Table 26. Alabama's role in U.S. clay production 

 the Interior, Bureau of Mines 1979b). 



in 1978 a (U.S. Department of 



Major commodity 



Share of U.S. output [%) Rank in Nation Reserves 



Clays: 

 Bentonite 

 Common 

 Fire 

 Kaol in 



5 



13 

 5 



4 

 7 

 4 

 3 



Smal 1 

 Large 

 Moderate 

 Small 



d Preliminary figures. 



b W = Withheld to avoid disclosing individual company confidential data. 



ported to the sea, where the process of rounding, sorting, and deposition 

 continues. If covered by thick sediments and consolidated by pressure, sand 

 may eventually form sandstone. Sandstone varies in texture from very coarse- 

 grained, when it is an aggregation of large particles, to sandy shale, when 

 it is intermixed with the much smaller silt particles (Jones 1926). 



Gravel originates in the same manner as sand, by the weathering of parent 

 rocks. The larger gravel particles are likewise abraded, rounded, and sorted 

 as they are transported downstream. Gravel may then be deposited on bars by 

 itself or with sand along streams, or less likely, transported out to sea. 

 Deposits of sand and gravel are usually intermixed, which necessitates wash- 

 ing to screen out the particle sizes desired for commercial purposes (Jones 

 1926). 



Deposits of sand and gravel within the Mobile-Baldwin County study area 

 are Miocene [25,000,000 to 10,000,000 years before present (ybp)], Pliocene 

 (10,000,000 to 600,000 ybp), Pleistocene (600,000 to 12,000 ybp), or Recent 

 (12,000 ybp to present) in age. Sand and clay deposits of Miocene age are 

 found in the northern half of the study area and include Catahoula sandstone 

 Hammock sand. Mid-Pliocene and early Pleistocene deposits 

 Citronelle Formation, which includes layers of sand, clay, 

 terrace and alluvial deposits surrounding the major streams 

 primarily late Pleistocene and Holocene 



and Paynes 

 comprise the 

 gravel . The 

 the area are 



Holocene, silty and clayey 

 (Moser and Chermock 1978). 



sands were also deposited 



in age. 

 along the 



and 

 in 

 During the 

 gulf coast 



Table 27, from Moser and Chermock (1978), shows the generalized strata 

 significant to coastal Alabama's mineral resources. A comprehensive 



119 



