Chemical Weathering of Detrital Sediments in the Taklamakan Desert,Northwestern China

Based on the analysis of major‐element compositions of detrital sediments from the Taklamakan Desert of northwestern China, this paper aims to study chemical weathering in a hyper‐arid desert environment. The major‐element compositions are basically similar to the Upper Continental Crust but show a clear enrichment of CaO and depletion of Na₂O and K₂O, indicating the enrichment of carbonates and the decomposition of sodium and potassium silicates. The indexes of chemical alteration are relatively low and correlate negatively with the content of Na₂O, implying that the degree of chemical weathering is weak and mainly controlled by the weathering of sodium feldspars. An A‐CN‐K model demonstrates that the detrital sediments from the Taklamakan Desert have a high homogeneity in the trend of chemical weathering. They are weathered less than sands and soil in many other Chinese deserts, and also less than similar detrital sediments in many other countries. This evidence suggests a low degree of mineralogical maturity in the Taklamakan Desert. The aeolian sediments of different ages have similar indexes of chemical weathering, suggesting that the degree of chemical weathering was consistent in the Taklamakan Desert throughout the period of aeolian deposition. The low degree of chemical weathering is caused principally by extreme aridity, rapid rejuvenation of detrital sediments associated with strong aeolian processes, and an intensive input of fluvial deposits, as well as a lack of vegetation. Due to the high concentration of erodible minerals, the desert is quite vulnerable to soil erosion and land degradation.     

A note on the geomorphological environment of Çatal Hüyük, Turkey

It had previously been proposed (Cohen, 1970) that after large-scale Early Holocene alluviation, no post-occupational sediment accumulated around the neolithic site of Çatal Huyuk in south-central Anatolia. Data presented here, however, indicate that several metres of archaeological deposit at both east and west mounds are overlain by alluvium. This implies that the modern distribution of soil and water resources cannot be used directly to assess past agricultural potential in the vicinity of the site.     

Les puits nabatéens de Mad in āli (Arabie Saoudite)

Close to the monumental graves, numerous ancient wells, some of which reach a depth of 18 m, were found in the Nabatean site of Mad     in     āli     . Their fascinating study was begun by the author, a well-known speleologist. It required a geomorphological and hydrological approach of the site which established the groundwater level and piezometric contours. Furthermore, research was conducted on the palaeoclimates and present-day pluviometry, which has concluded that the fall in the groundwater level since antiquity is mainly the result of modern exploitation. Since 1975 the high-yielding submerged pumps have provided intensive irrigation to the important agriculture of el Hijr, close to the Nabatean site. The wells, their construction, their shape and ancient mechanism are described in this paper.     

河北及京津地区早中全新世文化的时空分布及其气候环境因素

本文根据考古学14C年代数据和考古遗存情况,结合高分辨率的地层和古气候研究资料,分析了河北及京津地区早中全新世文化的时空分布格局以及影响遗址分布的地貌和气候因素。该地区早中全新世文化时间序列为:早期新石器时代文化(10,000~8,800 yr BP)、新石器早中期之间的文化缺环(约8,800~7,300 yr BP)、7,300~6,500yr BP的磁山.兴隆洼.北福地一期三大文化系统并立发展时期以及6,500~6,000 yr BP的前仰韶文化时期。文化序列与气候序列对比发现:文化发展很大程度上受到气候条件的制约。从文化分布空间来看,具有如下特征:首先,早中全新世时期的文化分布在与当时海岸线平行的弧形地带上,这种分布格局与气候和地貌条件有关。在排除了地势高亢和海侵影响地区后,太行山东麓到古海岸线之间的弧形地带成为最佳选择。其次,从遗址分布高度来看,当时人仍居住在较高地貌面上,海侵及众多湖沼阻止了人类向东部平原腹地迈进的步伐。     

Exploitation of groundwater in the oasis of Masāfī (UAE): A diachronic perspective

In order to understand the role of water resources in the establishment and long-term evolution of settlements investigated by the French Archaeological Mission in the UAE in the oasis of Masāfī, wells and springs of all periods, identified at the surface and in stratified contexts, were mapped and studied thanks to a multidisciplinary approach combining archaeology, geomorphology, geoarchaeology and ethnography. Our study demonstrates that:

• – The Masāfī oasis was located in a specific geological setting entailing the accumulation of groundwater resources at reachable depth.
• – The groundwater resources remained rather stable from the mid-second millennium BC to the second half of the twentieth century AD. In this respect, the apparent abandonment of the oasis during some periods cannot be explained by water depletion.
• – The groundwater resources have decreased sharply since the second half of the twentieth century AD, due to the introduction of new water extraction technologies, motor pumps and then drillings, as a result of the modernisation and industrialisation of UAE economy.

Our study also stresses the importance of well and spring irrigation in the development of the sedentary settlements in south-eastern Arabia, technologies that have often been neglected in the regional archaeological literature in favour of the qanāt.     

Late quaternary alluviation and soil formation in the southern Argolid: its history,causes and archaeological implications

In the context of an archaeological survey of the southern Argolid, Greece, studies have been carried out to elucidate the evolution of the landscape since its earliest known human occupation about 50,000 years ago. One of these studies was a detailed geological mapping of the late Quaternary alluvium and soils in the area. Dated by means of thorium-uranium disequilibria, archaeological finds, and historical information, seven periods of alluviation were identified, each of short duration relative to long intervening periods of stability and soil formation. The three earliest alluvial phases, falling before and during the last glacial interval, range from about 330,000 to 32,000 years in age. No alluviation accompanied the last glacial maximum around 20,000 years ago. In fact, a stable landscape persisted until about 4500 years ago, when debris flows and widespread aggradation in the valleys resulted from major slope destabilization and soil erosion, probably as a result of extensive land clearance in the Early Bronze Age. A subsequent stable period lasted through the many upheavals of the later Bronze Age, the Dark Ages, and the early historical period. It came to an end with a brief phase of alluviation between about 300 and 50 BC. Stability returned through the late Roman period, notwithstanding considerable expansion of the settled area. Another period of destabilization, this one marked by debris flows and hence major soil erosion, is poorly fixed in time, but probably coincides with expanded maquis clearance accompanying the resettlement of the area around AD 1000. Subsequent events of soil erosion and aggradation vary in nature and timing from one drainage to the next and, in some areas, continue today.Nature and chronology of the soil forming and alluviation events show that simple correlations with climatic events do not suffice to explain them. For the latter ones, past about 2500 BC, human activity seems to be the dominant cause, but once again the relation between cause and effect is not straightforward. Land clearing, or neglect of soil conservation efforts during economic downturns, appear to have a more devastating effect upon the landscape than do intensive land use or total land abandonment.     

Coastal and marine studies in the department of geography and environment at the University of Aberdeen

ABSTRACT

The Department of Geography and Environment at the University of Aberdeen has a long history of coastal and marine teaching and research from the 1960s to the present day. Beginning with the work of Walton and latterly Ritchie, the paper traces the coastal and marine studies in the Geography degree programme, the development of the Marine and Coastal Resource Management degree, and the introduction of more recent courses such as Managing Our Coasts and Seas, Hydrography, and Land and Marine Conservation. Establishment of the Centre for Marine and Coastal Zone Management (CMCZM), and later the Aberdeen Institute for Coastal Science and Management (AICSM), provided a clear focus for continuing academic research into integrated coastal management and marine spatial planning. This complemented long-term involvement with Shell, SOTEAG (Shetland Oil Terminal Environmental Advisory Group), the Association for Geographic Information (AGI), OceanLab, the EUCC, and several Scottish coastal fora. The creation of the Unmanned Airborne Vehicle (UAV)/Unmanned Airborne System (UAS) Centre for Environmental Monitoring and Mapping (UCEMM) in 2014 brought together the role of remote sensing, GIS and photogrammetry in monitoring, mapping and modelling the coastal environment.