... corresponding with the fifthdepositionalcycle of ThaiBinhFormation. In spatial distribution, the sediments of the first and second sequences are ratherwidespread in the plain. The thirdsequencehasa ... andmarinefacies(formed in the finalstage of eachcycle). Based on this point of view, the Quaternarysedim e nts in the Red River Delta canbe divided into the following hydrogeologicalunits: ... m.However,dueto the action of old river systems, in someplacesthereisnotrace of the finegrainsediments, but there remain only the coarsegrainedsediments of river bedfacies,whichare of ...