 The stratigraphic characteristics of a flood tide delta deposit include the existence of a layer of plain sand (often containing terrestrial vegetation debris) sandwiched between sediments containing numerous small bivalve mollusc shells that are indicative of deposition in a normal lagoon environment.This uneven sand layer lacking shells suggests an interruption in the normal accretion of benthic sediments by a rapid deposition of dune material being washed in by severe wave action.There are about 100 islands in the Thousand Islands, The actual number of islands is meaningless due to the inundation of many areas during seasonal high water during summer.