Stefan Dreibrodt

A high-quality annually laminated sequence from Lake Belau, Northern Germany: Revised chronology and its implications for palynological and tephrochronological studies

The annually laminated record of Lake Belau offers an exceptional opportunity to investigate with high temporal resolution Holocene environmental change, aspects of climate history and human impact on the landscape. A new chronology based on varve counts, 14C-datings and heavy metal history has been established, covering the last 9400 years. Based on multiple varve counting on two core sequences, the easily countable laminated section spans about 7850 varve years (modelled age range c. 9430 to 1630 cal. BP). Not all of the record is of the same quality but approximately 69% of the varves sequence is classified to be of high quality and only c. 5% of low quality. The new chronology suggests dates generally c. 260 years older than previously assumed for the laminated section of the record. The implications for the vegetation and land-use history of the region as well as revised datings for pollen stratigraphical events are discussed. Tephra analysis allowed the identification of several cryptotephra layers. New dates for volcanic eruptions are presented for the Lairg B event (c. 6848 cal. BP, 2s range 6930–6713 cal. BP), the Hekla 4 event (c. 4396 cal. BP, 2s range 4417–4266 cal. BP), and Hekla 3 eruption (c. 3095 cal. BP, 2s range 3120–3068 cal. BP).

Investigations on buried soils and colluvial layers around Bronze Age burial mounds at Bornhöved (northern Germany): an approach to test the hypothesis of `landscape openness' by the incidence of colluviation

The idea of open landscapes around prehistoric burial mounds is founded on their topographical position and findings of plaggen clots within the hills at some sites. We have investigated the surroundings of four Bronze Age burial mounds at Bornhöved (northern Germany) to test whether this assumed landscape openness enabled soil erosion and colluviation or not. The soils and colluvia within a watershed below the burial mounds were investigated in six large exposures and additional auger cores. The chronology is based on 21 AMS-radiocarbon dates, complemented by charcoal analysis and the content of selected heavy metals in the sediments. Colluvia were deposited in the Late Neolithic (~2500—2200 cal. BC), Roman Emperor Times (~ 250—400 cal. AD), Mediaeval Times (~ AD 600—1400) and Modern Times (~ AD 1800—2000). Our findings indicate that the soil surfaces were protected against soil erosion during the phase of Bronze Age funeral use (~ cal. 1800—600 BC). Either the prehistoric gravediggers practised a well suited form of pasturing to keep the scenery open or the surroundings of the burial mounds were forested at the time of funeral use. The results of charcoal analysis reflect the known succession of woody taxa in the region and underline the great potential of anthracology on colluvial layers for palaeoenvironmental reconstructions apart from traditional archives such as lakes or mires. Bulk radiocarbon dating of organic matter overestimated the time of burial of a buried soil as well as the time of deposition of colluvial layers considerably.

Lake Belau and its catchment (northern Germany): A key archive of environmental history in northern central Europe since the onset of agriculture

The environmental history since the onset of agriculture was reconstructed from sediments and soils in the catchment area of Lake Belau (Schleswig-Holstein, northern Germany). The established chronologies are based on varve counts, radiocarbon data, embedded Icelandic tephra (lake sediments), radiocarbon dates, and embedded artifacts (slope deposits). Neolithic land use triggered small-scale erosion. Lake trophic indicators and pollen data clearly reflect the onset of agriculture and the middle Neolithic expansion of agricultural activity. Despite numerous archaeological findings, less intensive field use and no soil erosion occurred during the older and younger Bronze Age. Perhaps, animal husbandry was more important than cereal cultivation. Between 2000 and 500 cal. bc, Aeolian input from a distant source can be observed. During the late Bronze Age and Pre-Roman Iron Age, intensified field use enabled severe soil erosion (gullies c. 200 cal. bc). The degradation of soils started in this period, influenced by excessive land use, climatic variability, and/or the reduction in Aeolian deposition. The Roman Iron Age and Migration Period were phases of reduced human impact and soil formation. During medieval times, the intensity of field use increased again and another phase of soil erosion (gully in the 14th century, probably reflecting the ‘Magdalenenflut’ 1342) and soil degradation started. After the late medieval crisis caused by the ‘black death’ and several armed conflicts, another increase in soil erosion may reflect the rearrangement of estates (18th−19th century) and introduction of industrial agriculture (20th century). A recurrence of high-intensity erosion events is indicated at c. 1540, 1710, and probably 1939 ad. Whereas the lake trophic status is influenced by human impact on the lake catchment, wetter and warmer climatic phases are reflected in increased carbonate precipitation modulated by solar activity, human impact, and the long-term evolution of vegetation and soils in the lake catchment.

Holocene landscape dynamics at the tell Arslantepe, Malatya, Turkey – Soil erosion, buried soils and settlement layers, slope and river activity in a middle Euphrates catchment

Alluvial and colluvial sequences were studied around the prehistoric tell Arslantepe in 11 exposures and additional auger cores. The chronology is based on 11 optically stimulated luminescence (OSL) ages, four radiocarbon ages, and the embedded artifacts. Sediments contained wood charcoals, providing information on former vegetation. Fluvial activity is documented during Late Glacial times (15.4 ± 2.5, 12.8 ± 3.1 kyr) and frequently after Roman times. Slope and soil erosion occurred in the early (10.6 ± 1.4, 8.2 ± 0.7 kyr) and mid–late Holocene (6.7 ± 0.9, 5.4 ± 0.7–4.7 ± 0.7, 2.6 ± 0.2–2.5 ± 0.2, 1.9 ± 0.2–1.8 ± 0.2 kyr, and during the last 1000 years). The early Holocene erosion phases pre-date the so far established onset of settlement at the tell. This either indicates an earlier onset of agricultural land use than assumed or climatic influence on erosion, such as the 10.3 and 8.2 kyr climate events known from Western Europe. The erosion phases at around 5.0 and 2.6 kyr could reflect geomorphic responses to societal collapse (Late Chalcolithic state, Neo-Hittite kingdom) at Arslantepe. Most intensive Holocene soil erosion and landscape degradation occurred after occupation of the region by the Roman Empire. This is paralleled by the onset of river activity. A part of the lower neo-Hittite town as well as an early Holocene Terra Rossa–like soil that had formed rapidly were found buried. So far, no indication for mid–late Holocene fluvial activity of the adjacent creeks until Roman times has been found. Our results illustrate the large potential of slope deposits for long term reconstructions of human induced landscape transformation in Anatolia.

Palaeoclimatic indicators in soils buried under archaeological monuments in the Eurasian steppe: a review.

The Russian experience of the local reconstruction of the Eurasian steppe climate during the last 5000 years based on geoarchaeological approaches is reviewed. Examples of traditional palaeoclimatic reconstructions in Russia based on organic matter, highly soluble salts and gypsum content and location of salts and gypsum horizons in the profile of buried soils are given. Pedogenic carbonate as a palaeoclimatic indicator is considered. The possibilities of the quantitative reconstruction of the palaeoprecipitation based on magnetic properties of buried soils are observed. The innovative approach of palaeoclimatic reconstruction based on soil microbiology methods is reviewed. The problem of temporary transformation of palaeoclimatic indicators in buried soils is shown. A methodology for the interpretation of palaeoclimatic indicators of buried soils for a local palaeoclimatic reconstruction is given.

Mid-Holocene humid periods reconstructed from calcite varves of the Lake Woserin sediment record (north-eastern Germany)

Time-series of varve properties and geochemistry were established from varved sediments of Lake Woserin (north-eastern Germany) covering the recent period AD 2010–1923 and the mid-Holocene time-window 6400–4950 varve years before present (vyr BP) using microfacies analyses, x-ray fluorescence (µ-XRF) scanning, microscopic varve chronology, and 14C dating. The microscopic varve chronology was compared with a macroscopic varve chronology for the same sediment interval. Calcite layer thickness during the recent period is significantly correlated to increases in local annual precipitation (r = 0.46, p = 0.03) and reduced air-pressure (r = −0.72, p < 0.0001). Meteorologically consistent with enhanced precipitation at Lake Woserin, a composite 500 hPa anomaly map for years with >1 standard deviation calcite layer thickness depicts a negative wave train air-pressure anomaly centered over southern Europe, with north-eastern Germany at its northern frontal zone. Three centennial-scale intervals of thicker calcite layers around the mid-Holocene periods 6200–5900, 5750–5400, and 5300–4950 vyr BP might reflect humid conditions favoring calcite precipitation through the transport of Ca2+ ions into Lake Woserin, synchronous to wetter conditions in Europe. Calcite layer thickness oscillations of about 88 and 208 years resemble the solar Gleissberg and Suess cycles suggesting that the recorded hydroclimate changes in north-eastern Germany are modified by solar influences on synoptic-scale atmospheric circulation. However, parts of the periods of thicker calcite layers around 5750–5400 and 5200 vyr BP also coincide with enhanced human catchment activity at Lake Woserin. Therefore, calcite precipitation during these time-windows might have further been favored by anthropogenic deforestation mobilizing Ca2+ ions and/or lake eutrophication.

A mid-Holocene annually laminated sediment sequence from Lake Woserin : The role of climate and environmental change for cultural development during the Neolithic in Northern Germany

Annually laminated sediments of Lake Woserin in north-eastern Germany are investigated using sedimentological and palynological methods. They facilitate high-resolution reconstruction of environmental and land-use change during ca. 7000–4000 cal. BP. Between 6100 and 5800 cal. BP, changes in woodland composition and structure are evident which coincide with a change in subsistence strategy, that is, the adoption of animal husbandry. For the remaining period, eight phases of enhanced human impact (5750–5390, 5270–5150, 4890–4750, 4670–4600, 4520–4450, 4390–4350, 4250–4170 and 4070–3930 cal. BP) are identified. Hereby, the first phase relates to an opening of the landscape in connection with the adoption of large-scale, extensive cereal cultivation. Phases of decreased human impact are generally characterised by woodland regeneration. Over-regional comparison of the results reveals similar and synchronous fluctuation of human impact in the young moraine area of the south-western Baltic region and hints at a large-scale driver. In order to evaluate the role of environmental change for human activity, evidence for coinciding shifts in palaeoclimate records and their potential implication for human–environment interactions are discussed and generally support the idea that environmental changes played an important role for the cultural development during the Neolithic in Northern Germany. Hereby, climate change probably favoured the adoption of new subsistence strategies during the early Neolithic (6100–5350 cal. BP). Furthermore, the fluctuating human impact during Middle and Younger Neolithic (5350–4100 cal. BP) could indicate a socio-economic system susceptible for short-termed climatic fluctuation.

Interpretation of prehistoric reddish pit fillings on Easter Island: A micromorphological perspective

In the context of geoarchaeological investigations on Easter Island several hundred human-made pits filled with reddish silty material were discovered in fluvial terraces of two valleys on the southern slope of Maunga Terevaka, the highest volcano of the island. Micromorphological analysis of one representative pit filling and comparison of its geochemical and physical properties with sediments in the surrounding terrace was performed in order to reconstruct the probable formation and use of the material in the pits. A hypothesis of pigment production by heating of minerogenic iron-rich substrate with grass fuel resulting in formation of hematite is suggested. It is assumed that the pits represented the places for production and storage of the pigments, which were used by Rapa Nui for cultural and ritual purposes. The ongoing interdisciplinary research will enhance the interpretation of the pits and their fillings and contribute to a better understanding of cultural development on Easter Island.