Ghazali Season 2012

The first fieldwork season went on in January 2012. Its main objective was to survey and map the site using noninvasive remote sensing methods of archaeological prospection to get the best overview of the project’s area and to plan subsequent activities at the site. Furthermore, preparations for conservation and presentation of the site have been started by removal of sand accumulated after the end of archaeological research in 1954-5. Survey of the site was carried out using traditional method and geomagnetic prospection and kite photography. The last was also used for photogrammetric documentation of the site.

Geomagnetic prospection

The nondestructive survey was carried out with the instrument which consists of three elements: two GPS (GPS RTK Topcon Hiper Pro) receivers (base and rover) with cesium magnetometer (Geometrics G-858g Magmapper). GPS receivers communicate using radio modems. Mobile GPS receiver (rover) connected to the magnetometer obtains reference corrections from base radio receiver. The set uses radio frequency range 410-470 MHz what allowed to work in an open area with a radius of more than 1km. The data defined in CMR format (Compact Measurement Record) is sent from base to rover receiver during survey. Packet of information contains: signals L1, L2 of GPS satellites, GLONASS, position (coordinates) and parameters of the base. The Mobile RTK rover receiver is connected with cesium magnetometer G-858 via RS-232 serial what allows sending data from GPS and downloading it by the magnetometer recorder. Geographical coordinates and height has the accuracy of equipment: GPS measurement has the level of horizontal precision: H: ± 10 mm + 1 ppm, and vertical V: ± 15 mm + 1 ppm.). The NMEA (National Marine Electronics Association) output data format sent from GPS contains GGA records (Global Positioning System Fixed Data) informing about the longitude, latitude and height (above sea level) with 1 mm instrument accuracy. GPS sends the data by one per second interval time, finally interpolated due to the magnetometer measurements depending on the setting – usually 0.1 or 0.2 seconds. Location data is stored simultaneously with magnetic data and assigned by the time factor synchronous with the magnetic field measurements. Then the entire measurement data is transmitted using MagMap2000 software to the hard drive for further processing e.g. transformation of coordinate system from latitude and longitude values in degrees (BLH) to the metric system (UTM).

Survey carried out in settlement area allowed for recognizing locations with high magnetic anomalies which have polar (dipole) properties. These are clearly visible on the magnetic map as color scheme dots of lower values (light blue) and high values (red color). Hypothetically these are the remains of the industrial iron ore kilns production areas or deposits of industrial rubbish.

It is worth to mention that the instrument used for geomagnetic survey was invented and constructed by Wieslaw Malkowski, University of Warsaw.

Kite aerial photogrammetry and photography

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Weather conditions for kite aerial photography in Sudan are generally favorable and this was the case of 2012 season’s work. The wind blew every day at the speed of 2 – 13 m/s. The remains of the Ghazali monastery, cemeteries and settlement were clearly visible from the air, especially in the early morning and late afternoon. Several photo sessions were conducted and over 2000 photos were taken. For taking aerial photos three different size “flow foil” kites were used. Smallest kite was used with strongest wind, medium in moderate and big with light wind. Three hundred meters of line was used to control the height of aircraft. The highest flight’s altitude was about 150 meters. During the photo sessions Canon 5D with Canon 35mm 2.0 and Canon 24mm 2.8 lenses were mounted on self-constructed gimbal and controlled remotely what allowed for shooting oblique and vertical photos. Photographer had a wireless view of photos on the ground on the monitor via 2.4 Ghz video transmitter. Each session lasted about 2-3 hours. Vertical photos with GPS RTK measurements were processed in Image Master photogrammetric software into Digital Surface Models and orthophotos. Fourteen orthophotos and digital surface models of different areas within rectangle of 700 to 280 meters of site concession were created. The ortophotomaps have plane resolution between 1 and 5 cm depending on the size of area they cover. The digital surface model of the monastery was created from two photos and has a plane resolution 3.7 cm and depth resolution of 15 cm. The 3D surface model of church in the monastery was prepared also from two photos taken form the height of 56 meters. The plane resolution of this work is 1 cm and depth resolution is 3 cm. All of this data was prepared in the same coordinate system (WGS 84 UTM 36N). Three dimensional models were exported to VRML, OBJ and DXF file formats with texture. Orthophotomaps were saved in GeoTIFF standard. All this documentation will be combined with other results and investigated in GIS systems like Autocad or ArcGIS. In the course of processing information collected in the fieldwork an orthophotomap of the concession. Kite photos allowed correcting sketchy plan of the monastery published by Peter Shinnie. Thanks to the collected information in form of the photos and GPS data the team can now continue prospection of the area at home sitting by their computers.

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During the short season the katholikon of the monastery and attached building located north of the church with a tank sunk in the floor have been cleared of the sand and stone and brick rubble. The building has been so far interpreted of either baptistery or room used during celebration of Epiphany. The rubble contained elements of pillars flanking the apse and sundried brick vaulting once sprang over the southern aisle. Moreover, pillars and inner walls of the church were cleared of the stone rubble that caused danger for visitors to the monastery. This cleaning resulted in discovery of the features of the church absent in the plans published so far and of three fragments of the tombstones, two made of sandstone and one ceramic. Two of them were sunk in the floor of the church, one was found in western niche of the south-eastern pastophorium.

Katholikon of Ghazali monastery is a basilica built of sandstone in the lower part of the walls and of baked brick in the upper. Its orientation does not follow the cardinal directions. Inability of determination of the east according to the course of Nile in this area points to the conclusion that the main axis of the church was determined according to the sun movement or astronomical observations. On the basis on personal experience of the sun set at Ghazali I would rather acquiesce to the first method. The church features all characteristics of Makurian churches:

  • Tripartite western section with a staircase located in south-western room and a central western bay.
  • Central part of the church divided into nave and two side aisles. There were two entrances located parallel in the northern and southern wall immediately next to the western part of the church.
  • Tripartite eastern section of the church consisting of the apse filled with synthronon and two ancillary rooms on both sides of the apse connected by the passage behind the apse.

There was also western entrance to the church in the north-western room, an unorthodox feature in Nubian church architecture. The floor of the church was paved with pottery tiles in the pastophories, baked bricks in the aisles, marble and granite in the sanctuary and sandstone slabs in the western and middle part of the nave. Yet it was just an underlay for the lime plaster flooring identical to the plaster on the walls. It covered floor of the entire building except sanctuary and probably the north-western room. Walls of the church were decorated with the paintings preserved only in north-eastern room and central western bay. Wall paintings in the semi-dome over the apse were still to be seen in the nineteenth century.

As mentioned above western section of the church was divided into three parts. The south-western contained staircase consisting of three flights of steps. The entrance was located in its eastern wall and was finished with an arch with the capstone decorated with carved cross. The central bay was open to the nave and all along its walls ran a bench. The inner walls of western part were made of well-dressed sandstone blocks up to the height of 1.40 m. starting from that point on the rest of the wall was built of baked brick, making the construction considerably lighter.

Central part of the church was divided into a nave and two side aisles by two rows of pillars, four in each row. The pillars rectangular in plan were built of baked brick cushioned with wooden beams laid horizontally. Four central pillars were strengthened by pilaster masses which simultaneously supported the arches spanned between them on which in turn leaned a dome. Eastern part of the nave, from the point of the middle of the second pair of the pillars was turned into sanctuary and paved with marble and granite. In the distance of 4 m from the mouth of the apse there were four pots sunken in the floor in one line spanning over the width of the nave. They were used as a support for beams for the construction of wooden templon.

The apse is entirely filled with synthronon built of baked brick which was covered with lime plaster, the same that was laid on the walls and floor of the church. Ancillary rooms on both sides of the apse were accessible from the aisles. The entrance to the southern might have been divided off from the aisle by a screen similar to the one in the nave since in there was a pot sunken in the floor of the southern aisle immediately next to the south wall of the church in the line with the screen in the nave. Western walls of both rooms were built in lower part of stone and in the upper of baked brick. Entrances to them were crowned with the arches which didn’t preserve. In the eastern all of the north-western room there was a niche, and there was mastaba built against the northern wall of the apse. After abandonment of the monastery there was an aperture dug in the north-western corner of the northern pastophorium. It was shallow, oval in shape and oriented north-south shaft covered with the stone slab. A passage behind the apse led from this room to the southern pastophorium. The latter was furnished with three niches in northern, western and southern walls. There was a small mastaba analogous to the one in northern pastophorium built against the wall of the apse. No traces of baptismal font of any sort have been recovered. The most interesting discovery of the season in terms of architectural design of the site was the fact that escaped notice of all of the people who published church’s plans so far. The building is not rectangular in plan but equilateral with north wall moved slightly more to the east than the south one.

Photos from 2012 season