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Remotely-piloted aircraft (RPA) thermography is one of the least utilized remote-sensing methods in archaeology, yet it has great potential for visualizing subsurface archaeological features. Given the logistic constraints of remote fieldwork, arctic archaeologists have much to gain from this portable and effective remote-sensing application. This paper presents a novel methodological approach for the collection, processing, and analysis of RPA thermal imagery in the Canadian High Arctic that accounts for the unique environmental and logistic challenges of RPA applications in polar regions. The development of this approach is based on a case study of two Pre-Inuit (4500-1000 B.P.) archaeological sites from the Foxe Basin region, Nunavut. The presented workflow demonstrates the effectiveness of RPA ther-mography in archaeological feature detection in an Arctic-tundra setting. Thermal detection of several previously unidentified subsurface features in Foxe Basin suggest that surface feature visibility is lower than previously anticipated, calling attention to potential judgemental biases in pedestrian archaeological surveys in Arctic contexts. Based on the utility of low-altitude thermography for visualizing the internal structures of Tuniit dwellings, this paper proposes that thermography facilitates archaeological spatial analysis beyond feature prospection. RPA thermography is a non-destructive and economic remote-sensing solution to some of the persistent logistic challenges to fieldwork in remote locations that often inhibit large-scale archaeological analyses not only in the Canadian Arctic, but remote Arctic-Alpine regions worldwide.
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... Case studies from elsewhere in the circumpolar Arctic have demonstrated how UAVs have assisted heritage researchers in harsh environments with a remote sensing platform that is affordable, versatile, and customizable due to swappable sensor payloads . Ecological research in other cold climates has also benefited from the use of UAV technology . ...
The Yukon-Kuskokwim (Y-K) Delta is home to the Alaskan Native Yup'ik people who have inhabited this remote, subarctic tundra for over 1500 years. Today, their ancestral lifeways and cultural landscapes are at risk from severe climate change-related threats. In turn, we propose that remote sensing technologies, particularly with sensors mounted on Unmanned Aerial Vehicle (UAV) platforms, are uniquely suited for protecting Yup'ik landscape heritage. Based on collabora-tive, community-based fieldwork in Quinhagak, AK, we present evidence that cultural sites-ranging from historic fishing camps to pre-contact winter villages-exhibit predictably atypical vegetation patterns based on the local ecological biome. Furthermore, these vegetation patterns can be recorded and statistically quantified through the analysis of multispectral imagery obtained from UAV-mounted sensors with three different false color composite rasters and vegetation indices depending on biome type. Finally, we suggest how the Yupiit can combine these methodologies/work-flows with local knowledge to monitor the broader heritage landscape in the face of climate change.
... Although necessitating an operator to be physically present in the study area, UAV-based remote sensing can capture high-resolution aerial imagery at low altitudes to obtain data of a quality far in excess of what is possible from commercially available satellite-based platforms. Moreover, UAVs are no longer limited to using conventional visual-light cameras and can now carry a payload of different sensor types, including multispectral and thermal sensors, for investigating the physical environment (Agudo et al., 2018;Fenger-Nielsen et al., 2019;Walker, 2020). ...
The following article outlines a collaborative, multidisciplinary approach to remote sensing in Southwest Alaska's Yukon‐Kuskokwim (Y‐K) Delta that combines ethnographic inquiry and remote sensing to monitor, detect and preserve cultural resources for Alaskan Native communities. Because distinctive vegetation differences are readily visible on cultural sites during the summer months, the analysis of multispectral imagery obtained from remote sensing is particularly useful. In turn, we demonstrate the efficacy of this protocol on pre‐contact settlement sites along the Ayakulik River system on Kodiak Island using a normalized difference vegetation index (NDVI) raster of the study area. Here, support vector machine (SVM) supervised classification was highly effective at identifying spectral patterns associated with anthropogenic activity while ethnographic data helped rule out false‐positive cases. In addition, we provide the results of a 2019 archaeological prospection survey carried out in conjunction with the ongoing Nunalleq Project in Quinhagak, Alaska, to further highlight the value of ethnographic data collection, ethnobotanical surveys and unmanned aerial vehicle (UAV)‐based spectroscopy alongside SVM supervised classification. Finally, we propose three suggestions for future research on Yup'ik landscapes in the Y‐K Delta regarding citizen science, language preservation and the use of collaborative online maps for community‐based decision making.
... Importantly, since Feature 9 appeared much smaller in size from the surface vegetation it is quite possible there are additional large multi-family dwellings at the site, and elsewhere, that have not yet been identified. The full extent of large Middle Dorset dwelling use may in fact only be discovered through further excavation or possibly magnetometry (see Hodgetts and Eastaugh, 2017) or thermography (Walker, 2020). Accordingly, any attempt to determine actual population sizes based on surface expressions should be done so with caution. ...
This paper presents a detailed description of an unusual multi-family dwelling, recently excavated at Alarniq—one of the largest and most poorly understood Dorset archaeological sites in the Canadian Arctic and Greenland. The structure is located at 19.5 metres above sea level and tentatively dates to the Middle Dorset period (radiocarbon dates are forthcoming). Unlike the longhouses typically associated with the Late Dorset period (e.g., Appelt and Gulløv 1999; Damkjar 2000, 2005; Friesen 2007), which are largely warm weather occupations containing low frequencies of artefacts and faunal material (Damkjar 2000), the house at Alarniq appears to be a very large habitation structure. Three similar structures have been recorded at Alarniq (see Savelle and Dyke 2014; Meldgard 1960, 1962), however across the Canadian Arctic, few of these houses have been excavated and the details of none have yet been published (see Ryan 2003). Here we discuss architecture, faunal material, and the distribution of artefacts within the house, and help situate it’s use in relation to later communal structures dating to the Dorset period.
Our understanding of Dorset communal living is largely derived from the Late Dorset period when longhouses are prevalent throughout the Eastern Arctic. However, based on the recent identification of large multi-family dwellings that date to the Middle Dorset period communal living was seemingly a significant part of Dorset lifeways much earlier. To date, few such dwellings have been excavated, and none have been published in detail. In 2015 a large Middle Dorset multi-family dwelling, Feature 9, was excavated at Alarniq, northern Foxe Basin, Nunavut— one of the largest Dorset sites found across the Eastern Arctic. Feature 9 is the fourth large Middle Dorset multi-family dwelling recorded at Alarniq and radiocarbon dates indicate that these dwellings were not a short-term phenomenon, but instead were built (and rebuilt) at the site for several centuries. Unlike Late Dorset longhouses, which appear to be warm season occupations containing few artifacts and faunal material, Feature 9 was occupied during the cold season, perhaps even year-round, and contained abundant artifacts and faunal material. Undoubtedly, it is an enlarged version of the more typical winter dwelling used in the region. However, since all known large Middle Dorset multi-family dwellings are associated with dwellings of a more typical size they may have also served as gathering spaces, in some ways resembling qaqqiq used in traditional Inuit society.
Da jedes Jahr um die 100.000 Rehkitze in Deutschland bei Mäharbeiten verenden, wurde sich in dieser Arbeit mit dem Aufspüren von Jungwild in Wiesen beschäftigt. Zwar gibt es bereits Methoden für die Rettung von Rehkitzen, jedoch sind viele dieser zu teuer, zu personalaufwendig oder zu zeitintensiv für den breiten Einsatz. Ziel dieser Arbeit war es, eine Steuerungssoftware für ein UAV zu entwickeln, welche autonom Wildtiere entdeckt, anfliegt und verifiziert.
Over the last decade, we have witnessed momentous technological developments in unmanned aircraft systems (UAS) and in lightweight sensors operating at various wavelengths, at and beyond the visible spectrum, which can be integrated with unmanned aerial platforms. These innovations have made feasible close-range and high-resolution remote sensing for numerous archaeological applications, including documentation, prospection, and monitoring bridging the gap between satellite, high-altitude airborne, and terrestrial sensing of historical sites and landscapes. In this article, we track the progress made so far, by systematically reviewing the literature relevant to the combined use of UAS platforms with visible, infrared, multi-spectral, hyper-spectral, laser, and radar sensors to reveal archaeological features otherwise invisible to archaeologists with applied non-destructive techniques. We review, specific applications and their global distribution, as well as commonly used platforms, sensors, and data-processing workflows. Furthermore, we identify the contemporary state-of-the-art and discuss the challenges that have already been overcome, and those that have not, to propose suggestions for future research.
There is a long history of the use of aerial imagery for archaeological research, but the application of multisensor image data has only recently been facilitated by the development of unmanned aerial vehicles (UAVs). Two archaeological sites in the East Midlands U.K. that differ in age and topography were selected for survey using multisensor imaging from a fixed-wing UAV. The aim of this study was to determine optimum methodology for the use of UAVs in examining archaeological sites that have no obvious surface features and examine issues of ground control target design, thermal effects, image processing and advanced filtration. The information derived from the range of sensors used in this study enabled interpretation of buried archaeology at both sites. For any archaeological survey using UAVs, the acquisition of visible colour (RGB), multispectral, and thermal imagery as a minimum are advised, as no single technique is sufficient to attempt to reveal the maximum amount of potential information.
In 2008, four decades since Meldgaard's work at Alarniq—the type site for Dorset culture—Savelle and Dyke returned to resurvey the site. Archaeological investigations continued in 2015 and 2017 as part of the Foxe Basin Archaeological Project, when Howse conducted further surveys, excavated six semi-subterranean dwellings and two associated middens, and tested five additional features. The new site map and radiocarbon sequence have significantly changed our understanding of site use and beach-level chronology at Alarniq. The number of dwellings varies across the beach ridges, suggesting populations fluctuated throughout the site's use (2,700–800 cal BP). However, the new radiocarbon analyses also indicate that dwellings between 14.5 and 21.5 m above sea level are the same general age and that paleodemography at Alarniq is less straightforward than suggested by the number of features per beach ridge. It appears that ideal house construction location is a stronger indicator of the placement of winter houses at the site than proximity to the shoreline. We suggest this is largely related to site seasonality. These new data have significant implications for our understanding of current Dorset artifact typologies that have largely been developed using the material Meldgaard recovered at the site.
Miniaturized thermal infrared (TIR) cameras that measure surface temperature are increasingly available for use with unmanned aerial vehicles (UAVs). However, deriving accurate temperature data from these cameras is non-trivial since they are highly sensitive to changes in their internal temperature and low-cost models are often not radiometrically calibrated. We present the results of laboratory and field experiments that tested the extent of the temperature-dependency of a non-radiometric FLIR Vue Pro 640. We found that a simple empirical line calibration using at least three ground calibration points was sufficient to convert camera digital numbers to temperature values for images captured during UAV flight. Although the camera performed well under stable laboratory conditions (accuracy ±0.5 • C), the accuracy declined to ±5 • C under the changing ambient conditions experienced during UAV flight. The poor performance resulted from the non-linear relationship between camera output and sensor temperature, which was affected by wind and temperature-drift during flight. The camera's automated non-uniformity correction (NUC) could not sufficiently correct for these effects. Prominent vignetting was also visible in images captured under both stable and changing ambient conditions. The inconsistencies in camera output over time and across the sensor will affect camera applications based on relative temperature differences as well as user-generated radiometric calibration. Based on our findings, we present a set of best practices for UAV TIR camera sampling to minimize the impacts of the temperature dependency of these systems.
A significant problem in understanding the archaeology of standing buildings relates to the proscription to uncover features and structures within plastered and rendered walls due to the susceptibility and historic importance of such structures. Infrared thermography offers a method of visualization that is nondestructive and capable of revealing various types of archaeological anomaly that has been demonstrated on a small scale in the past. A passive infrared thermal camera is used to examine several historic buildings that are known or suspected to contain hidden archaeological information; the technique is also presented on complex, exposed historic building fabric. The results confirm that it is possible to detect various types of man-made anomaly and to differentiate building materials. In consequence, the use of passive thermal infrared imaging is shown to be a valuable tool in the examination and recording of historic buildings and structures.
The cold, wet climate of the Arctic has led to the extraordinary preservation of archaeological sites and materials that offer important contributions to the understanding of our common cultural and ecological history. This potential, however, is quickly disappearing due to climaterelated variables, including the intensiﬁcation of permafrost thaw and coastal erosion, which are damaging and destroying a wide range of cultural and environmental archives around the Arctic. In providing an overview of the most important effects of climate change in this region and on archaeological sites, the authors propose the next generation of research and response strategies, and suggest how to capitalise on existing successful connections among research communities and between researchers and the public.
Archaeological sites in the Canadian Arctic often contain substantial quantities of marine mammal bones and in some cases completely lack terrestrial mammal bones. A distrust of radiocarbon ( ¹⁴ C) dates on marine mammal bones among Arctic archaeologists has caused many sites to be insufficiently dated. The goal of this study was to investigate the marine reservoir effect on Atlantic walrus in the Foxe Basin region of the Canadian Arctic through a two-pronged approach: dating of live-harvested specimens of known age collected prior to AD 1955 and dating of pairs of animal remains (walrus and caribou) from stratigraphically contemporaneous levels within archaeological features. ¹⁴ C dates on pre-bomb, live-harvested walrus indicate that a ΔR value of 160±50 yr be used in calibrating dates on walrus from this region. These results differed significantly from a similar set of pre-bomb mollusks, which argues against applying mollusk-based corrections to marine mammals. The results of comparative dating of caribou and walrus from archaeological features provided maximum estimates of reservoir ages that were more varied than the directly measured ages. Although about half of inferred ΔR values overlap the museum specimen results, the others indicate that the assumption of contemporaneity does not hold true.
Lightweight drones have emerged recently as a remote sensing survey tool of choice for ecologists, conservation practitioners and environmental scientists. In published work, there are plentiful details on the parameters and settings used for successful data capture, but in contrast there is a dearth of information describing the operational complexity of drone deployment. Information about the practices of flying in the field, whilst currently lacking, would be useful for others embarking on new drone-based investigations. As a group of drone-piloting scientists, we have operated lightweight drones for research in over 25 projects, in over 10 countries, and in polar, desert, coastal and tropical ecosystems, with many hundreds of hours of flying experience between us. The purpose of this paper was to document the lesser-reported methodological pitfalls of drone deployments so that other scientists can understand the spectrum of considerations that need to be accounted for prior to, and during drone survey flights. Herein, we describe the most common challenges encountered, alongside mitigation and remediation actions that increase the chances of safe and successful data capture. Challenges are grouped into the following categories: (i) pre-flight planning, (ii) flight operations, (iii) weather, (iv) redundancy, (v) data quality, (vi) batteries. We also discuss the importance of scientists undertaking ethical assessment of their drone practices, to identify and mitigate potential conflicts associated with drone use in particular areas. By sharing our experience, our intention is that the paper will assist those embarking on new drone deployments, increasing the efficacy of acquiring high-quality data from this new proximal aerial viewpoint.
The current standard procedure for aligning thermal imagery with structure-from-motion (SfM) software uses GPS logger data for the initial image location. As input data, all thermal images of the flight are rescaled to cover the same dynamic scale range, but they are not corrected for changes in meteorological conditions during the flight. This standard procedure can give poor results, particularly in datasets with very low contrast between and within images or when mapping very complex 3D structures. To overcome this, three alignment procedures were introduced and tested: camera pre-calibration, correction of thermal imagery for small changes in air temperature, and improved estimation of the initial image position by making use of the alignment of RGB (visual) images. These improvements were tested and evaluated in an agricultural (low temperature contrast data) and an afforestation (complex 3D structure) dataset. In both datasets, the standard alignment procedure failed to align the images properly, either by resulting in point clouds with several gaps (images that were not aligned) or with unrealistic 3D structure. Using initial thermal camera positions derived from RGB image alignment significantly improved thermal image alignment in all datasets. Air temperature correction had a small yet positive impact on image alignment in the low-contrast agricultural dataset, but a minor effect in the afforestation area. The effect of camera calibration on the alignment was limited in both datasets. Still, in both datasets, the combination of all three procedures significantly improved the alignment, in terms of number of aligned images and of alignment quality
Small unmanned aircraft systems (UASs) are often suited to applications where the cost, resolution, and (or) operational inflexibility of conventional remote sensing platforms is limiting. Remote sensing with small UASs is still relatively new, and there is limited understanding of how the data are acquired and used for scientific purposes and decision making. This paper provides practical guidance about the opportunities and limitations of small UAS-based remote sensing by highlighting a small sample of scientific and commercial case studies. Case studies span four themes: (i) mapping, which includes case studies to measure aggregate stockpile volumes and map river habitat; (ii) feature detection, which includes case studies on grassland image classification and detection of agricultural crop infection; (iii) wildlife and animal enumeration, with case studies describing the detection of fish concentrations during a major salmon spawning event, and cattle enumeration at a concentrated animal feeding operation; (iv) landscape dynamics with a case study of arctic glacier change. Collectively, these case studies only represent a fraction of possible remote sensing applications using small UASs, but they provide insight into potential challenges and outcomes, and help clarify the opportunities and limitations that UAS technology offers for remote sensing of the environment.
The New World Arctic, the last region of the Americas to be populated by humans, has a relatively well-researched archaeology, but an understanding of its genetic history is lacking. We present genome-wide sequence data from ancient and present-day humans from Greenland, Arctic Canada, Alaska, Aleutian Islands, and Siberia. We show that Paleo-Eskimos (~3000 BCE to 1300 CE) represent a migration pulse into the Americas independent of both Native American and Inuit expansions. Furthermore, the genetic continuity characterizing the Paleo-Eskimo period was interrupted by the arrival of a new population, representing the ancestors of present-day Inuit, with evidence of past gene flow between these lineages. Despite periodic abandonment of major Arctic regions, a single Paleo-Eskimo metapopulation likely survived in near-isolation for more than 4000 years, only to vanish around 700 years ago.
This study examined the feasibility of using a very sensitive thermal video radiometer to derive information about subsoil objects from the air. In this study we mounted a thermal sensor onboard a helicopter and acquired digital data from an altitude of 1333 m over an archaeological site on the Golan Heights, Israel. The site, namely, Leviah Enclosure, is an Early Bronze Age settlement that is covered by a thin layer of soil. The buried structures, made from basalt, could not be observed from the ground or in aerial photos. However, in the thermal images, the buried basalt structures were significantly enhanced because they have different thermal characteristics than the ground's surface. Based on the thermal images, it was possible to generate a map to use for future excavation activity. Referring to the thermal maps, a selected area was excavated, and verification on the ground, using traditional archaeological methods revealed a positive agreement between the thermal-based map and the actual location of the buried structures. The research highlights the fact that this technology can contribute additional and useful information to the field of archaeology. Based on these results, further study is planned in order to examine the capability of the sensor under different conditions and to further excavate the entire Leviah Enclosure.
In 1995 and 1996 archaeological investigations were carried out by a joint Nordic research project in the southern Disko Bay area, West Greenland. The project focussed on Paleo‐Eskimo spatial organization, particularly the arrangements of dwelling structures. This paper presents some results from surveys and excavations of Saqqaq sites, and discusses issues related to Paleo‐Eskimo house forms and settlement organization. It is argued that considerable changes in housing and settlement patterns took place in West Greenland ca. 1700–1600 BC.
Wetlands and lakes in the Tanana Valley, Alaska, have provided important resources for prehistoric humans who inhabited this region. We examine an ~11,200 cal yr BP record of environmental and paleolimnological changes from Quartz Lake in the middle Tanana Valley. Our data are also presented in the context of recent archaeological findings in the lake’s general vicinity that have 18 associated AMS 14C dates. We analyzed the stable-carbon and nitrogen isotope composition of total organic matter from the core, coupled with oxygen and carbon isotope analyses of Pisidiidae shells (fingernail clams), in addition to chironomid assemblage changes. Lacustrine sediments began to accumulate at ~11,200 cal yr BP. Initially, autochthonous production was low and allochthonous organic input was negligible between 11,000 and 10,500 cal yr BP, and were associated with relatively cool conditions at Quartz Lake at ~10,700 cal yr BP. After 10,500 cal yr BP, autochthonous production was higher coincident with a shift to chironomid assemblages dominated by taxa associated with warmer summer climates. A decrease in δ13C values of total organic carbon (TOC) and organic content of the sediment between 9,000 and 4,000 cal yr BP may indicate declining autochthonous primary production. This period ended with an abrupt (~7 ‰) decrease in the δ18O values from Pisidiidae shells at ~3,000 cal yr BP, which we hypothesize represented an episodic connection (flood) of the lake with flow from the nearby (~6 km) Tanana River. Our findings coincide with evidence for major flooding at other locations connected to the Tanana River and further afield in Alaska. From ~3,000 cal yr BP Quartz Lake subsequently appeared to become a relatively closed system, as indicated by the δ18OPisidiidae and δ13CPisidiidae data that are positively correlated and generally higher, which also correlates with a shift to moderately higher abundances of littoral chironomids. The cause of the transition to closed-basin conditions may have been geomorphic rather than climatic. This evidence of a progressively stronger evaporative influence on the lake’s closed hydrology after ~3,000 cal yr BP is consistent with our modern δ18O and δD water data from Quartz Lake that plot along a regional evaporative line we base on isotopic measurements from other local lakes and rivers.
Hunter-gatherer mortuary practices identified in the Trent Valley region, ON are highly patterned for the Middle Woodland period (400 BCE-700 CE), but the importance of many of these mortuary sites can be recognized as far back as the Late Archaic period (2500–1000 BCE). A geospatial modelling approach is used to predict the distribution of mortuary sites based on ecological factors that may have influenced land use strategies. The assessment reveals that Late Archaic and Middle Woodland mortuary sites were primarily located near aerobic wetlands that were likely rich in emergent plant life. The predicted suitably of mineral soil horizons, when compared with Trent Valley floodplain behaviour, suggests that wild rice may have been a particularly abundant resource near mortuary sites. The position of wild rice in Anishinaabe traditional stories is discussed to contextualize its potential early food value to Indigenous occupants of the Trent Valley, prior to the resource’s documented historic importance. The highly selective positioning of mortuary sites and their continuity within the Trent Valley region shed light on how ancestral ties to key places were established and maintained in precolonial hunter-gatherer societies.
Thermal infrared imaging, or thermography, is the remote sensing technique of detecting variations in ground temperature caused by exposed or subsurface archaeological remains either absorbing or radiating heat. Despite its conception in the 1970s, the practice has to date been rarely utilized, as a result of the high cost of the technology and the complex interplay of environmental variables. However, recent studies have demonstrated the effectiveness of the technique, especially when combining modern thermal cameras with unmanned aerial vehicles (UAV). Yet these papers often focus on mid‐ to high‐altitude flights, where the technique is only effective at detecting larger thermal anomalies. This article presents a new method for terrestrial thermography, developed for the Zagora Infrared Photogrammetry Project (The University of Sydney and the Australian Archaeological Institute at Athens). The project undertook a six week thermal investigation of the Early Iron Age site of Zagora and the surrounding hinterland utilizing the newest commercial thermal cameras and UAVs. The method of terrestrial thermography involves using photographic poles and photogrammetry to create high‐resolution thermal orthophotographs, which allow the detection of smaller thermal anomalies, providing significantly more detail than aerial thermography. Several features were discovered using this method, including a possible kiln, which would be the first ever identified at the site.
Locating the subtle and uneven deposition of human activities across the landscape continues to challenge archaeologists. Existing tools (e.g. excavation, shovel testing, pedestrian survey, and terrestrial geophysics) have proven effective at locating many types of archaeological features but remain time-consuming and difficult to undertake on densely vegetated or topographically complex terrain. As a result of these limitations, key aspects of past communities remain largely outside of archaeological detection and interpretation. This flattening of past lifeways not only affects broader understandings of these communities, but can also negatively impact the preservation of archaeological sites. This paper presents the detection of archaeological features through an analysis of drone-acquired thermal, multispectral, and visible light imagery, alongside historical aerial photography, in the area surrounding Middle Grant Creek (11WI2739), a late prehistoric village located at Midewin National Tallgrass Prairie in Will County, IL. Our investigations discovered a probable housing area and a ritual enclosure, increasing the area of the site from 3.4 ha to 20 ha. The proposed housing and ritual areas of this village also help contextualize finds from the ongoing archaeological excavations at Middle Grant Creek. More broadly, results demonstrate the valuable contributions that these relatively new archaeological survey methods have in shaping our understandings of the archaeological landscape and highlight the importance of integrating them into the archaeological toolkit.
Infrared thermography, or thermal imaging, has been used as a remote sensing technique to determine whether subsurface features such as walls or pits generate a heat differentiation from the surrounding earth. To date, this form of remote sensing has been notoriously difficult to perform due to cost, low-resolution thermal cameras and an inability to provide a stable aerial photographic platform. Furthermore, thermal fluctuations produced by archaeological remains are highly volatile, and are dependent on a multitude of variables such as soil moisture, particle size, and the construction materials of features. These issues have restricted the use of infrared thermography within archaeology. Yet, with the rapid development and adoption of unmanned aerial vehicles (UAVs) over the last decade as well as developments in thermographic technology, thermal imaging is now affordable and can be attached with relative ease to a multitude of UAVs. This paper reviews a new, low-cost, FLIR Systems thermal camera made specifically for UAVs, which were successfully employed at the Ancient Methone Archaeological Project, Pieria, Greece. By utilizing the FLIR Vue Pro, along with a DJI Phantom 2, aerial thermography was performed at the site at a cost far below that proposed by previous studies, with results also equalling or exceeding those methodologies. In combination with high resolution aerial photogrammetry, this methodology has helped to clarify previous archaeological investigations at the site, as well as revealing significant rectilinear subsurface remains.
While a long history of experimental data shows that aerial thermal images can reveal a wide range of both surface and subsurface archaeological features, technological hurdles have largely prevented more widespread use of this promising prospecting method. However, recent advances in the sophistication of thermal cameras, the reliability of commercial drones, and the growing power of photogrammetric software packages are revolutionizing archaeologists' ability to collect, process, and analyze aerial thermal imagery. This paper provides an overview of the theory behind aerial thermography in archaeology, as well as a discussion of an emerging set of methods developed by the authors for undertaking successful surveys. Summarizing investigations at archaeological sites in North America, the Mediterranean, and the Near East, our results illustrate some contexts in which aerial thermography is very effective, as well as cases in which ground cover, soil composition, or the depth and character of archaeological features present challenges. In addition, we highlight novel approaches for filtering out noise caused by vegetation, as well as methods for improving feature visibility using radiometric thermal imagery.
Lichenometry—a method developed by geologists for dating Holocene moraines and other landforms—has many potential applications in archaeology. Maximum-diameter lichenometry can suggest ages for features that were initially lichen-free, such as the moai of Easter Island, and rock surfaces exposed by toolstone quarrying. Size-frequency analysis can provide dates for structures built of lichen-covered rocks, such as game-drive walls and blinds, meat caches, and tent rings. Both methods require local calibration curves, best constructed by measuring lichens on substrata of known exposure age. Most lichenometric studies have involved yellow members of the crustose genus Rhizocarpon, which grow slowly and can live for as long as 10,000 years. Lichenometry has been particularly successful on siliceous rock types in arctic, subarctic, and alpine-tundra environments. The effects of wildfire and of competition from foliose lichens make the technique less well suited for forested terrain. Few data are available for tropical or desert environments or for calcareous substrata. The reliability of a lichenometric date will depend on the quality of the calibration curve, the size of the sample, the nature and postoccupational history of the substratum, and the ability of the archaeologist to recognize potential disturbance factors. An ecological perspective is essential. Known archaeological applications and problems are discussed.
The study of historical field boundaries is based at first on the documentary evidence, but in the case of Lion-en-3eauce township there is no thing older thorn cje 1 808 land- register. But thermal prospection brings up useful information showing the headland ridges caracterised by the association of a warm strip and of cold strip (those ridges were controled by altmetric measurment on the field) ; other old limits appear which correspond to ancient ditches. The date of these boundaries can be shown by excavation of certain ones and of the sites located by surface remains, which allow a relative chronology to be obtain.
Le present article propose une approche methodologique concernant l'etude des foyers en general. Les foyers de la tradition paleoesquimaude sont souvent assez bien conserves, ce qui permet d'interpreter les processus de combustion utilises et comment ces derniers affectaient le climat a l'interieur de l'habitation. Pour obtenir ces informations, il est important de recueillir des donnees concernant les pierres fracturees par le feu. Les Paleoesquimaux utilisaient une pyro-technologie versatile, s'ajustant aux conditions les plus extremes dans des regions ou l'acces au bois de chauffage etait limite. Une reconstitution experimentale combinee a des calculs de la combustion hypothetique des matieres grasses demontre qu'il etait possible pour les Independanciens I de l'Arctique septentrional de passer confortablement l'hiver dans des tentes. Enfin, les aspects symboliques des foyers sont abordes dans le texte.
Dans la region du cercle polaire arctique, archeologues et gestionnaires du patrimoine sont de plus en plus preoccupes par la destruction des sites archeologiques due aux changements climatiques actuels. Cet article presente le projet Arctic CHAR cree pour resoudre ce probleme dans la region du delta de la riviere Mackenzie, dans le nord-ouest canadien. Plusieurs sites cotiers temoignent de l’histoire des Inuvialuit qui peuplent le delta du Mackenzie. En raison de la fonte du pergelisol et de la hausse du niveau marin relatif, ces sites sont detruits a une vitesse alarmante. Le projet Arctic CHAR se developpe sur deux axes principaux : des sondages pour evaluer l’etat des ressources patrimoniales a travers la region et la fouille des sites menaces les plus importants.
UAV-borne thermal imaging involves the determination of ground surface temperature from thermal infrared measurements deploying an unmanned airborne vehicle (UAV). A large variety of UAVs is available and applied for different military and civil tasks. UAV-borne thermal imaging provides spatially distributed information of the ground surface temperature. In contrast to satellite or ground based measurement, the usage of a UAV allows us to obtain spatially distributed and geometrically highly resolved information on the ground surface temperature without the need to access the ground. The area can be flat or hilly, and steep walls and hillsides can be investigated easily. However, some problems, especially tasks related to mosaicking of the images, are not fully resolved to date. We address the detection of the anomalies in ground surface temperature induced by underground burning coal seams as example and describe the challenges and opportunities of UAV-borne thermal imaging, based on our experiences in this field.
Cet article presente une synthese des vestiges architecturaux paleoesquimaux du Bas Arctique central canadien. Les Paleoesquimaux habiterent cette region pendant environ 4 000 ans decoupes par les archeologues en neuf periodes chrono-culturelles: le Paleoesquimau ancien (Predorsetien, Transition predorsetienne/dorsetienne, Lagoon et Groswaterien) et le Paleoesquimau recent (Dorsetien ancien, moyen, recent et terminal, ainsi que le Choris). Bien que la validite de ces divisions reste contentieuse, les recherches dans cette region ont documente une importante variabilite architecturale parmis ces groupes culturels. Cet article propose un systeme typologique decrivant et organisant les vestiges architecturaux signales jusqu'a ce jour afin de susciter de nouvelles discussions concernant les causes de la variabilite architecturale paleoesquimaude.
Discusses, on basis of studies in northern Alaska, soil forming processes in arctic regions and considers the relation between vegetation and soils and problems of classification and mapping. Tundra soils are poorly drained, mineral in nature, and underlain by permafrost at depths of 1-2 ft Arctic brown soils form under free drainage, are mineral in character, and confined to ridges, terrace edges, and stabilized dunes. The active layer in such soils is usually deep. Downslope movement and frost action tend to disrupt any orderly morphology in both wet and well-drained sites. Moisture conditions in arctic soils exert a marked selective influence on vegetation.--from SIPRE.
Aerial thermograms of an area in north-central Arizona immediately to the north of Merriam Crater have revealed the existence of parallel arrays of alternating ridge and swale linear features in the ashfall zone of Sunset Crater. The patterns are not easily identified on simultaneously acquired panchromatic photographs. Pollen and soil analyses confirm the highly geometric pattern to be a previously unrecognized prehistoric agricultural field. Recovery of Sinagua sherds of known age found at nearby living sites and in the field indicates that the farming activity occurred between A.D. 1065 and 1250. After 700 years of abandonment, local plant succession for the field has not yet fully re-established the probable former shrub community, apparently due to differences in physical and chemical properties existing between field and nonfield soil areas, related perhaps to prehistoric agricultural practices.
This paper discusses challenges facing archaeologists and archaeology remains at the “Tops of the World,” the Arctic, Subarctic, and Subantarctic regions of the globe, in light of climate change and human activities. One set of challenges includes climate change with rising sea levels, flood levels, decreasing permafrost, wind erosion, and tree re-growth. Another set includes increasing demographic and economic expansion with concurrent pollution, oil and mineral exploitation, and development of hydroelectricity, aquaculture, and tourism in the regions. The real and probable impacts and consequences of those factors on the archaeology—both generally and regionally—at the Tops of the World are outlined, leading to a discussion of how long-term research, cultural resource management, and educational strategies can be developed to deal with them.
This paper presents the first detailed record of Paleoeskimo occupation history of Foxe Basin, Nunavut, Arctic Canada, the traditional Paleoeskimo “core area.” Rather than continuous, stable occupations from approximately 4000–1000 B.P. traditionally assumed for the
core area, the region has undergone a series of demographic oscillations, including several instances of abandonment of key areas, most notably Igloolik. The Foxe Basin demographic trends are reminiscent of Paleoeskimo “boom and bust” cycles recognized elsewhere, but show no consistent
chronological pattern either within Foxe Basin or inter-regionally. Equally important, our results bear on the critical question of the Pre-Dorset to Dorset transition. Rather than having been a gradual in situ process centered within the core area, the demographic patterns, including the
abrupt and widespread appearance of semi-subterranean dwellings during earliest Dorset, are consistent with newly arrived populations from outside of Foxe Basin. While there is no obvious “parent” culture to Dorset within the Eastern Arctic, it is suggested that a Western Arctic
origin, specifically Norton Culture, invoking to some extent Jorgen Meldgaard's “smell of the forest”, may have played a significant role.
This thesis is a study of economic change in the Palaeoeskimo period (3200 B. P. to 1000 B. P.) at Igloolik Island, in the Foxe Basin, eastern Canadian Arctic. Evidence derived from the analysis of settlement, zooarchaeological and artefactual data was used to infer changes in settlement, subsistence and social organization between early PreDorset (3200 B. P.) and Late Dorset (1000 B. P.). The primary economic unit during early PreDorset was probably the nuclear family and at Igloolik the major subsistence activity was ringed seal hunting. PreDorset settlement was short-term and groups appear to have been highly mobile, moving away from Igloolik to exploit other resources on a seasonal basis. In contrast Dorset groups were less mobile, spending a greater proportion of the year at Igloolik and exploiting a wider range of resources. The Early Dorset period was characterized by the development of new technology, communal walrus hunting, storage practices and the appearance of larger economic and social units. In Late Dorset, this basic pattern remained the same, although subsistence strategies continued to broaden.
The development of communal walrus hunting, storage and the widening of the subsistence base combined to produce relative subsistence security in Dorset as compared to PreDorset. This relative security seems to have been expressed in the elaboration of material culture, particularly walrus hunting harpoon heads, and it may have resulted some socio-economic differentiation between Dorset groups in the Foxe Basin region and those in the central and high Arctic.
Arctic terrestrial ecosystems subjected to anthropogenic disturbance return to their original state only slowly, if at all. Investigations of abandoned settlements on three islands in the eastern Canadian Arctic Archipelago have detected striking similarities among contemporary and ancient human settlements with regard to their effects on tundra vegetation and soils. Ordination procedures using 240 quadrats showed the plant assemblages of Thule (ca. 800 B.P.) winter dwellings on northern Devon and southern Cornwallis Islands to be floristically similar to pedestrian-trampled meadows on northeast Baffin Island last used ca. 1969. Comparisons from the literature made with other North American sites in the Low Arctic reveal similar findings. The implication is that the depauperate flora of the Arctic has a limited number of species able to respond to disturbance, and that anthropogenically disturbed patches may be extremely persistent.
This study provides an assessment of changes in the occurrence frequency of four types of adverse-weather (freezing precipitation, blowing snow, fog, and low ceilings) and no-weather (i.e., no precipitation or visibility obscuration) events as observed at 15 Canadian Arctic stations of good hourly weather observations for 1953–2004. The frequency time series were subjected to a homogenization procedure prior to a logistic regression–based trend analysis.
The results show that the frequency of freezing precipitation has increased almost everywhere across the Canadian Arctic since 1953. Rising air temperature in the region has probably resulted in more times that the temperature is suitable for freezing precipitation. On the contrary, the frequency of blowing snow occurrence has decreased significantly in the Canadian Arctic. The decline is most significant in spring. Changes in fog and low ceiling (LC) occurrences have similar patterns and are most (least) significant in summer (autumn). Decreases were identified for both types of events in the eastern region in all seasons. In the southwest, however, the fog frequency has increased significantly in all seasons, while the LC frequency has decreased significantly in spring and summer. The regional mean rate of change in the frequency of the four types of adverse weather was estimated to be 7%–13% per decade.
The frequency of no-weather events has also decreased significantly at most of the 15 sites. The decrease is most significant and extensive in autumn. Comparison with the adverse-weather trends above indicates that the decline in no-weather occurrence (i.e., increase in weather occurrence) is not the result of an increase in blowing snow or fog occurrence; it is largely the result of the increasing frequency of freezing precipitation and, most likely, other types of precipitation as well. This is consistent with the reported increases in precipitation amount and more frequent cyclone activity in the lower Canadian Arctic.
The results of measurements of net total radiation flux and tempera- tures in the air and surface layers of the tundra and snow near Barrow, Alaska, are presented for the period September 1965 to September 1966. Lowest average monthly temperatures occurred in March, the highest in July. The minimum aver- age net total radiation occurred in January with the maximum in July. The tundra surface began to thaw by 18 June and to freeze by September.
This paper reviews hydrologie processes in the permafrost regions of northern North America. Much work has recently been done at spect$c experimental plots to parallel the progress in laboratory investigations, improving our understanding of the heat and water jluxes in thawed and froren grounds, injïltration in frozen soils, evaporation in a cold environment, interaction between snow and its frozen substrate, and the dynamics of storage in the active layer. Field research on permafrost slopes and in northern research basins adds to our knowledge of permafrost groundwater hydrology, runoff generating processes, river freeze-up and breakup processes and allows more precise definition of basin water balance. Sufficient hydrometric data are now available to analyse the streamflow charac- teristics in an area with permafrost, and more work should be done along this line. It is urged that process studies be continued to gain a better understanding of the effect of permafrost upon the hydrologie cycle. Further research is needed to predict the impacts of human activities on the movement and redistribution of water.
Infrared thermography transforms the thermal energy, emitted by objects in the infrared band of the electromagnetic spectrum, into a visible image. This feature represents a great potentiality to be exploited in many fields, but this technique is still not adequately enclosed in industrial instrumentation because of a lack of adequate knowledge; at first sight, it seems too expensive and difficult to use. The aim of the present paper is to shortly overview existing work and to describe the most relevant experiences devoted to the use of infrared thermography in three main fields, i.e. thermo-fluid dynamics, technology and cultural heritage, which have been performed in the department the authors belong to. Results may be regarded from two points of view, either as validating infrared thermography as a full measurement instrument, or as presenting infrared thermography as a novel technique able to deal with several requirements, which are difficult to perform with other techniques. This study is also an attempt to give indications for a synergic use of the different thermographic methods and sharing experiences in the different fields.
Interaction of archaeological features with the secular variation in surface heat flux generates an anomalous ground temperature distribution which can form the basis for a shallow geophysical prospecting tool. Earlier studies have concentrated on recording surface temperature disturbances via aerial thermography but these results can be biased towards minor variations in vegetation, albedo. and microclimate. A more promising approach is to record temperatures at a depth of 20cm using a simple probe. Anomalies at this depth arise from the interaction of objects with the annual heat-flux cycle and other long-term temperature variations. The amplitude, shape, and phase of anomalies have been modelled, together with the nature and magnitude of other, unwanted causes of ground temperature variation. Field equipment and data processing techniques for the direct-contact approach to thermal prospection have undergone trails in the U.K. at Verulamium and Fountains Abbey.