Geophysical Prospecting on Soils in Mesopotamia: From Mega-Cities in the Marches of Southern Iraq to Assyrian Sites in the Mountains of Kurdistan

Enrichment of magnetic minerals in the topsoil and thus enhancement of magnetic susceptibility in archaeological layers and soils, the so-called “Le Borgne effect” is a quite common and a widespread property of the majority of soils worldwide. This effect is widely regarded as the main fundament and plays a crucial role for a successful magnetometer prospecting of most case studies for prospecting worldwide (Le Borgne, Ann Geophys 11:399–419, 1955; Mullins, J. Soil Sci 28: 223–246, 1977; Fassbinder et al., Nature 343(6254):161–163, 1990; Fassbinder & Stanjek, Archeol Polona 31:117–128, 1993; Jordanova, Soil magnetism. Applications in pedology, environmental science and agriculture. Academic Press, Amsterdam, 2016). Case studies both, in the wetland and marches of the Shat el Arab in Southern Iraq as well as on some sites of mountain areas of Kurdistan however, show that this effect plays a minor role in Mesopotamia (Fassbinder & Asandulesei, Peshdar Plain Proj Publ 1:112–119, 2016; Fassbinder et al., Magnetometer prospection of neo-Assyrian sites in the Peshdar Plain, Iraqi-Kurdistan. In: 12th international conference of archaeological prospection, vol 12. Archaeopress, pp 70–72, 2017a, Geophysikal research in the Bora Plain: magnetometer prospection at the Dinka Settlement Complex and Gawr Miran, 2016, vol 2. Peshdar Plain Project Publications, pp 18–32, 2017b, The 2017 magnetometer survey of the Dinka Settlement Complex, Iraqi Kurdistan, vol 3. Peshdar Plain Project Publications, pp 19–30, 2018, Geophysical prospection campaign 2019: magnetometry and Earth Resistance Tomography (ERT) at the archaeological site of Ur, Iraq. Unpublished report Directorate of Antiquities, Iraq, 2019a, Venice in the desert: Archaeological geophysics on the world’s oldest metropolis Uruk-Warka, the city of King Gilgamesh (Iraq). In 13th international conference on archaeological prospection, vol 13, pp 197–200, 2019b, Petiti et al., Zeitschrift für Orientarchäologie Bd 15:120–162, 2023). Here we present a variety of further soil magnetic, rock magnetic and physical properties of archaeological sediments and features, explaining the success, failure, and pitfalls of these prospecting projects. While in the southern Iraq induced magnetisation and the variance in composition of mudstones dominates magnetic anomalies, the selected case study from Iraqi-Kurdistan is predominantly determined by the natural remanent magnetisation of rocks.