Geoarchaeology-An International Journal最新文献

The Monforte de Moyuela dam, also known as Ermita de la Virgen del Pilar dam, is a Roman reservoir built on a tributary of the Aguasvivas River (Ebro basin, Spain). A multidisciplinary study has been carried out to investigate this kind of Roman water infrastructure. It is the fifth-highest dam (16.8 m) in the Iberian Peninsula and the seventh in the Roman Empire. The initial dam was built ca. 100 B.C.–10 A.D., probably in the period of Augustus, like other nearby Roman dams. It was quickly filled due to the extreme and generalized anthropic degradation in the basin during the Roman period. During the mid-2nd century, the wall was increased in height and its final silting was dated to the early 7th century. The study of the opus caementicium mortars shows constructive differences between the initial and subsequent phases of the wall. These mortars provided charcoal for dating the two phases. In addition, the stratigraphic and edaphological study of the reservoir's sedimentary fill, together with the ¹⁴C ages, allowed us to reconstruct the two main activity cycles and the final siltation of the dam. Subsequently, the dam broke in two phases, which created the two stepped sections located on the current valley bottom. The data obtained allowed the creation of a geomorphological map and an evolutionary model of the valley showing the main differentiated stages, from the initial construction of the dam to its final opening. Although some remains of canals downstream of the dam have been identified, the use of this dam, which remained active for several centuries, still needs to be investigated in greater detail.

Human–environment interactions relating to changes in the hydrological system of the Upper Vistula valley are poorly understood. This valley lies in the foreland of the Transcarpathian transition, an area in Central Europe, which is crucial for the migration of people. Using palaeobotanical and geochemical analyses, archaeological data, and data on the river's fluvial activity, we retrace the sequence of environmental changes occurring in the vicinity of the bog in Strumień during the transition between the Iron Age and the Early Middle Ages. The stability of changes in the river valley under the influence of human activity is also assessed. It is shown that:

Archaeologists frequently invoke climate change as a driving cause for ancient expansions of human populations, but geomorphic changes can also play an important role in opening or closing routes of migration. In China, archaeological evidence demonstrates that valleys in the Jialing River's watershed were important routes for the movement of Neolithic populations from the catchments of the Yellow River to the Yangtze River. Here, we examine how fluvial geomorphological regime shifts may have also influenced the migration pathways and adaptive strategies of Neolithic people into the Sichuan Basin by using a combination of sedimentological and palynological analysis at Luojiaba, an archaeological site located on one of the eastern tributaries of the Jialing River. The results show that people settled on seasonally stable landforms, including the Zhonghe River floodplain at Luojiaba (5300–4800 cal. B.P.). They carried out fishing and hunting activities on the front edge of the floodplain close to the river channel and built dwelling features on the higher ground at the back edge of the floodplain, which was not affected by seasonal floods. We hypothesize that during the Holocene Climatic Optimum before 5500 cal. B.P., high water levels as well as severe surface erosion caused by a strong East Asian Summer Monsoon (EASM) blocked pathways into the upper reaches of the Jialing River watershed. Only after a series of cold, dry climate events driven by a decrease in EASM intensity ca. 5500–5000 cal. B.P. did water levels recede significantly. This allowed alluvial aggradation to occur, which created floodplains and terraces along the valley that may have opened a new route for the migration into the Sichuan Basin. Our results reveal the human–environment dynamics surrounding Luojiaba in the uplands of southwestern China and highlight the impact of coupled climatic-geomorphic regime shifts on human settlement and subsistence strategies, across both space and time.

A recent discovery of a Bronze Age harbor site in Çamçalık provides new data for the relative sea level history along the coast of the Bozburun Peninsula over the last 3600 years. In this study, we compared the new and previously published data from nearby sites to determine the long-term relative sea level changes. Further comparison of the observed sea level data and newly produced glacial isostatic adjustment (GIA) models clarified the tectonic contribution to the relative sea level changes. Our results suggest a nonlinear tectonic subsidence trend in the coastal zone since 3600 B.P. The increase in the relative sea level accelerated over the last 1400 years, mostly due to the seismic events controlled by the tectonic regime of the southeastern Aegean Sea. We can conclude that, as in the past, this active tectonic process will have a major impact on the future sea level evolution of the coastal sector of the Bozburun Peninsula. Notably, our study can be used to understand the historical trend of sea level rise while providing a foundation for future trend prediction.

Sodmein Playa is one of the rare Pleistocene open-air sites in the Eastern Desert of Egypt. Based on the associated stone artefact material, it could be assigned to the Middle Stone Age/Last Interglacial. However, it has not yet been possible to clarify whether the sediments at the basin originated during the Pleistocene or later during Holocene wet phases. Our integrative approach combining Optically Stimulated Luminescence chronology, and cryptotephra analysis, allows us to link the environmental archive of Sodmein Playa with the site of Sodmein Cave. Sodmein Playa indicates wetter climate conditions starting around 9 ka with a (relative) maximum around 7 ka, in line with the general framework of the Holocene Humid Period in Northeast Africa. Despite the climatic similarity, regional environmental differences can still be identified and the effective available water around Sodmein Playa is reduced. The results are well integrated into the current archaeological knowledge with the change from hunter-gatherers to herders during the Holocene in the area. Analyses of cryptotephra reveal a wide range of source regions, including Eastern and Central Anatolian, the Azores, and the Aegean, as well as those which remain uncorrelated. A tentative correlation with the Holocene cryptotephra record from Sodmein Cave is established.

The Hangjiahu Plain in the lower Yangtze is one of the core areas that sustained the flourishment of the Liangzhu Civilization. This study reconstructed Holocene environmental change on the Hangjiahu Plain based on a sediment core collected from the Tangqi ZK-3 location situated on the low-lying Hangzhou-Taihu region of the Yangtze Delta. We applied OSL dating, grain size analysis, pollen analysis, and magnetic susceptibility to reconstruct Holocene environmental change and compared our data with other published results. Our results showed that (i) before ~7.0 ka B.P., the ZK-3 core recorded a strong hydrodynamic force, resulting in the widespread deposition of light grayish silt clay or clayey silt in the region. The climate was warm and humid, and the vegetation was mixed evergreen deciduous coniferous forest. (ii) Between 7.0 and 6.0 ka B.P., the hydrodynamic condition in ZK-3 core became weaker, and the climate remained warm and humid. Although most of the Hangjiahu Plain were still covered by the light grayish silt clay or clayey silt, some higher grounds began to emerge as sea-level rise slowed, which coincided with the development of the Majiabang culture. (iii) Between 6.0 and 4.5 ka B.P., the deposition of yellowish silty clay indicates a shallow-water hydrological environment at ZK-3, as the regional water level was dropping while more land was emerging, which provided a favorable physical environment for the prosperity of the Songze and Liangzhu cultures. The period experienced a drier and cooler climate, with evidence of deforestation. (iv) Between 4.5 and 3.0 ka B.P., the sediments in the ZK-3 core were dominated by light grayish clay, indicative of a return to a deep-water environment with a prolonged waterlogging condition. The climate remained dry and cool with further deforestation. However, the widely distributed yellowish silt clay suggests frequent floods in the region, resulting in a sharp reduction of settlement sites and the eventual decline of the Liangzhu Civilization.

Calcium oxalate-rich rock coatings occur worldwide and commonly occur associated with prehistoric rock paintings. Radiocarbon dates of oxalates that cover or encapsulate rock paints have become the primary strategy for establishing chronologies of these artifacts. It is also apparent that oxalate films form episodically and are governed by particular climate conditions and thus could serve as a paleoclimate proxy. However, the mechanism(s) by which these coatings form remains unresolved. Here, we report on the trace organic composition of oxalate-coating samples from the Lower Pecos Canyonlands in southwestern Texas. The samples contained a suite of dicarboxylic acids that are similar to the organic composition established for atmospheric aerosols. The predominant organic species in aerosols is oxalic acid, which reacts with calcium to form calcium oxalate. This suggests that aerosols could be a mechanism for the production of naturally occurring calcium oxalate on rock surfaces.

Indigenous Fremont farmers in Cub Creek, a part of northeastern Utah's Dinosaur National Monument, occupied the northern ecological margin of maize cultivation in western North America from A.D. 300 to 1300. Agriculture in Cub Creek was a response to multidecadal precipitation variability, but when precipitation stabilized between A.D. 750 and 1050, agricultural conditions improved and populations expanded to form villages along the floodplains of local dryland streams. Did the very same conditions (i.e., decreased precipitation variability) that allowed the growth of agricultural societies make them simultaneously vulnerable to arroyo formation, a key geomorphic risk to floodplain agriculturalists? Preliminary results from Cub Creek show that rapid sedimentation punctuated by episodic arroyo formation characterized the last 2000 years. We use stratigraphic and chronological evidence formalized in a Bayesian age model to develop a set of working hypotheses that a 2.5 m-deep discontinuous arroyo formed before either A.D. 1020 or A.D. 1275. The earlier age corresponds with occupation of the Cub Creek village, while the later age corresponds with the end of Fremont agriculture in Cub Creek, and demonstrates regional synchronicity with arroyo formation across the Colorado Plateau. A second arroyo formed before A.D. 1490, indicating rapid alluvial cycling in Cub Creek. We conclude that floodplain instability and arroyo formation combined with the return of the dominant multidecadal precipitation variability regime beginning at A.D. 1050 was a key constraint on the growth potential of local populations. These findings have potential implications for the development of early Indigenous dryland agricultural systems throughout the interior of western North America.

Geomorphology generally aims to describe and investigate the processes that lead to the formation of landscapes, while geochronology is needed to detect their timing and duration. Due to restrictions on exporting geological samples from Egypt, modern geoscientific studies in the Nile Delta lack the possibility of dating the investigated sediments and geological features by standard techniques such as OSL or AMS ¹⁴C; therefore, this study aims to validate a new approach using machine-learning algorithms on portable X-ray fluorescence (pXRF) data. Archaeologically dated sediments from the archaeological excavations of Buto (Tell el-Fara'in; on-site) that pXRF analyses have geochemically characterized serve as training data for running and comparing Neural Nets, Random Forests, and single-decision trees. The established pXRF fingerprints are transferred via machine-learning algorithms to set up a chronology for undated sediments from sediment cores (i.e., the test data) of the nearby surroundings (off-site). Neural Nets and Random Forests work fine in dating sediments and deliver the best classification results compared with single-decision trees, which struggle with outliers and tend to overfit the training data. Furthermore, Random Forests can be modeled faster and are easier to understand than the complex, less transparent Neural Nets. Therefore, Random Forests provide the best algorithm for studies like this. Furthermore, river features east of Kom el-Gir are dated to pre-Ptolemaic times (before 332 B.C.) when Kom el-Gir had possibly not yet been settled. The research in this paper shows the success of close interactions from various scientific disciplines (Geoinformatics, Physical Geography, Archaeology, Ancient History) to decipher landscape evolution in the long-term-settled Nile Delta's environs using machine learning. With the approach's design and the possibility of integrating many other geographical/sedimentological methods, this study demonstrates the potential of the methodological approach to be applied in other geoscientific fields.

This study provides the first survey of Brazilian magnetic susceptibility (MS) data from varying archaeological and geological contexts, including open-air sites, quartzite, and limestone rockshelters, and Amazonian dark earths. Our MS analyses associated with archaeological findings allow us to propose MS values as proxies of intense anthropogenic burning activities for archaeological sites with (i) systematic use of large hearth lit in the same places; (ii) systematic burns and highly diverse uses; (iii) higher diversity use with few fire activities and knapping playing an essential role; and (iv) incipient human activities and the initial use of the archaeological site. Our data are limited to understanding anthropogenic burning activities and cannot be extended to reveal other archaeological aspects. The results have implications for understanding human occupation in a large area with numerous archaeological sites. This study was the first step in distinguishing archaeological fires from natural fires and provided a new perspective for further research that attempts to identify distinct types of human fires.