Geoarchaeology-An International Journal最新文献

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.

Lithic raw material variation is valuable for assessing the scale of human mobility, differential access to and from raw material sources, and prehistoric exchange patterns. Recent advancements in non-destructive reflectance spectroscopy have proven to be more accurate in provenance investigations compared with the macroscopic (visual) identification technique for lithic artifacts. Here, we use visible/near-infrared reflectance and Fourier transform reflectance spectroscopy on a collection of 845 lithic bifaces at Poverty Point (16WC5) site in northeastern Louisiana, a UNESCO World Heritage site that is well-known for the presence of nonlocal materials, including stone tools. This study describes the first systematic approach to analyzing and interpreting hyperspectral reflectance data for cryptocrystalline silicate (e.g., chert and flint) artifacts at Poverty Point site. The chert materials identified in this study reaffirm the idea that tool stones arriving at the Poverty Point site came from diverse geologic sources, covering an expansive geographic area.

The heartlands of many of the world's civilizations are situated within alluvial plains, where thick alluvial sediments obscure much of the archaeological record. However, the use of alluvial geoarchaeology remains patchy, particularly in the world's largest alluvial basins. We present results from our geoarchaeological survey at Neihuang County, Henan Province, China, as an example for alluvial geoarchaeological research in the North China Plain and to develop a generalized framework for landscape evolution in the area during the Holocene. We reconstruct the alluvial history of the area around Neihuang County by synthesizing stratigraphic data from seven outcrops into distinct depositional units. Our findings suggest that much of the archaeological record in the North China Plain is buried by meters of sediment or eroded away by the ancient channels of the Yellow River and other tributary streams. Therefore, the presence of buried archaeological sites and river scour in recorded outcrops suggests that the nonsystematic archaeological surveys that are commonly used to interpret cultural changes are not accurate reflections of archaeological site distributions. From the results of this case study, we recommend that archaeologists and paleoclimatologists should exercise more caution when using settlement distribution data gathered through nonsystematic pedestrian surveys to make inferences about ancient processes of cultural change or social dynamics in the North China Plain.

The availability of nutrient-rich soils capable of supporting intensive cultivation was a key factor in the relative vulnerability and resilience of traditional Polynesian societies, whose economies were based on agricultural production. We tested the hypothesis that geological age was a key controlling factor in determining the nutrient status of island soils, extensively sampling soils on two islands and a small archipelago in southeastern Polynesia: Mo‘orea (1.5–1.72 Ma), Maupiti (3.9–4.5 Ma), and the Gambier Islands (5.6–6.3 Ma). Rather than supporting a hypothesis of island age primarily determining soil fertility, our results indicate that topographic relief, the presence of active slope processes such as landslides and mass wasting, and rainfall are more important controlling factors. Rejuvenation of soil nutrients due to mass wasting, in particular, appears to be the most important factor contributing to soil fertility. Our field surveys also provide archaeological evidence showing that precontact Polynesians were finely attuned to local soil properties, targeting high soil fertility areas for agriculture and reserving lower fertility areas for other land use practices.

The conservation of archaeological heritage such as open-air petroglyphs is a major challenge due to the vulnerability of surfaces exposed to local environmental conditions. A precise knowledge of their nature therefore constitutes the cornerstone of their preservation. The surfaces of the valleys of the Mount Bego are characterized by a chromatic contrast between the thin red layer covering the outcrops and the underlying greenish substrate, revealed by thousands of prehistoric petroglyphs. To establish the mineralogical nature of the red layer, a spectroscopic, crystallographic, and petrographic study was carried out. Collectively, the results of this study evidence that, unlike rock coatings, this layer formed through the mobilization of structural iron, in the form of Fe (hydr)oxides, from the clay minerals that constitute the rocks. We thus discuss how the succession of events along the geological history of the site has created the environmental conditions for its formation. This study eventually provides useful data on the actual state of the petroglyphs toward their preservation. In a more global context, the conclusions of this study bring insights into the physicochemical mechanism leading to the reddening of recently exposed glacial valleys.

Reconstructing the evolution of fluvial landscapes is vital to our understanding of how and why early settlements used or abandoned locations in dynamic alluvial settings, especially places such as China's Central Plains where alluvial landforms have dominated since at least the late Pleistocene era. The Wangchenggang (WCG) site on the upper reaches of the Ying River is considered to be the legendary capital of the Great Yu who, according to historical documents, heroically tamed the big floods and founded the first dynasty of Xia. However, evolution of the alluvial landscape of the Holocene Ying River and its influence on the long-term settlement change at the WCG site remains unclear. We present a detailed reconstruction of long-term landscape evolution and settlement change at the site, based on the results of our geoarchaeological investigation, and published paleoclimate and archaeobotanical data. The results show that the region experienced an episode of extensive alluvial accretion in the late Pleistocene. From the end of the late Pleistocene to the early Holocene, the Ying River began to incise the alluvial plain, leading to the formation of the oldest terrace (T3). The middle and late Holocene in the Ying River valleys saw two episodes of alluvial aggradation between 7.7–5.4 ka B.P. (before present) and 4.5–3.8 ka B.P., respectively. Each of these events was followed by an alluvial incision, resulting in the formation of new alluvial terraces. During the historical periods, the youngest terrace T1 was formed. These cyclic changes in the regional fluvial landscape profoundly impacted the location and expansion of prehistoric settlements. During the Peiligang period (9.0–7.0 ka B.P.), the early stages of alluvial aggregation resulted in wide and shallow channels along the rivers. Early humans who relied on gathering and hunting for food chose to establish small settlements along such riverine environments. As alluvial aggradation continued in the Yangshao period (7.0–5.0 ka B.P.), they moved to a higher place, away from the rivers in the southwest, and flourished on high alluvial grounds. When a secondary terrace formed after the Longshan period (5.0–4.0 ka B.P.), people moved eastward again to build an early city on the T2 terraces and T3 terraces of the Ying River. When the water levels rose toward the terrace surfaces, they began to build moats and practiced mixed millet–rice farming. During the Eastern Zhou Dynasty (770–4256 B.C.), when the river started to down cut on a large scale, humans responded by building settlements on the lower and flat plains in the east.