Palaeohydrography of Ancient Tanais in the Context of the Don River Delta Development in the Late Holocene

The Greek-Barbarian settlement of Tanais, founded at the beginning of the 3rd century BC on the high northern shore of the present Don River delta and existing until the end of the 5th century AD, was described by Strabo at the turn of the eras as a port town lying on a river and on a lake. Today the remains of Tanais overlook the Mertvyi Donets, a dying arm of the Don River delta, 7–8 km from its mouth, but during the period of active existence of the ancient settlement, the hydrographic situation was different. Some researchers believe that Tanais was located on the marine edge of the delta, while others think it was on the seacoast. To clarify the hydrographic situation in the area of Tanais, a complex analysis (lithology, bulk chemistry, mollusc fauna, radiocarbon dating) of the sediments uncovered by drilling on the right bank of the Mertvyi Donets in the presumed port area was carried out. The drilled channel alluvium of the Mertvyi Donets arm indicated active flow in the modern low-flow arm. In the first centuries AD, the Mertvyi Donets was at least one and a half times wider and deeper than the modern one, which allowed it to fulfill the functions of the main transportation route. Immediately after the formation of the culture-bearing layer of the 3rd century AD, the water content and flow velocity in the Mertvyi Donets began to decrease, and the branch started to silt up. This was caused by the redistribution of runoff in favor of the arms of the central and southern parts of the delta. To assess the dynamics of the delta’s advancement, the sediments were drilled and dated. It was found that in the Tanais area, the marine edge of the delta was located between the 5th and 3rd millennia BC, and in the period of the post-Polemonian Tanais in the 2nd and 3rd centuries AD — 5–6 km downstream. An estimate of the advancement rate of the delta’s northern part — from 1.2 to 2.8 meters per year — shows that at the time of its foundation in the 3rd century BC, Tanais was located 3.5–5 km from the mouth. The foundation of a port settlement inside the delta arm, rather than on the coast, was due to the need for shelter from destructive sea storms.

deltaic floodpain, river channel processes, alluvial facies, ancient colonization, ancient harbor, Bospor Kingdom, Northern Black Sea coast archaeology, Azov Region