Archaeological Geophysics
Consulting
Çatalhöyük, Turkey       

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Don Johnson and Dr. Clark A. Dobbs conducted geophysical surveys at Çatalhöyük for two weeks during the 2000 field season.  The surveys were designed to evaluate the effectiveness of several different instruments at this specific site.  We used the following instruments:  a cesium vapor magnetometer (which allows measurement of both total magnetic field and vertical gradient); ground-penetrating radar using antennas ranging from 50 mHz to 1 gHz; and a Syscal Kid resistivity meter that collects data used in 2 and 3 dimensional resistivity modeling.

Catal Map

Wide-scale magnetic survey was conducted in two areas:  the Northern Eminence, immediately south of Structures 5 and 3, and in the Team Poznan (TP) area.  Ground-penetrating radar studies were undertaken in Buildings 3 and 5, as well as in a small portion of the North Area.  Some resistivity studies were also conducted in the North Area.

TP Mag

Only the results of the magnetometer survey over the TP area are summarized here.  Our geophysical survey results can be found in the 2000 archive reports on the Çatalhöyük web site.  Figures and text describing the TP excavations are taken from  the 2001 archive reports and their use is gratefully acknowledged here. 

The TP area results are particularly interesting because a portion of the area covered by the magnetometer was subsequently excavated by Team Poznan in 2001.  Team Poznan identified three occupation phases in their excavation block.  These included a Chalcolithic phase represented by numerous potsherds; a Late Roman/early Byzantine house that had been burned and partially rebuilt; and a Byzantine cemetery intruded into the house deposits.  No structural elements were associated with the Chalcolithic phase and we would not expect it to be represented in the magnetic data.  However, the Roman house contained several rooms, walls, kilns, ovens, and pits.  Some of these were associated with the original house and others with the post-fire phase of occupation.  The Byzantine cemetery contained 59 complete burials and 12 clusters of human bones not in anatomical order.

In considering the relationship between the magnetic and archaeological materials in the excavated portion of the TP area, several things become clear.  First, the strong magnetic responses are associated with areas of intense burning in the Roman house - the kilns, oven, and burning of the house itself.  These very strong magnetic highs tend to mask the weaker responses from mud-brick walls, burials, and so on.  Second, the burials are probably most commonly expressed as areas of weak magnetic lows, unless any heavily burned materials are associated with the graves.  The low magnetic response of the burials is probably because they contain relatively large amounts of weakly magnetic organic material which is similar to areas of organic midden, pits, and the like.  Although such weak responses may be apparent in areas where the magnetic response is generally low, it will be very difficult to consistently identify burials using image maps.  Third, line-by-line analysis of the magnetic data complements the image maps and allows us to identify weak anomalies not apparent in the image maps.  However, in areas where there are strong magnetic responses, there is no guarantee that all of the weak anomalies will be identified - or that they represent burials and not some other subtle archaeological feature.  Finally, it is worthy of note that much of the after-fire layer was removed prior to the partial (?) rebuilding of the Roman house.  This is apparent in the magnetic data where only the kilns and a small area of the remaining after-fire layer show up as magnetic highs.  Indeed, the areas where the after-fire layer were removed can be mapped using the magnetic information