Abstract:

 By field techniques of topographic surveys of Holocene beach and platform profiles in Xichong Bay，3 abrasion platforms including the presently eroding one are detected. According to the altimeter and tide tables, all altitudes are given in meters above mean sea level. The sand profile were divided into 6 layers and samples of seashells collected from the sand profile were performed 14C dating. Specimens of beachrock were examined using microscopy on thin sections. We conclude that although the rock of the platforms is granite which is hardly carved,the abrasion features,especially the platform, can be interpreted as an evidence of Holocene sea level. The altitudes of the beachrock and the platform represent that the mean sea level around 2,000 yr is at least 2.0 m higher than present mean sea level. We also point out a proposal on how to assess the eustatic sea-level movement and tectonic vertical motion of northern coast of South China Sea.

Key words: abrasion platform, marine terrace, marine bridge, beachrock, Xichong Bay