Changes in the Early Holocene lacustrine environment inferred from the subfossil ostracod record in the Varangu section, northern Estonia

The Varangu section is located on the southern slope of the Pandivere Upland in northern Estonia. A silty clay bed formed in the study area at 11 ;200–9300 ;cal ;yr ;BP, according to ostracod subfossils (e.g. Tonnacypris estonica, Leucocythere mirabilis, Limnocytherina sanctipatricii) in an oxygen-rich cool and oligotrophic profundal lacustrine environment, with an inflow of surface waters through springs. The record of specific ostracods (e.g. Cyclocypris ovum, Cypridopsis vidua, Metacypris cordata) reflects littoral environments, ongoing eutrophication, temperature increase and a progressive shallowing of the lake in the early Holocene (9300–7400 ;cal ;yr ;BP) when the tufa bed accumulated. A slight cooling and productivity decrease at 9100–8600 ;cal ;yr ;BP preceded further temperature rise and water level lowering, leading to the development of a eutrophic lake and cease of ; ;tufa precipitation (8600–7400 ;cal ;yr ;BP)

Mid-Late Quaternary Fluvial Archives near the Margin of the MIS 12 Glaciation in Southern East Anglia, UK: Amalgamation of Multi-Disciplinary and Citizen-Science Data Sources

This paper presents an updated geological reconstruction of the Quaternary evolution of the River Thames at its downstream extremities, close to the North Sea coast, based on new data from multi-disciplinary and citizen-science sources. In this area, the interaction of the Thames with the MIS 12 (Anglian) glaciation is an important part of the Quaternary archive. The Anglian ice sheet, which reached parts of north and east London, was responsible for diverting the Thames southwards into its present course, although the footprint of the maximum ice sheet(s) does not reach the North Sea coast south of Hollesley, Suffolk. Further south, the coastal zone hosts pre-Anglian and early Anglian river-terrace deposits of the pre-diversion Thames system, superimposed upon which are products of later post-Anglian rivers, of both Middle and Late Pleistocene age. On the peninsula between the Stour and Blackwater–Colne estuaries, the lowest and most recent terrace of the pre-diversion Thames includes evidence directly pertaining to the glacial disruption event, for which geochronological data are reported here for the first time. The first post-diversion terrace of the Thames also reaches this peninsula, the river having essentially re-joined its original valley before crossing the alignment of the modern coastline. This terrace passes beneath Clacton-on-Sea, where it includes the type locality of the Clactonian Palaeolithic Industry. The area of interest to this paper, in NE Essex and southern Suffolk, includes a number of interglacial and Palaeolithic sites, the data from which assist in constraining the chronostratigraphy of the sequence. In some cases, there has been uncertainty as to whether these sites represent pre-Anglian environments and hominin occupations, part of the palaeo-Thames sequence, or whether they are the product of later post-Anglian streams, formed after the Thames had migrated southwards. This paper compiles evidence from a wide range of recent sources, including developer-funded archaeological appraisal and citizen-science activities, to explore and update the evidence from sites at Ipswich, Upper Dovercourt and Thorpe-le-Soken, as well as a number of localities associated with the Clacton Channel Deposits (host to the type-Clactonian), amongst others. The resulting new data are placed within the wider context of the Quaternary fluvial archives in southern Britain, with a discussion of how disparate sources of information, including the work of citizen scientists, have contributed

Mid-late quaternary fluvial archives near the margin of the MIS 12 glaciation in Southern East Anglia, UK: amalgamation of multi-disciplinary and citizen-science data sources

This paper presents an updated geological reconstruction of the Quaternary evolution of the River Thames at its downstream extremities, close to the North Sea coast, based on new data from multi-disciplinary and citizen-science sources. In this area, the interaction of the Thames with the MIS 12 (Anglian) glaciation is an important part of the Quaternary archive. The Anglian ice sheet, which reached parts of north and east London, was responsible for diverting the Thames southwards into its present course, although the footprint of the maximum ice sheet(s) does not reach the North Sea coast south of Hollesley, Suffolk. Further south, the coastal zone hosts pre-Anglian and early Anglian river-terrace deposits of the pre-diversion Thames system, superimposed upon which are products of later post-Anglian rivers, of both Middle and Late Pleistocene age. On the peninsula between the Stour and Blackwater–Colne estuaries, the lowest and most recent terrace of the pre-diversion Thames includes evidence directly pertaining to the glacial disruption event, for which geochronological data are reported here for the first time. The first post-diversion terrace of the Thames also reaches this peninsula, the river having essentially re-joined its original valley before crossing the alignment of the modern coastline. This terrace passes beneath Clacton-on-Sea, where it includes the type locality of the Clactonian Palaeolithic Industry. The area of interest to this paper, in NE Essex and southern Suffolk, includes a number of interglacial and Palaeolithic sites, the data from which assist in constraining the chronostratigraphy of the sequence. In some cases, there has been uncertainty as to whether these sites represent pre-Anglian environments and hominin occupations, part of the palaeo-Thames sequence, or whether they are the product of later post-Anglian streams, formed after the Thames had migrated southwards. This paper compiles evidence from a wide range of recent sources, including developer-funded archaeological appraisal and citizen-science activities, to explore and update the evidence from sites at Ipswich, Upper Dovercourt and Thorpe-le-Soken, as well as a number of localities associated with the Clacton Channel Deposits (host to the type-Clactonian), amongst others. The resulting new data are placed within the wider context of the Quaternary fluvial archives in southern Britain, with a discussion of how disparate sources of information, including the work of citizen scientists, have contributed

Mageveelised karpvähid pärastjääaegsetes setetes ja nende kasutamine paleokeskkonna rekonstrueerimisel Eestis

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Paleokeskkonna uuringud on muutunud oluliseks kogu maailmas. Selleks, et näha ette võimalikke tuleviku arengusuundi, püütakse mõista minevikus toimunud kliimamuutusi. Antud töös kasutatakse esmakordselt Eestis karpvähkide subfossiile, interpreteerimaks keskkonna¬muutusi peale viimast jääaega. Karpvähid (u 0,5–2 mm) on veelised organis¬mid, kelle kahepoolmeline lubiainest koda säilib setetes pärast looma surma. Teades tänapäevaste karpvähkide keskkonna¬eelistusi on võimalik interpreteerida mineviku veelist keskkonda. Peale liustiku taandumist asustasid karpvähid kiiresti suured pärastjääaegsed mageveekogud. Karpvähkide koosluste struktuur sõltus temperatuurist ning ilmusid soojenemisele viitavad liigid (13800–13600 aastat tagasi). Järgnes kliima jahenemine u 13600–13000 a.t. ning karpvähiliste seas levisid külmalembesed liigid, näiteks Cytherissa lacustris ja Limnocytherina sanctipatricii. Erinevates uuritud läbilõigetes võib täheldada karpvähkide koosluste muutusi, mis viitavad veekogude vananemisele. Ilmneb teatud indikaatorliikide reeglipärane levik, nt madala toitelisusega hapnikurikkas jahedas ning sügavas järves oli levinud Candona candida, kuid avaveelisele madaldunud veekogule oli iseloomulik Darwinula stevensoni ning rohketoitelises soojas taimestikurikkas kaldavööndis domineeris Metacypris cordata. Poolmaismaalise eluviisiga Scottia pseudobrowniana esinemine järvesetete noorimates kihtides viitab kinni¬kasvamisjärgus järvenõole. Veekogude vananemine oli seotud veetaseme langusega, temperatuuri tõusuga ning toitelisuse kasvuga Holotseeni esimesel poolel. Ehkki selline arengu¬mudel on järvedele tüüpiline, ei ole muutused järvedes ega ostrakoodikooslustes leidnud aset samaaegselt. Järvede arengut mõjutasid lisaks temperatuurimuutustele ka sademete ja aurumise vahekord ning toitelisuse muutused. Karpvähkide kasutamine paleoklimaatilistes rekonstruktsioonides väärib edaspidi süvendatud tähelepanu, kuna nende kodade geokeemiline analüüsimine (isotoopkoostis) annab ainulaadset informatsiooni temperatuurikõikumiste kohta pärast jääaega.The thesis focuses on analysis of Quaternary freshwater ostracod (benthic crustaceans, 0.5-2 mm in size) subfossils and autecology of indicator species in order to reconstruct lacustrine palaeoenvironments after the last glaciation in Estonia. The composition of the ostracod fauna reflects changes in the water level, temperature, trophic status and vegetation cover of the lake. Pioneer species colonized large lake margin areas already at ca. 13.8–13.6 kyr BP following a temperature increase after ice decay. Temperature decrease at ca. 13.6–13.1 kyr BP favoured species which inhabit cold, oligotrophic, well-ventilated bottom waters in deep and large lakes (Limnocytherina sanctipatricii, Cytherissa lacustris). The succession of ostracod assemblages show a general evolution of lake environments: the “candida-fauna” represents phase of large oligotrophic lakes; the succeeding “stevensoni-fauna” indicates shallower mesotrophic open lakes; and the “cordata-fauna” refers to a shallow, aged, eutrophic water body with dense, emerged vegetation. The predominance of Metacypris cordata suggests an increasing temperature and higher productivity ca. 12.8-7.4 kyr BP. Finally, appearance of Scottia pseudobrowniana suggests paludification of lake margins. In the lakes studied changes in ostracod assemblages reveal like palaeo¬ecological signals. However, the environmental shifts were not contemporaneous, suggesting that the influence of local catchment features, such as water level, groundwater inflow, vegetation cover and nutrient input, was stronger than that of regional climatic conditions

Development of the late glacial Baltic basin and the succession of vegetation cover as revealed at Palaeolake Haljala, northern Estonia

The 4.5 m thick Haljala sequence in North Estonia was studied to provide information on palaeoenvironmental changes between 13 800 and 11 300 cal yr BP. Late glacial environmental history of North Estonia was reconstructed using AMS-dated pollen record, sediment composition, plant macrofossils, and ostracods. The obtained data show environmental fluctuations that are linked to the climate shifts of the Last Termination in the North Atlantic region. Decrease in the arboreal pollen accumulation rate around 13 700–13 600 and 13 300–13 100 cal yr BP refers to short deterioration of climate within the Allerød Interstadial and has been correlated with the cooling of the Greenland Interstadial GI-1c and GI-1b events, respectively. Between 13 100 and 12 850 cal yr BP the pollen accumulation rate of trees, shrubs, and herb as well as organic matter increased, indicating short-term climate amelioration and establishment of pine-birch woods. This change has been correlated with the GI-1a event. Climate deterioration during the Younger Dryas (GS-1) was inferred from the reduction of tree pollen and flourishing of cold-tolerant species, such as Artemisia, Chenopodiaceae, and Cyperaceae. New data show that ice cover of the Pandivere Upland started to perish already about 13 800 cal yr BP

Mid–late Quaternary fluvial archives near the margin of the MIS 12 glaciation in southern East Anglia, UK: amalgamation of multi-disciplinary and citizen-science data sources

This paper presents an updated geological reconstruction of the Quaternary evolution of the River Thames at its downstream extremities, close to the North Sea coast, based on new data from multi-disciplinary and citizen-science sources. In this area, the interaction of the Thames with the MIS 12 (Anglian) glaciation is an important part of the Quaternary archive. The Anglian ice sheet, which reached parts of north and east London, was responsible for diverting the Thames southwards into its present course, although the footprint of the maximum ice sheet(s) does not reach the North Sea coast south of Hollesley, Suffolk. Further south, the coastal zone hosts pre-Anglian and early Anglian river-terrace deposits of the pre-diversion Thames system, superimposed upon which are products of later post-Anglian rivers, of both Middle and Late Pleistocene age. On the peninsula between the Stour and Blackwater–Colne estuaries, the lowest and most recent terrace of the pre-diversion Thames includes evidence directly pertaining to the glacial disruption event, for which geochronological data are reported here for the first time. The first post-diversion terrace of the Thames also reaches this peninsula, the river having essentially re-joined its original valley before crossing the alignment of the modern coastline. This terrace passes beneath Clacton-on-Sea, where it includes the type locality of the Clactonian Palaeolithic Industry. The area of interest to this paper, in NE Essex and southern Suffolk, includes a number of interglacial and Palaeolithic sites, the data from which assist in constraining the chronostratigraphy of the sequence. In some cases, there has been uncertainty as to whether these sites represent pre-Anglian environments and hominin occupations, part of the palaeo-Thames sequence, or whether they are the product of later post-Anglian streams, formed after the Thames had migrated southwards. This paper compiles evidence from a wide range of recent sources, including developer-funded archaeological appraisal and citizen-science activities, to explore and update the evidence from sites at Ipswich, Upper Dovercourt and Thorpe-le-Soken, as well as a number of localities associated with the Clacton Channel Deposits (host to the type-Clactonian), amongst others. The resulting new data are placed within the wider context of the Quaternary fluvial archives in southern Britain, with a discussion of how disparate sources of information, including the work of citizen scientists, have contributed