THE LAFOURCHE DELTA
Delta ID # 70.
Air temperature range: oC to oC
Mean wave height:
Drainage Basin area:
Contributed by Professor George F. Hart, LSU.
The modern depositional environments are part of the highstand systems tract. The High Stand System Tract shows switching takes place about every 1,500 years. Each of these deltaic complexes, formed by a river switch, covers an average area of 30,000 sq km and has an average thickness of some 35 meters. The Lafourche delta is one of four major delta complexes presently existing over coastal Louisiana. Within this complex at least 12 individual sub-deltas have formed during the last 4,000 years.
The main Lafourche Delta was formed over the Caminada-Moreau coastal area. Since the abandonment of the delta shore-face erosion has moved sand to the flanking barrier islands [Grande Isle to the east and Timbalier Isle to the west. Large tidal inlets separate the islands at Barataria Pass, Caminada Pass, Little Pass Timbalier, and Cat Island Pass. Lagoons are formed by Barataria Bay, Caminada Bay and Timbalier Bay. Ebb-tidal delta off the passes a up to 6 km long and 8 km wide [Penland et al., 1988]. The Bayou Petit Caillou sub-delta was responsible for the sedimentation in the Isle Derniers region. The Isles formed with the abandonment of this part of the Lafourche delta and form a barrier about 32 km long and 0.5 - 2.0 km wide. The chain consists of four small islands separated by tidal inlets [Text figure X-210]. Distributary channels [4-5 meter thick] underlie the island are associated with inter-distributary and beach facies overlain by the barrier [up to 5 meters thick] and lagoonal facies [1-2 meters thick].