LATE-PLEISTOCENE AND HOLOCENE GEOMORPHOLOGY OF THE DARKHAD BASIN, MONGOLIA: IMPLICATIONS FOR HUMAN SETTLEMENT PATTERNS
We focused on two sites near the southwestern end of the basin, Soyo and Bagsgiin Bulan, which record evidence of human occupations spanning from >10 ka to the present. These sites are located on glaciofluvial outwash terraces of different ages that formed after the last glacial maximum (LGM). At both sites, an upper paleosol marks the most recent surface of human occupation, which is now capped by <50-cm-thick aeolian dunes near the river margin, but merges with the present day surface <100 m from the sites. The stratigraphy beneath the sites is broadly similar, with interbedded fine sands and conglomerates interpreted to be glaciofluvial in origin. At Soyo, excavations yielded artifacts indicative of human occupation from multiple levels dating back to >10 ka within an overall more complex stratigraphy. In contrast, at Bagsgiin Bulan, artifacts from excavations of a structure were dated to ~4500 BP. We propose that the widespread terrace surfaces selected for site occupation were formed by paleoclimatic and lake level changes within the basin between the end of the LGM (11-18 ka) and the middle Holocene (4-5 ka), and the surfaces were occupied shortly after their formation.