THE CHARACTERISTICS OF TIDAL SAND RIDGES IN THE MOUTH OF JIAOZHOU BAY, SHANDONG, CHINA

Submarine tidal ridges on certain scale occur on both the flood and ebb tidal deltas inside and outside the Jiaozhou Bay mouth. Multi-beam acoustic sounding, sub-bottom profiling and sediment analysis are conducted for study of the characteristics of the tidal sand ridges. The Maodao sand ridge, Zhongyang sand ridge and Daoer River sand ridge occur on the flood tidal delta inside the Jiaozhou Bay mouth, whereas the Dazhu sand ridge, Nansha sand ridge, Beisha sand ridge and the arc-shaped sand ridges occur on the ebb tidal delta outside the Jiaozhou Bay mouth. The sand ridges are developed as the continuation of the sand cores which were formed in the Holocene transgression. The sand ridges are mainly composed of coarse sands. Our data suggests that the sands of tidal sand ridges are primarily from estuarine sandy shoals during the period of low sea-level. They are still active now according to the study of the recent marine hydrodynamics. They are growing slowly due to the deficiency of sediment input and strong erosion.