Coastal Classification Atlas

Geologic Setting

The western Louisiana coast between Lower Mud Lake Entrance Channel and Sabine Pass is the western extension of the Mississippi delta plain. This coastal region is a product of deposition by nearshore waves and currents. A prominent physiographic feature of the region is the chenier plain (Gould and McFarlan, 1959) that encompasses a complex of narrow, elongate, moderately high sand ridges surrounded by low muddy marshes. The western Louisiana shore zone consists of narrow sandy beaches overlying marsh mud. Because it is a sand-starved muddy coast, erosion rates are high (McBride and others, 1992) and the backbeach is typically characterized by an overwash terrace rather than dunes. The rapid erosion, absence of dunes, and low elevation of this coastal segment make it vulnerable to frequent inundation and overwash (Penland and Boyd, 1985). The beach sand along this coastal segment typically contains some broken shell as a result of high rates of beach erosion and associated wave reworking of the underlying bay-estuarine deposits.

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