| State | Texas |
|---|---|
| Name | Alluvium in Rio Grande, subdivided into areas predominantly of clay |
| Geologic age | Quaternary; Holocene |
| Lithologic constituents | Major
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). |
| References | 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.https://pubs.er.usgs.gov/publication/i1420(NG14) 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. |
| NGMDB product | |
| Counties | Cameron - Hidalgo |