Cemented slabs of fine-grained sandstone litter the beach along the central Chandeleur Islands, St. Bernard Parish, Louisiana. Such slabs are found elsewhere on the coastal islands of Louisiana. The factors responsible for secondary cementation of beach sands are: (1) the long, narrow, barrier nature of the Chandeleurs which makes possible a difference in height of sea level on opposite sides of the islands, (2) the presence of calcium carbonate in the form of finely pulverized shell in the beach sands and (3) the availability of organic acids from decaying mangrove vegetation. Cemented sandstone slabs originate at the plugged mouths of tidal channels.

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