The paleosol horizons on the lower terrace of Wadi Shuwayhi are the first buried soils from the Holocene Humid Period in Central Oman have been studied; they occur in alluvial sediments (terrace fill) deposited approximately 11.5 to 7 ka, with radiocarbon ages of soil organic matter range from 10,600 to 5300 cal BP (8700-3500 cal BC). The youngest buried soil horizons in profile KS3 show disturbances in soil structure, consistent with Early Bronze cultivation at 4800-4400 cal BP (2800-2500 cal BC). Pedogenic features in the buried A and B horizons of all paleosols show subangular blocky and crumb macro- and microstructure, bioturbation features, and secondary calcification within root channels. In two soils, tabular and lenticular gypsum is particularly pronounced. Although the organic carbon content is low at all sites, soil formation suggests earlier vegetation establishment during the Holocene Humid Period as is also known from other arid areas. Alternating phases of alluvial aggradation and lateral erosion, i.e. stability and instability of the wadi terraces, are reflected in the preserved, albeit relic paleosol horizons. The study describes and classifies the buried soils, place them within a stratigraphic framework, and evaluates their significance as proxies of the HHP as well as early human-environment interactions in Southern Arabia.

Local-scale climate reconstruction in arid regions is challenging due to the scarcity of suitably preserved archives. While several well-studied climate proxy datasets exist for southeastern Arabia, including those preserved in speleothems, sedimentary deposits and paleosoils, and occasionally sediment cores collected for pollen analysis, snails have not yet been explored as a potential archive. This study investigates the potential of the terrestrial gastropod Zootecus insularis collected from geoarchaeological sections as new climate archive for arid environments. Isotope analysis was conducted on specimens from Holocene contexts in Oman to reconstruct long-term climate trends. Previously published water temperatures calculated from oxygen isotope data of Melanoides tuberculata, a freshwater gastropod species found in the same geoarchaeological sections as the terrestrial Zootecus shells, were interpolated to the age of the terrestrial snails, allowing for the recalculation of an oxygen isotope signal used to identify wet or dry periods. The resulting dataset showed a strong correlation with existing paleoclimate datasets from speleothems and paleolakes. Additionally, the δ13C values of Z. insularis indicated a significant shift towards more negative values over time, which probably suggests a transition from C4 grass-dominated vegetation to mixed C4/C3 xerophilic vegetation. This integrated approach suggests that snails could provide a valuable new archive for paleoclimate studies in arid regions.

The Early Bronze Age in southeastern Arabia is characterized by a significant shift in the archaeological record that coincides with the regional deterioration of climatic conditions associated with the end of the Holocene Humid Period. This study presents evidence for human modification of the local landscape around Building VII, a large circular structure at Al-Khashbah, Oman dating to the late third millennium BC. Through multiproxy analyses combining archaeological, geophysical, geomorphological, pedological and malacological, geochemical, palynological, and archaeobotanical datasets, we found evidence for the excavation of sediments at the foot of Building VII during the Umm an-Nar period. This excavation was subsequently filled by sediment presenting evidence for soil development, increased organic carbon, salt enrichment, microcharcoal, and snails. We suggest that both the excavation and subsequent aggradation may be related to gardening activities, though archaeobotanical and palynological analyses did not yield sufficient preserved material for local vegetation reconstruction. Nevertheless, our results contribute valuable insights into local human-environmental interactions and show that investigations beyond the visible archaeology of the monumental buildings of Early Bronze Age Oman can record a wide range of human activities and land modification near these important sites. These results have the potential to provide information on the resilience and adaptation to climate aridification by Umm an-Nar period peoples in central Oman and landscape modification during this period of economic transformation, increasing sedentarization, and growing social differentiation.

Multi-proxy data from Lizq, northern Central Oman, document the vegetation, climate, and fire history, as well as the local human activity since the Samad Late Iron Age from around 400 cal yr BCE (2350 cal yr BP) to present. The pollen record provides information about vegetation changes due to climatic fluctuations over Southeastern Arabia as well as about changes in the cultivated vegetation due to dynamic human practices (political and cultural developments, agriculture, herding, and grazing). We reconstructed a clear shift to more xerophytic vegetation and long-distance transport of Pinus pollen grains from the North indicating a weakening of the (summer) monsoon activity in northern Central Oman from around 250 to 500 cal yr CE (1700-1450 cal yr BP). Since then, the influence of southern-directed dry polar-continental air masses prevails. Palynological results also indicate plant cultivation on site from at least 250 cal yr BCE (2200 cal yr BP), but possibly already since the building of the Lizq Early Iron Age fort in the 5th to 4th century BCE. Over the last 2420 years there has been limited influence of animal husbandry and natural or anthropogenic fires on the local vegetation in the Lizq area.

Shells of the aquatic gastropod Melanoides tuberculata and the terrestrial gastropod Zootecus insularis were analysed using high-resolution isotope sampling (up to 274 samples per shell) to assess their potential use as a proxy for hydroclimatic and palaeoenvironmental reconstruction in drylands. A total of 169 snails (fossil and modern) were collected from 37 sites in Northern Oman and Dhofar, with each site selected for its specific geomorphological, archaeological or ecological context. This included fluvial terraces, playa environments, modern oasis gardens, irrigation channels and archaeological sites from the Neolithic (6,000-3,200 BCE) and Early Bronze Age (3,200-2,000 BCE) periods. The delta O-18 data obtained from these gastropods could be classified into eight different patterns, three for the aquatic snails (Type 1 A-C) and five for the terrestrial snails (Type 2 A-E), which were linked to the environmental context of their habitat. Furthermore, the use of the aquatic snails enabled us to distinguish between groundwater and surface water signals, whereas the terrestrial snails were employed to reconstruct changes in rainfall origin, humidity, evaporation, regular wet-dry cycles, and meteorological events. According to the results, gastropods can be used to elucidate the long-term, local evolution of rain-fed floodplain ecosystems in drylands and to identify the hydrological resources present in the vicinity of archaeological sites, particularly with regard to type 1 A-C (e.g., surface water vs groundwater).

Fossil shells of terrestrial and aquatic snails provide important information for the reconstruction of the Early Bronze Age environmental conditions in the Sultanate of Oman. Terrestrial species can be used to reconstruct available and thus consumed vegetation and the origin of precipitation, while aquatic species are useful for temperature estimates. The aim of this study is to identify past environmental conditions by generating high-resolution stable isotope series from well-preserved aragonitic shells of gastropods. A total of seven shells of the terrestrial species Zootecus insularis and five aquatic snails, Melanoides tuberculata, from Al-Khashbah were sampled. Eight of them were dated to the Early Bronze Age and four belong to the Late Islamic period that can be used as a reference. Stable isotope data of carbon (δ13Cshell) of the terrestrial snails indicate a change in digested vegetation from C3 plants in the Early Bronze Age to C4 plants in the Late Islamic period. δ18Oshell data obtained by the fully aquatic snails (range of max. 1 ‰) suggests a habitat, e.g., groundwater, with a strong environmental buffering effect. Though sudden rainfall events followed by subsequent evaporation are not recorded in the isotope record, data suggest highly variable palaeoprecipitation regimes with different origins (Indian Ocean and Mediterranean).

About 4200 charcoal fragments have been identified from the fourth- to third-millennium BC archaeological sites of Bat and Al-Khashbah in order to gain an understanding of plant resources available at the sites. Acacia sp., Ziziphus sp., and Tamarix sp. were the main taxa identified at both sites and indicate a similar vegetation composition as today. Phoenix sp. (date palm) charcoal also has been found at both sites. Whereas the cultivation of date palm for the 2700-2300 BC layers from Bat was likely, given other circumstantial evidence (i.e. local cereal cultivation and floodwater irrigation), it is unclear whether date palm was cultivated at Al-Khashbah. Especially for the older periods (3300-2700 BC) it is possible that nomadic pastoralists were exploiting and/or managing wild date palms. The find of Avicennia marina at Al-Khashbah indicates long-distance contacts with the coast.

Magnetometer surveys carried out as part of the al-Khashbah Archaeological Project have revealed the plan of two monumental buildings dating to the third millennium BC as well as the surrounding landscape. Evidence from excavations confirms that this complex can be dated to the Hafit period, marking it as an important site for the development of social complexity in the interior of northern Oman. The results of two seasons of magnetometer surveys, conducted in 2015 and 2017, are instructive in two major ways. The fused magnetograms are a record of the prehistoric cultural landscape immediately surrounding Building I and Building XI. The two surveys provide a direct comparison of two different geophysical methods of magnetometer survey: fluxgate gradiometry (2015 survey) and total field magnetometry (2017 survey), which can aid analysis of survey results. The surveys took place near the geomagnetic equator where the shallow inclination of the Earth's magnetic field can make archaeological interpretation of magnetic anomalies rather complex.

The transition from the Hafit to the Umm an-Nar period on the Oman peninsula in the third millennium BC is regarded as a period of substantial social and economic change. Although many thousands of tombs from the Hafit period remain, other archaeological evidence, such as settlements, is scarce. In 2015 therefore, a new archaeological research project conducted by the University of Tubingen and funded by the German Research Foundation was launched at al-Khashbah to investigate its Hafit and Umm an-Nar period remains. During the first two seasons research consisted of an intensive field survey, aerial survey, two geophysical surveys, as well as archaeological excavations in selected areas within the site. Among other archaeological remains, al-Khashbah features three Hafit-period stone towers and six towers from the Umm an-Nar period, including the famous rectangular building. The most important discoveries are a Hafit-period settlement with monumental mud-brick architecture and a stone-built tower dating to the end of the fourth millennium BC, associated with the oldest evidence of copper processing in Oman. Both findings testify to the importance of al-Khashbah for the investigation of the development of complexity at the end of the fourth and the beginning of the third millennium BC.

The sites of Bat and al-Ziba (Zebah) in the Sultanate of Oman offer a range of different archaeological features dating to the Umm an-Nar period. In this paper we present the pottery assemblages from two burial pits detected just outside a group of Umm an-Nar tombs in the necropolis of Bat, from the monumental Building II in Area B at Bat, and from two house complexes in al-Ziba, which were all excavated by the University of Tubingen between 2010 and 2015. By comparing the assemblages with each other, it will be demonstrated that there is a clear distinction in shapes, wares, and decorations between the burial pits, on the one hand, and Building II and on the other. We argue, therefore, for a functional difference between grave and non-grave pottery in the Umm an-Nar period. Furthermore, we show that the Umm an-Nar pottery is astonishingly homogeneous in the whole of the northern Oman peninsula and discuss its implications for the understanding of the social structure at that time.