|Name||Alluvium in Rio Grande, subdivided into areas predominantly of clay|
|Geologic age||Quaternary; Holocene|
Unconsolidated > Fine-detrital > Silt (Bed)
Unconsolidated > Fine-detrital > Clay (Bed)
|Comments||Flood-plain and backswamp silt and clay--dark-gray to dark-brown or brownish-gray silt, clay, and silty clay. Contains minor amounts of medium to fine quartz sand. Interdistributary fine sediment of the Rio Grande delta. Mostly inactive; deposition occurs during floods that accompany large, relatively infrequent tropical storms. Unit burrowed by animals; locally very organic with abundant plant fragments. Extensively cultivated. Overlies older distributary sand deposits (Moore and Wermund, 1993b).|
Moore, D.W. and Wermund, E.G., Jr., 1993b, Quaternary geologic map of the Monterrey 4 x 6 degree quadrangle, United States: U.S. Geological Survey Miscellaneous Investigations Series Map I-1420 (NG-14), scale 1:1,000,000.
Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000.
|Counties||Cameron - Hidalgo|