The Song Hong (Red River) delta occurs on the northwest coast of the South China Sea. Its
evolution in response to Holocene sea-level changes was clarified on the basis of sedimentary facies and 14
radiocarbon dates from the 40 m long Duy Tien core from the delta plain, and using previously reported
geological, geomorphological, and archaeological data. The delta prograded into the drowned valley as a
result of early Holocene inundation from 9 to 6 cal. kyr BP, as sea-level rise decelerated. The sea-level
highstand at +2-3 m from 6 to 4 cal. kyr BP allowed widespread mangrove development on the delta plain
and the formation of marine notches in the Ha Long Bay and Ninh Binh areas. During sea-level lowering
after 4 cal. kyr BP, the former delta plain emerged as a marine terrace, and the delta changed into the present
tide- and wave-influenced delta with accompanying beach ridges. Delta morphology, depositional pattern,
and sedimentary facies are closely related to Holocene sea-level changes. In particular, falling sea level at 4
cal. kyr BP had a major impact on the evolution of the Song Hong delta, and is considered to be linked to
climate changes. ?? 2003 Elsevier Ltd. All rights reserved.
