The middle Quitman Formation is composed of 95-195 m (310-640 ft) of interbedded shale, sandstone, and limestone in the southern Quitman Mountains and Hueco Bolson, Hudspeth County, Texas. The lower and upper members consist of interbedded sandstone/limestone and thin to thick-bedded carbonate strata, respectively. The Quitman Formation was deposited along the eastern slope of the Chihuahua trough during the late Aptian and early Albian. The formation is interpreted as the oldest transgressive phase of 4 transgressive-regressive cycles that occur throughout the Lower Cretaceous within the Chihuahua trough.

Eight major facies representing nearshore to offshore environments of the middle Quitman Formation are listed below. They are: (1) nodular, sandy, peloidal to skeletal wackestone (lagoonal, basinal); (2) nodular, sandy, peloidal to skeletal packstone (lagoonal, basinal); (3) laminated to cross-bedded sandy ooid to skeletal packstone and grainstone (upper shoreface, storm); (4) laminated to cross-bedded sandstone/siltstone (upper shoreface, storm); (5) massive sandstone/siltstone (lower shoreface, lagoonal); (6) Exogyra biostromes (offshore-lower shoreface transition); (7) sandy, bioclastic, marly silt-shale (offshore-lower shoreface transition); (8) mudstone (offshore, lagoonal).

Vertical and lateral relations of strata within the middle member have shown several transgressive and regressive cycles. The more applicable terms of progradation and aggradation describe the lateral and vertical buildup of terrigenous and carbonate clastic rocks within the upper half of the middle member in the southern Quitman Mountains. These sequences are not present at the section west of the southern Quitmans.

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