The Study of lithic assemblages on deflation surfaces. The case study of Arroyo Verde, Northern Patagonia coast, Argentina
The Study of lithic assemblages on deflation surfaces. The case study of Arroyo Verde, Northern Patagonia coast, Argentina
复制标题
紧缩表面上的石块组合的研究。
作者：
E. Carranza
本文重点研究阿罗约维德考古地点（阿根廷北巴塔哥尼亚里奥内格罗省）全新世沿海狩猎采集者职业的地表石制品。对在海岸线附近被稳定沙丘包围的收缩表面收集的石器组合的研究表明，风会对文物产生显着的腐蚀（风磨损），并影响中小型文物的保存。样品主要由燧石打碎，边缘和表面经过打磨和抛光。文物的尺寸分布表明，该组合的一个子集表现出良好的保存，可能是由于最近的地面暴露。此外，在与地面接触的文物表面上记录了碳酸盐和霉菌涂层，这表明沙丘塌陷区域存在潮湿条件。为了探索影响该位点组合稳定性条件的因素，应用了基于机器学习的决策树。该模型预测并定义可能出现不稳定情况的阈值。此外，它还表明，通气空洞内文物的相对高度是解释文物中记录的暴露条件的主要变量，并指出了随时间变化的差异通气过程。这里提供的数据说明了风如何改变当地的表面材料，并强调需要从埋藏学的角度来评估巴塔哥尼亚北部沿海考古组合的形成过程。
This paper focuses on surface lithic artefacts from Holocene coastal hunter gatherer occupations of Arroyo Verde archaeological locality (Rio Negro province, Northern Patagonia, Argentina). The study of lithic assemblages collected at a deflation surface surrounded by stabilised sand dunes near the coastline, shows that wind produce significant corrasion (wind abrasion) of artefacts and affects preservation of small and medium size artefacts. The sample is mainly composed of chert knapping debitage with abraded and polished edges and surfaces. The artefact size distribution suggests that a subset of the assemblage exhibits good preservation, possibly due to the recent subaerial exposure. Furthermore, carbonate and mould coatings were recorded over the artefacts surface in contact with the ground, which indicates the presence of humid conditions in the sand dunes deflation area. In order to explore the factors that affected assemblage stability conditions in the locus, a machine learning based decision tree was applied. The model predicts and defines a threshold at which the occurrence of instability conditions may appear. Also, it suggests that relative altitude of artefacts within the deflation hollow is the primary variable explaining the exposure conditions recorded in the artefacts and it points out processes of differential deflation over time. The data presented here illustrates how wind alters local surface materials and emphasizes that a taphonomic perspective is needed to assess the formation processes within northern Patagonia coastal archaeological assemblages.