Sand Ridges are distributed widely along the coastal ocean of China seas especially in the Yellow Sea area, such as finger-shaped ridges off west side of Bohai strait, three ranks of sand ridges off Liu Gu River mouth in the Bohai Sea; sand ridge field off Yalu River mouth and the north end of Yellow Sea; sand ridges field off Hanjiang River mouth of Korea in the east side of Yellow Sea; radiative pattern sand ridges field off west coast of the south Yellow Sea, residual Sandy ridges of the outer continental shelf of East China Sea; and finger shaped sand ridges off west side off west side of Qiongzhou Strait in the South China Sea. There are Larger Sandy bodies developed in the area with abounded sandy deposits and predominant tidal dynamics in the inner continental shelf environment (Off, 1963, Collins, 1995). The semi-closed Yellow Sea is located in the mid latitude zone, there, the progressive tidal waves of the pacific are transferring towards the north Yellow Sea and reflected by Shandong Peninsular, thus, the reflected waves meet and converge with the continuing progressive tidal waves to form movable "standing wave" (Zhang Dongsheng, 1998). As a result, the largest tidal ranges up to 9.28m and the strong tidal currents developed in the area. The transgressive tidal dynamics of the Holocene time Perform on the coastal Sandy deposits, accumulated by the ancient Changjiang River and others during lower sea level of late Pleistocene time, to evolve the larger Sandy ridge fields. Tidal dynamics in China seas are strengthened by the convergence processes either in the embayed of north Yellow Sea or by reflected waves, and also through the narrow sea strait effict.

Tidal sandy ridges are the larger sediment bodies in the continental shelf environment, the bodies preserve the geological history records of Sea level changes, land-sea environment changes and the shelf evolution. It is a kind of new land and navigation channel resources and biological habitat. Thus, it has great scientifical and utilizable value for study. Following is the example from South Yellow Sea.

The South Yellow Sea sand ridge field is located offshore of the north Jiangsu Coast of China in a radiative fan pattern. The length of the sand ridge field is 199.6km from north to south, and 140.0km in width from east to west. It consists of more than 70 sand ridges and tidal channels in the water depth from 0 to 25 m. The total area encompasses 22470 km², of which 3782 km² is above 0 meter.

Fine sands and silts, originated from old Changjiang River sediment during late Pleistocene period, are major sediment components of the sand ridge field. Late Holocene sand strata have well-preserved liminal bedding with more clay particles reflecting the influence from the Yellow River. Present, silt and clayey materials are supplied both by Changjiang River sediments and the abundoned Yellow River delta.

The radiative sand ridge field consists of essentially three genetic types according to seismic profiles and sediment core data.

1. Reformed old river depositional bodies in the center and southern parts, consisted of late Pleistocene sand ridges and superimposed by Holocene sediments.
2. Radiative current ridges in the northeast formed during early and middle Holocene.
3. Eroded-depositional sandy bodies in the northern part, outer part and small ridges out of the large one formed mainly during Holocene time.

The tidal channels have also three types.

1. The tidal channel developed along the old river valley (Changjiang), which were formed during the end of late Pleistocene to the present.
2. Patrimonial valley types were mature valleys or depressions during the end of the Pleistocene or early Holocene.
3. The tidal current erosional trough, formed during the late part of middle Holocene transgression.

Several times of the ridge-trough imposed records have been seen in the seismic profiles, all indicated the developing process of the sand ridges has a periodic nature. That is, the period of sediment accumulation by rivers started during 30 ka B.P. of cold epoch while low sea level of -20m, at that time the accent Changjiang River was entered Yellow Sea from Haian-Libao in the north Jiangsu provenance. Then, the erosional formation period by tidal currents during warm epoch of Holocene transgression, such as, several erosional boundaries preserved in the strata of sandy ridges may indicate the transgression of sea level rising during 10 ka B.P. and 8.0 ka B.P. of the initial and early Holocene time; 6-5 ka B.P. of mid-Holocene high sea level, and the latest erosional period of 1 ka B.P. sea level. Thus, the river-sea interactive process in this area is closely related with the climate change, the rising and falling of the sea level is the key agent to free the coast zone land-sea dynamic interactive processes. It can be summarized as "transgression-dynamic-sedimentation" process pattern.