Revisiting Stratigraphy of Ali Kosh, Deh Luran Plain

Ali Kosh is known as one of the most important Neolithic sites across the Near East as it has already yielded informative evidence of early sedentary lifestyle and domestication. However, the site’s chronology has been a controversial issue over the last several decades. F. Hole had generally placed it within a long time spanning ca. 7500-6000 B.C. Later dates by M. Zeder indicated much shorter time duration in the second half of the 8th millennium B.C., and believed that the site was under occupation for only 500 years. These chronological challenges along with attaining new evidence of subsistence, paved the way for a new stratigraphy at the site in the spring of 2017. Thus, an area, 3by3 m in size, was initially opened in adjacent to the location of previous excavations areas. This provided us with not only benefiting from a predictive section but also reaching stratigraphic proposes similar to Hole’s ones and to revise his results as much as possible. The trench then reduced to 2.5by 2.5 m down to the virgin soil at 710 cm below the surface. As the result, 18 occupational levels were distinguished in the way that levels 1-5, 6-11 and 12-18 can be placed within the so-called phases of Mohammad Jaffar, Ali Kosh and Bus Mordeh respectively. However, Hole defined these three general phases based on trajectory of subsistence strategies although other technological indications were somewhat given attention. Therefore, they should be regarded as “cultural” phases, not indicators of occupational sequences. However, new stratigraphy showed three gaps as well. Based on the new radiocarbon dates the site was occupied during one thousand years lasting from 7500 to 6500 B.C. Pre-pottery deposits, ie. Bus Mordeh and Ali Kosh phases, are both placed within the second half of the 8th millennium Bc, while upper pottery deposits, i.e. Mohammad Jaffar phase, is wholly dated to the first half of the 7th millennium B.C. This new chronology shows that the pottery was appeared at the site around 7000 B.C., contemporaneously with other regions across the Near East. In general, the new stratigraphy has revised not only sequences of occupation but also the time and duration of the phases previously known from Tapeh Ali Kosh.