Barge or tjalk? A wreck investigation in the tidal flats of North Frisia

We present a case study on the applicability of geophysical methods to map shipwrecks in the coastal zone. We present results of magnetic gradiometry, electromagnetic induction, and photogrammetry

Hyperbola detection with Retinanet: application to new sites and scalability

The application of Retinanet to new datasets detected about half of the hyperbola present. Combining the detections from images with different aspect ratios results in better performance. The aspect ratio of the images is a crucial factor for detection

Seismic imaging of medieval dike remains in the Wadden Sea (North Frisia, Germany)

Dikes protected cultural lands along the Wadden Sea coast in medieval North Frisia. Remains of dikes must be found to reconstruct the drowned and lost landscapes. Certain imprints in sediment layers due to former load can be linked to eroded dikes. Sediment echosounding provides sections of these imprints and reveals dike courses. Medieval dikes have been traced at Hallig Südfall and south of Sylt

Multi-Coil FD-EMI in Tidal Flat Areas: Prospection and Ground Truthing at a 17th Century Wooden Ship Wreckage

We present a case study of multi-coil frequency-domain electromagnetic (FD-EMI) prospection of a wooden ship wreckage from the 17th century. The wreckage is buried in a sandbar in the German part of the tidal flat area of the North Sea. Furthermore, the wreckage was excavated in advance and covered again after investigation. This ground truthing background and the position of the wreckage makes it a unique investigation object to test the feasibility of FD-EMI for prospecting wooden archaeological objects in the high conductive sediments of tidal flat areas. Our results reveal the shape and position of the wreckage in terms of conductivity maps. The resulting signal change caused by the wreckage in conductivity is only 10% of the value of the water-saturated sandy background, respectively, making a cautious process necessary, including a precise height correction. The data, furthermore, reveals a sensitivity to the vertical shape of the wreckage and thus sufficient depth sensitivity, but with reduced sensing depth. The study highlights the great potential of EMI for both in situ heritage management and archaeological research in the Wadden Sea

Combining teaching and research: a BIP on geophysical and archaeological prospection of North Frisian medieval settlement patterns

We performed a research-oriented EU Erasmus+ Blended Intensive Program (BIP) with participants from four countries focused on North Frisian terp settlements from Roman Iron Age and medieval times. We show that the complex terp structure and environment can be efficiently prospected using combined magnetic and EMI mapping, and seismic and geoelectric profiling and drilling. We found evidence of multiple terp phases and a harbor at the Roman Iron Age terp of Tofting. In contrast, the medieval terp of Stolthusen is more simply constructed, probably uni-phase. The BIP proved to be a suitable tool for high-level hands-on education adding value to the research conducted in on-going projects

A new light on early medieval North Frisia: Harbours and trading sites on the islands of Föhr and Sylt

During the years of 2013-2018, the North Sea Harbour Project investigated early medieval settlement sites of the 7th-11th centuries along the German North Sea coast with a methodological bundle of archaeological and geophysical surveys, geoarchaeological investigations of their local settings and archaeological excavations. One of the core research areas were the North Frisian Islands of Föhr, Amrum and Sylt, which have a unique setting in the German Wadden Sea area. The islands consist of elevated Pleistocene moraine cores with adjacent marshes and easy access to the open sea. Their topography offers favoured settlement locations with high arable land and fertile pasture in the marshes. Natural harbour situations like small rivers and tidal creeks through the marshland provide navigable access to the maritime trade networks along the North Sea coast. It was possible to investigate sites at Witsum, Nieblum and Goting on the island of Föhr and Tinnum and Wenningstedt on the island of Sylt. The surveys revealed a pattern of enclosed village complexes, open complexes with separated functional areas and protective ring fortresses. During the 8th and 9th centuries, the sites show a high level of specialised craft production focused on textiles and amber, but also numerous imports and the refining of imported raw materials, especially glass bead production. It is argued that these sites acted as trading sites for production and re-distribution on a local and regional level, firmly connected to the maritime trade along the North Sea Coast and the nearby emporium of Ribe. The high level of trade and production activities can be traced until the middle of the 9th century, when the maritime trade routes shift focus towards Hedeby and bypass the islands. Subsequently, settlement structures change and the harbour locations lose relevance, although the strong involvement of North Frisian residents in the maritime trade is maintained throughout the Viking Age

Die nordfriesischen Inseln im 8. Jahrhundert.: Grabungsergebnisse von Handelsplätzen auf der Insel Föhr, Kr. Nordfriesland.

During the recent years, the North Sea HarbourProject investigated Early Medieval settlementsites (7th – 11th century) on the NorthFrisian Island of Föhr (Germany). The extensivefieldwork combined geophysical andgeoarchaeological surveys as well as archaeologicalexcavations to uncover the harbourlocations as well as the settlement sites. Thepaper presents results from the harbour andtrading sites of Goting and Witsum. The sitesare located in small inlets along the edge ofthe high pleistocene cores of the islands withaccess to the low marshlands, beaches or tidalcreeks. The geoarchaeological surveys showa clear maritime impact and navigability ofthe waterways, providing natural harboursfor the settlements. The nearby ring fortressBorgsumburg housed a military elite andprovided security and control for the tradingsites. The prospections and excavations revealeda distinctive settlement pattern dominatedby pit houses with traces of craft activitiessuch as glass and amber working and alarge-scale textile production. Remains fromsmithing workshops prove the constructionor repair of boats. Numerous finds of importedgoods from the core Frisian area, theFrankish empire, and Scandinavia indicate astrong connection to the cross-regional traderoutes along the North Sea coasts. Especiallythe analysis of glass objects shows that theNorth Frisian Islands were strongly embeddedin the North Sea trade networks of the8th and 9th centuries with connections towardsthe Rhineland as well as the importantemporium of Ribe (South Denmark)

Hyperbola Detection with RetinaNet and Comparison of Hyperbola Fitting Methods in GPR Data from an Archaeological Site

Hyperbolic diffractions in Ground Penetrating Radar (GPR) data are caused by a variety of subsurface objects such as pipes, stones, or archaeological artifacts. Supplementary to their location, the propagation velocity of electromagnetic waves in the subsurface can be derived. In recent years, it was shown that deep learning tools can automatically detect hyperbola in radargrams using data measured over urban infrastructure, which are relatively clear. In contrast, in this study, we used an archaeological dataset with diverse underground structures. In the first step we used the deep learning network RetinaNet to detect hyperbola automatically and achieved an average precision of 0.58. In the next step, 10 different approaches for hyperbola fitting and thus velocity determination were applied. The derived information was validated with manually determined velocities and apex points. It was shown that hyperbola extraction by using a threshold and a column connection clustering (C3) algorithm followed by simple hyperbola fitting is the best method, which had a mean velocity error of 0.021 m/ns compared to manual determination. The average 1D velocity-depth distribution derived in 10 ns intervals was in shape comparable to the manually determined one, but had a systematic shift of about 0.01 m/ns towards higher velocities

Versunkene Landschaften im Nordfriesischen Watt – Das aktuelle RUNGHOLT-Projekt zur Erforschung von Kulturspuren

The North Frisian Wadden Sea is regardedas an important natural area and isnow protected as a national park and aUNESCOWorld Heritage Site. At thesame time, it is a relic of a submerged culturallandscape. Environmental influences,extreme weather conditions but alsodyke construction and artificial land reclamationhave constantly changed the regionover the past millennia. While someareas could be regained after a devastatingflood, other parts sank into the sea forever. Remains of the lost terps and theiragricultural land are preserved under thepresent-day surface of the Wadden Sea.An interdisciplinary, partly DFG-fundedresearch project is addressing the systematicinvestigation of selected areasin the North Frisian Wadden Sea. Largescalenon-invasive methods of geophysicstogether with analyses of aerial photographsand drone photography are combinedwith targeted geoarchaeological andarchaeological investigations.A defined working area is located nearthe present-day Hallig Südfall, where thetrading centre of Rungholt, which sank on16 January 1362, is assumed to have beenlocated. Here, for the first time, the pathof a medieval dyke, terps, and drainageditches could be reconstructed, and variouslocations of tide gates identified.Hallig Hooge and the surrounding tidalflats form another area of investigation.A large number of submerged settlement60areas as well as new insights into the extentand organisation of medieval salt peatquarrying are the focus of the current investigationshere

Portal. Pløyejord som kontekst. Nye utfordringer for forskning, forvaltning og formidling. Artikkelsamling. Kulturhistorisk museum, Universitetet i Oslo.

I dette bindet presenteres elleve bidrag om funnene fra pløyejorden. Denne typen funn kalles i Norge normalt løsfunn eller løse kulturminner selv om de i regelen blott er løsrevne deler av underliggende uforstyrrede deler av faste kulturminner. De «løse» gjenstander inneholder altså stadig informasjon om lokaliteten de kommer fra. Kvaliteten på denne informasjonen avhenger i høy grad av hvordan funnene, finnestedet og informasjonen om finnested håndteres. Målet med denne utgivelsen er derfor å bringe oppmerksomhet på de såkalte løsfunn og ikke minst deres kontekst. Da metallsøkerfunnene utgjør en stadig økende andel av denne funngruppen, er de det naturlige fokusområde for diskusjonen, men mange av de metodiske over­veielsene gjelder for de øvrige løsfunn også. Hvordan ser formasjonsprosessene ut, hva kan man gjøre for å sikre størst mulig vitenskapelig potensial, og hva kan man gjøre for å utnytte dette potensialet på best mulig måte? For å belyse dette presenterer vi fire forskjel­lige nasjonale måter å løse problemene på, og både forskningsmessige, praktiske, konserveringsmessige, administrative og juridiske variabler analyseres og diskuteres