During periods of slight sediment supply, wave action on the gulf shore 

 winnowed away fine sediments and brought in nearshore shelf sands to form 

 beach ridges, or cheniers. The alteration of sediment supply and "starvation" 

 resulted in net progradation of the marshland, with cheniers incorporated into 

 the marshland paralleling the coast and standing out in topographic relief. 

 The cheniers are steep on the gulf side and slope away on their shoreward 

 side, where washover sands and gravels are interbedded with marsh sediments 

 (Morgan, 1972). Radiocarbon dating of mollusc shells occurring in the cheniers 

 indicates that the area including the Sabine Refuge was formed about 2,100 yr 

 ago. yery little of the bulk of the cheniers actually occurs on the Sabine 

 Refuge; most are restricted to the eight-km (five-mi) wide strip of land sepa- 

 rating the Gulf of Mexico from the refuge boundary. One exception is Back 

 Ridge, to the west of Calcasieu Lake. Several Pleistocene terraces, rising 

 only about 0.6 m (2 ft) above the marsh surface, are in the northeast and 

 northwest poritons of the refuge (Van Dyck, 1963). 



Other ridges not of terrace origin are the lake ridges. The ancient and 

 larger Calcasieu and Sabine Lakes were responsible for the formation of low 

 ridges and associated bac'' slopes, which are located on the east and west 

 sides of the refuge. Thus, the refuge is roughly a shallow basin - bound on 

 the south by cheniers and on the east and west by lake-formed ridges. Net- 

 works of large and small canals and channels have disturbed this natural basin 

 morphology within the last 50 yr (Van Dyck, 1963). 



Soils and topography . Pleistocene terraces formed as deltaic deposits of 

 the Mississippi. These subsiding units are overlain in most of the Sabine 

 Refuge by recent alluvial and marine deposition. The general terrain is wery 

 flat, with ground elevations ranging from to 0.6 m (2 ft) above sea level. 

 A number of small lakes and potholes are interspersed throughout the Pleisto- 

 cene terraces and the recent coastal marsh. 



Most of the area of the refuge basin is comprised of soils in the Harris 

 Salt Water Marsh association - saline soils (predominantly oxidized, gray, 

 silty clays) with an organic topsoil (peats and muck formed by submergent, 

 emergent, and floating vegetation). The soil is poorly drained because of the 

 impervious clay hardpan. The Harris, Cheniere Variant - Palm Beach soil 

 association comprises the soils of the cheniers. The poorly drained Harris 

 soils make up the leeside of the relict beach ridges ot the south. The soil 

 of the lake ridges is composed of saline clays and shallow organic matter 

 formed by grasses (USDA, 1976). There are few differences distinguishing the 

 general physical features of the terrace from the lake ridges; the latter are 

 usually slightly lower in elevation. 



Climatology . The climate of this area is generally humid subtropical 

 with warm summers. Prevailing winds from the Gulf of Mexico provide a moderat- 

 ing oceanic climate - daily temperatures are warmer in winter and cooler in 

 summer tan for inland locations. 



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