THE FORMATION OF SAND BARS ON THE LUANHE RIVER DELTA AND THE CHANGE OF THE COAST LINE

The Luanhe River Delta is a delta plain built up by the action of rivers and sea waves together.Owing to the migrations of the distributary region sincethe Holocene Period five secondary delta depositional masses were formed during the Early Holocene, the Middle Holocene, the early historical, the late historical and recent periods,respectively. To the south of the Luanhe River estuary,there is a series of sand bars and sand islands. They to be considered as the mark of the South-eastern sedimemt drift of Luanhe River The authors have studied the morphological features,the grain size distribution,the heavy mineralo composition and the quartz sand surface micro-textune of these bars and islands.They conclude that that these bars and islands were a barrier built by the transversal movement of sea waves,formed at the Luanhe River delta front during different periods of the past. To the north of the outlet,there are coastal dunes,about 30-40 km long and 1.5-2 km wide. Their distribution is mainly controlled by the strong north-east wind.Not only is the direction and sand size distribution of the dunes identical with the coastal bar's, but also the fractions of the marine creature relic are mixed in the dunes.It proves that the dunes are reformed by the aeolian action from the coastal bars.