Mysteries of the Khormusan
Institute of Archaeology and Ethnology, Polish Academy of Sciences
Among the many mysteries of Egyptian prehistory are those concerning the age of the Khormusan, a Late Middle Paleolithic technocomplex whose chronology, environmental whereabouts, stylistic associations, and fortunes are not very well explored.
Since the end of the 70s, we have known that the Lower Nubian Khormusan is older than 40,000 radiocarbon years, but how much older? It is the crucial question. The answer to this query is found in aging the Late Pleistocene lakes in Atmur El Kibeish Peneplain and Nile aggradations in the mouth of Wadi Kubbaniya, north of Aswan. All the more so as a series of TL age estimates relating to the Late Middle Paleolithic beds of the aggrading Nile in Wadi Kubbaniya bore a sizeable ± error margin.
Strata of the Late Middle Paleolithic alluviation are underlain by thick beds of gravelly wadi deposits including Middle Paleolithic flint artifacts. Aging of the pluvial phase responsible for the alluvial beds is crucial in dating the Late Middle Paleolithic Aggradation since the overlying Late Paleolithic beds are exceptionally well radiocarbon dated to the Last Glacial Maximum and the following Late Pleniglacial. Hopefully, the dating of the pluvial immediately preceding the Late Paleolithic Alluviation would reveal the time ranges of the Khormusan as known from the Nile Valley.
During both the aggradations, local rains are not evident, and the wadis are dry. The desert is hyper-arid and not inhabited. The Nile floods reach at least an elevation of 105 – 115 m asl or about 25 m above the modern floodplain. The sedimentological characteristics of the eolian sandy deposits, as well as riverine overbank sedimentation and pedogenic features of the lower series of Wadi Kubbaniya, point to the desert (eolian) and the riverine Nilotic environments with occasional lacustrine episodes. These are responsible for creating the morphology and sediment texture of the Late Middle Paleolithic aggradation as well as the Late Paleolithic one. In both cases. The makeup of the deposits indicates a vast influx of eolian sand fraction.
Aging the Pleistocene Lakes in the Atmur El Kibeish as well as in other desert areas is a tough chore, particularly those beyond the reach of the radiocarbon dating method. Various technical problems relating to the Uranium Series, Electron Spin Resonance, Epimerization of Isoleucine made thermoluminescence, OSL and SAR optical methods relatively favorite technique of dating among archaeologists and geologists. Despite improving precision, the results often remain quite fuzzy, mostly because of sizeable statistical error and a relatively low statistical significance of the measurements. Use of proxy data in the evaluation of ages becomes a must.
The Late Pleistocene Green and West 4 lakes at Bir Tarfawi and Bir Sahara Basins were the last Pleistocene lakes in the Atmur El Kibeish Peneplain. The TL and OSL ages obtained for the last Late Pleistocene lakes of Bir Torfawi and Bir Sahara Basins imply that the lakes were active in warm Marine Isotope Stages 5e, 5c, and 5a. The basins were dry in Cool and Dry MIS 5d, mid-MIS 5c, MIS 5b and MIS 4, as well as during Nabtian Pluvial.
The above proposition implies that the high alluvial activity of Wadi Kubbaniya directly preceding the deposition of the beds relating to the Late Middle Paleolithic Aggradation has to be correlated with MIS 5a. Formation of the Nilotic, lacustrine and eolian LMP beds, on the other hand, took place in MIS 4. A clue to more detailed information may yield the TL assays measured in Wadi Kubbaniya, although high margins of the ± errors of the estimates exclude precision.
Nevertheless, the TL dates obtained in the lower and middle section of the Middle Paleolithic sequence suggest the ages around 70 ka and in the upper 60s ka, while the ages for the upper section of the Late Middle Paleolithic suite of beds would be placed in the late 60s/early 50s ka.