A survey of British metamorphic hone stones of the 9th to 15th centuries AD in the light of potassium-argon and natural remanent magnetization studies

Hone stone trade and use during the period of Scandinavian-English interaction (9th–15th centuries AD) was dominated by two metamorphic petrological types represented by the “Norwegian Ragstone” (NR) a quartz-mica schist, and the “Purple Phyllite” (PP) a quartz-mica phyllite, and finds are abundant throughout the Viking world. Petrology associates the NR type with the known quarries at Eidsborg, southern Norway, and this has been endorsed by isotopic evidence. The source of the PP type remains unknown, but has been postulated to be a second facies of Eidsberg material, or even a Variscan phyllite from Belgium. It was the purpose of this study to further refine the possible source area of the PP material. Age data now indicate a “Caledonian” source for the PP type. Within Europe the superposition of metamorphic belts has led to the occurrence of both schist and phyllitic metamorphic lithologies. Petrological criteria therefore rarely provide evidence of the source of such rocks. The zonation of Europe by metamorphic belts does, however, allow isotopic age studies to be used as an aid to provenancing. The PP hones exhibit a range of mineralogy which may indicate a variety of sources, although no archaeological sites capable of producing such a quantity of material have been identified within the Viking world. The evidence, however, indicates a source in the Norwegian Caledonides.     

Possible isotopic fractionation of argon in source obsidians and archeological artifacts from Kulkuletti, Ethiopia

Despite uniform geochemistry ⁴⁰Ar/³⁹Ar ages of 0.6, 1.25, and 1.3 Ma on obsidians from a source flow (Worja) and from archeological artifacts at the sites of Kulkuletti (near Gademotta, Ethiopia) have been interpreted to suggest that they derive from different source flows of different ages. A further suggestion is that the magmatic source of the obsidian flows was chemically homogeneous between 1.3 Ma and 0.6 Ma. Chemical analysis of these obsidians indeed suggests that they derive from a single flow. Reexamination of the argon isotopic data reveals that argon isotopes may have been fractionated within the flow, so that the assumption of an atmospheric ⁴⁰Ar/³⁶Ar ratio of 295.5 is inappropriate to use for computing ages. Three groups of data are apparent, and internally all yield ages near 1.3 Ma if the intercept value for ⁴⁰Ar/³⁶Ar from an isotope correlation plot is used for computation instead of using the atmospheric ratio. The Soret thermal diffusion effect provides a possible mechanism of fractionation of argon within the obsidian flow that is of approximately the right magnitude to explain the observations by in-diffusion of already fractionated atmospheric argon.     

Social status in the Merovingian and Viking periods in Norway from archaeological and historical sources

Generally, the social structure (stratification of the society) in the Merovingian and Viking periods in Norway has been studied by historians using mainly historical and linguistic material. However, prehistoric burials are supposed to reflect the social status of the deceased, and in the present study social status in the Merovingian and Viking periods in western, central and eastern Norway has been examined through 4629 grave finds recorded in the museums’ list—3796 were defined as men's grave finds and 833 as women's. On the basis of the composition of the grave material both the men's and women's graves could be divided into three groups: a large lower group with plain grave material, a small upper group with the richest finds, and an intermediate group. This grouping was supported by studies of the professionally excavated graves from 1956–1978 and indicated three distinctive social groups of free men and women. The grouping of the men's graves on the basis of weapon composition showed only a fair association with the weapon requirements and the social status indicated by the provincial laws from the early Middle Ages. However, studies of 177 precisely dated weapon graves demonstrated a closer association between the requirements of the laws and the weapon composition of the 10th century graves than of those from the 8th and 9th centuries. Accordingly, the grave finds from the Merovingian and Viking periods as well as the historical sources from the early Middle Ages reflect a society with marked differences in social status, the grave finds from the 10th century showing the best correspondence to the provincial laws.     

Representative archaeological finds of <Emphasis Type="Italic">pietra ollare</Emphasis> from Comacchio (Italy): identifying provenance and high-T mineral breakdown reactions hindering lithotype classification

Three different lithotype groups have been recognized in representative fragments of pietra ollare artefacts found in the mediaeval archaeological excavations of Comacchio (Italy). Petrographic, mineralogical and chemical compositions clearly show that Valchiavenna and Valmalenco, in the Central Alps, represent the provenance areas of two of the pietra ollare groups, i.e. grey carbonate talc schist (also known as soapstone) and green chlorite schist, respectively. The third representative pietra ollare group consists of whitish-yellowish rocks inferred to be Alpine talc schists that have suffered some artificial pyrometamorphic transformation hindering their classification in the framework of pietra ollare lithotype categories and source localities reported in literature. A distinguishing feature of these high temperature-fired (HT-fired) talc schist samples is the occurrence of talc and chlorite dehydroxylation and subsolidus reaction products, mainly protoenstatite/enstatite + forsterite, together with relatively low loss on ignition values. These talc schists might have been exposed to temperatures >900 °C (with the resulting talc dehydroxylation producing a void-rich texture), but never reaching 1200 °C, which is the sintering temperature for soapstones. The whitish-yellowish artefacts were definitely not used as containers for cooking food at temperatures below or around 500–600 °C (as instead shown by the preservation of the original physical features of the grey pietra ollare lithotypes), but in some kind of higher-T pyrotechnological processes.     

Influence of fault map resolution on pore pressure distribution and secondary hydrocarbon migration; Tune area,North Sea

Pressure and hydrocarbon migration modelling was carried out in the Tune Field area, Viking Graben, offshore Norway. The pressures are considered to be controlled by compartments bounded by mapped faults. Two different interpreted fault maps at the top reservoir level (Brent Group) are used as input to the modelling. First, a low‐resolution fault map is used, with only the large faults interpreted, and next, both large and small faults are included. The simulations show high overpressures generated in the western area, in the deeper part of the Viking Graben, and hydrostatic in the eastern areas. A sharp transition zone results from using the low‐resolution fault map in the simulations. Small N–S striking faults situated in between the wells have to have higher sealing capacity than expected from juxtaposition analysis alone, to be able to match the overpressures measured in well 30/5‐2 and 30/8‐1S in the Tune Field, and well 30/8‐3 east of Tune. The intermediate pressure in the western part is probably related to flow in the deeper parts of the sedimentary column in the compartment, where well 30/8‐3 is situated. The secondary oil migration models show that overpressures have major effects on the migration pathways of hydrocarbons. The level of detail in the fault interpretation is important for simulation results, both for pressure distribution and for hydrocarbon migration.     

Viking woollen square-sails and fabric cover factor

The discovery of the five scuttled Viking ships of Roskilde Fjord in Denmark and the subsequent excavation, preservation and analysis of the remains has initiated a programme of reconstructive archaeology led by the Viking Ship Museum of Roskilde in which four of the five hulls have now been reconstructed together with their rigs and square-sails. The reconstruction of the sails has been based on fragments of heavy woollen cloth found within the roof of Trondenes church in Norway dating to the mid-13th century. This paper uses the'cover-factor' modelling methods of modern textile engineering to analyse the'Viking' sail fabrics and assess their strength, resilience and performance in comparison with the linen sails from the wreck of the Vasa .     

A vector of high‐temperature paleo‐fluid flow deduced from mass transfer across permeability barriers (quartz veins)

Quartz veins acted as impermeable barriers to regional fluid flow and not as fluid‐flow conduits in Mesoproterozoic rocks of the Mt Painter Block, South Australia. Systematically distributed asymmetric alteration selvedges consisting of a muscovite‐rich zone paired with a biotite‐rich zone are centered on quartz veins in quartz–muscovite–biotite schist. Geometric analysis of the orientation and facing of 126 veins at Nooldoonooldoona Waterhole reveals a single direction along which a maximum of all veins have a muscovite‐rich side, irrespective of their specific individual orientation. This direction represents a Mesoproterozoic fluid‐flow vector and the veins represent permeability barriers to the flow. The pale muscovite‐rich zones formed on the downstream side of the vein and the dark biotite‐rich zones mark the upstream side. The alteration couplets formed from mica schist at constant Zr, Ga, Sc, and involved increases in Si, Na, Al and decreases in K, Fe, Mg for pale alteration zones, and inverse alteration within dark zones. The asymmetry of the alteration couplets is best explained by the pressure dependence of mineral–fluid equilibria. These equilibria, in combination with a Darcian flow model for coupled advection and diffusion, and with permeability barriers imposed by the quartz veins, simulate the pattern of both fluid flow and differential, asymmetric metasomatism. The determined vector of fluid flow lies along the regional foliation and is consistent with the known distribution of regional alteration products. The presence of asymmetric alteration zones in rock containing abundant pre‐alteration veins suggests that vein‐rich material may have generally retarded regional fluid flow.     

THE SECTILIA PANELS OF FARAGOLA (ASCOLI SATRIANO,SOUTHERN ITALY): A MULTI‐ANALYTICAL STUDY OF THE GREEN,MARBLED (GREEN AND YELLOW), BLUE AND BLACKISH GLASS SLABS

Analyses at the Cu–K, Fe–K and Mn–K edge were performed to study the green, marbled (green and yellow), blue and blackish (deep greyish olive green) glass slabs decorating three sectilia panels from the archaeological site of Faragola. Results indicate that all slabs were made by mixing siliceous sand with natron, sometimes probably mixed with small percentages of plant ash. Cu²⁺ and Pb antimonates should be responsible for the opaque green colours. The dark green and yellow portions of the marbled slabs are respectively comparable to the slabs comprising only one of these colours. Cu²⁺ together with Ca antimonates probably produced light blue slabs, whereas cobalt was used to produce dark blue slabs. We consider it possible that the abundance ratio of Fe²⁺/Fe³⁺ and the complex Fe³⁺S^2? would have an effect on the blackish slabs. The contribution of Mn cannot be ascertained even if it could have played a role in darkening glass colour. The comparison between the chemical composition of Faragola samples and several glass reference groups provided no conclusive evidence of provenance; whereas, the presence of a secondary local workshop can be hypothesized.     

Rapid denudation of Higher Himalaya during late Pliestocence, evidence from OSL thermochronology

Optically Stimulated Luminescence (OSL) of quartz, with closure temperatures of 30–35°C in conjunction with Apatite Fission Track (AFT; closure temp. ～120°C) and ⁴⁰Ar-³⁹Ar (biotite closure temperature ～350°C), were used to obtain cooling ages from Higher Himalayan crystalline rocks of Western Arunachal Himalaya (WAH). Cooling age data based on OSL, AFT and Ar-Ar thermochronology provide inference on the exhumation — erosion history for three different time intervals over million to thousand year scale. Steady-state exhumation of ～0.5 mm/yr was observed during Miocene (>7.2 Ma) till Early Pleistocene (1.8 Ma). Onset of Pleistocene glacial/interglacial conditions from ～1.8 Ma formed glaciated valleys and rapid erosion with rivers incising deep valleys along their course. Erosion enables midcrustal partial melts to move beneath the weak zone in the valley and causes an erosion-induced tectonic uplift. This resulted in a rapid increase in exhumation rate. The OSL thermochronology results suggest increased erosion over ～21 ka period from Late Pleistocene (2.5 mm/yr) to Early Holocene (5.5 mm/yr) and these are to be contrasted with pre 1.8 Ma erosion rate of 0.5 mm/yr. Enhanced erosion in the later stage coincides with the periods of deglaciation during Marine Isotope Stages (MIS) 1 and 2. The results of the present study suggest that in the present setting OSL thermochronology informed on the short-term climatic effect on landscape evolution and techniques like the AFT and ⁴⁰Ar-³⁹Ar provided longer-term exhumation histories.     

Whetstone Typology: Or the First Shipwreck of Turid Fiskarbekk and Marine Archaeologists Who Had to Think Again

Finds from the Viking period, the middle ages and from more recent historical trading places and towns in northern Europe show that the export of whetstones from Eidsborg in the Telemark district of southern Norway has a history of more than 1,000 years. The water-based route from the quarry area, 600 m above sea level, to the nearest shipping port consists of 120 km of lakes, rivers and portages. This article takes up the export history in the light of a recently discovered cargo of whetstones found in Flåvann, Telemark. The history of the recovery of the find shows that the cargo examined most probably leads to an incident in the 1820s and, to a woman named Turid Fiskarbekk. The find leads to a wider perspective, more specific to the life of Turid Fiskarbekk. Therefore the article presents a side-story about her, where the intention is to show how integrating a gender perspective in maritime archaeology makes new knowledge possible.     

Forensic Ar/Ar dating: a provenance study of Middle Stone Age obsidian artifacts from Ethiopia

Obsidian sourcing based on geochemistry is widely applied to reconstruct commerce patterns and dissemination of early hominid groups. Due to problems concerning potential intra-source variability or homogeneity of a geological source over large areas, parameters additional to this classical approach are desirable. Here we present the first ⁴⁰Ar/³⁹Ar investigation of Middle Stone Age (MSA) obsidian artifacts (i.e. debitage pieces) for this purpose, as well as of potential geological obsidian sources from Ethiopia. With the present pilot study we demonstrate that ⁴⁰Ar/³⁹Ar geochronology represents a reliable and powerful tool for archaeological provenance studies complementary to the geochemical approach and more recently applied techniques like fission track counting or Mössbauer spectroscopy. Two independent sets of debitage and potential source rock samples were dated by the ⁴⁰Ar/³⁹Ar method. Debitage pieces from the Kulkuletti excavation site and obsidian samples from the nearby obsidian outcrop Worja (central Ethiopia) exhibit basically identical age ranges as well as similar Ca/K and Cl/K ratios, supporting the debitage/source rock relationship previously inferred on geochemical grounds. A second small set of geochemically characterized debitage samples from the Porc Epic cave and potential source rocks from an obsidian outcrop at Kone (Eastern Ethiopia) however have different ⁴⁰Ar/³⁹Ar ages and Ca/K and Cl/K ratios. These results contradict the previous conclusion about a debitage/source rock relationship of the Porc Epic and Kone samples made on the basis of geochemistry [A. Negash, M.S. Shackley, Archaeometry 48 (2006) 1]. Additional sampling at the Kone outcrop as well as of other obsidian occurrences in the greater area is needed to unambiguously pinpoint the origin of these obsidian tools.     

Multiple origins of Bondi Cave and Ortvale Klde (NW Georgia) obsidians and human mobility in Transcaucasia during the Middle and Upper Palaeolithic

Using PIXE four types of elemental compositions were found among obsidian artefacts from the Bondi Cave and Ortvale Klde, Middle to Upper Palaeolithic sites in NW Georgia. One of those types corresponds to obsidians from the Chikiani source, whose compositions were determined with a very good agreement by PIXE and ICP-AES/MS. The composition of Chikiani obsidians is remarkably constant despite K–Ar and ³⁹Ar/⁴⁰Ar extrusion ages from ca 2.4 and 2.8 Ma. The compositions of two other groups of obsidian artefacts are similar to source materials from eastern Anatolia and Armenia, in particular Ikisdere, Sarikamis, Gutansar, and Hatis. Obsidian is only a minority component in the lithic assemblages at the Bondi Cave and Ortvale Klde. Both Neanderthal and Modern Human populations used obsidian in particular from Chikiani. Considering that the shortest walking distance to this nearest source is at minimum of about 180 km, and to other potential sources of more than 350 km it is suggested that this material reached these two sites mostly, if not exclusively, by a series of ‘down the line’ exchanges.     

Hydrothermal control on organic matter alteration and illite precipitation, Mt Isa Basin, Australia

Abundant illite precipitation in Proterozoic rocks from Northern Lawn Hill Platform, Mt Isa Basin, Australia, occurred in organic matter‐rich black shales rather than in sandstones, siltstones and organic matter‐poor shales. Sandstones and siltstones acted as impermeable rocks, as early diagenetic quartz and carbonate minerals reduced the porosity–permeability. Scanning and transmission electron microscopy (SEM and TEM) studies indicate a relation between creation of microporosity–permeability and organic matter alteration, suitable for subsequent mineral precipitation. K–Ar data indicate that organic matter alteration and the subsequent illite precipitation within the organic matter occurred during the regional hydrothermal event at 1172 ± 50 (2σ) Ma. Hot circulating fluids are considered to be responsible for organic matter alteration, migration and removal of volatile hydrocarbon, and consequently porosity–permeability creation. Those rocks lacking sufficient porosity–permeability, such as sandstones, siltstones and organic matter poor shales, may not have been affected by fluid movement. In hydrothermal systems, shales and mudstones may not be impermeable as usually assumed because of hydrocarbons being rapidly removed by fluid, even with relatively low total organic carbon.     

WASTE GLASS,VESSELS AND WINDOW‐PANES FROM THAMUSIDA (MOROCCO): GROUPING NATRON‐BASED BLUE–GREEN AND COLOURLESS ROMAN GLASSES

A collection of window‐panes, vessels and alleged waste from Thamusida has been investigated by OM, SEM–EDS, ICP–MS, ICP–OES and XAS at the Fe–K and Mn–K edges. Glass samples have been characterized as natron‐based soda–lime–silica glasses, with low magnesium and low potassium. The results have been compared with 43 reference groups available for ‘naturally coloured’ and colourless glasses of both Roman and later ages. Two main types were distinguished: RBGY 1 (R oman B lue–G reen and Y ellow 1) and RBGY 2 (R oman B lue–G reen and Y ellow 2). Given their compositional similarity to the Levantine I or, to a lesser extent, HIMT glasses, the Syrian–Palestinian coast for RBGY 2 and Egypt for the RBGY 1 have been suggested for their provenance. Most Thamusida samples have been assigned to the RBGY 2 type. A small group of Thamusida colourless vessels was included into the RC (R oman‐C olourless) compositional field; the latter still being defined. The alleged waste pieces may define a local production that should have been of secondary type. The investigations performed on local raw materials seem to discount the possibility of a primary glass‐making site. XAS measurements determined that Fe²⁺ contents ranging between 30 and 52% are able to assure an aqua blue colour; below 30%, the glasses turn light green or light yellow.     

Distal cryptotephra found in a Viking boathouse: the potential for tephrochronology in reconstructing the Iron Age in Norway

Distal tephra deposits from Icelandic volcanic eruptions have been found in Norway and can be used to precisely date a variety of sedimentary environments. Tephrochronology has not yet been applied to archaeological investigations in Norway because tephra are generally not found as visible layers, but are present as very low concentrations of glass shards (i.e. cryptotephra). In this study, we present results from the analysis of cryptotephras found in an Iron Age boathouse in northern Norway. The boathouse was associated with the chieftain center at Borg on Vestvågøy in the Lofoten Islands. In 2003, a trench was excavated and the stratigraphy of the boathouse was described. Radiocarbon ages from cultural deposits show that it was constructed in the Early Iron Age c. AD 540–660 and the main period of use was at the end of the Iron Age between c. AD 1030 and AD 1270. Volcanic glass shards were isolated from sediment samples collected above and below the cultural deposit representing the main period of use. Electron microprobe analysis of the glass shards showed that the lower sample resembles the AD 860 Layer B tephra and the upper sample resembles tephra erupted from the Hekla volcanic system between AD 1104 and AD 1300. These tephrochronologic dates agree with the radiocarbon-derived dates and possibly further constrain the boathouse’s main period of use to c. AD 1030–1104. Our results demonstrate the value of using tephrochronology for archaeological studies in Norway and the potential for finding cryptotephra from other large explosive volcanic eruptions during the Iron Age.     

Sebbersund: isotopes and mobility in an 11th−12th c. AD Danish churchyard

The important Viking Age and early Medieval site of Sebbersund in northern Jutland, Denmark, contains a large churchyard from the 11th–12th century AD. Sebbersund was an important trading center in this period and the location of one of the first churches in Denmark, perhaps an entry point for the introduction of Christianity to the country. Excavations have exposed almost 500 graves of an estimated 700 individuals in the cemetery. Here we report on the analysis of strontium isotopes in human tooth enamel from burials in the cemetery as a signal of place of birth. Some 19 samples have been measured and at least three non-local outliers identified. Futhermore, six archaeological fauna samples had been analyzed in order to define the local bioavailable strontium isotope baseline range and these values were compared to the more general bioavailable baseline range values for Denmark. The burials are evaluated in light of the available archaeological, chronological, anthropological, and isotopic information.     

Commerce and trade in Viking Age Norway. Exchange of products or organized transactions?

In this paper the difficulties of distinguishing between commerce in the sense of exchange of products (i.e. more locally organized trade between neighbours/districts) and trade carried out as the main occupation for certain people, are discussed. These are questions very closely connected with the urbanization process of Norway. With the material from Kaupang (Skiringssal) as a point of departure, the author discusses two ways of finding out what type of trade was carried out in Viking Age Norway: A) One may look for the same combination of names found at Kaupang in other places. These seem to reveal ‘town‐making’ features. B) Ask whether any of the still existing medieval towns in Norway have had a pre‐urban stage. At the end of the paper the author discusses the possibilities of tracing different commodities which were traded over the different ports or market‐places.     

Examining Possible Driftwood Use in Viking Age Icelandic Boats

While boat and ship graves are known from across northern Europe, and are particularly associated with the Viking Age, only seven examples of such monuments have been excavated in Iceland. Furthermore, no shipwrecks are known dating from this period in Iceland, and examples of boat timbers preserved by waterlogging are very rare. As such, the mineralized wood remains from these burials comprise the vast majority of direct archaeological evidence currently available for the boats used in daily life in early Iceland. This paper uses taxonomic identification of mineralized wood remains from the Icelandic boat graves, along with comparative data from Europe and Scandinavia, to discuss boat construction and repair in early Iceland, including the possibilities of driftwood utilization and the importation of boats from Norway. The economic and social significance of the practice of boat burial in Iceland is also explored, with regard to the importance of boats as transport and the limited availability of wood suitable for boat construction and repair.     

UPPÅKRA. A CENTRAL SITE IN SOUTH SCANDINAVIAN IRON AGE: STABILITY AND CHANGE THROUGH MORE THAN A MILLENNIUM

In the 1930s, during the construction of a house south of Lund in south‐western Scania (southern Sweden), a thick occupation layer was discovered. The layer formed as a result of settlement during the Early Iron Age as a small‐scale excavation demonstrated. The article is a presentation of recent investigations of the site in 1996–2014. The occupation layer, which covers an area of some 40 hectares, contained traces of settlements from the late Pre‐Roman Iron Age to the Viking Age. Of particular significance are the remains of a small timber structure interpreted as a ceremonial building. It was reconstructed seven times during the 1^st millennium AD and used for around seven hundred years. On each side of the ceremonial building were depositions of weapons combined with animal bones from large feasts. Besides the ceremonial building, several large halls were excavated, dating from the Roman Iron Age to the Viking Age. These produced evidence of repeated and deliberate arson. Several years of metal detector surveys have resulted in 14,000 registered finds that give a good foundation for interpreting the significance of the site in local, regional and international perspectives as an important religious, political and economic centre in southern Sweden. Contributions by a large number of scholars have helped to provide a well‐based insight into different crafts and sources of artistic inspiration.     

The Scale and Impact of Viking Settlement in Northumbria

DISCOVERIES AT the Viking winter camp at Torksey indicate that the armies that invaded Anglo-Saxon England in the late 9th century were much larger than is often assumed, and that a literal reading of the Anglo-Saxon Chronicle’s assessment of the size of Viking fleets may, after all, have been correct. Furthermore, study of the Torksey metalwork assemblage has allowed the identification of the archaeological signature of the Viking Great Army, and when applied to Cottam, it confirms the identification of an initial phase of raiding by an element of the Army, followed shortly thereafter by settlement represented by the development of a hybrid Anglo-Scandinavian culture. Taken together, over 25 categories of non-ferrous artefacts are diagnostic of Viking or Anglo-Scandinavian activity in Northumbria. Applying this model to sites, largely known only from metal-detecting, we can observe a common pattern. At the majority of sites, a large and fairly standardised middle Anglo-Saxon finds assemblage is succeeded by just a few Viking finds, which we attribute to raiding following Halfdan’s return to Northumbria with part of the Great Army in AD 876. At a smaller number of sites, assemblages of Anglo-Scandinavian finds relate to the establishment of settlements by the new landowners. The overall picture is of major settlement disruption and dislocation of existing land holdings and populations in the late-9th century. This demonstrates, for the first time from archaeological evidence, the scale and impact of Viking activity in Northumbria.