Magnetometric investigations of stone constructions within large ancient barrows of Denmark and Crimea

摘要

Two examples of magnetic investigations of large barrows in Denmark and Crimea (Ukraine) are presented. The magnetic field over the Danish barrows containing megalithic graves results from the superposition of many different dipole anomalies from granite boulders. The magnetic map revealed a corridor and a chamber of a barrow in Draaby, which are adjacent to a similar, previously excavated feature. A circular wall of smaller stones, which surrounds the two chambers and corridors, is clearly visible on the magnetic map. The limestone building material used for the internal construction of the Scythian barrows in Crimea is practically nonmagnetic, while the soil in these regions has a significant magnetic susceptibility (about 10-100 * 10~(-5) ISO). This makes it possible to identify stone structures by their negative anomalies on magnetic maps. Each of the three large barrows is surrounded by a circular negative anomaly that is 50 m in diameter. The anomaly is caused by walls (cromlechs) inside the barrows. Within each barrow, a long negative anomaly (up to -20 nT) that starts at the cromlech and leads toward the center of the barrow is an indication of a rectangular stone construction inside the barrow (side crypt). The central part of each barrow is characterized by a positive or a negative anomaly, which reflects the state of preservation of the central chamber.