Cotulla and Mercedes soils are on slightly higher elevations on uplands as are Maverick and Montell soils. Maverick soils are moderately deep to shale and Montell soils have surfaces over 12 inches thick with colors with chroma less than 1.5. Many small channels crisscross areas of this soil in all directions. These channels are mostly 12 to 30 inches deep and 2 to 10 feet wide at the top. They are 25 to 75 feet apart.
Native grasses are dominantly gulf cordgrass with some sacaton and buffalograss.
Spiny aster occurs along the main drainageways and along roads. Flood plains of streams in the western and northcentral Rio Grande Plain of Texas. The series is of moderate extent. This soil was formerly included in the Arroyada series. Cambic horizon - 5 to 74 inches.