Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Re-enacting the sequence: combined digital methods to study a prehistoric cave

Re-enacting the sequence: combined digital methods to study a prehistoric cave This contribution seeks to demonstrate how recently developed 3D GIS platforms can help archeologists in relating to the original context legacy data that can be employed to digitally reconstruct the sequence of arbitrary layers as it was observed and then excavated in the end of the nineteenth century. This research has been conducted on the prehistoric cave of Stora Förvar, located on the small island of Stora Karlsö, in South-Eastern Sweden. As a part of a research project titled BThe pioneer settlements of Gotland,^ this line of enquiry has sought to combine 3D-based digital acquisition techniques, Geographical Information Systems (GIS), and old archival material (hand-made drawings, artifacts lists, historical pictures) in order to virtually reconstruct the original sequence as it was excavated through the method of arbitrary layers. At a later stage, the reconstructed sequence has been employed to re-contextualize and analyze the distribution of artifacts so as to detect any possible pattern that could have been useful for defining the chronological boundaries of the Mesolithic phase of habitation of the cave. In brief, three main objectives can be defined: (a) to re-create a spatial connection between the artifacts retrieved at the time of the excavation and the sequence of layers, (b) to define density maps showing the relationship between volumes of layers and categories of artifacts belonging to the sequence, and (c) to further our knowledge about the Mesolithic habitation of the cave, not only vertically (chronologically) but also horizontally. . . . . Keywords 3D GIS Mesolithic Scandinavian archeology 3D spatial analysis Volumetric analysis Introduction titled BThe pioneer settlements of Gotland,^ this line of enquiry has sought to combine 3D-based digital acquisition techniques, This contribution seeks to demonstrate how recently developed Geographical Information Systems (GIS), and old archival ma- 3D GIS platforms can help archeologists in relating to the terial (hand-made drawings, artifacts lists, historical pictures) original context legacy data that can be used to virtually recon- in order to virtually reconstruct the original sequence as it was struct and interpret the sequence of arbitrary layers as it was excavated through the method of 30-cm-thick arbitrary layers. observed and then excavated in the end of the nineteenth cen- At a later stage, the reconstructed sequence has been employed tury. This research has been conducted on the Prehistoric cave to re-contextualize and analyze the distribution of artifacts so of Stora Förvar, located on the small island of Stora Karlsö, in as to detect any possible pattern that could have been useful for South-Eastern Sweden (Fig. 1). As a part of a research project defining the chronological boundaries of the Mesolithic habi- tation of the cave. The pioneer settlement phase of Gotland extended * Giacomo Landeschi between 9200 and 7600 BP. The cave site of Stora giacomo.landeschi@ark.lu.se Förvar was according to a summed probability distribu- tionanalysis basedon65C14-dates datedtotheperiod Department of Archaeology and Ancient History, Lund University, 9200–7800 so the cave was abandoned earlier than the Helgonavägen 3, Box 192, 221 00, Lund, Sweden settlements on Gotland Island, probably because of the Department of Archaeology and Classical Studies, Stockholm effects of the Litorina I transgression (Apel et al. 2017). University, Wallenberglaboratoriet, Lilla Frescativägen 7, 106 91 Stockholm, Sweden The cave site of Stora Förvar is unique and has played a key role in understanding the Stone Age of Gotland. Humanities Lab, Lund University, Helgonabacken 12, 221 00 Lund, Sweden The cave sequence of Stora Förvar was excavated 2806 Archaeol Anthropol Sci (2019) 11:2805–2819 Fig. 1 The cave site of Stora Förvar is located on the island of Stora Karlsö, in the Baltic Sea, South-eastern Sweden ( © Lantmäteriet, Swedish cadastral agency; freevectormaps.com) between 1888 and 1893 by Lars Kolmodin and Hjalmar out her own excavations on Stora Karlsö and was well Stolpe. Unfortunately, the final excavation report was aware of the archeology of the island. Already in 1926, not published until 50 years later by Bror Schnittger Adolf Pira published the first analysis of faunal remains and Hanna Rydh (1940), who had not participated in from the Stora Förvar cave. He investigated the seal the actual fieldwork. However, Hanna Rydh had carried bones in the cultural layers and noticed that the Archaeol Anthropol Sci (2019) 11:2805–2819 2807 frequencies of seal bones from different species varied field of Computer Science (Dellepiane et al. 2012; De Reu et al. over time. For the present study, we will focus attention 2013;Dell’Unto 2014). Site acquisition and documentation on the presence of harp seal, a species that entered the strategies have been enormously improved thanks to the adop- Baltic basin some 6000 years BP. This coincides rough- tion of innovative methodological approaches (Dellepiane et al. ly with the time when the cave was resettled again in 2012; De Reu et al. 2013;Dell’Unto 2014; Katsianis et al. 2008; the Late Mesolithic/Early Neolithic. Thus, the bones of Callieri et al. 2011; Opitz and Nowlin 2012; Campana 2014;De harp seals are an important chronological proxy to dis- Reu et al. 2014), which contributed to reinforce reflexivity in the tinguish the Neolithic layers of the cave, together with practice of archeological excavation (Hodder 2000); this also pottery and also harpoons. raised up additional questions on which contribution three- One of the main aims of the BThe pioneer settlements of dimensionality could provide to archeological research (Forte Gotland^ project has been to evaluate the integrity and et al. 2012:Berggrenetal. 2015). In particular, based on the character of the Mesolithic component of the cave se- recent advances in digital technology, there is an increasing quence Stora Förvar. As part of the project, a small exca- Bheuristic^ potential connected to the use of three- vation was carried out in summer 2013 and a digital 3D dimensionality in archeology which could lead to interesting scanning of the cave was made (Apel et al. 2015;Apeland openings in the field of spatial data analysis, as predicted by Storå 2017a, b). We had on previous visits found bones and some authors a few years ago (Gillings and Goodrick 1996; stone in the soil layers of the cave floor, which suggested Frischer 2008). Recently, the introduction of more advanced that there could be preserved cultural layers pockets that 3D GIS software, namely ESRI ArcGIS 10.x package (ESRI had not been excavated. The purpose of the field work was 2015), opened new ways of analyzing archeological data, by to investigate this further by performing limited test exca- combining spatial analysis tools and geometrically complex vations. Three smaller trenches were excavated of which 3D boundary models (Landeschi 2018; Landeschi et al. two contained pristine Mesolithic layers. The content of 2016b;Dell’Unto et al. 2015). Such an achievement led to a the test trenches was sieved through 4- and 2-mm meshes more accurate representation of the material evidence and novel and the find material was documented in units of 0.5 × methods of analysis were experimented in order to investigate 0.5 m and 5-cm spits. The layer that was encountered spatial relations in field excavation (Wilhelmson and Dell’Unto was interpreted as being homogenous, but with intrusions 2015), to perform visibility analysis in a reconstructed architec- of chalk that had penetrated the soil with water that is tural space (Landeschi et al. 2016a) and to assess structural dripping from the cave walls (Apel and Storå 2017b). degradation in historical buildings (Campanaro et al. 2015). The quality of the bone material and two flint blades that Another relevant aspect is the multiscalarity of the dataset, where could be refitted are indication of the stratigraphic integrity analysis can be performed either on the single artifact or extend- ed to the whole landscape in the same georeferenced space. of the layer (Apel and Storå 2017a). A mobile 3D-scanner was used to build a digital, three-dimensional model of the Indeed, by adjusting the size of the polygonal mesh associated cave (Lundström 2016; Landeschi et al. 2018). We here to each 3D model, it is possible to optimize the model represen- evaluate the potential of combining information from the tation in relation to the scale of analysis. Remarkably, the pre- 3D-technique with data in the archival material from the historic caves constitute an interesting case study to observe the excavations in order to highlight the Mesolithic use of the advantage of such an approach, due to the complex environmen- cave. The purpose is therefore to take advantage of an tal settings in which traditional methods of survey fail in provid- entirely three-dimensional environment: (a) to re-create a ing an adequate representation on the original space. spatial connection between the artifacts retrieved at the time of the excavation and the sequence of layers, (b) to Background in cave studies define density maps showing the relationship between vol- umes of layers and categories of artifacts belonging to the As reported by several authors, archeologists have tried to sequence, and (c) to further our knowledge about the introduce digital technologies in the study of Prehistoric caves Mesolithic habitation of the cave. (Galeazzi and Moyes 2011; Galeazzi et al. 2014). Still, a very limited number of studies succeeded in combining 3D and GIS-based methods. An interesting example of the combina- Methodological framework tion of different acquisition techniques is given by a research conducted in a Paleolithic cave in Spain, where Terrestrial Theoretical background Laser Scanning (TLS) and close-range photogrammetry have been combined together to provide archeologists with an ac- In the last few years, an increasing interest on the combined use curate dataset of information that represented a significant step of techniques for collecting and analyzing archeological data has forward compared to traditional, bi-dimensional methods of been characterized by the significant advances occurred in the documentation (Lerma et al. 2010). Similarly, a multi- 2808 Archaeol Anthropol Sci (2019) 11:2805–2819 Prehistoric rock art (Beraldin et al. 2006). Analogously, the adoption of GIS-based methods and tools for investigating Prehistoric caves, allowed archeologists to quantitatively ex- plore relations between artifacts, human remains and their orig- inal contexts, by taking advantage of the spatial information derived in the process of site documentation (Herrmann 2002; Moyes 2002). One of the main limitations in this approach is still represented by the lack of three-dimensionality, which does not allow to properly observing the physical relationships among the objects being excavated. Furthermore, this prevents from fully understanding problems related to the artifacts dis- tribution along the z-axis, such as their vertical movement through the deposits (Hiscock 1985). More recently, some at- tempts of virtually reconstructing a stratigraphic sequence in combination with a cave 3D model have been done in the frame of a research project developed in the Pastora cave, Eastern Spain (Puchol et al. 2013). By combining old site documentation sources, it has been possible to reconstruct Fig. 2 The terrestrial laser scanner employed for the acquisition (Faro and spatially locate the cultural layers dated between the Focus 120S phase shift variation 3D-scanner) placed at the entrance of the cave as it looks today Neolithic and the Bronze Age. Still, due to the lack of a method of excavation based on stratigraphic units (it was conducted during the 1940s by an amateur archeologist), it was not pos- resolution laser scanner combined with a digital camera was employed to provide a high-resolution textured 3D model for sible to define the original appearance of the deposits and the the analysis of pictographs observed within the Neolithic cave layers were basically defined by the plans on which the arti- of Grotta dei Cervi, Italy, and this represented an interesting facts were laying at the time of the excavation. Nonetheless, case in which digital methods were used to document some important advances have been showed in the way 3D Fig. 3 ESRI ArcGIS geodatabase management system (GDBMS) has been set up to integrate different datasets: basemap layers made by vector and raster cartographic data, legacy data in the form of scanned hand-made drawings, tables containing information on artifacts distribution throughout the sequence, and 3D multipatch feature classes of the cave and the reconstructed sequence. Output data have been finally derived and used in support of archeological interpretation of the site Archaeol Anthropol Sci (2019) 11:2805–2819 2809 visualization has been adopted to locate and display artifacts in Acquiring the cave relation to their original context and in their reciprocal position in the space of the cave. This would be a good example on how In the summer of 2013, the cave Stora Förvar was acquired by 3D-based methods might be used in support of museum com- means of terrestrial laser scanner. A Faro Focus 120S phase munication, where visitors could better understand issues re- shift variation 3D-scanner was employed (Fig. 2). Each scan- lated to the different phases of inhabitation of a Prehistoric ning position produced a point cloud with 12 million points. cave. To sum up, there is an increasing acknowledgment of Due to the short timeframe in which the recording had to be the role that 3D and GIS-based methods have in the process of done and the complex geometry of the ceiling of the cave, the site documentation and data analysis. Still, more studies need method used was to record a relatively large number of scans to be carried on in order to effectively explore the potential to get a good overlap between them. Thirty different positions derived from the combination of both of them. Despite a gen- for the scanner were defined to cover the entire space of the eral acknowledgement of the importance of using digital cave. In the post processing phase, the scans were manually methods as a way to improve the documentation strategies, registered using the open source software Meshlab (Cignoni there is still a lot of work to be done, in order to effectively et al. 2008). The same software was also used to combine, use three-dimensionality as an additional factor in support not clean, simplify, and mesh the scans in order to produce the just to data visualization but also, for the analysis of complete 3D-model of the cave. During the recording, some archeological evidence and its original context. As this contri- easily recognized features were marked out to be measured bution seeks to demonstrate, the integration of 3D technology with a total station later on, making it possible to correctly and GIS platforms could provide significant advantages in the georeference the model of the cave in a 3D GIS platform. study of prehistoric caves and their related material, enhancing the possibility for archeologists to investigate relations and Reconstructing the sequence interactions among the objects, along the full space of x, y, and z Cartesian coordinates, in a way that would not be possi- Different sources have been integrated to virtually reconstruct ble with bi-dimensional site documentation methods. the sequence of layers as it was reported by Schnittger and Fig. 4 Different datasets have been integrated to generate the final three-dimensional sequence as it was excavated in the end of the nineteenth century. In ESRI ArcScene, a LIDAR-derived DEM has been used to contextualize the 3D model of the cave in the surrounding landscape of Stora Förvar (a)(© Lantmäteriet, Swedish cadastral agency). Then a combination of digitally scanned and georeferenced original plan and profile drawings gave the possibility to exactly reconstruct the 30-cm-thick layers and to rename them based on the original excavation reports information (b)(© Antiquarian Topographical Archives in Stockholm) 2810 Archaeol Anthropol Sci (2019) 11:2805–2819 Rydh (1940). They basically consist of documents available at to better fit the informative function associated to every single the Antiquarian Topographical Archives in Stockholm, (lists of layer. As a part of the basemap, information derived from the artifacts, hand-made drawings of the site, field reports) and data Swedish National Land Survey agency was added in order to derived either from laser scanning acquisition or completely provide a general spatial context to the site of Stora Förvar. An generated in GIS. More information has been derived from additional dataset has been added to collect as multipatch feature the Swedish National Land Survey agency (Lantmäteriet classes, all the 3D entities describing the cave. More shapefiles 2015) in order to put the original sequence in the wider context were then created in the process of data analysis, including those of the landscape of Stora Karlsö. All the data have been imple- volumetric layers used to represent the three-dimensional se- mented and processed through the ESRI ArcGIS 10.3 software quence of the cave. As an additional data source, archival ma- package, which is to date the only GIS platform enabling users terial was also imported into the geodatabase. This material to effectively import and handle geometrically complex 3D consisted of data derived from the twentieth century field docu- boundary models, derived both from laser scanning acquisition mentation that was produced and published approximately and image-based 3D modeling (Opitz and Nowlin 2012). Here, 50 years after the completion of the excavation. This dataset, different editing tools can be used in support of data analysis to which included original plans and profile drawings, provides us improve the quality of data interpretation (Dell’Unto et al. with a picture of how the cave sequence looked like at the time 2015; Landeschi et al. 2015). To better serve the purpose of of the excavation and it was therefore a crucial element to be managing the data sets, a geodatabase (GDBMS) has been built used in the process of reconstruction. In particular, one of the and several types of sources were integrated (Fig. 3). digitally scanned profile drawings was employed as a main ref- The data framework, based on the geodatabase standard, erence to reconstruct both the vertical parcels and the 30-cm- widely used in several archeological projects (Tennant 2007; thick horizontal units that composed the original sequence, ex- Katsianis et al. 2008; Nekhrizov et al. 2012; Müllerova et al. cavated according to the arbitrary layers method (Hughes and 2013; Van Ruymbeke et al. 2015), has been customized accord- Lampert 1977). Then an additional hand-made drawing was ing to the specific needs of this project. As a result, the final employed to define the original plan of the sequence and it users are provided with an effective tool for querying and ana- was integrated along with the 3D model of the cave to enable lyzing the dataset. To this scope, different categories of data a direct link between the final digital reconstruction and the were defined and raster, vector and tabular format were designed artifacts information (Fig. 4). Fig. 5 As a result of the reconstruction process, the complete sequence of documented during the excavation phases. Each unit was then provided layers has been obtained in the form of a multipatch feature class. The with a volumetric value and linked to the tables of finds featuring different relational geodatabase previously established enabled to query and categories of artifacts and ecofacts belonging to the sequence retrieve information from the original arbitrary layers as they were Archaeol Anthropol Sci (2019) 11:2805–2819 2811 Data setup boundaries to be used to reconstruct the sequence, no texture was added, as it would have only made the process of data visu- Once the data framework was designed, datasets were optimized alization and management more time-consuming. Subsequently, and imported in the geodatabase. The point cloud derived from the digitally scanned version of the original profile drawing was the 3D-scanned model of the cave was decimated and the original rescaled and turned into a multipatch feature class and 10 million-faces mesh reduced to 1 million, in order to be better georeferenced in GIS so as to spatially match the 3D model of handled in the ArcScene viewer. Then it was exported as a the cave. From such a drawing information about the position, VRML file, which is still one of the standard formats recognized thickness and length of each single arbitrary unit was extracted by ArcGIS (ESRI 2014). In ArcCatalog, the model was converted and employed in combination with the 3D boundary model of the into a multipatch feature class and added to the geodatabase. To cave to reconstruct the original shape and spatial location along x, georeference it, some total station points that had been previously y,and z axes of the layers composing the sequence. Then, based collected in the field were employed. Since the main purpose of on the information available, 3D shapefiles were employed to the 3D model implementation was to provide the geometric mark the original partition of the sequence in six different parcels, Fig. 6 Three different 3D maps of density have been produced to show bones, and harpoons. Such information was crucial to better understand the relationship between each spit unit and its content of finds. From which portion of the original sequence could be connected to the above to below, they are illustrating the distribution of pottery, harp seal Mesolithic phases of inhabitation of the cave 2812 Archaeol Anthropol Sci (2019) 11:2805–2819 starting from the cave entrance to the innermost part and then containing the volume information. As a final result, all the layers marked with letters spanning from A to I. All the interface lines were linked to the artifacts geodatabase tables, so that it was marking each unit boundary were converted into horizontal possible to define how the different classes of material were as- panels that were intersected with the mesh of the cave walls. sociated and distributed throughout the stratigraphic sequence. From this intersection, polyline shapefiles were derived to repre- Such an operation was an essential step in the process of data sent the external boundaries of each arbitrary layer previously analysis and this allowed us to spatially investigate the original originated from the interface line. Each polyline was then con- distribution of the artifacts and to possibly detect patterns of pres- verted into a polygon that was representing the original surface ence linked to the different phases of inhabitation of the cave. interface between two different stratigraphic units. From this poly- gon, a series of extrusions were employed to describe the volu- metric portion of space corresponding to each unit described in Results and discussion the original site documentation (Fig. 5; Landeschi et al. 2018). In this way, the whole sequence of spit layers was reconstructed as it The digital reconstruction of original spit units enabled us to cal- was excavated in the end of the twentieth century with each unit culate and assign the volumetric value to each layer. This was a Fig. 7 Results obtained from the density analysis have been summarized important relationship required in order to more accurately define the (Diagrams 1–7). The columns labeled BPottery density per m ^ and Btotal Mesolithic portion of the cave sequence volume excavated^ are of particular interest as they emphasize the Archaeol Anthropol Sci (2019) 11:2805–2819 2813 crucial point to let us to generate maps of finds frequency and pattern might very well be explained by the notion that parcel F density, based on the different categories of archeological objects was excavated at two occasions, in which the excavators dug described in the final excavation report and associated to the var- halfway down into the sequence in parcel F after which excavation ious parcels and units visualized in the original profile drawing. of the first couple of spit units in neighboring parcel G began. It is The 3D maps produced were respectively, a map of pottery, harp in this specific event that the authors recall how masses of soil had seal bones, and bone harpoons (Fig. 6). been thrown down from the top of parcel G into the previously excavated parcel F (Schnittger and Rydh 1940, p. 45) and it is thus very likely that this sudden increase is a result of excavators having Pottery analysis trampled any pottery remain further down into the parcel causing an accidental intrusion of some of the lower levels. To add support A review of the results indicate an overall trend of diminishing to this hypothesis, one only needs to review the development in pottery density towards the lower levels of the Stora Förvar cave the neighboring parcel G. Reviewing the parcel in reverse order, sequence—despite occasional peaks of increased density in par- up until spit unit G.8, there is no occurrence of pottery. After spit cels such as D, E, and F (Fig. 7, Diagrams2,3,and4).Over time unit G.8, the density of pottery peaks briefly with a dramatic however, the levels of pottery density eventually decrease with increase, whereas towards to top it resumes its diminish (Fig. 7, some of the spit units reaching as low levels as 0.8 to 0.1 fragments Diagram 5). More importantly, results published by Lindqvist and per unit of volume (m ). Acting as a deviation to this trend is Possnert (1999) introduced the presence of Early to Late parcel A (Fig. 7, Diagram 1). According to the original publication Mesolithic remains within this sequence. Thus, if the neighboring from the 1940s, parcel A and B came about as a result of the same bottom spit units of parcel F were to be contemporary with that of parcel being excavated at two separate occasions, and thus it was the bottom spit units of parcel G, then the density of pottery should also divided accordingly. Unfortunately, as it is rather difficult to either be very low, or absent altogether as pottery makes its intro- understand from the original publication as to how this divide was duction into the Baltic region in the Late Mesolithic (Hallgren carried out spatially, the strategy was to treat parcel A and B with 2004, p. 123; Glykou 2014,p.24). its artefactual assemblage as one single 3D-reconstructed unit. As Parcel H displays an overall low density of pottery per spit such, the results from the density analysis are not entirely reliable unit with layer H.3 amounting to marginally more than a pottery as most of the bottom spit units were neglected for analysis, but fragment per unit of volume contributing to the general trend of also because of the necessity to bundle together a majority of the low densities of pottery towards the bottom (Fig. 7, Diagram 6). spit units that were labeled A.1-A.4 and A.5-A.6 to name but a It should be mentioned once again however that bundled spit few. Another deviant development also occurs in parcel F. The units have been neglected, and thus any analysis of spit units densities of pottery display a somewhat chaotic sequence in which BH.4-H.5^ has yet to be performed. The final parcel at the very there are two valleys of increase in pottery density throughout the end of the cave is parcel I. Providing us with only three spit parcel (Fig. 7, Diagram 4). However, what is interesting is the units, the pattern is still consistent with previous parcels in sudden increase that occurs between spit units F.10 and F.13. which the amount of pottery fragments per unit of volume de- Ever since spit unit F.4, parcel F had seen a gradual decrease in creases towards the bottom of the sequence (Fig. 7, Diagram 7). pottery density that went from almost six fragments per each unit By using indices of varying pottery densities and results from of volume to its very lowest at just half a fragment. However, all of the osteological analysis (Fig. 8), we argue that additional spit a sudden, the density increases once again. This rather irregular Fig. 8 Section of the cave from north. The dotted line marks the soil surface prior to the excavations. The circles mark the occurrence of bones of harp seal identified by Pira (1926) and Apel and Storå (2017a, b). Scale in meter. Modified from Schnittger and Rydh 1940, Figure 30 2814 Archaeol Anthropol Sci (2019) 11:2805–2819 units of the Stora Förvar cave sequence may be added to the Early Fig. 10 a Distribution of the bone finds in each excavation year and parcel of the cave, weight (g). b Distribution of the bone finds in each section and Mesolithic component for further investigation such as radiomet- layers of the cave, weight (g). Data from the catalog at the Swedish ric dating and artefactual studies. This inference is built on the Historical Museum. Due to the sloping cave floor the same layers do not idea of groups of hunter-gatherers that either use, or do not use, correspond to the same dates. The borders between the different periods are ceramic technology. For the Early Mesolithic portion, the density not to be considered exact (*Dom = finds with bones of domestic animals, apparently younger than c.3000/3500 cal BP, most often though Iron Age/ of pottery is at a significantly low level that it may very well be Historical period). c Amount of bone finds, total volume, and density of ascribed to pioneering groups that precede the Kongemose and bone finds in combined layers of the cave Ertebølle cultures. As of yet however, any further analysis as to the cultural affinities of the pottery at Stora Förvar has been made, the sections and layers I4, G4, I5, G5, B6, H7, and G7 (Fig. 8). and so a possibility could be that there is a presence of Ertebølle A later analysis has confirmed the presence in these layers and pottery (or later) in the lowest of levels. Although, this would not added finds in F9 and E7 (Apel and Storå 2017a). be consistent with the numerous AMS-dates from some of the The deepest—and chronologically oldest—occurrences of lowest levels of parcel G (Lindqvist and Possnert 1999:Table 2), the harp seal bones roughly coincide with the appearance of a and thus lends further strength to the idea of intrusion caused by a large number of bone harpoons and also fish hooks. Bones of systematic and arbitrary method of excavation. domesticated animals became more common and even more common than seal bones in the uppermost layers which date Osteological analysis the Iron Age and Historical period (Ibid.). However, there are some finds of sheep and other domestic animals as deep as The osteological analyses of faunal remains have provided G8. The harp seal entered the Baltic basin around 6000 BP cal, additional clues to the relative chronology of the finds from i.e., around the time when the hiatus in the cave ends (Bennike the cave. Early on, the analyses of Adolf Pira (1926)showed et al. 2008; Storå and Ericson 2004). The identifications of harp seal bones show that the layers that the occurrence of seal species varied in different layers. Bones from Gray seal (Halichoerus grypus) and ringed seal associated with the oldest Mesolithic phase were up to 1- to 1.2- (Phoca hispida) were most common in the bottom layers of m thick at the entrance of the cave, in sections A, D, E, and F but the cave while harp seal (Phoca groenlandica)appeared thinner in sections G, H, and I. At the far end of the cave in section higher up in the stratigraphy (e.g., G7 and H7), from approx- I, harp seal bones appear already at c.30 cm above the cave floor. imately 1.2 m above the bedrock (Fig. 8). The estimations of the volume of the layers in each section We now know that the oldest layers of the cave date to provide a possibility to evaluate the Mesolithic depositional pat- approximately 9200 cal BP, i.e., the Mesolithic. The oldest terns of bones and, thus, the use of the cave, both horizontally use of the cave spans a period of around 1000 years after and vertically (Figs. 9 and 11). It has so far been very difficult to which there is a hiatus in the stratigraphy when the cave ap- investigate the horizontal use of the different parts of the cave. parently was more or less abandoned between approximately We here consider the sections inside of the cave and those that date to the Mesolithic. The small amounts of bone finds in 8200 cal BP to around 6000 cal BP (Apel and Storå 2017a; Apel et al. 2017; Lindqvist and Possnert 1997, 1999). section D may be a result of recovery bias. There are some For the present study, the presence of bones of harp seal noteworthy differences in the density of bone finds in different may be used as an important chronological indicator together layers and sections (Fig. 10). In section D, the lowest layer 12 with the pottery. Pira (1929) identified bones of harp seal in contained smaller amounts of bone finds than layer 11, after Fig. 9 C14-dated faunal remains’ samples have been georeferenced and put in spatial relation with the 3D model of the cave: a sheep 85–225 calAD (5.4%); b sheep 55–211 calAD (95.4%); c sheep 745–404 calBC (95.4%); d ringed seal 7184–7028 calBC (93.2%). They acted as an additional independent chronological indicator to define the boundaries of the Mesolithic portion of the sequence. e shows the same portion of the wall cave as it can be observed on site Archaeol Anthropol Sci (2019) 11:2805–2819 2815 2816 Archaeol Anthropol Sci (2019) 11:2805–2819 we discern a Mesolithic depositional pattern to deposit the refuse after the hunted seals. Noteworthy in the comparison is also the drop in density of finds in layers 8 in sections F and G. These layers probably belong to the end of the Mesolithic, at the time of the hiatus in the occupation. It seems that the intensity of deposi- tion, as seen in smaller mean amounts of bone per m , decreased through time, possibly in the period prior to the abandonment of the cave. This change in depositional patterns is also associated to changes in seal hunting patterns (Apel and Storå 2017a, b). To summarize, some elements are particularly worth of attention as they provide information in terms of relative and absolute chronology, useful to trace and define certain spatial boundaries. In particular: Fig. 11 View of profile of section G, from west after it has been properly georeferenced in the 3D cave model. The change in the character of the stratigraphy, marked by an arrow, slightly below the shoulders of the (a) Density values of pottery and faunal remains act as chro- standing man probably marks the hiatus, i.e., a soil surface layer when nological indicators to define the temporal boundaries of the cave apparently was not in use for around 1000 years. Reproduced the Mesolithic phase of inhabitation of the cave. Most with permission by the Antiquarian Topographical Archives, Stockholm importantly, they provide a terminus that here can be (Photo 1492:2) marked to spatially define the volume of the sequence which, the find density decreases higher up in the stratigraphy. characterized by Mesolithic and post-Mesolithic events. A similar pattern may be seen in sections E and F, although the In this respect, the presence of harp seal, which entered deposits with higher amounts of finds are thicker in section F. the Baltic basin around 6000 Cal BP, is another good This could reflect a difference in soil cover in the front end of chronological indicator to be considered. the cave and at the end of the cave. Thus, the bones could have (b) More traces indicate the uppermost boundary of the been deposited on an existing soil cover at the entrance of the Mesolithic portion of the sequence and they can be ob- cave. Section G and also H and I exhibit the highest densities of served in a historical picture of the profile of section G finds in the layers immediately on top of the bedrock (floor). which is recognizable by the dark color of the soil ma- Considerably, larger amounts of finds were deposited in the trix. The possibility of georeferencing the picture let us Mesolithic layers in sections G and F compared to sections D to put in connection the visible hiatus in turn with the and E. Possibly, the areas at the entrance of the cave, which volumetric model of parcel G, the digitized hand-made actually had large floor areas, were kept cleaner from refuse of profile drawing and the 3D model of the cave (Fig. 11). the seals. There is a marked difference in the floor areas be- (c) In terms of absolute chronology, further indication about the tween the layers and sections. spatial pattern related to the Mesolithic phases of the cave is Thus, the absolute amounts of bone finds are highest in the provided by the c14-dated faunal remains from wall con- central part of the cave, but the density of bone finds is actually cretions, which have been georeferenced and put in spatial higher at the end of the cave, and lowest at the entrance. Indeed, connection with the above-mentioned datasets (Fig. 9). Fig. 12 Interpretative line (M) illustrating the uppermost boundary of the concretions; 3D density maps for pottery finds, harp seal bones and Mesolithic phase of Stora Förvar cave. Such interpretation comes has a harpoons, identification of a clear stratigraphic boundary visible on the result from the combination of different independent chronological section of parcel G within a georeferenced historical picture indicators, that include: c14-dated faunal remains from wall Archaeol Anthropol Sci (2019) 11:2805–2819 2817 Conclusions single site on a local level, in broader terms, but also to expand our knowledge about the pioneer settlement of Gotland. In a This contribution has sought to demonstrate how the integrated broader perspective, a similar workflow can be extended to combination of digital methods can significantly improve the countless case studies in which archeological documentation interpretative framework of a Prehistoric sequence. In particu- has been produced in pre-digital era and used to build an inter- lar, advanced 3D GIS functions together with legacy data pro- pretation of the site. Any previous study can thus be revised and vided the opportunity to partially re-contextualize archeological possibly improved by giving a spatial dimension to features and finds belonging to the Prehistoric cave of Stora Förvar and to objectsthathad been alreadyexaminedbytakingintoaccount take advantage of the digitally reconstructed sequence of arbi- of their vertical position and their temporal relation with the trary layers to quantitatively assess the distribution of several space. Indeed, the possibility of collecting the data in a classes of artifacts in order to detect patterns associated to the geodatabase would allow more scholars to integrate further different phases of cave inhabitation. Noteworthy is the study of information into the system so as to integrate additional ele- those categories of artifacts which act as important indicators ments that can be used in support of site interpretation. for the chronology of the layers. Having those artifacts repre- Further research needs to be conducted in order to cope with sented as a numerical attribute linked to the volumetric model issues concerning data integrity and consistency especially in of the sequence allowed to create 3D maps that could visually relation to the material derived from archival source, for which represent the distribution of each class based on values of fre- a bit more of uncertainty characterize the act of data collecting. quency and, more importantly, on the density as a result from Nonetheless the results obtained seem to foster this approach the relation between each layer’s volume and number of finds. and to mark a significant advance in the practice of data-reuse The emerging patterns have been thus put in relation to other which will be beneficial to the reinterpretation of many spatially datasets consisting of legacy data that had been properly and temporally diverse archeological contexts. georeferenced in order to contextualize their contents. Besides Acknowledgements The authors wish also to thank the Humanities being an attempt of promoting a Bheuristic^ usage of three- Laboratory and the DARK Lab, Lund University, for the opportunity to dimensionality in the context of a site investigation, this com- use instruments and the anonymous reviewers for their useful comments. bined approach allowed archeologists to answer some ques- tions related to the site, which could not have been addressed Funding information This research activity was generously supported by without a spatial analysis of the original layers. the Berit Wallenberg Foundation, Swedish Research Council and Palmska Foundation, and by the Birgit och Sven Håkan Ohlssons As a final result of the analysis, an interpretative line can be Foundation. traced in order to highlight the chronological boundaries of such phases (Fig. 12). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// Nonetheless, some biases must be taken into account, as creativecommons.org/licenses/by/4.0/), which permits unrestricted use, there are several issues that influence the original position of distribution, and reproduction in any medium, provided you give appro- the finds and so, any possible interpretation. First of all, the priate credit to the original author(s) and the source, provide a link to the excavation techniques employed, consisting of arbitrary layers, Creative Commons license, and indicate if changes were made. by definition do not follow the actual stratigraphy made up of natural and anthropic layers as they deposited. It is very likely that the same spit unit contains more original stratigraphic layers which correspond to different chronological phases in References the cave. Additionally, some inaccuracy in the documentation Apel J, Storå J (2017a) The Pioneer settlements of Gotland: a behavioural process did not allow to properly link all the finds to their ecology approach. The ecology of early settlement in northern original unit, making the reconstruction of the 3D maps more Europe - conditions for subsistence and survival (Volume 1). uncertain, especially in parcels A and B, which do not even Equinox eBooks Publishing, United Kingdom. Dec 2017. ISBN have clear boundaries on their uppermost layers, as they were originally located just outside the entrance of the cave. To sum Apel J, Storå J (2017b) Ett återbesök i Stora Förvar och en ny bild av mesolitikum på Gotland. Arkeologi på Gotland 2. Tillbakablickar up, the approach as it has been illustrated demonstrates the key och nya forskningsrön. Institutionen för arkeologi och antik historia, role three-dimensionality that plays in enabling to understand Uppsala Universitet & Gotlands Museum. Uppsala och Visby an archeological stratigraphy. Combining relative and absolute Apel J, Storå J, Landeschi G (2015) Ett återbesök I Stora Förvar. chronological indicators in a same georeferenced space can Efterundersökning av stenålderslokalen Stora Förvar, Stora Karlsö, Eksta sn, RAÄ 138:1, Gotland. Rapport arkeologisk undersökning. enormously contribute to define areas of artifacts’ accumulation Lunds Universitet. Lund and to understand the way the anthropic actions affected the Apel J, Wallin P, Storå J, Possnert G (2017) Early Holocene human making of the observed deposits so as to identify different population events on the island of Gotland in the Baltic Sea (9200- phases of inhabitation of the cave. Such information is an im- 3800 cal. BP). Quaternary International, available on-line 28 portant premise not only to improve our understanding of the March 2017 2818 Archaeol Anthropol Sci (2019) 11:2805–2819 Bennike O, Rasmussen P, Aaris-Sørensen K (2008) The harp seal (Phoca techniques for 3D Intrasite data recording. Adv Archaeol Pract 2(4): groenlandica Erxleben) in Denmark, southern Scandinavia, during 353–365 the Holocene. Boreas 37:263–272 Gillings M, Goodrick GT (1996) Sensuous and reflexive GIS: exploring Beraldin JA, Blais F, Cournoyer L, Picard M, Gamache D, Valzano V, visualization and VRML. Internet Archaeology, 1. Available at: Bandiera A, Gorgoglione M (2006) Multi-resolution digital 3D im- http://intarch.ac.uk/journal/issue1/gillings_index.html. (Accessed aging system applied to the recording of grotto sites: the case of the 22 June 2016) grotta dei cervi. In proceedings of the 7th international conference Glykou A (2014) Late Mesolithic - Early Neolithic Sealers: a case study on virtual reality, archaeology and intelligent cultural heritage, 45– on the exploitation of marine resources during the Mesolithic- 52. Eurographics Association Neolithic transition in the south-western Baltic Sea. In: R. Berggren Å, Dell’Unto N, Forte M, Haddow S, Hodder I, Issavi J, Lercari Fernandes, and J. Meadows, eds. Human Exploitation of Aquatic N, Mazzuccato C, Mickel A, Taylor J (2015) Revisiting reflexive Landscapes. Special issue. Internet Archaeology [online], archaeology at Çatalhöyük: integrating digital and 3D technologies 37.Available from: https://doi.org/10.11141/ia.37.7 at the trowel’s edge. Antiquity 89:433–448 Hallgren F (2004) The introduction of ceramic technology around the Callieri M, Dell Unto N, Dellepiane M, Scopigno R, Soderberg B, Baltic Sea in the 6th millennium. In: Knutsson, H. Coast To Coast Larsson L (2011) Documentation and interpretation of an - Arrival: Results And Reflections: Proceedings Of The Final Coast archeological excavation: an experience with dense stereo recon- To Coast Conference, 1–5 October 2002 In Falköping, Sweden, struction tools. In VAST The 11th International Symposium on Uppsala: Coast to Coast Project, Department of Archaeology and Virtual Reality Archaeology and Cultural Heritage, 33–40. Ancient History Eurographics Herrmann N (2002) GIS applied to bioarchaeology: an example from the Campana S (2014) 3D modeling in archaeology and cultural heritage – Rio Talgua caves in Northeast Honduras. Journal of Cave and Karst theory and best practice. In: Campana S, Remondino F (eds) 3D Studies 64(1):17–22 surveying and modeling in archaeology and cultural heritage theory Hiscock P (1985) The need for a taphonomic perspective in stone artefact and best practices. BAR international series, Oxford, pp 151–158 analysis. Queensland Archaeological Research 2:82–97 Campanaro DM, Landeschi G, Dell'Unto N, Leander Touati A-M (2015) Hodder I (2000) Developing a reflexive method in archaeology. In 3D GIS for cultural heritage restoration: a ‘white box’ workflow. J Hodder, I. (ed.) Towards reflexive method in archaeology: the ex- Cult Herit, 18, 321–332. Elsevier ample at Çatalhöyük. McDonald Institute for Archaeological Cignoni P, Callieri M, Corsini M, Dellepiane M, Ganovelli F, Ranzuglia Research, Cambridge. (3–14) G (2008) Meshlab: an open-source mesh processing tool. In Hughes PJ, Lampert RJ (1977) Occupational disturbance and types of Eurographics Italian chapter conference (Vol. 2008, pp. 129–136) archaeological deposit. J Archaeol Sci 4(2):135–140 De Reu J, Plets G, Verhoeven G, Bats M, Cherretté B, De Maeyer W, De Katsianis M, Spyros T, Kotsakisa K, Kousoulakoub A (2008) A 3D Smedt P, Deconynck J, Herremans D, Laloo P, Van Meirvenne M, digital workflow for archaeological intra-site research using GIS. J De Clercq W (2013) Towards a three-dimensional cost-effective Archaeol Sci 35:655–667 registration of the archaeological heritage. J Archaeol Sci 40(2): Landeschi G, Dell’Unto N, Ferdani D, Leander Touati A-M, Lindgren S 1108–1121 (2015) Enhanced 3D-GIS: documenting insula V 1 in Pompeii. In De Reu J, De Smedt P, Herremans D, Van Meirvenne M, Laloo P, De Giligny, F., Djindjian, F., Costa, L., Moscati, P. and Robert, S. (Eds.), Clercq W (2014) On introducing an image-based 3D reconstruction Proceedings of the 42nd conference on computer applications and method in archaeological excavation practice. J Archaeol Sci 41: quantitative methods in archaeology – Paris 22nd to 25th Apri (pp. 251–262 349–360). Oxford: Archaeopress Dell’Unto N (2014) The use of 3D models for intra-site investigation in Landeschi G, Nilsson B, Dell’Unto N (2016a) Assessing the damage of archaeology. In: Campana S, Remondino F (eds) 3D surveying and an archaeological site: new contributions from the combination of modeling in archaeology and cultural heritage theory and best prac- Image-based 3D modelling techniques and GIS. J Archaeol Sci Rep tices. BAR international series, Oxford, pp 151–158 10:431–440 10 p Dell’Unto N, Landeschi G, Leander Touati A-M, Dellepiane M, Callieri Landeschi G, Dell’Unto N, Lundqvist K, Ferdani D, Campanaro DM, M, Ferdani D (2015) Experiencing ancient buildings from a 3D GIS Leander Touati A-M (2016b) 3D-GIS as a platform for visual anal- perspective: a case drawn from the Swedish Pompeii Project. J ysis: investigating a Pompeian house. J Archaeol Sci, 65, 103–113. Archaeol Method Theory, 23, 73–94. Plenum Press Academic Press Dellepiane M, Dell’Unto N, Callieri M, Lindgren S, Scopigno R (2012) Landeschi G, Apel J, Lindgren S, Dell’Unto N (2018) An exploratory use of Archeological excavation monitoring using dense stereo matching 3D for investigating a prehistoric stratigraphic sequence. Proceedings techniques. J Cult Herit 14:201–210 of the 44th Computer Applications and Quantitative Methods in ESRI (2014) Import 3D files. Available at: http://resources.arcgis.com/ Archaeology Conference, CAA 2016 Oslo, 29 March—2 April 2016 EN/HELP/MAIN/10.2/index.html#/Import_3D_Files/ Lantmäteriet (2015) Lantmäteriet 2015. Available at: https://www. 00q900000097000000/ (Accessed22June2016) lantmateriet.se/globalassets/om-lantmateriet/om-oss/dokument/ ESRI (2015) GIS Tutorial 10 - ArcGIS 3D Analyst. Available at: http:// 2016/webb.160222.lm.verksamhetberattelse.2015.pdf. (Accessed downloads2.esri.com/ESRIpress/images/144/GISTutorial_ 22 June 2016) samplechapter.pdf. (Accessed 22 June 2016) Lerma JL, Navarro S, Cabrelles M, Villaverde V (2010) Terrestrial laser Forte M, Dell’Unto N, Issavi J, Onsurez L, Lercari N (2012) 3D archae- scanning and close range photogrammetry for 3D archaeological ology at Çatalhöyük. International Journal of Heritage in the Digital documentation: the upper Palaeolithic cave of Parpalló as a case Era 1(3):351–378 study. J Archaeol Sci 37(3):499–507 Frischer B (2008) From digital illustration to digital heuristics. In: Lindqvist C, Possnert G (1997) The subsistence economy and diet at Frischer B, Dakouri-Hild A (eds) Beyond illustration. 2D and 3D Jakobs/Ajvide, Eksta parish and other prehistoric dwellings and digital technologies as tools for discovery in archaeology. BAR burial sites on Gotland in long-term perspective. In: Burenhult, G. International Series 1805, Oxford, pp 5–24 (ed), Remote sensing vol 1. These and papers in north-European Galeazzi F, Moyes H (2011) 3D documentation in archaeology: recording archaeology 13a. Stockholm Las Cuevas site, Chiquibul Reserve, Belize. In CAA 2012 Lindqvist C, Possnert G (1999) The first seal hunter families on Gotland. Ga On the Mesolithic occupation of the Stora Förvar cave. Current leazzi F, Moyes H, Aldenderfer M (2014) Defining best 3D practices Swedish Archaeology 7:65–88 in archaeology: comparing laser scanning and dense stereo matching Archaeol Anthropol Sci (2019) 11:2805–2819 2819 Lundström V (2016) Exploring new horizons through the use of legacy funerary deposit of Pastora cave, eastern Spain. J Archaeol Sci 40(3):1593–1601 data. An innovative approach for assessing the early mesolithic chronology at the cave site Stora Förvar using 3D-GIS and density Schnittger B, Rydh H (1940) Grottan Stora Förvar på Stora Karlsö. analysis. M.A. Thesis Archaeology. Lund University. (unpublished) Wahlström & Widstrand, Uppsala Moyes H (2002) The use of GIS in the spatial analysis of an archaeolog- Schnittger B, Rydh H, Kolmodin L, Stolpe H (1940) Grottan Stora Stora ical cave site. Journal of Cave and Karst Studies 64(1):9–16 Storlsö Stora Karlsö: investigated by Lars Kolmodin and Hjalmar Müllerova J, Szabo P, Kopecky M, et al. (2013) LONGWOOD - integrating Stolpe. Described by Brother Schnittger and Hanna Rydh. woodland history and ecology in a geodatabase through an interdisci- Wahlström & Widstrand plinary approach. First international conference on remote sensing and Storå J, Ericson PGP (2004) A prehistoric breeding population of harp Geoinformation of the environment (Rscy2013). Volume: 8795 seals (Phoca groenlandica) in the Baltic Sea. Marine Mammal Nekhrizov G, Tzvetkova J, Kecheva N (2012) Archaeological GIS: Kazanlak Science 20(1):115–133 (January 2004) surface survey in 2009-201. In Proceedings of the First European Tennant EW (2007) A sample Geodatabase structure for managing ar- SCGIS Conference BBest practices: Application of GIS technologies chaeological data and resources with ArcGIS. Technical Briefs in for conservation of natural and cultural heritage sites^ 21–23 Historical Archaeology 2:12–23 May 2012, Sofia, Bulgaria, (pp. 53-62). Available at: http://proc.scgis. Van Ruymbeke M, Carré C, Delfosse V, Pfeiffer M, Billen R (2015) scgisbg.org/S2-1_Nekhrizov.pdf. (Accessed 10 March 2016) Towards an archaeological information system: improving the Opitz R, Nowlin J (2012) Photogrammetric modeling + GIS: Better Core data model. In: Giligny F, Djindjian F, Costa L, Moscati P, methods for working with mesh data. Available at: http://www. Robert S (eds) CAA 2014 21st century archaeology: concepts esri.com/news/arcuser/0312/photogrammetric-modeling-plus-gis. methods and tools: proceedings of the 42nd annual conference on html (Accessed 12 July 2016) computer applications and quantitative methods in archaeology. Pira G (1926) On bone deposits in the cave Stora Förvar on the isle of Archaeopress, Oxford, pp 245–253 Stora Karlsö, Sweden Acta Zoologica 7 Wilhelmson H, Dell’Unto N (2015) Virtual taphonomy: a new method Puchol OG, McClure SB, Senabre JB, Villa FC, Porcelli V (2013) integrating excavation and post-processing of human remains. Am J Increasing contextual information by merging existing archaeo- Phys Anthropol 157:305–321 logical data with state of the art laser scanning in the prehistoric http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Archaeological and Anthropological Sciences Springer Journals

Re-enacting the sequence: combined digital methods to study a prehistoric cave

Download PDF
15 pages

Loading next page...
 
/lp/springer-journals/re-enacting-the-sequence-combined-digital-methods-to-study-a-FPySh0W8PJ

References (53)

Publisher
Springer Journals
Copyright
Copyright © 2018 by The Author(s)
Subject
Earth Sciences; Earth Sciences, general; Archaeology; Chemistry/Food Science, general; Geography, general; Life Sciences, general; Anthropology
ISSN
1866-9557
eISSN
1866-9565
DOI
10.1007/s12520-018-0724-5
Publisher site
See Article on Publisher Site

Abstract

This contribution seeks to demonstrate how recently developed 3D GIS platforms can help archeologists in relating to the original context legacy data that can be employed to digitally reconstruct the sequence of arbitrary layers as it was observed and then excavated in the end of the nineteenth century. This research has been conducted on the prehistoric cave of Stora Förvar, located on the small island of Stora Karlsö, in South-Eastern Sweden. As a part of a research project titled BThe pioneer settlements of Gotland,^ this line of enquiry has sought to combine 3D-based digital acquisition techniques, Geographical Information Systems (GIS), and old archival material (hand-made drawings, artifacts lists, historical pictures) in order to virtually reconstruct the original sequence as it was excavated through the method of arbitrary layers. At a later stage, the reconstructed sequence has been employed to re-contextualize and analyze the distribution of artifacts so as to detect any possible pattern that could have been useful for defining the chronological boundaries of the Mesolithic phase of habitation of the cave. In brief, three main objectives can be defined: (a) to re-create a spatial connection between the artifacts retrieved at the time of the excavation and the sequence of layers, (b) to define density maps showing the relationship between volumes of layers and categories of artifacts belonging to the sequence, and (c) to further our knowledge about the Mesolithic habitation of the cave, not only vertically (chronologically) but also horizontally. . . . . Keywords 3D GIS Mesolithic Scandinavian archeology 3D spatial analysis Volumetric analysis Introduction titled BThe pioneer settlements of Gotland,^ this line of enquiry has sought to combine 3D-based digital acquisition techniques, This contribution seeks to demonstrate how recently developed Geographical Information Systems (GIS), and old archival ma- 3D GIS platforms can help archeologists in relating to the terial (hand-made drawings, artifacts lists, historical pictures) original context legacy data that can be used to virtually recon- in order to virtually reconstruct the original sequence as it was struct and interpret the sequence of arbitrary layers as it was excavated through the method of 30-cm-thick arbitrary layers. observed and then excavated in the end of the nineteenth cen- At a later stage, the reconstructed sequence has been employed tury. This research has been conducted on the Prehistoric cave to re-contextualize and analyze the distribution of artifacts so of Stora Förvar, located on the small island of Stora Karlsö, in as to detect any possible pattern that could have been useful for South-Eastern Sweden (Fig. 1). As a part of a research project defining the chronological boundaries of the Mesolithic habi- tation of the cave. The pioneer settlement phase of Gotland extended * Giacomo Landeschi between 9200 and 7600 BP. The cave site of Stora giacomo.landeschi@ark.lu.se Förvar was according to a summed probability distribu- tionanalysis basedon65C14-dates datedtotheperiod Department of Archaeology and Ancient History, Lund University, 9200–7800 so the cave was abandoned earlier than the Helgonavägen 3, Box 192, 221 00, Lund, Sweden settlements on Gotland Island, probably because of the Department of Archaeology and Classical Studies, Stockholm effects of the Litorina I transgression (Apel et al. 2017). University, Wallenberglaboratoriet, Lilla Frescativägen 7, 106 91 Stockholm, Sweden The cave site of Stora Förvar is unique and has played a key role in understanding the Stone Age of Gotland. Humanities Lab, Lund University, Helgonabacken 12, 221 00 Lund, Sweden The cave sequence of Stora Förvar was excavated 2806 Archaeol Anthropol Sci (2019) 11:2805–2819 Fig. 1 The cave site of Stora Förvar is located on the island of Stora Karlsö, in the Baltic Sea, South-eastern Sweden ( © Lantmäteriet, Swedish cadastral agency; freevectormaps.com) between 1888 and 1893 by Lars Kolmodin and Hjalmar out her own excavations on Stora Karlsö and was well Stolpe. Unfortunately, the final excavation report was aware of the archeology of the island. Already in 1926, not published until 50 years later by Bror Schnittger Adolf Pira published the first analysis of faunal remains and Hanna Rydh (1940), who had not participated in from the Stora Förvar cave. He investigated the seal the actual fieldwork. However, Hanna Rydh had carried bones in the cultural layers and noticed that the Archaeol Anthropol Sci (2019) 11:2805–2819 2807 frequencies of seal bones from different species varied field of Computer Science (Dellepiane et al. 2012; De Reu et al. over time. For the present study, we will focus attention 2013;Dell’Unto 2014). Site acquisition and documentation on the presence of harp seal, a species that entered the strategies have been enormously improved thanks to the adop- Baltic basin some 6000 years BP. This coincides rough- tion of innovative methodological approaches (Dellepiane et al. ly with the time when the cave was resettled again in 2012; De Reu et al. 2013;Dell’Unto 2014; Katsianis et al. 2008; the Late Mesolithic/Early Neolithic. Thus, the bones of Callieri et al. 2011; Opitz and Nowlin 2012; Campana 2014;De harp seals are an important chronological proxy to dis- Reu et al. 2014), which contributed to reinforce reflexivity in the tinguish the Neolithic layers of the cave, together with practice of archeological excavation (Hodder 2000); this also pottery and also harpoons. raised up additional questions on which contribution three- One of the main aims of the BThe pioneer settlements of dimensionality could provide to archeological research (Forte Gotland^ project has been to evaluate the integrity and et al. 2012:Berggrenetal. 2015). In particular, based on the character of the Mesolithic component of the cave se- recent advances in digital technology, there is an increasing quence Stora Förvar. As part of the project, a small exca- Bheuristic^ potential connected to the use of three- vation was carried out in summer 2013 and a digital 3D dimensionality in archeology which could lead to interesting scanning of the cave was made (Apel et al. 2015;Apeland openings in the field of spatial data analysis, as predicted by Storå 2017a, b). We had on previous visits found bones and some authors a few years ago (Gillings and Goodrick 1996; stone in the soil layers of the cave floor, which suggested Frischer 2008). Recently, the introduction of more advanced that there could be preserved cultural layers pockets that 3D GIS software, namely ESRI ArcGIS 10.x package (ESRI had not been excavated. The purpose of the field work was 2015), opened new ways of analyzing archeological data, by to investigate this further by performing limited test exca- combining spatial analysis tools and geometrically complex vations. Three smaller trenches were excavated of which 3D boundary models (Landeschi 2018; Landeschi et al. two contained pristine Mesolithic layers. The content of 2016b;Dell’Unto et al. 2015). Such an achievement led to a the test trenches was sieved through 4- and 2-mm meshes more accurate representation of the material evidence and novel and the find material was documented in units of 0.5 × methods of analysis were experimented in order to investigate 0.5 m and 5-cm spits. The layer that was encountered spatial relations in field excavation (Wilhelmson and Dell’Unto was interpreted as being homogenous, but with intrusions 2015), to perform visibility analysis in a reconstructed architec- of chalk that had penetrated the soil with water that is tural space (Landeschi et al. 2016a) and to assess structural dripping from the cave walls (Apel and Storå 2017b). degradation in historical buildings (Campanaro et al. 2015). The quality of the bone material and two flint blades that Another relevant aspect is the multiscalarity of the dataset, where could be refitted are indication of the stratigraphic integrity analysis can be performed either on the single artifact or extend- ed to the whole landscape in the same georeferenced space. of the layer (Apel and Storå 2017a). A mobile 3D-scanner was used to build a digital, three-dimensional model of the Indeed, by adjusting the size of the polygonal mesh associated cave (Lundström 2016; Landeschi et al. 2018). We here to each 3D model, it is possible to optimize the model represen- evaluate the potential of combining information from the tation in relation to the scale of analysis. Remarkably, the pre- 3D-technique with data in the archival material from the historic caves constitute an interesting case study to observe the excavations in order to highlight the Mesolithic use of the advantage of such an approach, due to the complex environmen- cave. The purpose is therefore to take advantage of an tal settings in which traditional methods of survey fail in provid- entirely three-dimensional environment: (a) to re-create a ing an adequate representation on the original space. spatial connection between the artifacts retrieved at the time of the excavation and the sequence of layers, (b) to Background in cave studies define density maps showing the relationship between vol- umes of layers and categories of artifacts belonging to the As reported by several authors, archeologists have tried to sequence, and (c) to further our knowledge about the introduce digital technologies in the study of Prehistoric caves Mesolithic habitation of the cave. (Galeazzi and Moyes 2011; Galeazzi et al. 2014). Still, a very limited number of studies succeeded in combining 3D and GIS-based methods. An interesting example of the combina- Methodological framework tion of different acquisition techniques is given by a research conducted in a Paleolithic cave in Spain, where Terrestrial Theoretical background Laser Scanning (TLS) and close-range photogrammetry have been combined together to provide archeologists with an ac- In the last few years, an increasing interest on the combined use curate dataset of information that represented a significant step of techniques for collecting and analyzing archeological data has forward compared to traditional, bi-dimensional methods of been characterized by the significant advances occurred in the documentation (Lerma et al. 2010). Similarly, a multi- 2808 Archaeol Anthropol Sci (2019) 11:2805–2819 Prehistoric rock art (Beraldin et al. 2006). Analogously, the adoption of GIS-based methods and tools for investigating Prehistoric caves, allowed archeologists to quantitatively ex- plore relations between artifacts, human remains and their orig- inal contexts, by taking advantage of the spatial information derived in the process of site documentation (Herrmann 2002; Moyes 2002). One of the main limitations in this approach is still represented by the lack of three-dimensionality, which does not allow to properly observing the physical relationships among the objects being excavated. Furthermore, this prevents from fully understanding problems related to the artifacts dis- tribution along the z-axis, such as their vertical movement through the deposits (Hiscock 1985). More recently, some at- tempts of virtually reconstructing a stratigraphic sequence in combination with a cave 3D model have been done in the frame of a research project developed in the Pastora cave, Eastern Spain (Puchol et al. 2013). By combining old site documentation sources, it has been possible to reconstruct Fig. 2 The terrestrial laser scanner employed for the acquisition (Faro and spatially locate the cultural layers dated between the Focus 120S phase shift variation 3D-scanner) placed at the entrance of the cave as it looks today Neolithic and the Bronze Age. Still, due to the lack of a method of excavation based on stratigraphic units (it was conducted during the 1940s by an amateur archeologist), it was not pos- resolution laser scanner combined with a digital camera was employed to provide a high-resolution textured 3D model for sible to define the original appearance of the deposits and the the analysis of pictographs observed within the Neolithic cave layers were basically defined by the plans on which the arti- of Grotta dei Cervi, Italy, and this represented an interesting facts were laying at the time of the excavation. Nonetheless, case in which digital methods were used to document some important advances have been showed in the way 3D Fig. 3 ESRI ArcGIS geodatabase management system (GDBMS) has been set up to integrate different datasets: basemap layers made by vector and raster cartographic data, legacy data in the form of scanned hand-made drawings, tables containing information on artifacts distribution throughout the sequence, and 3D multipatch feature classes of the cave and the reconstructed sequence. Output data have been finally derived and used in support of archeological interpretation of the site Archaeol Anthropol Sci (2019) 11:2805–2819 2809 visualization has been adopted to locate and display artifacts in Acquiring the cave relation to their original context and in their reciprocal position in the space of the cave. This would be a good example on how In the summer of 2013, the cave Stora Förvar was acquired by 3D-based methods might be used in support of museum com- means of terrestrial laser scanner. A Faro Focus 120S phase munication, where visitors could better understand issues re- shift variation 3D-scanner was employed (Fig. 2). Each scan- lated to the different phases of inhabitation of a Prehistoric ning position produced a point cloud with 12 million points. cave. To sum up, there is an increasing acknowledgment of Due to the short timeframe in which the recording had to be the role that 3D and GIS-based methods have in the process of done and the complex geometry of the ceiling of the cave, the site documentation and data analysis. Still, more studies need method used was to record a relatively large number of scans to be carried on in order to effectively explore the potential to get a good overlap between them. Thirty different positions derived from the combination of both of them. Despite a gen- for the scanner were defined to cover the entire space of the eral acknowledgement of the importance of using digital cave. In the post processing phase, the scans were manually methods as a way to improve the documentation strategies, registered using the open source software Meshlab (Cignoni there is still a lot of work to be done, in order to effectively et al. 2008). The same software was also used to combine, use three-dimensionality as an additional factor in support not clean, simplify, and mesh the scans in order to produce the just to data visualization but also, for the analysis of complete 3D-model of the cave. During the recording, some archeological evidence and its original context. As this contri- easily recognized features were marked out to be measured bution seeks to demonstrate, the integration of 3D technology with a total station later on, making it possible to correctly and GIS platforms could provide significant advantages in the georeference the model of the cave in a 3D GIS platform. study of prehistoric caves and their related material, enhancing the possibility for archeologists to investigate relations and Reconstructing the sequence interactions among the objects, along the full space of x, y, and z Cartesian coordinates, in a way that would not be possi- Different sources have been integrated to virtually reconstruct ble with bi-dimensional site documentation methods. the sequence of layers as it was reported by Schnittger and Fig. 4 Different datasets have been integrated to generate the final three-dimensional sequence as it was excavated in the end of the nineteenth century. In ESRI ArcScene, a LIDAR-derived DEM has been used to contextualize the 3D model of the cave in the surrounding landscape of Stora Förvar (a)(© Lantmäteriet, Swedish cadastral agency). Then a combination of digitally scanned and georeferenced original plan and profile drawings gave the possibility to exactly reconstruct the 30-cm-thick layers and to rename them based on the original excavation reports information (b)(© Antiquarian Topographical Archives in Stockholm) 2810 Archaeol Anthropol Sci (2019) 11:2805–2819 Rydh (1940). They basically consist of documents available at to better fit the informative function associated to every single the Antiquarian Topographical Archives in Stockholm, (lists of layer. As a part of the basemap, information derived from the artifacts, hand-made drawings of the site, field reports) and data Swedish National Land Survey agency was added in order to derived either from laser scanning acquisition or completely provide a general spatial context to the site of Stora Förvar. An generated in GIS. More information has been derived from additional dataset has been added to collect as multipatch feature the Swedish National Land Survey agency (Lantmäteriet classes, all the 3D entities describing the cave. More shapefiles 2015) in order to put the original sequence in the wider context were then created in the process of data analysis, including those of the landscape of Stora Karlsö. All the data have been imple- volumetric layers used to represent the three-dimensional se- mented and processed through the ESRI ArcGIS 10.3 software quence of the cave. As an additional data source, archival ma- package, which is to date the only GIS platform enabling users terial was also imported into the geodatabase. This material to effectively import and handle geometrically complex 3D consisted of data derived from the twentieth century field docu- boundary models, derived both from laser scanning acquisition mentation that was produced and published approximately and image-based 3D modeling (Opitz and Nowlin 2012). Here, 50 years after the completion of the excavation. This dataset, different editing tools can be used in support of data analysis to which included original plans and profile drawings, provides us improve the quality of data interpretation (Dell’Unto et al. with a picture of how the cave sequence looked like at the time 2015; Landeschi et al. 2015). To better serve the purpose of of the excavation and it was therefore a crucial element to be managing the data sets, a geodatabase (GDBMS) has been built used in the process of reconstruction. In particular, one of the and several types of sources were integrated (Fig. 3). digitally scanned profile drawings was employed as a main ref- The data framework, based on the geodatabase standard, erence to reconstruct both the vertical parcels and the 30-cm- widely used in several archeological projects (Tennant 2007; thick horizontal units that composed the original sequence, ex- Katsianis et al. 2008; Nekhrizov et al. 2012; Müllerova et al. cavated according to the arbitrary layers method (Hughes and 2013; Van Ruymbeke et al. 2015), has been customized accord- Lampert 1977). Then an additional hand-made drawing was ing to the specific needs of this project. As a result, the final employed to define the original plan of the sequence and it users are provided with an effective tool for querying and ana- was integrated along with the 3D model of the cave to enable lyzing the dataset. To this scope, different categories of data a direct link between the final digital reconstruction and the were defined and raster, vector and tabular format were designed artifacts information (Fig. 4). Fig. 5 As a result of the reconstruction process, the complete sequence of documented during the excavation phases. Each unit was then provided layers has been obtained in the form of a multipatch feature class. The with a volumetric value and linked to the tables of finds featuring different relational geodatabase previously established enabled to query and categories of artifacts and ecofacts belonging to the sequence retrieve information from the original arbitrary layers as they were Archaeol Anthropol Sci (2019) 11:2805–2819 2811 Data setup boundaries to be used to reconstruct the sequence, no texture was added, as it would have only made the process of data visu- Once the data framework was designed, datasets were optimized alization and management more time-consuming. Subsequently, and imported in the geodatabase. The point cloud derived from the digitally scanned version of the original profile drawing was the 3D-scanned model of the cave was decimated and the original rescaled and turned into a multipatch feature class and 10 million-faces mesh reduced to 1 million, in order to be better georeferenced in GIS so as to spatially match the 3D model of handled in the ArcScene viewer. Then it was exported as a the cave. From such a drawing information about the position, VRML file, which is still one of the standard formats recognized thickness and length of each single arbitrary unit was extracted by ArcGIS (ESRI 2014). In ArcCatalog, the model was converted and employed in combination with the 3D boundary model of the into a multipatch feature class and added to the geodatabase. To cave to reconstruct the original shape and spatial location along x, georeference it, some total station points that had been previously y,and z axes of the layers composing the sequence. Then, based collected in the field were employed. Since the main purpose of on the information available, 3D shapefiles were employed to the 3D model implementation was to provide the geometric mark the original partition of the sequence in six different parcels, Fig. 6 Three different 3D maps of density have been produced to show bones, and harpoons. Such information was crucial to better understand the relationship between each spit unit and its content of finds. From which portion of the original sequence could be connected to the above to below, they are illustrating the distribution of pottery, harp seal Mesolithic phases of inhabitation of the cave 2812 Archaeol Anthropol Sci (2019) 11:2805–2819 starting from the cave entrance to the innermost part and then containing the volume information. As a final result, all the layers marked with letters spanning from A to I. All the interface lines were linked to the artifacts geodatabase tables, so that it was marking each unit boundary were converted into horizontal possible to define how the different classes of material were as- panels that were intersected with the mesh of the cave walls. sociated and distributed throughout the stratigraphic sequence. From this intersection, polyline shapefiles were derived to repre- Such an operation was an essential step in the process of data sent the external boundaries of each arbitrary layer previously analysis and this allowed us to spatially investigate the original originated from the interface line. Each polyline was then con- distribution of the artifacts and to possibly detect patterns of pres- verted into a polygon that was representing the original surface ence linked to the different phases of inhabitation of the cave. interface between two different stratigraphic units. From this poly- gon, a series of extrusions were employed to describe the volu- metric portion of space corresponding to each unit described in Results and discussion the original site documentation (Fig. 5; Landeschi et al. 2018). In this way, the whole sequence of spit layers was reconstructed as it The digital reconstruction of original spit units enabled us to cal- was excavated in the end of the twentieth century with each unit culate and assign the volumetric value to each layer. This was a Fig. 7 Results obtained from the density analysis have been summarized important relationship required in order to more accurately define the (Diagrams 1–7). The columns labeled BPottery density per m ^ and Btotal Mesolithic portion of the cave sequence volume excavated^ are of particular interest as they emphasize the Archaeol Anthropol Sci (2019) 11:2805–2819 2813 crucial point to let us to generate maps of finds frequency and pattern might very well be explained by the notion that parcel F density, based on the different categories of archeological objects was excavated at two occasions, in which the excavators dug described in the final excavation report and associated to the var- halfway down into the sequence in parcel F after which excavation ious parcels and units visualized in the original profile drawing. of the first couple of spit units in neighboring parcel G began. It is The 3D maps produced were respectively, a map of pottery, harp in this specific event that the authors recall how masses of soil had seal bones, and bone harpoons (Fig. 6). been thrown down from the top of parcel G into the previously excavated parcel F (Schnittger and Rydh 1940, p. 45) and it is thus very likely that this sudden increase is a result of excavators having Pottery analysis trampled any pottery remain further down into the parcel causing an accidental intrusion of some of the lower levels. To add support A review of the results indicate an overall trend of diminishing to this hypothesis, one only needs to review the development in pottery density towards the lower levels of the Stora Förvar cave the neighboring parcel G. Reviewing the parcel in reverse order, sequence—despite occasional peaks of increased density in par- up until spit unit G.8, there is no occurrence of pottery. After spit cels such as D, E, and F (Fig. 7, Diagrams2,3,and4).Over time unit G.8, the density of pottery peaks briefly with a dramatic however, the levels of pottery density eventually decrease with increase, whereas towards to top it resumes its diminish (Fig. 7, some of the spit units reaching as low levels as 0.8 to 0.1 fragments Diagram 5). More importantly, results published by Lindqvist and per unit of volume (m ). Acting as a deviation to this trend is Possnert (1999) introduced the presence of Early to Late parcel A (Fig. 7, Diagram 1). According to the original publication Mesolithic remains within this sequence. Thus, if the neighboring from the 1940s, parcel A and B came about as a result of the same bottom spit units of parcel F were to be contemporary with that of parcel being excavated at two separate occasions, and thus it was the bottom spit units of parcel G, then the density of pottery should also divided accordingly. Unfortunately, as it is rather difficult to either be very low, or absent altogether as pottery makes its intro- understand from the original publication as to how this divide was duction into the Baltic region in the Late Mesolithic (Hallgren carried out spatially, the strategy was to treat parcel A and B with 2004, p. 123; Glykou 2014,p.24). its artefactual assemblage as one single 3D-reconstructed unit. As Parcel H displays an overall low density of pottery per spit such, the results from the density analysis are not entirely reliable unit with layer H.3 amounting to marginally more than a pottery as most of the bottom spit units were neglected for analysis, but fragment per unit of volume contributing to the general trend of also because of the necessity to bundle together a majority of the low densities of pottery towards the bottom (Fig. 7, Diagram 6). spit units that were labeled A.1-A.4 and A.5-A.6 to name but a It should be mentioned once again however that bundled spit few. Another deviant development also occurs in parcel F. The units have been neglected, and thus any analysis of spit units densities of pottery display a somewhat chaotic sequence in which BH.4-H.5^ has yet to be performed. The final parcel at the very there are two valleys of increase in pottery density throughout the end of the cave is parcel I. Providing us with only three spit parcel (Fig. 7, Diagram 4). However, what is interesting is the units, the pattern is still consistent with previous parcels in sudden increase that occurs between spit units F.10 and F.13. which the amount of pottery fragments per unit of volume de- Ever since spit unit F.4, parcel F had seen a gradual decrease in creases towards the bottom of the sequence (Fig. 7, Diagram 7). pottery density that went from almost six fragments per each unit By using indices of varying pottery densities and results from of volume to its very lowest at just half a fragment. However, all of the osteological analysis (Fig. 8), we argue that additional spit a sudden, the density increases once again. This rather irregular Fig. 8 Section of the cave from north. The dotted line marks the soil surface prior to the excavations. The circles mark the occurrence of bones of harp seal identified by Pira (1926) and Apel and Storå (2017a, b). Scale in meter. Modified from Schnittger and Rydh 1940, Figure 30 2814 Archaeol Anthropol Sci (2019) 11:2805–2819 units of the Stora Förvar cave sequence may be added to the Early Fig. 10 a Distribution of the bone finds in each excavation year and parcel of the cave, weight (g). b Distribution of the bone finds in each section and Mesolithic component for further investigation such as radiomet- layers of the cave, weight (g). Data from the catalog at the Swedish ric dating and artefactual studies. This inference is built on the Historical Museum. Due to the sloping cave floor the same layers do not idea of groups of hunter-gatherers that either use, or do not use, correspond to the same dates. The borders between the different periods are ceramic technology. For the Early Mesolithic portion, the density not to be considered exact (*Dom = finds with bones of domestic animals, apparently younger than c.3000/3500 cal BP, most often though Iron Age/ of pottery is at a significantly low level that it may very well be Historical period). c Amount of bone finds, total volume, and density of ascribed to pioneering groups that precede the Kongemose and bone finds in combined layers of the cave Ertebølle cultures. As of yet however, any further analysis as to the cultural affinities of the pottery at Stora Förvar has been made, the sections and layers I4, G4, I5, G5, B6, H7, and G7 (Fig. 8). and so a possibility could be that there is a presence of Ertebølle A later analysis has confirmed the presence in these layers and pottery (or later) in the lowest of levels. Although, this would not added finds in F9 and E7 (Apel and Storå 2017a). be consistent with the numerous AMS-dates from some of the The deepest—and chronologically oldest—occurrences of lowest levels of parcel G (Lindqvist and Possnert 1999:Table 2), the harp seal bones roughly coincide with the appearance of a and thus lends further strength to the idea of intrusion caused by a large number of bone harpoons and also fish hooks. Bones of systematic and arbitrary method of excavation. domesticated animals became more common and even more common than seal bones in the uppermost layers which date Osteological analysis the Iron Age and Historical period (Ibid.). However, there are some finds of sheep and other domestic animals as deep as The osteological analyses of faunal remains have provided G8. The harp seal entered the Baltic basin around 6000 BP cal, additional clues to the relative chronology of the finds from i.e., around the time when the hiatus in the cave ends (Bennike the cave. Early on, the analyses of Adolf Pira (1926)showed et al. 2008; Storå and Ericson 2004). The identifications of harp seal bones show that the layers that the occurrence of seal species varied in different layers. Bones from Gray seal (Halichoerus grypus) and ringed seal associated with the oldest Mesolithic phase were up to 1- to 1.2- (Phoca hispida) were most common in the bottom layers of m thick at the entrance of the cave, in sections A, D, E, and F but the cave while harp seal (Phoca groenlandica)appeared thinner in sections G, H, and I. At the far end of the cave in section higher up in the stratigraphy (e.g., G7 and H7), from approx- I, harp seal bones appear already at c.30 cm above the cave floor. imately 1.2 m above the bedrock (Fig. 8). The estimations of the volume of the layers in each section We now know that the oldest layers of the cave date to provide a possibility to evaluate the Mesolithic depositional pat- approximately 9200 cal BP, i.e., the Mesolithic. The oldest terns of bones and, thus, the use of the cave, both horizontally use of the cave spans a period of around 1000 years after and vertically (Figs. 9 and 11). It has so far been very difficult to which there is a hiatus in the stratigraphy when the cave ap- investigate the horizontal use of the different parts of the cave. parently was more or less abandoned between approximately We here consider the sections inside of the cave and those that date to the Mesolithic. The small amounts of bone finds in 8200 cal BP to around 6000 cal BP (Apel and Storå 2017a; Apel et al. 2017; Lindqvist and Possnert 1997, 1999). section D may be a result of recovery bias. There are some For the present study, the presence of bones of harp seal noteworthy differences in the density of bone finds in different may be used as an important chronological indicator together layers and sections (Fig. 10). In section D, the lowest layer 12 with the pottery. Pira (1929) identified bones of harp seal in contained smaller amounts of bone finds than layer 11, after Fig. 9 C14-dated faunal remains’ samples have been georeferenced and put in spatial relation with the 3D model of the cave: a sheep 85–225 calAD (5.4%); b sheep 55–211 calAD (95.4%); c sheep 745–404 calBC (95.4%); d ringed seal 7184–7028 calBC (93.2%). They acted as an additional independent chronological indicator to define the boundaries of the Mesolithic portion of the sequence. e shows the same portion of the wall cave as it can be observed on site Archaeol Anthropol Sci (2019) 11:2805–2819 2815 2816 Archaeol Anthropol Sci (2019) 11:2805–2819 we discern a Mesolithic depositional pattern to deposit the refuse after the hunted seals. Noteworthy in the comparison is also the drop in density of finds in layers 8 in sections F and G. These layers probably belong to the end of the Mesolithic, at the time of the hiatus in the occupation. It seems that the intensity of deposi- tion, as seen in smaller mean amounts of bone per m , decreased through time, possibly in the period prior to the abandonment of the cave. This change in depositional patterns is also associated to changes in seal hunting patterns (Apel and Storå 2017a, b). To summarize, some elements are particularly worth of attention as they provide information in terms of relative and absolute chronology, useful to trace and define certain spatial boundaries. In particular: Fig. 11 View of profile of section G, from west after it has been properly georeferenced in the 3D cave model. The change in the character of the stratigraphy, marked by an arrow, slightly below the shoulders of the (a) Density values of pottery and faunal remains act as chro- standing man probably marks the hiatus, i.e., a soil surface layer when nological indicators to define the temporal boundaries of the cave apparently was not in use for around 1000 years. Reproduced the Mesolithic phase of inhabitation of the cave. Most with permission by the Antiquarian Topographical Archives, Stockholm importantly, they provide a terminus that here can be (Photo 1492:2) marked to spatially define the volume of the sequence which, the find density decreases higher up in the stratigraphy. characterized by Mesolithic and post-Mesolithic events. A similar pattern may be seen in sections E and F, although the In this respect, the presence of harp seal, which entered deposits with higher amounts of finds are thicker in section F. the Baltic basin around 6000 Cal BP, is another good This could reflect a difference in soil cover in the front end of chronological indicator to be considered. the cave and at the end of the cave. Thus, the bones could have (b) More traces indicate the uppermost boundary of the been deposited on an existing soil cover at the entrance of the Mesolithic portion of the sequence and they can be ob- cave. Section G and also H and I exhibit the highest densities of served in a historical picture of the profile of section G finds in the layers immediately on top of the bedrock (floor). which is recognizable by the dark color of the soil ma- Considerably, larger amounts of finds were deposited in the trix. The possibility of georeferencing the picture let us Mesolithic layers in sections G and F compared to sections D to put in connection the visible hiatus in turn with the and E. Possibly, the areas at the entrance of the cave, which volumetric model of parcel G, the digitized hand-made actually had large floor areas, were kept cleaner from refuse of profile drawing and the 3D model of the cave (Fig. 11). the seals. There is a marked difference in the floor areas be- (c) In terms of absolute chronology, further indication about the tween the layers and sections. spatial pattern related to the Mesolithic phases of the cave is Thus, the absolute amounts of bone finds are highest in the provided by the c14-dated faunal remains from wall con- central part of the cave, but the density of bone finds is actually cretions, which have been georeferenced and put in spatial higher at the end of the cave, and lowest at the entrance. Indeed, connection with the above-mentioned datasets (Fig. 9). Fig. 12 Interpretative line (M) illustrating the uppermost boundary of the concretions; 3D density maps for pottery finds, harp seal bones and Mesolithic phase of Stora Förvar cave. Such interpretation comes has a harpoons, identification of a clear stratigraphic boundary visible on the result from the combination of different independent chronological section of parcel G within a georeferenced historical picture indicators, that include: c14-dated faunal remains from wall Archaeol Anthropol Sci (2019) 11:2805–2819 2817 Conclusions single site on a local level, in broader terms, but also to expand our knowledge about the pioneer settlement of Gotland. In a This contribution has sought to demonstrate how the integrated broader perspective, a similar workflow can be extended to combination of digital methods can significantly improve the countless case studies in which archeological documentation interpretative framework of a Prehistoric sequence. In particu- has been produced in pre-digital era and used to build an inter- lar, advanced 3D GIS functions together with legacy data pro- pretation of the site. Any previous study can thus be revised and vided the opportunity to partially re-contextualize archeological possibly improved by giving a spatial dimension to features and finds belonging to the Prehistoric cave of Stora Förvar and to objectsthathad been alreadyexaminedbytakingintoaccount take advantage of the digitally reconstructed sequence of arbi- of their vertical position and their temporal relation with the trary layers to quantitatively assess the distribution of several space. Indeed, the possibility of collecting the data in a classes of artifacts in order to detect patterns associated to the geodatabase would allow more scholars to integrate further different phases of cave inhabitation. Noteworthy is the study of information into the system so as to integrate additional ele- those categories of artifacts which act as important indicators ments that can be used in support of site interpretation. for the chronology of the layers. Having those artifacts repre- Further research needs to be conducted in order to cope with sented as a numerical attribute linked to the volumetric model issues concerning data integrity and consistency especially in of the sequence allowed to create 3D maps that could visually relation to the material derived from archival source, for which represent the distribution of each class based on values of fre- a bit more of uncertainty characterize the act of data collecting. quency and, more importantly, on the density as a result from Nonetheless the results obtained seem to foster this approach the relation between each layer’s volume and number of finds. and to mark a significant advance in the practice of data-reuse The emerging patterns have been thus put in relation to other which will be beneficial to the reinterpretation of many spatially datasets consisting of legacy data that had been properly and temporally diverse archeological contexts. georeferenced in order to contextualize their contents. Besides Acknowledgements The authors wish also to thank the Humanities being an attempt of promoting a Bheuristic^ usage of three- Laboratory and the DARK Lab, Lund University, for the opportunity to dimensionality in the context of a site investigation, this com- use instruments and the anonymous reviewers for their useful comments. bined approach allowed archeologists to answer some ques- tions related to the site, which could not have been addressed Funding information This research activity was generously supported by without a spatial analysis of the original layers. the Berit Wallenberg Foundation, Swedish Research Council and Palmska Foundation, and by the Birgit och Sven Håkan Ohlssons As a final result of the analysis, an interpretative line can be Foundation. traced in order to highlight the chronological boundaries of such phases (Fig. 12). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// Nonetheless, some biases must be taken into account, as creativecommons.org/licenses/by/4.0/), which permits unrestricted use, there are several issues that influence the original position of distribution, and reproduction in any medium, provided you give appro- the finds and so, any possible interpretation. First of all, the priate credit to the original author(s) and the source, provide a link to the excavation techniques employed, consisting of arbitrary layers, Creative Commons license, and indicate if changes were made. by definition do not follow the actual stratigraphy made up of natural and anthropic layers as they deposited. It is very likely that the same spit unit contains more original stratigraphic layers which correspond to different chronological phases in References the cave. Additionally, some inaccuracy in the documentation Apel J, Storå J (2017a) The Pioneer settlements of Gotland: a behavioural process did not allow to properly link all the finds to their ecology approach. The ecology of early settlement in northern original unit, making the reconstruction of the 3D maps more Europe - conditions for subsistence and survival (Volume 1). uncertain, especially in parcels A and B, which do not even Equinox eBooks Publishing, United Kingdom. Dec 2017. ISBN have clear boundaries on their uppermost layers, as they were originally located just outside the entrance of the cave. To sum Apel J, Storå J (2017b) Ett återbesök i Stora Förvar och en ny bild av mesolitikum på Gotland. Arkeologi på Gotland 2. Tillbakablickar up, the approach as it has been illustrated demonstrates the key och nya forskningsrön. Institutionen för arkeologi och antik historia, role three-dimensionality that plays in enabling to understand Uppsala Universitet & Gotlands Museum. Uppsala och Visby an archeological stratigraphy. Combining relative and absolute Apel J, Storå J, Landeschi G (2015) Ett återbesök I Stora Förvar. chronological indicators in a same georeferenced space can Efterundersökning av stenålderslokalen Stora Förvar, Stora Karlsö, Eksta sn, RAÄ 138:1, Gotland. Rapport arkeologisk undersökning. enormously contribute to define areas of artifacts’ accumulation Lunds Universitet. Lund and to understand the way the anthropic actions affected the Apel J, Wallin P, Storå J, Possnert G (2017) Early Holocene human making of the observed deposits so as to identify different population events on the island of Gotland in the Baltic Sea (9200- phases of inhabitation of the cave. Such information is an im- 3800 cal. BP). Quaternary International, available on-line 28 portant premise not only to improve our understanding of the March 2017 2818 Archaeol Anthropol Sci (2019) 11:2805–2819 Bennike O, Rasmussen P, Aaris-Sørensen K (2008) The harp seal (Phoca techniques for 3D Intrasite data recording. Adv Archaeol Pract 2(4): groenlandica Erxleben) in Denmark, southern Scandinavia, during 353–365 the Holocene. Boreas 37:263–272 Gillings M, Goodrick GT (1996) Sensuous and reflexive GIS: exploring Beraldin JA, Blais F, Cournoyer L, Picard M, Gamache D, Valzano V, visualization and VRML. Internet Archaeology, 1. Available at: Bandiera A, Gorgoglione M (2006) Multi-resolution digital 3D im- http://intarch.ac.uk/journal/issue1/gillings_index.html. (Accessed aging system applied to the recording of grotto sites: the case of the 22 June 2016) grotta dei cervi. In proceedings of the 7th international conference Glykou A (2014) Late Mesolithic - Early Neolithic Sealers: a case study on virtual reality, archaeology and intelligent cultural heritage, 45– on the exploitation of marine resources during the Mesolithic- 52. Eurographics Association Neolithic transition in the south-western Baltic Sea. In: R. Berggren Å, Dell’Unto N, Forte M, Haddow S, Hodder I, Issavi J, Lercari Fernandes, and J. Meadows, eds. Human Exploitation of Aquatic N, Mazzuccato C, Mickel A, Taylor J (2015) Revisiting reflexive Landscapes. Special issue. Internet Archaeology [online], archaeology at Çatalhöyük: integrating digital and 3D technologies 37.Available from: https://doi.org/10.11141/ia.37.7 at the trowel’s edge. Antiquity 89:433–448 Hallgren F (2004) The introduction of ceramic technology around the Callieri M, Dell Unto N, Dellepiane M, Scopigno R, Soderberg B, Baltic Sea in the 6th millennium. In: Knutsson, H. Coast To Coast Larsson L (2011) Documentation and interpretation of an - Arrival: Results And Reflections: Proceedings Of The Final Coast archeological excavation: an experience with dense stereo recon- To Coast Conference, 1–5 October 2002 In Falköping, Sweden, struction tools. In VAST The 11th International Symposium on Uppsala: Coast to Coast Project, Department of Archaeology and Virtual Reality Archaeology and Cultural Heritage, 33–40. Ancient History Eurographics Herrmann N (2002) GIS applied to bioarchaeology: an example from the Campana S (2014) 3D modeling in archaeology and cultural heritage – Rio Talgua caves in Northeast Honduras. Journal of Cave and Karst theory and best practice. In: Campana S, Remondino F (eds) 3D Studies 64(1):17–22 surveying and modeling in archaeology and cultural heritage theory Hiscock P (1985) The need for a taphonomic perspective in stone artefact and best practices. BAR international series, Oxford, pp 151–158 analysis. Queensland Archaeological Research 2:82–97 Campanaro DM, Landeschi G, Dell'Unto N, Leander Touati A-M (2015) Hodder I (2000) Developing a reflexive method in archaeology. In 3D GIS for cultural heritage restoration: a ‘white box’ workflow. J Hodder, I. (ed.) Towards reflexive method in archaeology: the ex- Cult Herit, 18, 321–332. Elsevier ample at Çatalhöyük. McDonald Institute for Archaeological Cignoni P, Callieri M, Corsini M, Dellepiane M, Ganovelli F, Ranzuglia Research, Cambridge. (3–14) G (2008) Meshlab: an open-source mesh processing tool. In Hughes PJ, Lampert RJ (1977) Occupational disturbance and types of Eurographics Italian chapter conference (Vol. 2008, pp. 129–136) archaeological deposit. J Archaeol Sci 4(2):135–140 De Reu J, Plets G, Verhoeven G, Bats M, Cherretté B, De Maeyer W, De Katsianis M, Spyros T, Kotsakisa K, Kousoulakoub A (2008) A 3D Smedt P, Deconynck J, Herremans D, Laloo P, Van Meirvenne M, digital workflow for archaeological intra-site research using GIS. J De Clercq W (2013) Towards a three-dimensional cost-effective Archaeol Sci 35:655–667 registration of the archaeological heritage. J Archaeol Sci 40(2): Landeschi G, Dell’Unto N, Ferdani D, Leander Touati A-M, Lindgren S 1108–1121 (2015) Enhanced 3D-GIS: documenting insula V 1 in Pompeii. In De Reu J, De Smedt P, Herremans D, Van Meirvenne M, Laloo P, De Giligny, F., Djindjian, F., Costa, L., Moscati, P. and Robert, S. (Eds.), Clercq W (2014) On introducing an image-based 3D reconstruction Proceedings of the 42nd conference on computer applications and method in archaeological excavation practice. J Archaeol Sci 41: quantitative methods in archaeology – Paris 22nd to 25th Apri (pp. 251–262 349–360). Oxford: Archaeopress Dell’Unto N (2014) The use of 3D models for intra-site investigation in Landeschi G, Nilsson B, Dell’Unto N (2016a) Assessing the damage of archaeology. In: Campana S, Remondino F (eds) 3D surveying and an archaeological site: new contributions from the combination of modeling in archaeology and cultural heritage theory and best prac- Image-based 3D modelling techniques and GIS. J Archaeol Sci Rep tices. BAR international series, Oxford, pp 151–158 10:431–440 10 p Dell’Unto N, Landeschi G, Leander Touati A-M, Dellepiane M, Callieri Landeschi G, Dell’Unto N, Lundqvist K, Ferdani D, Campanaro DM, M, Ferdani D (2015) Experiencing ancient buildings from a 3D GIS Leander Touati A-M (2016b) 3D-GIS as a platform for visual anal- perspective: a case drawn from the Swedish Pompeii Project. J ysis: investigating a Pompeian house. J Archaeol Sci, 65, 103–113. Archaeol Method Theory, 23, 73–94. Plenum Press Academic Press Dellepiane M, Dell’Unto N, Callieri M, Lindgren S, Scopigno R (2012) Landeschi G, Apel J, Lindgren S, Dell’Unto N (2018) An exploratory use of Archeological excavation monitoring using dense stereo matching 3D for investigating a prehistoric stratigraphic sequence. Proceedings techniques. J Cult Herit 14:201–210 of the 44th Computer Applications and Quantitative Methods in ESRI (2014) Import 3D files. Available at: http://resources.arcgis.com/ Archaeology Conference, CAA 2016 Oslo, 29 March—2 April 2016 EN/HELP/MAIN/10.2/index.html#/Import_3D_Files/ Lantmäteriet (2015) Lantmäteriet 2015. Available at: https://www. 00q900000097000000/ (Accessed22June2016) lantmateriet.se/globalassets/om-lantmateriet/om-oss/dokument/ ESRI (2015) GIS Tutorial 10 - ArcGIS 3D Analyst. Available at: http:// 2016/webb.160222.lm.verksamhetberattelse.2015.pdf. (Accessed downloads2.esri.com/ESRIpress/images/144/GISTutorial_ 22 June 2016) samplechapter.pdf. (Accessed 22 June 2016) Lerma JL, Navarro S, Cabrelles M, Villaverde V (2010) Terrestrial laser Forte M, Dell’Unto N, Issavi J, Onsurez L, Lercari N (2012) 3D archae- scanning and close range photogrammetry for 3D archaeological ology at Çatalhöyük. International Journal of Heritage in the Digital documentation: the upper Palaeolithic cave of Parpalló as a case Era 1(3):351–378 study. J Archaeol Sci 37(3):499–507 Frischer B (2008) From digital illustration to digital heuristics. In: Lindqvist C, Possnert G (1997) The subsistence economy and diet at Frischer B, Dakouri-Hild A (eds) Beyond illustration. 2D and 3D Jakobs/Ajvide, Eksta parish and other prehistoric dwellings and digital technologies as tools for discovery in archaeology. BAR burial sites on Gotland in long-term perspective. In: Burenhult, G. International Series 1805, Oxford, pp 5–24 (ed), Remote sensing vol 1. These and papers in north-European Galeazzi F, Moyes H (2011) 3D documentation in archaeology: recording archaeology 13a. Stockholm Las Cuevas site, Chiquibul Reserve, Belize. In CAA 2012 Lindqvist C, Possnert G (1999) The first seal hunter families on Gotland. Ga On the Mesolithic occupation of the Stora Förvar cave. Current leazzi F, Moyes H, Aldenderfer M (2014) Defining best 3D practices Swedish Archaeology 7:65–88 in archaeology: comparing laser scanning and dense stereo matching Archaeol Anthropol Sci (2019) 11:2805–2819 2819 Lundström V (2016) Exploring new horizons through the use of legacy funerary deposit of Pastora cave, eastern Spain. J Archaeol Sci 40(3):1593–1601 data. An innovative approach for assessing the early mesolithic chronology at the cave site Stora Förvar using 3D-GIS and density Schnittger B, Rydh H (1940) Grottan Stora Förvar på Stora Karlsö. analysis. M.A. Thesis Archaeology. Lund University. (unpublished) Wahlström & Widstrand, Uppsala Moyes H (2002) The use of GIS in the spatial analysis of an archaeolog- Schnittger B, Rydh H, Kolmodin L, Stolpe H (1940) Grottan Stora Stora ical cave site. Journal of Cave and Karst Studies 64(1):9–16 Storlsö Stora Karlsö: investigated by Lars Kolmodin and Hjalmar Müllerova J, Szabo P, Kopecky M, et al. (2013) LONGWOOD - integrating Stolpe. Described by Brother Schnittger and Hanna Rydh. woodland history and ecology in a geodatabase through an interdisci- Wahlström & Widstrand plinary approach. First international conference on remote sensing and Storå J, Ericson PGP (2004) A prehistoric breeding population of harp Geoinformation of the environment (Rscy2013). Volume: 8795 seals (Phoca groenlandica) in the Baltic Sea. Marine Mammal Nekhrizov G, Tzvetkova J, Kecheva N (2012) Archaeological GIS: Kazanlak Science 20(1):115–133 (January 2004) surface survey in 2009-201. In Proceedings of the First European Tennant EW (2007) A sample Geodatabase structure for managing ar- SCGIS Conference BBest practices: Application of GIS technologies chaeological data and resources with ArcGIS. Technical Briefs in for conservation of natural and cultural heritage sites^ 21–23 Historical Archaeology 2:12–23 May 2012, Sofia, Bulgaria, (pp. 53-62). Available at: http://proc.scgis. Van Ruymbeke M, Carré C, Delfosse V, Pfeiffer M, Billen R (2015) scgisbg.org/S2-1_Nekhrizov.pdf. (Accessed 10 March 2016) Towards an archaeological information system: improving the Opitz R, Nowlin J (2012) Photogrammetric modeling + GIS: Better Core data model. In: Giligny F, Djindjian F, Costa L, Moscati P, methods for working with mesh data. Available at: http://www. Robert S (eds) CAA 2014 21st century archaeology: concepts esri.com/news/arcuser/0312/photogrammetric-modeling-plus-gis. methods and tools: proceedings of the 42nd annual conference on html (Accessed 12 July 2016) computer applications and quantitative methods in archaeology. Pira G (1926) On bone deposits in the cave Stora Förvar on the isle of Archaeopress, Oxford, pp 245–253 Stora Karlsö, Sweden Acta Zoologica 7 Wilhelmson H, Dell’Unto N (2015) Virtual taphonomy: a new method Puchol OG, McClure SB, Senabre JB, Villa FC, Porcelli V (2013) integrating excavation and post-processing of human remains. Am J Increasing contextual information by merging existing archaeo- Phys Anthropol 157:305–321 logical data with state of the art laser scanning in the prehistoric

Journal

Archaeological and Anthropological Sciences – Springer Journals

Published: Oct 24, 2018

There are no references for this article.