By Jαn Tirpαk

Main goals of geophysical prospecting at Al-Khidr site:

• prove the existence and extent of the Bronze Age site,
• interprete the anomalies,
• identify and limit the archaeological structures.

Geophysical methods

Two geophysical methods were used:

• magnetic method,
• dipole electromagnetic profiling method (DEMP).

Measurements were realized at the area 7500 m² within the network 1 x 1 m. For DEMP ground conductivity meter EM 38 from the Geonics company (Canada) and for magnetic method Cesium Vapour Gradiometer SMARTMAG 4G from the company Scintrex (Canada) have been used.

For data processing and creating of all the basic and derived maps the standard methods incorporated in Oasis Montaj V 5.08 system (Geosoft Inc., Canada) have been applied.

Data processing

Input information for the processing of magnetic measurement was the values of total vector of magnetic field that were further processed into the derived magnetic map of analytical signal.

Input information for the processing of DEMP measurement was the map of electric conductivity from that the maps of ground resistivity for 2 depths – 0.7 m and 1.5 m – have been derived.

Consequently maps were derived for each settlement mound (KH-1 = area 1 and 2; KH-2 = area 4; KH-3 = area 3) with following interpretation:

• Map of analytical signal of magnetic field for areas 1 and 2 (Fig. 1)
• Map of apparent resistivities for the areas 1 and 2, depth 0 – 0.7 m (Fig. 2)
• Interpretation of the map of apparent resistivities for the areas 1 and 2, depth 0 – 0.7 m (Fig. 3)
• Map of apparent resistivities for the areas 1 and 2, depth 0.7 – 1.5 m (Fig. 4)
• Interpretation of the map of apparent resistivities for the areas 1 and 2, depth 0.7 – 1.5 m (Fig. 5)
• Map of apparent resistivities for the area 3, depth 0 – 0.7 m (Fig. 6)
• Interpretation of the map of apparent resistivities for the area 3, depth 0 – 0.7 m (Fig. 7)
• Map of apparent resistivities for the area 3, depth 0.7 – 1.5 m (Fig. 8)
• Interpretation of the map of apparent resistivities for the area 3, depth 0.7 – 1.5 m (Fig. 9)
• Map of apparent resistivities for the area 4, depth 0 – 0.7 m (Fig. 10)
• Interpretation of the map of apparent resistivities for the area 4, depth 0 – 0.7 m (Fig. 11)
• Map of apparent resistivities for the area 4, depth 0.7 – 1.5 m (Fig. 12)
• Interpretation of the map of apparent resistivities for the area 4, depth 0.7 – 1.5 m (Fig. 13)

Results of geophysical prospecting 2004

Measured areas are situated in the territory highly contaminated by the remains and rubble from the war 1991 that contains high amount of metal fragments with the size from few centimetres up to meters.

This fact considerably affected the usage of magnetic method. Its results could be finally used only for the identification of the spots within the areas 1 and 2 highly damaged by recent metal rubbles and as so unsuitable for the archaeological excavation (Fig. 1).

Method of dipole electromagnetic profiling (DEMP) was then applied at the site with the successful results (Fig. 2 – 13).

Areas 1 and 2

It is possible to define the spots with anomalies of different size according to the size and volume of metal material on the map of analytical signal (Fig. 1). All the significant anomalies were identified and marked by red to violet colour spectrum on the map.

On the map of the apparent resistivities for the depth 0 – 0.7 m the local anomalies with the magnitude 16 – 34 Ohm (Fig. 2). Anomalies with the magnitude 28 – 34 Ohm indicate the probable archaeological structures.

Fig. 3 presents the interpretation of the map of apparent resisitivities of the areas 1 and 2 for the depth 0 – 0.7 m. Blue colour marks the limits of archaeological structures, red and brown colours represent the probable archaeological structures.

On the map of the apparent resistivities for the depth 0.7 – 1.5 m the local anomalies with the magnitude 8 – 20 Ohm (Fig. 4). Anomalies with the magnitude 18 – 20 Ohm indicate the probable archaeological structures.

Fig. 5 presents the interpretation of the map of apparent resisitivities of the areas 1 and 2 for the depth 0, 7 – 1.5 m. Blue colour marks the limits of archaeological structures, red and brown colours represent the probable archaeological structures.

Area 3

On the map of the apparent resistivities for the depth 0 – 0.7 m the local anomalies with the magnitude 12 – 32 Ohm (Fig. 6). Anomalies with the magnitude 26 – 32 Ohm indicate the probable archaeological structures.

Fig. 7 presents the interpretation of the map of apparent resisitivities of the area 3 for the depth 0 – 0.7 m. Green colour marks the limits of archaeological structures, red and brown colours represent the probable archaeological structures.

On the map of the apparent resistivities for the depth 0.7 – 1.5 m the local anomalies with the magnitude 8 – 22 Ohm (Fig. 8). Anomalies with the magnitude 17 – 22 Ohm indicate the probable archaeological structures.

Fig. 9 presents the interpretation of the map of apparent resisitivities of the area 3 for the depth 0, 7 – 1.5 m. Green colour marks the limits of archaeological structures, red and brown colours represent the probable archaeological structures.

Area 4

On the map of the apparent resistivities for the depth 0 – 0.7 m the local anomalies with the magnitude 15 – 32 Ohm (Fig. 10). Anomalies with the magnitude 27 – 32 Ohm indicate the probable archaeological structures.

Fig. 11 presents the interpretation of the map of apparent resisitivities of the area 4 for the depth 0 – 0.7 m. Green colour marks the limits of archaeological structures, red, brown and black colours represent the probable archaeological structures.

On the map of the apparent resistivities for the depth 0.7 – 1.5 m the local anomalies with the magnitude 9 – 20 Ohm (Fig. 12). Anomalies with the magnitude 17 – 20 Ohm indicate the probable archaeological structures.

Fig. 13 presents the interpretation of the map of apparent resisitivities of the area 4 for the depth 0, 7 – 1.5 m. Green colour marks the limits of archaeological structures, red and brown colours represent the probable archaeological structures.

Conclusion

As the results of the geophysical prospecting show, it was possible to identify and limit the Bronze Age archaeological structures.

For the future research of the Al Khadir site we propose to apply 2 geophysical methods – already used dipole electromagnetic profiling (DEMP) to finish the prospecting of horizontal extent of the site (under surface structures Areas 1 and 2, Area 3 and Area 4) and georadar to obtain the picture about the vertical patterns of archaeological structures.

Comparison of geophysical and archaeological results (2004)

By Lucia Benedikovα

Regarding the archaeological results of campaign 2004 it is clear that the chosen geophysical method appeared to be the suitable tool for estimating the potential of the site.

It clearly demarked the N and S edges of the intensive occupation and usage of the area along the sea shore during the Bronze Age – the edges that were confirmed during the excavation (Fig. 14 – 17): sounding IX without clear BA remains and distribution of storage jars confirm the N border limit of the occupational zone as measured geophysically; for S border the area between the trench 25AC without solid architectonical and BA remains and 24AA yielding the cultural layers without solid architectures in upper layers (see the scattered distribution of remains according to geophysics on Fig. 14, 15 – diagram for the depth 0 – 0.7 m). Deeper (60 and more cm below surface) in 24AA more solid stone remains started to appear what would be the confirmation for the higher density of remains in the depth 0.7 – 1.5 m on Fig. 16, 17.

Continuation of the anomalies (red and pink at the map of apparent resistivities, Fig. 14, 16) from the surroundings of 24AA to SW (inside Islamic cemetery) is evidenced by same anomalies (cut from NE edge of the measured area) in geophysically measured area 4 at the E foot of the highest ruin heap inside the cemetery namely for the both measured depths, i.e. 0 – 70 cm and 70 – 150 cm (Fig. 14, 16). Distance between geophysical area 3 (in SW corner of the cemetery) and 4 is too large so the course of the settlement ruins in this part can be only assumed. The area is intended to be geophysically prospected in the next excavation season (2006).

It is also possible to recognize some of the unearthed structures on the geophysical diagrams – either on the basic maps of apparent resistivities (Fig. 14, 16) or at their interpretational maps of apparent resistivities (Fig. 15, 17).

For 22S there is rectangular structure recognizable for the depth 0 – 0.7 m at the basic as well as on interpretational map (here as red – brown spot) of apparent resistivities (Fig. 18, 19). Whether it is S1 is questionable as the anomalies on the maps for lower depth (Fig. 20, 21) seem to be closer to S1 with their shape. S1 is higher, however, than 70 cm from contemporary surface, what makes results for 22S disputable.

Most interesting for comparison is 23W. In the basic map of apparent resistivities (Fig. 22) there is clear relation between W wall and anomaly and the E wall in variant with F15 (see above). N wall has not yet been uncovered, it was probably detected as the pink and red anomaly N to trench 23W on the map of apparent resistivities for the depth 0 – 0.7 m (Fig. 22, 23).

On the map of apparent resistivity for the depth 70 – 150 cm (Fig. 24, 25) there is completely different orientation of the structures (assumed architectural remains – brown) in this level recognizable from the orientation of the both unearthed and still covered structures in the higher level.

In 24AA semicircular structure unearthed just before the end of the season 2004 at the depth ca. 25 cm could be probably traced on the basic map of apparent resistivity in the E half of the trench (Fig. 26). Interpretation of this map shows no anomalies in this part (Fig. 27).

For lower depth (0.7 – 1.5 m) the maps are not interpretable at the moment as this depth has not yet been reached (Fig. 28, 29).

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