Table 27. Geologic strata containing commercial sand, clay, and gravel in 

 coastal Al abama . 



System Series Unit Material 



Quaternary Holocene Alluvium, terrace, Silty and clayey 



beach, and deltaic sand and gravel, 



deposits 



Late Pleistocene Terrace deposits 



Early Pleistocene Citronelle Formation Sand, gravel 



and clay. 



Tertiary Pliocene Citronelle Formation Sand, gravel, 



and clay. 



Miocene Catahoula sandstone Sand and clay. 



and Paynes Hammock 

 sand, undifferentiated 



discussion of the subsurface stratigraphy of the Alabama coastal area is 

 found in 'Neil and Mettee (1982). Additional detailed information is found 

 in Reed (1971a, 1971b), Isphording and Lamb (1971), and Isphording (1976). 



Sand and gravel from both the Citronelle Formation and the more recent 

 terrace deposits are used for construction aggregates, foundry sand, and 

 other applications. Many of the terrace and alluvial deposits are too poorly 

 sorted (i.e., contain too much clay and silt) to be of commercial use, al- 

 though they are sometimes used in road construction and maintenance. High- 

 quality, fine- to medium-grained quartz sand deposits are located along 

 several creeks and adjacent to the Mobile River. In some areas the sand 

 contains shell, which limits its uses (Moser and Chermock 1978). In the 

 nearshore waters off Dauphin Island (Biloxi quadrangle) lie reserves of heavy 

 mineral sands which are not currently being exploited (Alabama Coastal Area 

 Board and U.S. Dept. of Commerce 1979). 



The use for which the sand or gravel is intended determines which proper- 

 ties are desirable. The following general guide to specifications is given 

 in Moser and Chermock (1978): 



"Sand used as aggregate in asphalt, concrete, mortar, and plaster should 

 be clean, siliceous, angular, and free from salts and organic matter. 



"Gravel used as coarse aggregate in concrete, as base coarse in roads, as 

 fill material, and as ballast should consist of material that is tough, 

 durable, and chemically stable. Quartz gravel is preferred for use in 

 concrete aggregate. 



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