mpumalanga province, South Africa) focussed on the homesteads, their contents, layout and chronology. This paper suggests a terminology and typology of agrarian structures in Bokoni in order to improve comparative approaches in Africa and beyond. The typology and an excavation of the terracing permit possible preliminary conclusions relevant for the further analysis of the terracing and stone-walling in Bokoni. The terracing developed incrementally, whereby cultivation, stone-clearing and terracing were intermixed processes. This is supported both by the organic content in a section of a terrace and by a phytolith analysis. The phytolith analysis furthermore indicated that maize was cultivated on the terraces, but this should be seen as a pilot study only, and presence of maize in Bokoni must be tested with other archaeobotanical methods.