Two types of investigations were carried out. The first one, a field survey, covered the entire territory of the site as well as the surrounding area. The work included drilling, sampling, and the preparation of geological profiles and cross sections. The second one consisted of laboratory work which was carried out at the University of Mining and Metallurgy in Cracow, using among others the following methods:
         * polarising light microscopy
         * digital microscopy
         * scanning electron microscopy
         * x-ray diffractometry.

Drilling holes as well as observation of the natural geological outcrops confirmed that site is localised on top of a sandy gezira. The yellowish sands contain skeletons of Helicigona molluscs, confirming relatively dry climatic conditions during the sedimentation of the gezira's sands.

The localisation of the archaeological site at the upper part of the sandy gezira presents a unique opportunity for the determination of Nile oscillations during the last 10.000 years. Monotonous grey Nile silts interfere with the sandy gezira sediments. This situation helps to investigate the reconstruction of climatic changes and also to improve our understanding of human activity.

Field observations showed that the walls of the discovered buildings dating to different periods were constructed using various types of dried bricks (tab. 1). Mineralogical examination of these bricks documents their differing mineral and grain size composition.

The oldest Naqada bricks (A1) are grey in colour. Their form is elongated and they show a cylinder-like shape. They are mainly composed of pure grey Nile silt. They did not contain an organic admixture or grains of burned clay but only traces of charcoal.

Slightly younger bricks (A2), representing most probably the younger Nagada culture, have the shape which is normal for bricks. They show a light-greyish colour and are composed of Nile silt, but with the addition of a "tempering material" consisting of fragments of burned clay, traces of charcoal and organic matter.

Early dynastic bricks (B) have the normal brick shape but they are of poor quality. They are yellowish in colour, due to the mixture of Nile silt with grains of yellowish gezira sand.

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Dynastic bricks (C) are also of the normal brick shape but of a completely different mineral and grain size composition. They are slightly brownish in colour due to admixture of fragments of burned silt as well as fragments of pottery. Under the microscope one can see in the bricks fragments of plants, bones and charcoal. The examination suggests that the top part of the sediments of the site were used for many destroyed bricks of type C.

Table 1 - Results of the mineralogical examination (volumetric %) of dried bricks from structures at Tell el-Farkha.

clay minerals* - natural and burned together

The results presented here show that various raw materials and technologies for the production of dried bricks were used at various historical periods. The dates confirm also that mineralogical investigations allow to determine the historical sequence of monuments as well as to establish the correlation of building phase belonging to the same age. The use of the proposed method of mineralogical investigation of dried bricks should also be possible for solving similar problems at other archaeological sites.

With video projection (10 minutes)

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