Non-destructive archaeological research of Kaltenstein Castle

As part of the activities of the Department of Archaeology of Silesian Museum and in connection with the agreement with the Institute of Archaeology of the Czech Academy of Sciences, Brno, the implementation of a long-standing project of mapping and preventive protection of fortified medieval fortifications in the Jeseníky region has begun this year (2020). The project aims to identify the most endangered sites, verify their level of damage, undertake research using non-destructive methods and then carry out preventive prospection using metal detectors. The castles in the mentioned area have been threatened in recent decades not only by natural conditions (erosion, growth of trees), but especially by the illegal activities of so-called amateur treasure hunters.

In cooperation with the Museum of the Jeseníky Region, Kaltenštejn Castle was selected in the first phase. This is the site most affected by illegal activities of amateur detectorists, both from the Czech Republic and, due to the proximity of the state border, from Poland. Unfortunately, at least in the last 20 years, vandalism has been taking place here, also associated with the destruction of stone relics of the castle. The theft of the torso of the gothic second gate is a deterrent example of the treatment of our cultural heritage.

The aim of the non-destructive research is to map, visually digitise and accurately locate the castle complex, which consists not only of the castle core itself, but also the forecourt. An important aspect of the project is also preventive character, aimed at active protection of an important monument of our history. Another important aspect is to draw the public's attention to the need to protect the destroyed monuments, which are an integral part of our cultural awareness, with the task of preserving them for future generations.

We cannot say much about the history of archaeological research at Kaltenštejn Castle, as standard professional archaeological excavation was not carried out at the site at all - in 1935, W. Tietze carried out only a surface collection, part of which is stored in the Silesian Museum and the other part in the Javorník Castle. Among the older events, one can mention the collection of G. Stumpf from 1921 and 1925, deposited in Silesian Museum, and references to finds from earlier literature, but these are now unknown. In 1992, large-scale illegal excavations by amateur collectors destroyed the finds situation directly at the castle, leaving over 3,000 pieces of pottery and fragments of metal objects on the site, and it is impossible to imagine how many finds were irretrievably stolen in this way.

Within the framework of this year's (2020) preventive non-destructive research of the Silesian Museum in cooperation with the Museum of the Jesenik Region, the castle complex is being surveyed using the GeoMax ZENITH35 PRO GNSS receiver. This is one of the most advanced measurement technologies, it has 555 channels for receiving the signal of all satellite systems and all their frequencies (including the newly built ones), a 5 Hz speed when updating the position, with an integrated spirit level and compass for fast and reliable RTK measurements even with a tilted stick. Provides accurate height and positioning of points and objects, their entry in field documentation or on maps. Furthermore, photographic, digital and visual documentation is carried out via a DJI Phantom 4 drone with a 4K Ultra HD camera mounted on a 3-axis stabilised mount, with an integrated OcuSync digital image transmission and video positioning system. As a result, even hard-to-reach locations or situations at altitude can be accurately documented. The drone provides us with a unique aerial view, providing a context of wider spatial vision. Inaccessible places in the form of cavities, cracks or gaps are then examined using the inspection camera. It is a professional waterproof camera with a range of up to 30 meters with attached camera, camera and monitor, with remote control and LEDs for working in the dark.

Within the selected sites, the Minelab CTX 3030 metal detector is used to search the forest surface clay, which in the hands of archaeologists can complement the knowledge of the material equipment of the castle, as only an archaeologist can react flexibly and evaluate the current field situation in order to minimize or directly limit destructive interventions into the ground. The detector survey is carried out by the museum staff in cooperation with the Archeo Silesia Association. To verify the assumptions of the existence of now extinct walls, corridors, underground spaces or other situations imperceptible to the human eye below the surface, the Georadar OPERA DUO 2 WHEEL was used. The principle is to measure the time of reflected electromagnetic waves in different environments. In this way, the radar searches to a depth of several metres for interfaces between environments with different electromagnetic properties. A single radar measurement records the transverse profile of the terrain, but does not show specific objects, like a tomograph, but only places of greater reflection or beam transmission. We can thus find various stone structures, foundations and cavities (caves, crypts). Thanks to this, it was possible to verify the assumption of the location of the stables in the forecourt. All the data obtained is subsequently digitized using the Allplan Linear 2020 software. The result is a spatial map of the individual castle components in confrontation with the location and distribution of the findings from the metal detector survey.

The most numerous group of archaeological finds from the castle are ceramic fragments from kitchen and tableware, over 3500 pieces. Most of the sherds are from the final period of life on the site, i.e. the 15th century, and more rarely from the previous century. These are fragments of jugs, pots, cups, tripods, etc., fired mostly in greyish shades, sometimes covered with light brown or greenish-brown glaze. Occasionally, light-coloured pottery painted in red appears. This is usually described as a relatively luxurious ware, being vessels made of finely floated clay and with painted decoration, generally appearing from the 13th to the 15th century. The fragments we have recorded come from an exposed area by the outer gateway and associated access road.

An exceptional find are fragments of cups of the so-called Falke group. The name of this group is based on the name of its discoverer, the German art historian Otto von Falke, who defined it in 1907 as luxury gothic stoneware pottery. It is currently described as ceramics with characteristic wheel-thrown and/or anthropomorphic decoration; the vessels were salt-glazed and chronologically date to the 15th century. In our countries, it is an import, its origin is placed in German-speaking countries, in Saxony (probably in the towns of Bautzen or Zittau). The Kaltenštein specimens were found in a hillside, where they were placed secondarily, probably after the demolition of the palace, where they served as representative tableware (a jug and a cup).

Other imports found are fragments of the so-called Loštice cups, which were distributed throughout Europe from their place of origin, the North Moravian town of Loštice. Ceramic vessels with a characteristic surface made of 'blisters' were produced from the end of the 14th to the 16th century and were discovered in a few fragments at Kaltenštejn.

The metal finds are represented by a collection of mainly iron objects, both parts of buildings ( shingle nails, nails from gates and building fittings, possibly door or chest fittings, hasp hooks) and personal equipment of the castle inhabitants (parts of knives, buckles, coins, dagger shields, etc.). The equipment of riders and their horses is represented by evidence of spurs, stirrups, iron currycombs, bits or horseshoes, and militaria by crossbow and bow arrowheads or sword shields. Many of the arrowheads show damage to the point caused by impact, evidence of an active siege of the castle, when some arrows were found in a position perpendicularly stuck in the ground. An interesting find is an iron candlestick with a thorn or a bronze square fitting of a knight's belt with an engraved stylized motif of two intertwined gothic majuscules of the letter M symbolizing Maria Mater, the Virgin Mary as the protector of chivalric qualities, purity, morality and honour.

Thanks to the archaeological findings, it was also possible to locate or specify some situations, e.g. to document the roofing of the tower-bergfried with a shingle roof or to identify the location of horse stables or forge.