As responsible for the archaeological prospection measurements conducted at Uppåkra I would like to comment on the entries above.
Anybody who has seen the
high-quality magnetometer prospection results from the large-scale archaeological prospection case study Uppåkra and believes that a less successful application of the method some 500m to the north justifies the statement that the method should be regarded as an insufficient tool in Scanian agricultural soils should get their head checked.
The same systems with the same survey parameters were used. The data processing has been state-of-the-art and no other processing would have resulted in the detection of weaker anomalies. Possibly the use of Cesium magnetometry instead of the applied Förster/Fluxgate type sensors would have helped to detected weaker magnetized features.
The lack of detection success is due to a lack of contrast between the archaeological structures and the surrounding soil, due to the local geological and soil conditions. The survey at Stora Uppåkra has been conducted as a test. In general we recommend that always both high-resolution Ground Penetrating Radar (GPR) and Magnetometry are applied at the same location in such circumstances. Many examples are known were only one of either methods results in the detection of archaeological structures, not only in Sweden but anywhere in the world. Just came back from Cyprus where either method clearly detected archaeological structures that were not discernible with the other method. By applying both methods one stands a good chance to detect and understand a large percentage of the buried archaeological structures.
There exists currently not a single non-invasive archaeological prospection method that is overused in Sweden, and metal detection is neither non-invasive nor, in its standard form used, capable to generate maps of subsurface anomalies in comparable resolution or coverage compared to high-resolution large-scale GPR or magnetics. Of course metal detection is generating pretty finds – and unfortunately many people involved in archaeology still believe that’s what it is all about. This is so 1874 and so wrong.
There exists hardly any better method in order to prospect, explore and map non-destructively an Iron Age settlement or trading place than combined magnetic and GPR measurements, as our surveys at
Uppåkra,
Birka,
Gokstad, Kaupang and Borre have demonstrated.
If the stratification is rather thick GPR will in general be more successful than magnetometry since magnetics as passive method measures only the combined effect of all features below the probe, while GPR is an active method.
The expression “övertro på magnetometerundersökninger” indicates that the amateur is exaggerating again in order to provoke a reaction. However, such statememts are damaging to the reputation of the methods, as well as the nonsense that their use should be irrational or overly expensive. People tend to forget the important characteristic of geophysical archaeological prospection methods in being non-destructive. You can excavate only once since excavations by their very nature are destructive processes.
Archaeological excavations can be similarly “unreliable” in their ability to detect archaeological features of interest, due to lack of contrast in colour or texture. The
possible redoubt at Uppåkra had been cut by earlier search trenches but the excavators did not recognize that it actually is a rather special structure.