Geomorphology and Late Holocene morphogenesis of Tchinguiz Tepe hill (Old Termez, Uzbekistan, Central Asia)

摘要

Tchinguiz Tepe Hill is the southernmost outcrop, interrupted at the shores of the Amu Darya, of the Cenozoic sediments that form the Baysuntau-Kugitangtau alignment. The initiation points of the recent morphogenesis are the slopes and a pediment controlled structurally by the unequally weathered substrate. The hill is covered by sediments of varying thickness on the south side, which is exposed to dominant winds from the SE and was occupied by humans, at least during Kushan times (1st and 2nd centuries AD). Its form is derived from two systems of natural processes (slope and aeolian) and an anthropic one, which have operated under arid-to-semiarid conditions. These processes have mobilized sands from the weathered substrate and from the Afghan dunes, and pebbles and gravels from early Kushan-time constructions, such as the fortress of the Tchingiz Tepe Hill. Slope-wash processes have contributed materials, which have evolved as slope-aeolian sediment in the mantled pediment. Part of the aeolian sand has been re-exported, together with primary (autochthonous) sand outside the hill towards the north. Thus, in Tchinguiz Tepe the current morphogenesis has slowed down considerably and is currently in dynamic equilibrium, with a slow increase in sediments. The carbonate crusts, which are not very well developed, have formed a complex host sediment. Anthropic morphogenetic action has modified the natural shape of the hill from the earliest times of occupation to the present day, and has generated materials that are now incorporated in the slope wash and govern the current topography and the distribution of sediments from the wall of the fortress and other buildings.