Our first season officially kicked off on June 26th with an early heat wave and the geoarchaeology group hitting the ground running (Tim Kinnaird, Neil McGlashan Rebecca Bateman and Anastasia Dakouri-Hild). We discussed research questions and priorities vis a vis the footprint of the 2019 season (as well as the tentative footprint for 2020), and having consulted a combination of layers (satellite imagery, LIDAR DEM, LIDAR-derived terrace features, the IGME-derived geology layer etc.), we spent a considerable amount of time surveying the broader landscape surrounding Kotroni by car and on foot, initially to gauge the accuracy of the IGME map from the 1970s, and also to familiarize ourselves with the rocks, soils and geomorphology of the area of interest.
The geo collection was also useful as a trial run for our born-digital data collection system, which consists of several AGOL layers downloaded for offline use on Samsung Active2 tablets equipped with ESRI’s Collector and Trimble’s R1 survey grade GPS units. The system performed well, giving a variety of geospatial information in the field, easy syncing, ample battery life and submeter (typically 80 cm but frequently 40-50 cm) horizontal accuracy in most settings with SBAS correction. The vertical accuracy was lesser, as expected from an antenna-less system, but since a LIDAR geotiff was available to us through our offline web app on the tablets, we did not have to rely on the vertical accuracy of the R1.
We created dedicated GIS layers to receive the new geology and geomorphology spatial data created in the field (geology polygon, polyline and point-based layers, plus image attachments). We also sampled geological (natural) terraces, formed by the river system in the area, and agricultural (manmade) terraces using portable OSL equipment. Tim was able to run the preliminary analyses within the hour using this equipment, which gave a tentative sense of the relative age of sampled terrace layers right in the field. Further analyses of collected samples will be undertaken at the CERSA Luminance Lab to clarify the dates of the associated deposits.
Through these investigations, we hope to get a better sense of whether the agricultural terraces surrounding the citadel are ancient, at least in part; to define geomorphological units and extent of manmade intervention in the landscape subject to intensive survey collection later on in the season (which will help refine the methodology and guide the interpretation of artifacts); to understand the geological characteristics of the landscape in question (including natural resources); and to clarify the geomorphological processes that have brought about the landscape in its current form.
We are are currently working on watershed/erosion/deposition models to use in conjuction with this new geomorphological/geological data. Such information will tint our understanding of visibility and recovery rates during the intensive survey.
