The sediment layers of intertidal zone, the higher sea mattress which has a plain surface conserving ancient rivers, techniques of caves and its sediments, traces of historical marine action forming distinctive notches, beaches and marine terraces, mangrove swamps are important evidence of geological occasions and processes taking place throughout Quaternary.[18] https://felixfasja.blogsumer.com/9826953/an-unbiased-view-of-tour-thuỷ-phi-cơ-ngắm-vịnh-hạ-long