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July 2003-July 2010InteractiveDig Sagalassos
The Slovenian team starts the magnetometric (foreground) and georadar (background) at Düzen Tepe.
Magnetic map (left) of Tepe Düzen with several areas showing strong thermoremanent magnetization. Right map shows part of the site with the location of walls, a street, and kilns of furnaces.
One of the areas surveyed on the right map by means of ground-penetrating radar and showing the same orientation of houses as on the magnetic map on the right.
Architectural remains and the height of their walls as produced by the echo in the time slices produced by the ground-penetrating radar.

Photos courtesy Sagalassos Archaeological Research Project. Click on images to enlarge.
by Marc Waelkens

Geophysical Survey: June 24-29, 2006

The first results of the geophysical survey at Tepe Düzen are quite impressive. An area of 160 by 160 m was selected for geophysical survey. Combination of magnetometry and georadar (GPR), which has been proven to be the most efficient strategy at Sagalassos, was applied also at Tepe Düzen. Magnetic profiles with Geometrics G-858 magnetometer in the gradient mode provided us with a high resolution magnetic map of the surveyed area.

Magnetic anomalies can be classified according to their shape and magnitude. Archaeologically significant features are linear anomalies of induced magnetization which often show clearly rectangular shapes. These stem from the shallowly buried remains of houses made of limestone. The limestone walls, many of them even visible at the surface, most certainly formed only a socle for a superstructure in mud brick or pise, burnt fragments of which have been found last year. Strong contrasts between the magnetic susceptibility of limestone and the topsoil make architectural remains easily recognizable, allowing to trace internal subdivisions in some of the houses. The magnetograms thus far convey a picture of a rather regular (urban) settlement plan. Most houses form clusters with more or less a similar orientation and contain one to several rooms. Some communications/streets are also clearly visible. This layout ressembles that of some Aegean Early Iron Age sites, such as Zagora on Andros or Karphi on Crete. As the occupation covered at least four centuries (eighth to fourth century B.C.), some houses with internal courtyards may represent later phases (Classical to Post-Classical).

[image] Magnetic prospection map (right) of part of Düzen Tepe, which. in blue, suggests iron mineralizations and shows a site with single to multiple-room houses, with clusters and a rather regular layout.

Time slices (right) produced by means of GPR of the area surveyed by magnetometry show structures with the same orientation as other maps. These clearly show houses with internal courtyards.

Apart from these linear magnetic anomalies, distinct magnetic anomalies characteristic of ancient industrial activities, such as kilns, forges, and furnaces, can also be distinguished. Other magnetic anomalies are the result of debris from ruined structures which can be aligned in the direction of assumed architectural remains underneath. In the case of Tepe Düzen this is highly probable since no major disturbing activities seem to have taken place after the settlement was largely abandoned after 300 B.C. Some magnetic anomalies of irregular shape can be classified as geological in origin. In karstic areas, such as Tepe Düzen, we have to take into account the variable morphology of the bedrock. This morphology can be frequently distinguished on magnetograms and may be incorrectly interpreted as archaeological features.

Because of heaps of stone debris on the surface of Tepe Düzen, the site is not the obvious place for georadar survey. GPR was therefore used in the standard mode for profiles every 0.5 m only in smaller areas that are supposedly internal spaces of houses or courtyards. Through the implementation of GPR we can expect more information about some of these internal structures. The only larger nearly flat area available on the whole site is a cultivated field on a modern terrace 50 m to the west of the magnetically surveyed area. Results are incredibly clear and geophysical interpretation will benefit a lot from this GPR survey. On GPR plan views (time slices), the orientation of the houses is the same as was previously observed on magnetograms. The important contribution of GPR data sets to the general geophysical interpretation is the fact that they allow an estimate of depth, thickness, and height of the walls. This information, together with the plan views, enables us to provide a more reliable interpretation of the results from magnetmetry. Additionaly, this field campaign will be for the first time use the Slovenian "home made" one frequency GPS system, which was developed for archaeo-geophysical surveys.

Because of the stony surface at Tepe Düzen, the plastic lining under the georadar quickly fell apart. We bought a roll of linoleum at a local shop to protect the radar from more damage. This week also saw the end of geophysical surveys at Düzen and subsequent activities at Tekkeli Tepe. At Düzen the mapping of surface remains by Sabri Aydal continued.

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