Rocks of ages: propagation of hot-rock cookery in western North America

Cook-stone technology's Old-World roots were established by 30,000 B.P. and reappeared in the New World by 10,000 B.P., after millennia of direct-fire cooking. Hot-rock cookery, which is necessary for foods that require prolonged cooking, facilitated land-use intensification by affording greater utilization of nutrients in available foods on a given landscape. This technology gradually diversified during the early Holocene in western North America. By 4000 B.P. its initial intensification was underway; final intensification began by 2000 B.P. and typically peaked during the last 1500 years. Propagation of hot-rock cookery exemplifies pre-Columbian food crises and signals carbohydrate revolutions wherein more high-cost foods feed growing populations. As modeled, cook-stone griddles, earth ovens and steaming pits with rock heating elements are more costly facilities, insofar as fuel is used to heat rocks that, in turn, extend cooking time and temperature. More expensive still is stone boiling, given that fuel heats rocks that, in turn, heat water that cooks the food. Even more expensive in terms of energy expended is the manufacture of heating elements in the form of stone, ceramic, and metal cooking containers, all of which afford further evidence of land-use intensification.     

The Middle and Later Stone Age faunal remains from Diepkloof Rock Shelter,Western Cape,South Africa

The faunal sample from the Middle Stone Age (MSA) and overlying Later Stone Age (LSA) deposits of Diepkloof Rock Shelter (Western Cape Province, South Africa) includes at least 40 taxa, mostly mammals, but also tortoises, snakes, birds (especially ostrich represented by eggshell), and intertidal mollusks. The LSA sample contains only species that occurred nearby historically, including domestic sheep, which LSA people introduced to the region by 1800 years ago. In contrast, like other Western Cape MSA faunas, the Diepkloof MSA sample has more species and it is especially notable for five large extralimital grazing species. These imply a greater-than-historic role for grasses in the local vegetation, particularly in the post-Howiesons Poort (latest MSA) interval where the grazers appear most abundant. Extreme fragmentation and dark-staining impedes analysis of the MSA bones, but cut-marks, abundant burning, and numerous associated artifacts suggest that people were the main accumulators. Rare coprolites imply that carnivores could have contributed some bones, and concentrations of small mammal bones, particularly near the bottom of the MSA sequence, suggest a role for raptors. Tortoise bones are common throughout the sequence, and the MSA specimens tend to be especially large, as in other MSA assemblages. The LSA specimens are smaller, probably because LSA human populations were denser and preyed on tortoises more intensively. The most surprising aspect of the Diepkloof assemblage is its marine component. The coast is currently 14 km away and it would have been even more distant during much of the MSA when sea levels were often lower. Intertidal mollusks, particularly black mussels and granite limpets, are concentrated in the LSA and in the Late and Post-Howiesons Poort layers. Only LSA shells are complete enough for measurement, and the limpets are small as at other LSA sites. The implication is again for more intense LSA collection by relatively dense human populations. Both the LSA and MSA deposits also contain bones of shorebirds and Cape fur seals. Whale barnacles and occasional dolphin bones indicate that MSA people scavenged beached cetaceans.     

Introduction to the project and excavation of Diepkloof Rock Shelter (Western Cape,South Africa): a view on the Middle Stone Age

This introduction presents the background to the present research project at Diepkloof Rock Shelter, initiated in 1998. It is followed by a series of original papers that were presented in November 2010 at the join 13th PAA Congress (Panafrican Association of Prehistory and Associated Disciplines) and 20th conference of SAfA (Society of Africanist Archaeologists) at the University Cheikh Anta Diop in Dakar (Senegal). These papers were presented in a “Symposium on the MSA sequence of Diepkloof Rock Shelter: a view on the cultural evolution of southern African modern humans” organized by Pierre-Jean Texier, Guillaume Porraz, John Parkington and Jean-Philippe Rigaud. This series of papers is a first attempt at a multidisciplinary reconstruction of the way Middle Stone Age people inhabited the site of Diepkloof and the way they interacted with their environment. The resultant narrative outlines artifactual change through the sequence and discusses the factors that might underlie it.     

Methods for calculating brine evaporation rates during salt production

Salt is recognized by archaeologists as an important commodity due to the biological need for sodium and other cultural uses. Numerous studies have described the various techniques used in converting brine to crystallized salt, but few, if any, have attempted to quantify the physical processes of evaporation in pre-industrial societies. Apart from the few areas where salt mining is possible, nearly all forms of salt production require evaporation of water to concentrate brine and ultimately produce salt crystals. This study quantifies three of the most common evaporation techniques and provides insight into the production rates of salt and fuel requirements. Methods of calculation are provided for determining evaporation through (1) direct solar heating of brine, (2) applied external heat to a vessel, and (3) an immersed heated object (e.g., stone). These results provide physical constraints on the evaporation process and provide investigators with techniques for estimating efficiency and total production of prehistoric and historic saltworks.     

明代石拱桥永昌桥的加固修缮技术研究

为明晰明代石拱桥的结构性能,并提出适宜的加固修缮方法,以典型的明代石拱桥永昌桥为例进行研究。首先对其进行精确测绘,获得其准确可靠的几何信息;然后对其建筑形制、构造工艺及残损状况进行研究,为结构性能分析提供依据;接着利用ANSYS软件建立永昌桥主体结构的有限元模型,进行包括荷载影响分析、重要度分析和裂缝分析的结构性能研究;最后基于现状分析和结构性能研究,通过对比拱背套钢筋混凝土拱加固法和拱背粘贴碳纤维布加固法对石拱桥的结构性能的影响,提出了明代石拱桥永昌桥的加固修缮方法。研究成果可为同类型石拱桥的加固修缮提供参考。     

云冈石窟风化检测研究进展

云冈石窟,作为我国规模最大的古代石窟群,是文化遗产的重要组成部分。由于年代久远,许多石质文物都遭受着严重的风化病害侵蚀,对其风化程度进行检测已经成为石质文物保护中的一项紧迫任务。随着检测技术的不断发展,石质文物风化的检测方法也越来越多,并且每种检测方法都有其侧重的检测目的和优势。本研究综述近几十年内曾使用过的重点检测方法,并分析每种检测方法的原理、优势和局限性,为云冈石窟风化检测和保护提供参考。     

有机-无机复合疏水型二氧化硅涂层制备及性能

为研究制作保护石质文物的加固材料,采用溶胶-凝胶法,以两种有机硅材料(正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES))为共同前驱体,少量正辛胺为催化剂,聚二甲基硅氧烷(PDMS)(方法 1)或硅烷偶联剂KH-570(方法 2)为有机改性剂,制备了有机-无机复合疏水型Si O2涂层。通过红外光谱(FT-IR)、扫描电镜(SEM)和水接触角(WCA)来表征在砖块表面形成的SiO_2膜层化学组成、表面形貌以及疏水性能,然后再通过测试砖块加固前后外观、吸水性能和孔隙率的变化来验证实际加固效果。结果表明,两种方法均可以制备骨架带-CH3基团的SiO_2溶胶。采用方法 1(添加前驱体质量10%的PDMS)或者方法 2(MTES/TEOS质量比为2),加固后的砖块对水接触角均超过140°,毛细吸水率降低到未处理时的1%~2%,并且砖块的色差和光泽度改变较小。通过耐候性能测试表明,方法 2的保护效果相对较好,说明用此种方法合成的疏水性二氧化硅涂层可以作为砖块加固材料。     

宁波地区露天梅园石质文物病害机理研究

梅园石是宁波地区使用历史悠久的石材,早在西晋时期就已经开发,由于其加工性能优良而被广泛用于建筑构件及石刻雕塑。梅园石质文物由于多处于露天展示状态,在多种因素的共同作用下,病害状况较严重。为对梅园石质文物进行保护,本工作选取庆安会馆、东钱湖石刻群等几个代表性文物点进行了分析研究。通过岩矿检测,得知梅园石属于凝灰质砂岩,孔隙率较大。宁波地区梅园石质文物主要病害类型有生物病害、风化、机械损伤、表面污染物沉积等,与石材性质、用途及保存环境条件密切相关。通过此次研究,形成了初步的保护策略,为后续保护材料及保护方法的研究提供了依据。     

地面核磁共振方法在石质文物保护中的应用

石质文物破坏问题不仅在于人为破坏和表面污染,更多来自自然因素对文物的破坏,例如,日晒雨淋、风沙吹蚀、地表水的冲刷、地震、地下水的侵蚀溶蚀。为对第六批全国重点文物保护单位阳华岩摩崖石刻露天石质文物病害进行探查,采用无损探测的地面核磁共振方法和探地雷达方法,直接找水的地面核磁共振方法成功探测出摩崖石刻依附岩体地层含水分布状况。探地雷达方法探测出依附岩山体内岩溶、裂隙的发育状况。两种方法探测结果发现,石刻依附岩体内岩溶、裂隙发育,部分区域岩溶裂隙带已成为地下水汇聚场所或流通通道,对阳华岩摩崖石刻构成了极为严峻的侵蚀威胁。两种方法解释结果互为验证,研究结果为阳华岩摩崖石刻的病害治理和保护提供了宝贵的基础资料。     

砂岩质文物风化的空气耦合超声检测方法研究——以云冈石窟为例

在石质文物的风化检测领域中,耦合剂式和无耦合剂接触式超声检测技术均被广泛应用。然而,这两种方法均存在技术局限性,例如,耦合剂式超声检测可能引发文物表面污染,无耦合剂接触式超声检测可能对文物表面造成损伤。空气耦合超声检测技术的出现为石质文物风化检测提供了更安全的方式,但其稳定性和在风化程度检测的适用性尚待评估和验证。基于此,以云冈石窟的砂岩样品为研究对象,开展了冻融循环和酸性劣化两种风化模拟循环试验,搭建了空气耦合超声检测系统,并基于获取的原始波形计算出砂岩样品的波速。同步采用耦合剂式超声检测与无耦合剂接触式超声检测技术,对不同风化程度的砂岩样品进行了检测;通过最小二乘回归模型、震荡系数计算方法,对获取的超声波速数值及其随风化进程的变化趋势进行了分析。结果表明:空气耦合超声在重复检测中的波速离散程度明显低于其余两种传统超声检测技术;获得的波速与风化程度的变化趋势一致性更强,在石质文物风化程度检测中具有较高的适用性。综上,空气耦合超声检测技术能够提供更为准确、安全、有效的风化检测数据,在石质文物检测中具有较强的适用性和广阔的应用前景,可为石质文物的保护工作提供重要支持。