Radiocarbon dating of prehistoric hearths in alpine northern Sweden: problems and possibilities

The chronology of prehistoric Sami settlement sites has previously been established by conventional radiocarbon dating of bulk charcoal samples associated with hearths from sunken hut floors (stállo-foundations). Here we present results of a comprehensive dating exercise of stállo-foundations in the alpine area of northern Scandinavia using Accelerator Mass Spectrometry (AMS) radiocarbon dating of charcoal. Over a 3 km² study area, AMS calibrated ages of hearth charcoal from 22 stállo-foundations across 12 sites securely date these features to between cal. AD 640 and AD 1180. Only small variations in age were found between charcoal samples from different areas of a given hearth. Statistical analysis of all the charcoal AMS radiocarbon dates obtained reveals that 12 stállo-foundations across nine sites are contemporaneous and date to the Viking Period (AD 800–AD 1050). The tightly constrained AMS-based chronology of stállo-foundations contrasts with the existing chronology based on conventional radiocarbon analysis, which places these features within a significantly greater time-frame of between AD 600 and AD 1900, with most dates ranging between AD 800 and AD 1350.This discrepancy is likely to result from the necessity of collecting composite hearth charcoal particles, which may originate from different phases of occupation, in order to achieve the required final carbon content for conventional radiocarbon analysis. We argue that the new AMS-based radiocarbon chronology of stállo-foundations presented here supersedes the existing chronology based on conventional (Gas Proportional counting) radiocarbon analysis and we advocate the use of AMS radiocarbon dating in future hearth investigations.     

A charcoal-rich horizon at Ø69, Greenland: evidence for vegetation burning during the Norse landnám?

It is often assumed that the colonisation of Greenland by Norse settlers in c. A.D. 985 had a sudden and dramatic effect on the environment, involving substantial vegetation clearance and environmental degradation. Consequently, it has been argued that charcoal-rich horizons, visible in many sections in Greenland, represent the initial burning of the vegetation by Norse farmers to create land suitable for agriculture. In this study a charcoal-rich layer, visible in a modern drainage ditch beside the Norse farm of Ø69, was analysed using archaeobotany, sedimentary analysis and radiocarbon dating to test the date and formation processes of the horizon. It is demonstrated that the charcoal-rich layer at Ø69 was not derived from in situ vegetation burning in the 10th century and concluded that the layer was probably formed by the addition of midden material to the infields around Ø69 in the 13th and 14th centuries cal AD, perhaps as part of a soil amendment strategy. It is argued that caution must be exercised when interpreting charcoal-rich horizons as time-specific chronological markers in palaeoenvironmental sequences in Greenland.     

Radiocarbon reservoir effects in human bone collagen from northern Iceland

Human bone collagen from a series of Icelandic human pagan graves was radiocarbon (¹⁴C) dated to aid understanding of early settlement (landnám) chronologies in northern Iceland. These individuals potentially consumed marine protein. The ¹⁴C age of samples containing marine carbon requires a correction for the marine ¹⁴C reservoir effect. The proportion of non-terrestrial sample carbon was quantified via measurement of carbon stable isotopes (δ¹³C) using a simple mixing model, based on δ¹³C measurements of archaeofaunal samples. Non-terrestrial carbon was also quantified in six pig bones from the archaeofaunal dataset. Assuming all non-terrestrial carbon in human and pig bone collagen was marine-derived, calibrated age ranges calculated using a mixed IntCal09/Marine09 calibration curve were consistent with an early settlement date close to landnám, but several samples returned pre-landnám age ranges. Measurements of nitrogen stable isotopes (δ¹⁵N) strongly suggest that many of the human bone collagen samples contain freshwater diet-derived carbon. Icelandic freshwater systems frequently display large freshwater ¹⁴C reservoir effects, of the order of 10,000 ¹⁴C years, and we suggest that the presence of freshwater carbon is responsible for the anomalously early ages within our dataset. In pig samples, the majority of non-terrestrial carbon is freshwater in origin, but in human samples the proportion of freshwater carbon is within the error of the marine component (±10%). This presents a major obstacle to assessing temporal patterns in the ages of human remains from sampled graves, although the majority of grave ages are within the same, broad, calibrated range.     

Paleoenvironmental catastrophies on the Peruvian coast revealed in lagoon sediment cores from Pachacamac

Paleoenvironmental reconstruction combining data from diatom, pollen, macrophytic, and archaeological analyses had not been attempted previously for coastal Peru. We analyzed two radiocarbon-dated sediment cores extracted from the “sacred” Urpi Kocha Lagoon at the pre-Hispanic religious center of Pachacamac (ca. AD 350-1533), near Lima, to characterize the paleoenvironment of the site. The data reveal an environmental history characterized by alternating periods of severe drought and catastrophic flood. Recurrent pulses with distinctive sediment, diatom, pollen, and macrophytic characteristics reflecting variations in water depth, substrate, turbidity and salinity, usually contain a thick basal sandy storm deposit overlain by thin organic accumulations of peat, gyttja, and snails. The most intense of these disturbance pulses, when correlated with pollen, plant macrofossils, radiocarbon dates, and regional proxy data, provide local evidence of four major floods associated with sustained, catastrophic El Niño events, tsunamis and/or severe storms in the Andean highlands over the last 2000 years.     

Soils and palaeo-climate based evidence for irrigation requirements in Norse Greenland

Establishing and sustaining agricultural production was a key factor in the success of Norse settlements during the landnám colonisation across the North Atlantic. In light of the occurrence of channel features in several abandoned home-field areas of the Norse Eastern Settlement of Greenland, and the irrigation requirements of present-day Greenlandic sheep-farmers questions are raised: was irrigation used by the Norse settlers of Greenland on their home-field areas? and, if so, how frequently? Modelling of soil chemical, physical and soil-water hydraulic properties integrated with contemporary high-resolution climatic data demonstrate a frequent requirement for irrigation. Soil moisture deficits are related to the duration and intensity of winter temperature. Using the winter Dye 3 ice core δ¹⁸O record as a climatic proxy, the frequency of moisture deficits, based on comparing mean winter temperatures, indicates that there was a frequent irrigation requirement to maintain home-field productivity, increasing throughout the period of settlement until the 14th Century.     

Fuel Fodder and Faeces: An Ethnographic and Botanical Study of Dung Fuel Use in Central Anatolia

Abstract

The Norse inhabited Greenland between AD 1000 and AD 1500 and, toward the end of the occupation, according to archaeological evidence, they were predominately marine mammal hunters. Despite the fact that marine resources became important for subsistence, the Norse Greenlanders settled the area in o?der to farm. This is indicated by site locations, faunal material, archaeobotanical, and palynological evidence.

Phytolith analysis from a quern stone, likely made from stone of local origin, found at Gården Under Sandet, a Norse farmstead in Greenland, was examined to determine if there was any evidence indicating domestic cereal processing. The phytoliths found on the quern stone can be associated with grasses and sedges, but the absence of dendritic phytoliths likely indicates that the quern stone was not used to grind seed. This preliminary study demonstrates that information about Norse agriculture may be obtained by examining the phytolith remains from a quern stone.     

Tephrochronology,Environmental Change and the Norse Settlement of Iceland

Abstract

The first human impacts on the Icelandic environment came with the Norse colonisation or Landnám of the ninth century AD. The colonisation represents a fundamental environmental change that is both rapid and profound. In this paper we assess geomorphological dimensions of the initial settlement period using a tephrochronology that includes the Landnám Tephra, erupted ca. 870 AD, two tenth century AD tephras KR 920 and E 935, and 11 other well dated tephra layers. We report a new ¹⁴C age of 1676 ±12 ¹⁴C yr BP (cal AD 345 (400) 419) for the tephra SILK-YN which forms a key prehistoric marker horizon that constrains rates of environmental change in the centuries before Norse Settlement. Aeolian sediment accumulation rates show five geomorphological responses to settlement that differ in the rate and trajectory of change. These distinct anthropogenic signals are the result of spatially variable sensitivity to grazing and deforestation, and reflect the extent of local soil erosion. This critical erosion threshold is variable in space and time.     

Interdisciplinary studies of spring mire deposits from Radzików (South Podlasie Lowland,East Poland) and their significance for palaeoenvironmental reconstructions

The paper presents the results of interdisciplinary (multiproxy) palaeoenvironmental studies of peat — calcareous tufa depositional sequences of spring mire from Radzików site (east Poland). Analyses of three biotic proxies (plant macrofossils, pollen, molluscs) were supplemented with sedimentological, geochemical, oxygen and carbon stable isotopes analyses and radiocarbon dating and used for reconstruction of environmental changes in Late Glacial and Holocene. The obtained results enable us to (1) reconstruct main phases of mire development and (2) determine environmental factors influencing changes of water supply.     

Vegetation history at the multi-period prehistoric complex at Ballynahatty,Co. Down,Northern Ireland

Palaeoecological methods can provide an environmental context for archaeological sites, enabling the nature of past human activity to be explored from an indirect but alternative perspective. Through a palynological study of a small fen peatland located within the catchment of a multi-period prehistoric complex at Ballynahatty, Co. Down, Northern Ireland, we reconstruct the vegetation history of the area during the early prehistoric period. The pollen record reveals tentative evidence for Mesolithic activity in the area at 6410–6220 cal BC, with woodland disturbance identified during the Mesolithic–Neolithic transitional period ca. 4430–3890 cal BC. A more significant impact on the landscape is observed in the Early Neolithic from 3950 to 3700 cal BC, with an opening up of the forest and the establishment of a mixed agricultural economy. This activity precedes and continues to be evident through the Mid-Neolithic during which megalithic tombs and related burial sites were constructed at Ballynahatty. Due to chronological uncertainties and a possible hiatus in peat accumulation in the fen, the contemporary environment of the Ballynahatty timber circle complex (constructed and used ca. 3080–2490 cal BC) and henge (dating to the third millennium cal BC) cannot certainly be established. Nevertheless, the pollen record suggests that the landscape remained open through to the Bronze Age, implying a long continuity of human activity in the area. These findings support the idea that the Ballynahatty prehistoric complex was the product of a gradual and repeated restructuring of the ritual and ceremonial landscape whose significance continued to be recognised throughout the early prehistoric period.     

Paleo-Eskimo kitchen midden preservation in permafrost under future climate conditions at Qajaa,West Greenland

Remains from Paleo-Eskimo cultures are well-documented, but complete preservation is rare. Two kitchen middens in Greenland are known to hold extremely well-preserved organic artefacts. Here, we assess the fate of the Qajaa site in Western Greenland under future climate conditions based on site characteristics measured in situ and from permafrost cores. Measurements of thermal properties, heat generation, oxygen consumption and CO₂ production show that the kitchen midden can be characterized as peat but produces 4–7 times more heat than natural sediment. An analytical model from permafrost research has been applied to assess future thawing of the midden. Results show that the preservation conditions are controlled by freezing temperatures and a high water/ice content limiting the subsurface oxygen availability. Threats to the future preservation are related to thawing followed by drainage and increasing subsurface oxygen availability and heat generation. The model predicts that the unique 4000-year-old Saqqaq layer below more than 1 m of peat is adequately protected against thawing for the next 70 years.     

Pastures lost? A dental microwear study of ovicaprine diet and management in Norse Greenland

The management of ovicaprines by the Medieval Norse farmers in Greenland is explored using dental microwear analysis. Adult and juvenile ovicaprines from Norse contexts in Greenland are shown to exhibit microwear patterns very different to those in modern Greenlandic sheep; while modern sheep demonstrate microwear consistent with low levels of soil ingestion under extensive, low stocking-rate grazing regimes, Norse sheep/goat display striated microwear patterns indicative of high levels of soil ingestion and, potentially, overgrazing. This high abrasive grazing signature is present in the inland region of the Western Settlement from 1150 AD onwards, may be evident in the inland Eastern Settlement from an equally early date and is also detected during the later phases of occupation in the Western settlement (14th and 15th centuries AD). It is argued that these results provide further evidence that maladaptive grazing practices led to a decline in the viability of pastoral farming in Greenland, and, moreover, that overgrazing did not merely occur towards the end of the settlement as a consequence of the worsening climate of the ‘Little Ice Age’ but rather was present in both the Western and the Eastern Settlement from a relatively early date.     

Insects in an abandoned landscape: late Holocene palaeoentomological investigations at Sandhavn,Southern Greenland

Abstract

The late Holocene landscape and environment at Sandhavn in Greenland's Eastern Settlement are considered in the light of recent palaeoentomological investigations. Samples dating to post-Norse peat accumulation suggest that Norse activity had no lasting effect on the beetle fauna and environment at Sandhavn after its abandonment in the Medieval period. The faunas recovered may be assumed to be characteristic of the surrounding environment, and indicate that the site was situated in an area of wetland and heath. The assemblages are discussed in the context of the sub-fossil and modern coleopteran faunal history of the North Atlantic islands, and as evidence for post-abandonment environmental conditions in Greenland.     

A Bayesian AMS C chronology of the Classic Maya Center of Uxbenká, Belize

Archaeologists require precise chronologies of cultural change to understand the nature and timing, and causes and effects, of ecological and social transformations. The Uxbenká Archaeological Project (UAP) has made chronology building a main goal, employing epigraphic data, artifact seriation, and high-precision AMS ¹⁴C dating. With more than 60 ¹⁴C dates with measurement errors below ±25 ¹⁴C yr, primarily on single charcoal specimens, Uxbenká may be the most intensively dated Classic Period site in the tropical Maya Lowlands. Here we take the next step, combining this rich chronometric dataset with associated stratigraphic information in OxCal's Bayesian framework to generate a high-resolution chronology of Uxbenká's early development and expansion in southern Belize. We show how archaeologists may take advantage of complex architectural stratigraphy to constrain broad calibrated ranges during the Classic Period, and to estimate dates for observed construction events that can not be directly dated (e.g., clearing/leveling plazas, laying plaster floors, renovating/rebuilding structural elements). Our analysis confirms the antiquity of the ceremonial Stela Plaza (Group A), where first construction is estimated between 60 cal BC and cal AD 220 and is associated with a Pre-Classic structure obscured by later construction and reorientation of the group to a N-S alignment ca. AD 150–310. The analysis also indicates initial leveling and construction at plaza Group B from cal AD 60–310 and Group D from cal AD 20–240, both earlier than previously assumed. Though Late Classic contexts are not as well represented by direct dates, architectural modifications are documented at all three plaza groups after AD 550, including the extensive plastering, laying paving stones, and construction of facades on existing structures. The resulting chronology revises our previous thinking on the mode of settlement and development of Classic Maya society at Uxbenká and indicates specific areas of investigation to elucidate events in the Late and Terminal Classic at the site, including political and social fragmentation and the abandonment of the urban core late in the Classic Period.     

Pollen analysis in the context of clearance cairns from boreal forests – a reflection of past cultivation and pastoral farming

The former agricultural use of two sites located in the boreal forest of eastern Norway is investigated through pollen analysis. A peat profile was taken from the vicinity in each of two clearance cairn fields where several cairns were analysed for pollen. The pollen samples from the peat profiles give an environmental context for the pollen samples from the clearance cairns, and this combination of samples assists in evaluating the management practices that were in place on the cairn fields during different time periods. In both study areas cultivation layers under the clearance cairns are dated to the Late Roman Iron Age (cal. AD 200–400), while the oldest clearance cairns are dated to the Migration period (cal. AD 400–570), and a second phase of clearance cairn establishment is dated to the Medieval period (cal. AD 1030–1537). Abandonment of the two cairn fields is dated to c. AD 1700. Pioneer trees were a feature on or around the clearance cairn fields during most of the Iron Age, whereas the cairn fields were more open in medieval times. The investigation suggests that cereal cultivation on the clearance cairn fields is difficult to detect in local peat deposits, and that caution is needed when interpreting lack of Cerealia pollen. Management practices on the cairn fields are discussed and a change in management practice is indicated in association with medieval intensification.     

Red abalone collecting and marine water temperature during the Middle Holocene occupation of Santa Cruz Island,California

Oxygen isotope values derived from prehistoric mussel (Mytilus californianus) shell calcite are used to determine whether sea-surface temperatures in the vicinity of the Punta Arena site (CA-SCRI-109) on Santa Cruz Island, California, were cooler than present between 6300 and 5300 cal BP. This site and others in the western sector of the island dating to this period are distinctive because of the presence of large red abalone (Haliotis rufescens) shells, a species that historically has been subtidal around Santa Cruz and the other northern Channel Islands. Comparison of temperature values derived from archaeological shells with those from modern mussel shells, along with water temperatures derived from satellites, indicates that waters were cooler during the 6300 to 5300 cal BP period. These results are consistent with a previous study and support the interpretation that collection of red abalone during the 6300–5300 cal BP period was partly the result of cooler water temperatures that made this large mollusk more available to foragers in the intertidal or shallow subtidal zone.     

Sweet potato (Ipomoea batatas) and banana (Musa sp.) microfossils in deposits from the Kona Field System,Island of Hawaii

Analysis of plant microfossils (pollen, phytoliths, starch grains and xylem cells) was carried out on 12 soil samples from a variety of pre-contact archaeological features in South Kona within a portion of what has been termed the Kona Field System, on the Island of Hawaii. The oldest radiocarbon ages of the sampled deposits are 1300–1625 AD and 1310–1470 AD. The pollen and phytolith evidence suggests a change from more to less trees and shrubs in the area as a result of human activity. We found phytoliths of banana (Musa sp.) leaves in most and starch grains and xylem cells of tuberous roots of c.f. sweet potato (Ipomoea batatas) in all of the samples, suggesting that the sampled features were associated with these crops and that both crops were cultivated intensively within the study area. Higher concentrations (volumetric) of starch and xylem in samples from older deposits suggest that cultivation was more intensive then. The apparent absence of starch and xylem remains of other tuberous crops archaeologically identified elsewhere in Polynesia suggests that tuberous cropping within the study area was mono-specific.     

Pollen-wood analysis at the Neapolis harbour site (1st–3rd century AD,southern Italy) and its archaeobotanical implications

Three Roman shipwrecks (Napoli A and Napoli C – 1st cent. AD; Napoli B – 2nd century AD) were recovered in the sandy-silt sediments representing the infilling of a protected inlet of Neapolis harbour (Naples, southern Italy). Extensive wood analysis suggests that a very attentive selection of species was made in shipbuilding, the choice of timber being related to wood technological properties and to the structural uses of the construction elements. Pollen data obtained from the coeval sedimentary layers revealed that all the timber taxa (apart from Picea/Larix) were present in the surroundings of the study area. The identified forest taxa are very common in the Mediterranean basin and thus the pollen-wood comparison was not able to define the location of the shipyards. Broad comparison with western Mediterranean wrecks evidenced the peculiarity of the Neapolis ships where the systematic use of both Juglans regia and Cupressus sempervirens was highlighted. Archaeological, biogeographical and archaeobotanical considerations suggest the local provenance of the ship C and constrain the possible origin area of both the ship Napoli A and Napoli B to central-southern Tyrrhenian coasts.     

Frogs as a part of the Eneolithic diet. Archaeozoological records from the Czech Republic (Kutná Hora-Denemark site, Řivnáč Culture)

Within the site of Kutná Hora-Denemark (Kutná Hora distr., central Bohemia – Eneolithic, ?ivná? Culture, 3000–2800 BC), 893 frog bones or bone fragments were present in five archaeological features. All identified specimens are of the Common Frog (Rana temporaria Linnaeus, 1758). Males predominate, according to humeral morphology, and only adult individuals are present. The most important findings come from feature 36, where an accumulation of 739 frog bones (MNI = 123) were found, of which 10% (NISP) were burned. This and other contextual evidence indicates that they relate to activity of the Eneolithic people in the settlement. The predominance of hind leg bones and other circumstantial evidence suggest that the frogs were part of the human diet. Behavioural studies of this species suggest that the frogs were gathered from small ponds during the months of March or April. Similar findings are rare.     

Combining pollen and charcoal: evaluating Holocene vegetation composition and dynamics

Pollen analysis reveals vegetation change on a local and regional level over (ideally) continuous time spans but with complications when it comes to the reconstruction of spatially precise species occurrence and composition. Wood charcoal analysis provides site-related information on species occurrence and woodland composition, especially when sediments containing pollen are lacking, but is normally discontinuously available and has the danger of human bias due to potential selection of certain species for e.g. fire making, house construction or charcoal making. Combining the two methods – assuming that suitable palaeoarchives are neighbouring – might compensate for their disadvantages and strengthen the interpretations on vegetation composition and dynamics on a local, extra-local and regional scale. Three examples are given where pollen analysis from “classical” archives – mires and lake sediments – was carried out, and where additionally species identification of wood charcoals was done on samples extracted from close-by archives. The first example (Kugelstattmoos, Bavarian Forest, Germany) combines a Holocene pollen diagram derived from a small mire with late medieval/early modern times charcoal spectra from charcoal production sites which are situated on the margin of the mire. Results show the local occurrence of the main woodland species Fagus sylvatica and Abies alba, and raises new questions on the montane species composition of the formerly natural forests in the Bavarian Forest. The second example (Bargstedter Moor, Schleswig-Holstein, Germany) combines Holocene pollen diagrams from a peat bog with late medieval/early modern times charcoal spectra from charcoal production sites in a woodland close to the bog. It shows the role of Quercus, Fagus, Alnus and Carpinus in medieval and early modern times woodlands and its use by man. The third example (Kleiner Tornowsee, Brandenburg, Germany) combines pollen data from sediments of a small lake with charcoal data derived from Holocene colluvisols and soils. The examples show that anthracological and palynological data complement one another to create a more detailed picture of woodland history and landscape change than one method alone would provide.     

Intensifying collection and size increase of the tessellated nerite snail (Nerita tessellata) at the Coconut Walk site,Nevis, northern Lesser Antilles,AD 890–1440

Recent archaeological investigation at the Coconut Walk site on the Caribbean island of Nevis revealed dense 40 cm deep midden deposits that accumulated between cal AD 890–1440. Analysis of invertebrate faunal remains reveals an assemblage dominated by nerite snails. We measured the length and width of more than 2700 tessellated nerite (Nerita tessellata) shells to investigate evidence for changing mean size that might be indicative of intensifying human predation pressure or other cultural and natural processes. Contrary to similar archaeomalacological studies in which size decline is detected, we observed a statistically significant size increase for N. tessellata over time. This size increase is coupled with increasing levels of tessellated nerite exploitation at the Coconut Walk site. Results suggest that tessellated nerite use was sustainable over several centuries of site occupation. Our findings have important implications for investigations of anthropogenic impacts on prehistoric mollusc populations. In addition, the findings reported here provide important insight into human subsistence patterns during the Late Ceramic Age in the Caribbean and a framework for comparison with observations from other Pre-Columbian sites in the Caribbean.