Geophysikalische Prospektion der Stadtwüstung Corvey: Ein Zwischenstandsbericht

The former Reich Monastery of Chorwey in the 9th and 10th century was the center of cultural, spiritual and economic life. Today, the former monastery has the status of UNESCO World Heritage Site. Especially the vestry from the early days of the Benedictine Abbey is of outstanding importance. Chorwey was a very important monastery, a very early monastery foundation, which also played a very important role in the Christianization in North-Western Europe. And in the protection of this monastery, a larger city was created. So quite a medium-sized city for medieval conditions, which, above all, benefited from market law and, of course, from the Munich law and also from the bridge over the Weser, where the Westfälische Heilweg crossed the Weser. Preparations for the 2023 Landesgartenschau are currently underway in Chorwey. The construction measures are closely accompanied by archaeologists to ensure that the remains of the city and the monastery remain preserved. For the Landesgartenschau, the foundation of the parish church was recreated with stones. In 1265, the settlement was destroyed by an alliance between the city of Höxter and the bishop of Paderborn. In order to document all structures in the earth, archaeology works with the most modern methods. So the city was about 50 hectares high, the fortified area of ​​the city. This is an area that we can never completely excavate, which we also do not want to completely excavate. Nevertheless, of course, we want to map and explore this sunken city in as much detail as possible. But without digging it out, without destroying it. To do this, we use geophysical measuring methods, on the one hand ground radar, on the other magnetic, in order to clear the topography of this city and the structure of the city without destruction. Soon flowers will bloom over the sunken city. Chorwey has been a UNESCO World Heritage Site since 2014. You heard it in the video. This status is of course not only due to the well-known west work, the Carolingian west work, which is one of the best preserved specimens of Carolingian architecture in Central Europe, but also to the much larger invisible part of the medieval desert and the monastery, of which you can hardly see anything in today's terrain. We owe this knowledge mainly to the long-standing work of the former professor, the emeritus professor Hans-Georg Stephan, who invested many years here from the late 1960s to the early 2000s, with excavations, construction site observations, already there are also larger excavations, and has uncovered several remains of the city desert, some stone cellars and, as you can see in the picture at the top right, also the choir of the supposed parish church, as well as in some places a very elaborate paved road, which of course already clearly marks the status of this settlement or this city. After the first efforts of Hans-Georg Stephan, already in the 1980s, with Geophysical Prospection again a major initiative in advance of the World Heritage Act around 2011, where quite large-scale magnetic measurements were already carried out in the field of statuistics, also systematic flights with laser scans, i.e. LiDAR flights, but somehow these works were never to a really satisfactory end, so that we decided here in 2019 with our partner, the Ludwig-Boltzmann-Institut für Archäologische Prospektion und Virtuelle Archäologie aus Wien, to start a new attempt again, and here, in addition to magnetic, but also, above all, on systematic ground radar measurements, very high resolution ground radar measurements, which, above all, make the wall remains and the stone cellars very clearly visible, as you will see in the next slides. We have, again briefly, in the last few years, in two to three smaller campaigns, measured a total of over 50 hectares in Twissen with magnetic, as well as a good 12 hectares with radar, and you see here a first overview of the magnetic data. Of course, you don't see any details in this scale, but certainly good to see are the very large-scale disturbances in the picture at the top left, these white and black lines, which are almost vertical here through the picture, and if we zoom in here, on the northern edge of the city desert, then you see, no, I don't see anything now, here you see the last remnant of the fortification trench of the former city, also at the same time the only still visible remnant of the city desert, and of course I also appreciate this trench wonderfully in the magnetic data. And you also see that this trench is cut in at least two places, from these, so in this picture now light stripes, these are areas where the ground has certainly eroded more strongly, although at the moment we cannot say whether this is a natural erosion or whether we are dealing with paths from the city to hollow paths, although they can of course also affect each other, but natural erosion and erosion through human use. If we move further south to the center of the city at that time, then we also see some quite large, so linear disturbances, also anomalies, as they say in geophysics, which clearly correlate with the already known road network that Hans-Georg Stephan had already reconstructed. You can see here the road leading from west to west, where this plaster was also found, and which is equated with the historically surviving Brückenstrasse. And from the north to this Brückenstrasse, a further structure, which has always been interpreted as an older branch of the Westfälischen Hellweg, and was already very well visible in aerial images. I will now set up a new hypothesis, because we do see this supposed path in the magnetic and also in the radar. You see a direct contrast here, on the left the radar data, on the right the magnetic data. You can also see here how these two data sets complement each other very well. So in the radar data you can see very clearly the stone cellar, here a stone cellar, here a stone cellar, here a very, very large stone cellar. You can see the plaster of this Brückenstrasse here, and you can also see here how another linear anomaly from the north, a strongly reflective anomaly, a further plastered road probably leads to this Brückenstrasse. And this anomaly that we see on the radar is not, and we just have to believe that now, does not overlap with the anomaly in the loopbeat and in the magnetic, but runs parallel to it. And right at the point where we see the bright strip in the magnetic and where it crosses the Brückenstrasse, we have a very conspicuous narrowing in the Brückenstrasse. So I assume that we are actually dealing with a small bridge within the city and with a ditch or possibly even a small waterway through the city desert. You may also wonder what it is with the star-shaped object down here on the left in the picture. This has nothing to do with the city desert, but can be very clearly identified as a central object, a central element of the Baroque or late Renaissance temporary plantation that was located here. And of course that was also a very nice find with regard to the Landesgartenschau, which will take place here next year. Now to the previous highlight, I would say, of our measurements, the Markkirche, which was excavated in 1988 in parts by Hans-Georg Stephan. Here is a larger overview and here then the Markkirche in different deep areas. With the radar data, we get information about the depth through the different times between the transmitted signal and the received signal and can thus move through the ground in different deep layers. And the new thing about it is not only that we can now locate the excavation cut exactly again through the measurements, but also that we can see the entire floor plan of the church very clearly. So it's a three-shafted church with almost symmetrical floor plan, with a massive tower, with a mighty tower in the west, so no west face, as one might have suspected earlier. And the exciting thing is that we can see details in the data through this very high resolution, which allow the assumption that this church was already completely hollowed out in the longhouse. And that in itself is something very exciting. The church was already, due to the excavation, dated in the second half of the 12th century, around 1150. That would also be the earliest possible date for such a hollowed-out church. And if we now compare that with contemporary churches in the region, in the Weserraum and in the Raum Höxter, there are very clear parallels to the Bau III, the third phase of the St. Peter's Church in Höxter, as well as the monastery church of Tom Roden, also directly north of Korwei. These two also have a large tower in the west, also have these side partings, as well as our market church in Korwei. But you can see here, due to the different symmetry, it is clear that these two churches were never hollowed out, at least not in the longhouse. Here below you see two examples that are much better compared to our market church, the St. Kilianikirche in Lügde, as well as St. Petri in Höxter. Lügde is also part of the Weserraum, Höxter, on the other hand, a district of Arnsberg. The earliest hollowed-out church in the Weserraum is the monastery church of Lippolzberg. And there are definitely reasons, also that Lippolzberg is only 20 km from Korwe, that there is a direct connection between this Lippolzberger construction school and the Korwei market church. I think this is a really nice example of how far we can go into the interpretation, into the historical and architectural interpretation, without putting another spade in the ground. But I would also like to conclude with the latest results, but also something that gives us a little reason to maybe shake our expectations here. We will certainly not be able to clarify the entire start plan to the last detail. On the left you can see the measurements in the Remtergarten, directly behind the monastery church from last summer, before the construction measures. And on the right in the picture, the latest measurements that we took only two weeks ago, after the first 30 to 40 cm of topsoil was removed here in the forefield of the Landesgartenschau. And on the right in the picture, very, very nice to see, the graves of the cemetery behind the church, in a row and in a row, from which we could hardly see anything in the data from the summer. So that, of course, also gives a little reason to worry, but of course shows that we also have our limits here at the Geophysical Prospection. And with that I would like to thank you.