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Differentiating Fissure-Fed Lava Flow Types and Facies Using RADAR and LiDAR: An Example From the 2014â2015 Holuhraun Lava Flow-Field
Distinguishing between lava types and facies using remote sensing data is important for interpreting the emplacement history of lava flow-fields on Earth and other planetary bodies. Lava facies typically include a mixture of lava types and record the collective emplacement history of material preserved at a particular location. We seek to determine if lava facies in the 2014â2015 Holuhraun lava flow-field are discernible using radar roughness analysis. Furthermore, we also seek to distinguish between lava types using high resolution Light Detection and Ranging (LiDAR) data. We extracted circular polarization ratios (CPR) from the Uninhabited Aerial Vehicle Synthetic Aperture Radar and cross-polarization (VH/VV) data from the Sentinel-1 satellite to analyze the surface roughness of three previously mapped lava facies: rubbly, spiny, and undifferentiated rubblyâspiny. Using the Kruskal-Wallis test, we reveal that all but one pair of the facies are statistically separable. However, the populations overlap by 88%â89% for CPR and 64%â67% for VH/VV. Therefore, owing to large sample populations (n > 2 Ă 105), slight differences in radar data may be used to probabilistically infer the presence of a particular facies, but not directly map them. We also calculated the root-mean-square slope and Hurst exponents of five different lava types using LiDAR topography (5 cm/pixel). Our results show minute differences between most of the lava types, with the exception of the rubbly pÄhoehoe, which is discernible at 1Ï. In brief, the presence of âtransitionalâ lava types (e.g., rubbly pÄhoehoe) within fissure-fed lava flow-fields complicates remote sensing-based mapping. © 2022. American Geophysical Union. All Rights Reserved.6 month embargo; first published: 20 June 2022This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Sustainability and Resilience in Prehistoric North Atlantic Britain: The Importance of a Mixed Paleoeconomic System
Nohe two archipelagos of Orkney and Shetland, which form the Northern Isles of Britain, are an active focus of archaeological research. The rich Neolithic heritage of Orkney has been acknowledged by the granting of World Heritage status. Although set in both a biogeographically peripheral position and within what may be considered to be marginal landscapes, these North Atlantic islands have a large number of settlement sites with long occupational sequences, often stretching from the Neolithic to the Late Iron Age or into the Norse period. The mixed paleoeconomic strategy presented by three of these settlementsâTofts Ness, Sanday, Orkney (excavated 1985â1988); the Iron Age sequences at Old Scatness, Shetland (excavated 1995â2006); and Late Neolithic and Bronze Age cultivated middens from Jarlshof, Shetland (investigated in 2004)âprovide the core of the evidence discussed within this paper (the radiocarbon chronologies for the key sequences from these three sites are provided as Appendix 1). The role of the prehistoric paleoeconomy is argued to be of central importance in the longevity of these settlements. In particular, barley production is evidenced on all three sites by the plant macrofossils and by the human investment in the creation and management of manured soils, providing an infield area around the settlement.
This paper focuses on the identification of these anthropogenic soils in the archaeological record. The investment in and management of these arable soils provides clear evidence for resource creation on all three sites. It is argued that these soils were a crucial resource that was necessary to support intensive barley cultivation. The intensive management implied by the presence of these soils is seen as a catalyst for sedentary living and sustainability within a marginal landscape. The evidence also demonstrates the continuity of agricultural practice from the Neolithic to the Iron Age together with the social dynamics that such a practice generates.
This paper is in two parts: the first section examines in detail the evidence for the presence of anthropogenic soils and the mixed economic strategies for the Neolithic and Early Bronze Age presented by the evidence from Tofts Ness and Jarlshof. The evidence for the continuity of this intensive strategy of soil management is seen from the later evidence of the Bronze Age and Early Iron Age at Tofts Ness and the Middle Iron Age evidence at Old Scatness. The second part of the paper examines the importance of these soils as an inherited resource within the Neolithic and Early Bronze Age paleoeconomic system. Two models are presented. The first examines the cyclic importance of human creation and maintenance of small arable plots to high barley production yields and therefore to site viability, and the effect this has within a mixed resource system in providing settlement viability through time. The second explores the theoretical land and seascape that would provide this mixed resource base