Archaeological Constraints Research Articles

A revised radiocarbon calibration curve 350-250 BCE impacts high-precision dating of the Kyrenia Ship.

The Kyrenia Ship, found off the north coast of Cyprus, is a key vessel in the history of scientific underwater excavations and in the history of Greek shipbuilding. The first volume of the site's final publication appeared in 2023 and provides detailed archaeological information tightly constraining the dating of the ship. A very specific date range is proposed: ca. 294-290 BCE, but is based on a less than certain reading of one coin recovered from the ship. While there is clear benefit to finding high-precision dates for the Kyrenia Ship and its rich assemblage using independent scientific dating (combined with Bayesian chronological modeling), efforts to do so proved more challenging and complex than initially anticipated. Strikingly, extensive radiocarbon dating on both wooden materials from the ship and on short-lived contents from the final use of the ship fail to offer dates using the IntCal20 calibration curve-the current Northern Hemisphere radiocarbon calibration curve at the time of writing-that correspond with the archaeological constraints. The issue rests with a segment of IntCal20 ca. 350-250 BCE reliant on legacy pre-AMS radiocarbon data. We therefore measured new known-age tree-ring samples 350-250 BCE, and, integrating another series of new known-age tree-ring data, we obtained a redefined and more accurate calibration record for the period 433-250 BCE. These new data permit a satisfactory dating solution for the ship and may even indicate a date that is a (very) few years more recent than current estimations. These new data in addition confirm and only very slightly modify the dating recently published for the Mazotos ship, another Greek merchant ship from the southern coast of Cyprus. Our work further investigated whether ship wood samples impregnated with a common preservative, polyethylene glycol (PEG), can be cleaned successfully, including a known-age test.

Analysis of geomagnetic field intensity variations in Mesopotamia during the third millennium BC with archeological implications

We present new archeointensity results obtained at two multi-layer archeological sites, Tell Atij and Tell Gudeda (northeastern Syria), dated from the Early Bronze Period in the third millennium BC. The archeointensity data were obtained using the experimental protocol developed for the Triaxe magnetometer. In total, 68 fragments (204 specimens) of 151 fragments analyzed passed our selection criteria, allowing average intensity values to be estimated for 14 archeological layers, nine at Tell Atij and five at Tell Gudeda. Based on the available archeological constraints, the different archeological layers of Tell Atij and Tell Gudeda were dated between ∼2900 BC and ∼2600 BC and between ∼2550 BC and ∼2325 BC, respectively. The Tell Atij data show a significant increase in intensity over the dated period, while the results from Tell Gudeda exhibit a V-shape evolution. Using high-quality data available from Syria, the Levant and Turkey, a regional geomagnetic field intensity variation curve spanning the entire third millennium BC was constructed using a trans-dimensional Bayesian method. It clearly shows two intensity peaks, around 2600 BC and at ∼2300 BC, associated with variation rates of ∼0.1-0.2 μT/yr. This indicates that the occurrence of century-scale intensity peaks with rates of variation comparable to or even slightly higher than the maximum rates observed in the modern geomagnetic field is an ubiquitous feature of the geomagnetic secular variation. From an archeological point of view, the new archeointensity data strengthen the hypothesis that the successive occupation of Tell Atij and Tell Gudeda was synchronous with the two first urban phases of Mari, making possible a sustained trade network between these settlements during the third millennium BC. We further suggest that the end of Mari's first urban phase, contemporaneous with the abandonment of Tell Atij, might have been caused by a regional drought episode around 2600 BC. More generally, the Bayesian approach used to estimate the new reference intensity variation curve offers promising chronological constraints for archeological purposes.

The presence of elk (Alces alces) in Austria since the upper Pleistocene

Abstract This study reports new data on the occurrence of elk remains in the western, mountainous part of Austria and also provides a compilation of all currently known 107 elk finds of the upper Pleistocene to upper Holocene in this country. The altitudinal distribution reveals two maxima for Austria: a lower one at about 400 m a.s.l., which comprises the alpine foreland, and a second one at about 1600-1800 m a.s.l., reflecting the abundance of vertical caves in the Northern Calcareous Alps at this elevation (animal traps). Vorderkarhöhle in Tyrol is the highest known elk find in Austria (1860 m a.s.l.), interestingly located above the tree line. Although only 11% of all elk sites in Austria have been radiocarbon-dated, stratigraphic and archaeo-logical constraints allow to assign 90% of those sites that lack radiometric dating to either the upper Pleistocene (18%) or the Holocene (72%). Among the latter, upper Holocene sites dominate (78%), followed by middle (16%) and lower Holocene (6%) sites. The youngest radiocarbon-dated elk find in Austria is from Gaflein Valley (Tyrol, 1285-1359 cal BP), in agreement with data from the Swiss Alps, showing that the elk survived beyond Roman times in the Alps and became extinct before the onset of the Middle Ages.

Sedimentary records of holocene palaeo-mudflow events in Tianshui basin of the western Loess Plateau, China

During our field investigations, a Holocene aeolian loess-soil profile containing three units of palaeo-mudflow deposits is identified in Tianshui basin of the western Loess Plateau, China. Through field observation and the analysis of particle-size characteristics, three palaeo-mudflow deposit layers are differentiated from the interbedding aeolian loess and soil, and they record three episodes of palaeo-mudflow events. Based on stratigraphic correlation, OSL dates and archeological constraints, the three episodes of palaeo-mudflow events are estimated to occur in 7000–6000, 5500–4800, and 4200-4000 yr BP, respectively. Comparison of the ages of the three paleo-mudflow events with the paleoclimatic proxy data from different regions indicates that these three episodes of palaeo-mudflow events were most likely associated with the climatic instabilities and prehistorical human activities. The results of our study, as well as the results of other studies, may provide further insights into the Holocene climate change and also into the prehistoric human activities in environmentally sensitive areas.

Advances in the analysis of households in the early neolithic groups of the Iberian Peninsula: Deciphering a partial archaeological record

In this paper, we analyze the data related to the households of the first farmers in the Iberian Peninsula during the early Neolithic and discuss the theoretical and archaeological constraints on their recognition. Information is limited by different factors, such as the traditional excavation exclusively of caves and the difficulties in preserving the archaeological record at open-air sites. Most of these sites present diverse types of structures, from production-consumption, storage or waste areas, to different types of possible dwellings. We argue that the most common type of settlement within these groups were farms, which would constitute basic units of productive and social organization. Lastly, we highlight the research approach involving the open-air excavation at settlements large enough to allow the identification of domestic units.

Rapid geomagnetic field intensity variations in the Near East during the 6th millennium BC: New archeointensity data from Halafian site Yarim Tepe II (Northern Iraq)

We present new archeointensity results from a series of groups of pottery fragments that were collected from the multi-layered archeological site Yarim Tepe II in Northern Iraq (Northern Mesopotamia) dated to the 6th millennium BC. This site comprises a 7-m-thick sequence of archeological deposits encompassing the Middle Halaf, Late Halaf and the Halaf-Ubaid Transitional (HUT), between ∼5750 and ∼5000 BC according to the chronology currently considered for the Halafian archeological period. Three new radiocarbon dates obtained from bone fragments confirm that Yarim Tepe II was likely not occupied before the Middle Halaf, as was independently established from archeological constraints. Archeointensity determinations were carried out using the protocol developed for the Triaxe magnetometer. This procedure takes into account thermoremanent magnetization anisotropy and cooling rate effects. 114 fragments fulfilled our set of archeointensity selection criteria, with intensity data obtained from at least two but most often three specimens per fragment. Mean archeointensity values were estimated for 23 groups of fragments well distributed across the entire stratigraphic sequence from the averaging of the data obtained from a minimum of three fragments per group. These values were dated using a bootstrap procedure relying on the stratigraphic position of the different groups of fragments and on the different age constraints available inside the Yarim Tepe II sequence. The new data show a significant decrease in geomagnetic field intensity by ∼12 μT between the Middle Halaf and the Late Halaf–HUT time interval. This decrease was accompanied by a short intensity peak, which may have lasted only a few decades, around the Middle Halaf–Late Halaf boundary, at ∼5500 BC. This evolution is quite similar to that observed from Syrian and Bulgarian archeointensity data, even though the precise duration of the intensity peak is presently questionable. The Bulgarian data set further suggests that the intensity secular variation in the Near East and in Eastern Europe during the 6th millennium BC was in fact principally punctuated by two successive short-lasting intensity peaks, the first around 5800 BC and the second around 5500 BC. The scarcity of the intensity data available worldwide, however, prevents us constraining the geomagnetic dipole or non-dipole origin of these features. The variation rates associated with the rapid intensity fluctuations observed in Yarim Tepe II are of ∼0.15–0.25 μT/yr. This range of values appears similar to that of rapid intensity variations that sporadically occurred in more recent times, such as in Western Europe around 700 BC and 1000 AD. In contrast, it is lower than the variation rates that were proposed for geomagnetic spikes. Our results also have interesting implications on Halafian archeology; in particular, they suggest that the Late Halaf–HUT boundary was older by ∼ one century than previously considered.

New archaeomagnetic directions from Portugal and evolution of the geomagnetic field in Iberia from Late Bronze Age to Roman Times

This study presents new archaeomagnetic results from 33 combustion structures (kilns and hearths) from the archaeological sites of Castelinho, Crestelos, Olival Poço da Barca and Fonte do Milho in NE Portugal. The age of the investigated structures ranges from 1210 BC to 200 AD according to calibrated radiocarbon dating, thermoluminescence dating and archaeological constraints. Stepwise thermal and alternating field demagnetization isolate a single, stable, characteristic remanence component with very well defined directions. Rock magnetic analyses suggest low-Ti titanomagnetite/maghemite as the main magnetic carrier of the remanence. Mean directions are well grouped in most structures. The effect of thermoremanent anisotropy on mean directions has been evaluated and was found to be important. Inclination increases of between 2° and 13° after applying the anisotropy correction at specimen level. This highlights the requirement of evaluating this effect on the directions of small and flattened thin kilns and hearths. The 31 new directional data improve both the temporal and spatial distribution of the Iberian archaeomagnetic dataset from Late Bronze Age to Roman Times. Finally, a new directional palaeosecular variation curve for Iberia for the last twelve centuries BC is proposed. The curve has been computed using the bootstrap method and includes data coming from sites within 900km of Madrid. The new palaeodirectional secular variation curve for Iberia is consistent with the Western European palaeosecular variation curve and with the prediction of regional European models.

Variation of the Earth’s magnetic field strength in South America during the last two millennia: New results from historical buildings of Buenos Aires and re-evaluation of regional data

The causes of the systematic decay of the Earth’s Magnetic Field strength since eighteen century have been a matter of debate during the last decade. It is also well known that such variations may have completely different expressions under an area characterized with strong magnetic anomalies, such as the South Atlantic Magnetic Anomaly. To fully understand these atypical phenomena, it is crucial to retrieve the past evolution of Earth’s magnetic field beyond the observatory records. We report on detailed rock-magnetic and archeointensity investigations from some well-studied historical buildings of Buenos Aires city, located at the heart of the South Atlantic Magnetic Anomaly. Samples consist of bricks, tiles, fireplaces and pottery, which are considered as highly suitable materials for archaeointensity studies. The dating is ascertained by historical documents complemented by archeological constraints. Eighteen out of 26 analyzed samples yield reliable absolute intensity determinations. The site-mean archaeointensity values obtained in this study range from 28.5 to 43.5μT, with corresponding virtual axial dipole moments (VADMs) ranging from 5.3 to 8.04×1022Am2. Most determinations obtained in the present study are in remarkable agreement with the values predicted by the time varying field model CALS10k.1b (Korte et al., 2011). For the older periods the recently available SHA.DIF.14 model (Pavon-Carrasco et al., 2014) seems to have greater resolution.South American archaeointensity database now includes absolute intensities from 400 to 1930 AD based on 63 selected archaeointensity determinations. The data set reveals several distinct periods of quite large fluctuations of intensity. However, most data are concentrated into a relatively narrow interval from AD 1250 to AD 1450. At the beginning of the record, values between 400 AD and 830 AD match well with ARCH3k.1 model. Some general features may be detected: the time intervals from about AD 400 to 950 and 1150 to 1280 are characterized by a quite monotonic decrease of geomagnetic intensity, while some increase is observed from AD 950 to AD 1250. In contrast, a systematic intensity decay is detected from 1550 to 1930 in excellent agreement with the model prediction. No firm evidence of correlation between the climate changes over multi-decadal time scales and geomagnetic intensity was found for South America.

Palaeoseismology of the L’Aquila faults (central Italy, 2009, Mw 6.3 earthquake): implications for active fault linkage

SUMMARY Urgent urban-planning problems related to the 2009 April, Mw 6.3, L’Aquila earthquake prompted immediate excavation of palaeoseismological trenches across the active faults bordering the Aterno river valley; namely, the Mt. Marine, Mt. Pettino and Paganica faults. Cross-cutting correlations amongst existing and new trenches that were strengthened by radiocarbon ages and archaeological constraints show unambiguously that these three investigated structures have been active since the Last Glacial Maximum period, as seen by the metric offset that affected the whole slope/alluvial sedimentary succession up to the historical deposits. Moreover, in agreement with both 18th century accounts and previous palaeoseismological data, we can affirm now that these faults were responsible for the catastrophic 1703 February 2, earthquake (Mw 6.7). The data indicate that the Paganica–San Demetrio fault system has ruptured in the past both together with the conterminous Mt. Pettino–Mt. Marine fault system, along more than 30 km and causing an Mw 6.7 earthquake, and on its own, along ca. 19 km, as in the recent 2009 event and in the similar 1461 AD event. This behaviour of the L’Aquila faults has important implications in terms of seismic hazard assessment, while it also casts new light on the ongoing fault linkage processes amongst these L’Aquila faults.

Archeointensity in Northeast Brazil over the past five centuries

This study presents the first archeointensity results from Northeast Brazil obtained from 14 groups of architectural brick fragments sampled in the city of Salvador, Bahia State (13°S, 38.5°W) and dated between the middle of the XVIth century and the beginning of the XIXth century. The dating is ascertained by historical documents complemented by archeological constraints, yielding in all cases age uncertainties of less than 50 years. Analyses were carried out using two experimental protocols: 1 — the “zero field–in field” version of the classical Thellier and Thellier method as proposed by Coe (TT-ZI), including partial thermoremanent magnetization (pTRM) and pTRM-tail checks, and 2 — the Triaxe procedure involving continuous high temperature magnetization measurements. Both TRM anisotropy and cooling rate effects were taken into account for the intensity determinations. The cooling rate effect was further explored for the TT-ZI protocol using three increasing slow cooling times (5 h, 10 h and 25 h) between 450 °C and room temperature. Following archeological constraints, the slowest cooling time was retained in our study, yielding decreases of the raw intensity values by 4% to 14%. For each fragment, a mean intensity was computed and retained only when the data obtained from all specimens (between 2 and 6) satisfied a coherence test at ∼ 5%. A total of 57 fragments (183 specimens) was considered for the computations of site-mean intensity values, with derived standard deviations of less than 8% of the corresponding means. When separately computed using the two experimental techniques, the site-mean intensity values always agree to within 5%. A good consistency is observed between intensity values of similar or close ages, which strengthen their reliability. Our data principally show a significant and continuous decrease in geomagnetic field intensity in Northeast Brazil between the first half of the XVIIth century and the XXth century. One result dated to the second half of the XVIth century further suggests that the geomagnetic field intensity reached a maximum around 1600 AD. This evolution is in good agreement with that expected in the city of Salvador from the available global geomagnetic field models. However, the accuracy of these models appears less well constrained between ∼ 1550 AD and ∼ 1650 AD.

First archaeomagnetic data from northern Iberia

An archaeomagnetic study has been conducted on eight archaeological structures (two kilns, four fireplaces and two saunas) from two different areas in Asturias (northern Spain). The results provide the first archaeomagnetic directions from the northern Iberian Peninsula. The main goal of this paper is to improve on the non-uniform site distribution used to construct the first archaeomagnetic Secular Variation Curve for Iberia (“SVC-I”) by studying new sites from northern Spain, an area currently not represented. The lithologies of some of the studied archaeological structures from this zone (slates, quartzites) differ from those of the rest of the peninsula. Laboratory analysis includes both thermal and alternating field stepwise demagnetization and rock-magnetic studies. A low coercivity, moderate unblocking temperature ( T ub) phase, such as magnetite/maghemite, seems to be the carrier of the archaeomagnetic signal. This sometimes overlaps partially with a (geological) high coercivity/high T ub phase. Site-mean characteristic directions have been calculated following a hierarchical approach and applying Fisherian distribution tests. Archaeomagnetic results have been compared, applying Fisherian distribution tests, among themselves and with Roman age entries of the Spanish archaeomagnetic database. They have also been compared with the reference “SVC-I” using Bayesian methods. These analyses have served to validate the archaeological dating of the structures. There is a good agreement between the results of archaeomagnetic dating and radiocarbon dating, both of which are consistent with archaeological constraints. The uncertainties in the archaeomagnetic ages are relatively large mainly because the reference curve hardly varies in declination during Roman times. This highlights the need of more high quality archaeomagnetic data (from very well-dated structures) in order to reduce the errors associated with the reference “SVC-I” and the archaeomagnetic dating technique, particularly between 0 and 500 AD.

Archaeomagnetic dating of a vitrified wall at the Late Bronze Age settlement of Misericordia (Serpa, Portugal)

The age of cooling of a vitrified wall at the Late Bronze/Second Iron Age settlement of Misericordia (Serpa, Portugal) has been determined using archaeomagnetic dating. Vitrification occurred in the Late Bronze Age (842–652 BC), in agreement with archaeological constraints based on the style of the potteries recovered at the site. This demonstrates the suitability of vitrified structures for archaeomagnetic dating and the potential for developing absolute chronologies for similar structures in Iberia and across Europe as a whole. Magnetite, low Ti-content titanomagnetite and, to a lesser extent, metallic Fe carry the archaeomagnetic signal, thus representing phases formed during the heating event. Native Fe was preserved due to it being isolated within the glassy matrix. The vitrified structure underwent at least one strong heating event which led to partial melting of the rocks used in its construction. Both microprobe and archaeomagnetic data support a single heating event, although multiple heating to temperatures >600–800 °C cannot be excluded on archaeomagnetic grounds.

A catalogue of Spanish archaeomagnetic data

A total of 58 new archaeomagnetic directions has been determined from archaeological structures in Spain. Together with five previous results they allow the compilation of the first archaeomagnetic catalogue for Spain, which includes 63 directions with ages ranging between the 2nd century BC and the 20th century AD. Characteristic remanence directions have been obtained from stepwise thermal and alternating field demagnetization. The hierarchical structure has been respected in the calculation of the mean site directions. Rock magnetic experiments reveal that the main magnetic carrier is magnetite or titanomagnetite with different titanium contents. The age estimate of the studied structures is generally well justified by archaeological constraints. For six structures the proposed date is also supported by physical methods. The data are in close agreement with the French secular variation (SV) curve. This catalogue represents the first step in the construction of a SV curve for the Iberian Peninsula, which will be of much use in archaeomagnetic dating and in modelling of the Earth's magnetic field in Western Europe.

Archeomagnetic study of seven contemporaneous kilns from Murcia (Spain)

New archeointensity values have been determined from seven Spanish kilns sampled at the same archeological site and dated by archeological constraints as between 1100 and 1200 a. d. The directions of the characteristic remanent magnetization and paleointensities have been obtained from classical Thellier experiments conducted on 69 samples collected from the walls of the kilns. Thermoremanent magnetization (TRM) anisotropy and the cooling rate effect upon TRM intensity acquisition have been investigated in all the samples. Differences between mean archeointensities per site, before and after corrections for cooling rate are between 3 and 17%. The study of these seven “contemporaneous” kilns coming from the same archeological site and treated in the same way in the laboratory allows us to discuss the different factors that can cause the dispersion between sites generally observed in archeointensity studies. The results confirm, on one hand, the need for cooling rate corrections in this kind of study and, on the other hand, the need to obtain several archeointensity determinations per century in order to construct a reliable archeointensity curve. Finally, the new data provide a robust mean intensity (60.3 ± 3.3 μT at the latitude of Paris) for the middle of the XII century in Western Europe and constrain better the evolution of the geomagnetic field intensity during medieval times in this area.

Parcellaire et nécropoles de l'Âge du Bronze ancien à Bernières-sur-Mer (Calvados)

An archaeological diagnosis followed by a rapid assessment on the site of a future property development at Bernières-sur-Mer allowed the observation, unfortunately incomplete, of a network of ditches dividing plots of land, and of several funerary structures (enclosures and tombs) dating from the end of the 3rd millennium ВС (very beginning of the Bronze Age). These enclosures and burials probably belong to a funerary complex already partially discovered some 20 years ago about 100 metres away: the two "famous" Bernières tombs dated to the late 3rd or early 2nd millennium and described by G. Verron in 1976. One of the tombs discovered this year (tomb 102, enclosure 101) has been dated to between 2195 and 1918 ВС, which tends to indicate that the two sites form an almost contemporary complex. The remains discovered at Bernières-sur-Mer would thus constitute a single exceptional site, now for the most part destroyed (this site has not been excavated and the plots of land for development have been discharged from all archaeological constraints), covering over six hectares (approximately 15 acres) and related to a land use system dating back to the 3rd millennium.

Archaeological constraints on some geological interpretations of a Late Wisconsinan site at Varsity Estates, Calgary, Alberta

Late glacial history in western Alberta has been a subject of debate as this area lies in the zone of assumed contact of the Cordilleran glaciers and Laurentide ice shield. The geographic limits and timing of the coalescence of the two ice masses, however, are not clear except for the west-central part of the province with the documented merger in the Athabasca valley. Recently, arguments for a complete Late Wisconsinan coalescence in the prairies all along the Rocky Mountain foothills have been presented based on 14C dates >21 ka and cosmogenic 36Cl dates <17 ka from the areas 300 km north and 100 km south of Calgary, respectively, and undated streamlined landforms in the foothills. This scenario is in direct conflict with the archaeological and geological evidence from the key area in the upper Bow Valley, showing eloquently an asynchroneity in the last glacial dynamics in this portion of the province. The recorded early occupation horizon from the Varsity Estates site, NW Calgary , with palaeolithic stone tools sealed in situ on top of the Cordilleran Bow Valley till buried by the Laurentide Glacial Lake Calgary clays in corroboration with braided fluvial channel deposits in between the two major units attest clearly to a subaerial setting prior to the maximum continental ice advance. The interpretation on the alleged glacial contact ignores these facts and does not consider the undated time span of up to 4000 years (ca. 21–17 ka) allowing sufficient time for an early Late Wisconsinan peopling of unglaciated parts of western Alberta even if the area may have been subsequently covered by ice.

14C geochronological constraints for the volcanic history of the island of Ischia (Italy) over the last 5000 years

The chronology of the most significant eruptions at the island of Ischia in the last 5000 years has been studied by means of Accelerator Mass Spectrometry to obtain 14C data. The results are in good agreement with stratigraphical and archeological constraints. This allows interpretation of the measured dates as ages of the eruptions which produced the deposits overlying or incorporating the sampled paleosols and charcoal fragments, respectively. These ages define the timing of volcanism in the last 5000 years, suggesting that the recent volcanic activity at Ischia is characterized by periods of very intense volcanism alternating to periods of quiescence. This timing of the volcanism is correlated with the behaviour of the magmatic system and dynamics of resurgence of the Mt. Epomeo block.