The Huanghe River course and delta from end of Late Pleistocene to the 7th century BC

The Huanghe(Yellow)River course shifted from entering the northern Huanghai(Yellow)Sea to entering the southern Huanghai Sea at the northern part of North Jiangsu Province approximately in 9 600 a BP and continued to enter the southern Huanghai Sea to 8 500 a BP.The river mouth was some 100 km distance from north of the Changjiang River mouth.The huge sediments carried by the two large rivers made the Huanghe River-Changjiang River compound delta to be formed in this period.Then,the Huanghe River shifted to north and entered the Bohai Sea.This is inferred with the following facts:southw ard bending of the isopach of the postglacial marine sediments of the nearshore depocenter in the southern Huanghai Sea,the sedimentary sequences of drill hole QC4 and some sections,and the characteristics of the coastal ridges in North Jiangsu Province.These coastal ridges are mostly composed of non-biogenic fine and middle sands.It is much different from composition of the shell ridges being mainly composed of molluscan shells and their fragments on the west coast of the Bohai Sea,where is the abandoned Huanghe River Delta area.In 8 500~7 000 a BP,the west coastline of the Bohai Sea retreated for tens kilometers,the Huanghe River channel free shifted and the fine sediments carried into the Bohai Sea by the Huanghe River were resuspended,transported and reworked into the shallow marine deposits.The Huanghe River subaqueous delta could not be formed in this period.The Holocene Huanghe River Delta has been formed since 7 000 a BP, when the sea level rise decelerated and close to the stable level.