| State | Texas |
|---|---|
| Name | Jackson Group, undivided |
| Geologic age | Oligocene and Eocene |
| Lithologic constituents |
Major
Unconsolidated > Fine-detrital > Clay (Bed)
Minor
Sedimentary > Clastic > Sandstone (Bed)
Incidental
Sedimentary > Clastic > Siltstone (Bed)
|
| Comments | clay, sandstone, siltstone, and tuff. as much as 875 ft thick, mapped generally south of Frio River |
| References | Bureau of Economic Geology, 1974, Seguin Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.Bureau of Economic Geology, 1966, Texarkana Sheet, Geologic Atlas of Texas, University of Texas, Bureau of Economic Geology, scale 1:250,000.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. |
| NGMDB product | |
| Counties | Duval - Jim Hogg - La Salle - McMullen - Starr - Webb - Zapata |