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We present the results of the geomorphological mapping of a region of the Dhofar (Sultanate of Oman) including two contrasting physiographic units sharing a common drainage system into the Arabian Sea: the Jebel Qara limestone massif and the coastal plain of Salalah. Neogene to Quaternary tectonic activity controlled the formation of an extensive system of faults and caused the uplift of the Jebel Qara, forming structural escarpments. The massif underwent karstification and subsequent linear erosion. Today the Jebel is cut by a dendritic net of dry valleys, occasionally dammed by calcareous tufa dams. The transition between the southern escarpment of the Jebel and the plain below displays flat alluvial fans, bordered by a strip of beachrock, coastal dunes, and coastal lagoons, located in correspondence to estuaries. Dramatic soil erosion is evident, linked to intense human-triggered zoogeomorphological processes started in the Mid-Late Holocene after the introduction of pastoral land-use. [ABSTRACT FROM AUTHOR]

Digital documenting of archaeological evidence represents a crucial tool in the study, preservation, management, and promotion of archaeological sites in remote regions and in fragile landscapes. In fact, in marginal environment, the knowledge related to archaeological heritage can quickly disappear, especially when policies to protect cultural heritage are unreliable or lacking. In the last few decades, archaeological fieldwork has seen the increasing use of Structure-from-Motion (SfM) photogrammetric technique as a tool for mapping and recording archaeological evidence. This technique allows the creation of highly detailed 3D models of archaeological sites, monuments, and artefacts from sets of simple but accurately taken pictures, thus preserving the data for further research or (digital) cultural valorisation. Nowadays, low-cost/commercial off-the-shelf sensors (professional and semi-professional digital cameras and smartphones as well) are widely available and accessible by most of the users operating in cultural heritage documentation. This has made the acquisition of field pictures in archaeological research much more flexible and cost-effective. 3D models obtained from these pictures through photogrammetric commercial software can be scaled with a known-measure providing highly detailed models for archaeological purposes. This enhances the ability of archaeologists to record archaeological features during field surveys and rapidly obtain 3D models. This is especially useful in the case of archaeological surveys carried out in remote and barely accessible areas. In this paper, we present the results of the application of the above-mentioned methods during archaeological surveys in the Sultanate of Oman, where several archaeological features have been recorded through SfM photogrammetry using commercial devices and portable scale-bars. We demonstrate that this is a highly-flexible and fast process to record archaeological heritage in low-accessible or fragile contexts, where a 3D model (with centimetric precision) represents a valuable dataset for further in-lab analysis and cultural dissemination. [ABSTRACT FROM AUTHOR]

The preservation of rock art in open-air contexts is a global issue controlled by several environmental processes, which are less investigated than the cultural significance of engravings and paintings. For that reason, we discuss the age, preservation, and palaeoenvironmental context of petroglyphs discovered on the flat, almost vertical face of a large boulder fallen along the western slope of Jabal Hammah, a rocky hill that borders the oasis of Salut (northern Sultanate of Oman). Geoarchaeological investigation highlighted that, in the region, the preservation of petroglyphs is due to the interplay of two contrasting weathering processes. On one hand, karst dissolution – even if it is a very slow process in arid and semi-arid lands – gradually levels the surface of boulders. On the other hand, a biomineralized Mn- and Fe-rich rock varnish has developed inside the grooves of the engravings, thus sheltering them from extreme dissolution and promoting the preservation of the pristine shape of the representations. Moreover, organics trapped within the rock varnish have been radiocarbon dated to 2600 ± 60 uncal. years BP. This result allows establishing a limit ante quem for the production of these specific engravings and to root it to the Bronze or Iron Age exploitation of the area. This result is of particular relevance in a region where well-dated rock art is virtually absent. Today, the biogeochemical processes leading to the formation of the protective crust are almost inactive, and not consistent with the present dry environmental settings. Their occurrence is in accordance with other local palaeoclimatic record, and suggests Bronze and Iron Age climatic conditions wetter than today. A broader implication of our work is that it shows how a multidisciplinary approach to the study of rock art provides the opportunity of understanding the age of rock art and its paleoenvironmental significance. We demonstrate that physical, chemical, and biological weathering processes are in charge of the preservation and/or destruction of rock art; such processes have to be seriously taken into account in projects of rock art field assessment. [ABSTRACT FROM AUTHOR]