The sediment layers of intertidal zone, the upper sea bed by using a basic surface conserving historic rivers, techniques of caves and its sediments, traces of historic maritime action forming unique notches, shorelines and marine terraces, mangrove swamps are important proof of geological gatherings and procedures going down during Quaternary.[18] http://tour-thu-phi-c-ng-m-v-nh47901.blog2news.com/10604538/5-tips-about-tour-thuỷ-phi-cơ-ngắm-vịnh-hạ-long-you-can-use-today