Alluvium in Rio Grande, subdivided into areas predominantly of sand (TXQas;0)

State	Texas
Name	Alluvium in Rio Grande, subdivided into areas predominantly of sand
Geologic age	Phanerozoic \| Cenozoic \| Quaternary \| Holocene
Original map label	Qas
Comments	Point-bar and distributary sand and silt--yellowish-gray or brownish-gray quartz sand and silt; contains plant debris and some biotite. Accretionary point-bar, levee, and crevasse-splay deposits formed by distributary channels on the Rio Grande delta. Point-bar deposits grade upward from corssbedded basal sandy gravel and coarse sand to silt and fine sand and locally are as thick as 12 m (Moore and Wermund, 1993b).
Primary rock type	sand
Secondary rock type	silt
Other rock types
Lithologic constituents	Major Unconsolidated > Coarse-detrital > Sand (Fluvial) Unconsolidated > Fine-detrital > Silt (Fluvial) Minor Unconsolidated > Coarse-detrital > Gravel (Fluvial)
Map references	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
Unit 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. [http://pubs.er.usgs.gov/publication/i1420(NG14)]
Geographic coverage	Cameron - Hidalgo