Figure 9.  Schematic representation during the formation of Lake Pontchartrain as sea-level rose.

(A)  The Louisiana area was emergent during the late Wisconsinan lowstand, ~18k yr B.P.  (B) As sea-level rise neared present levels, the Pine Island Barrier developed, ~6k yr B.P.  (C) Sea-level rise slows, and a relatively short stillstand initiates development of the Pine Island Spit forming the Pontchartrain Embayment, ~5k yrs B.P.  (D) A subdelta of the Mississippi River, the St. Bernard, progrades across the area (E) forming Lake Pontchartrain and associated lakes.

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