The Fredericksburg Division of Texas ranges in age from the Middle Albian zones of subdelaruei or nitidus upward into the Upper Albian cristatum zone. The overlying Kiamichi Formation of the Washita Division is largely the equivalent of the varicosum zone. The base of the Upper Albian falls within the Goodland Formation of Texas. Previously the stratigraphic range of Venezoliceras has been misunderstood. In Texas this genus is restricted to the uppermost Middle Albian and the lowermost Upper Albian. Common occurrence in Texas with other South American ammonites, such as Oxytropidoceras buarquianum (White), O. douglasi Knechtel, Manuaniceras carbonarium (Gabb), and M. peruvianum multifidum (Steinmann), indicates that the range of Venezoliceras cannot be greatly different in South America. Venezoliceras is most abundant in the Comanche Peak and Goodland Formations but appears in the top of the Walnut Formation, and one species continues into the basal Kiamichi. In Texas Adkinsites is restricted to the Kiamichi Formation and most basal Duck Creek Formation, Washita Division. Oxytropidoceras first appears just above the middle of the Walnut Formation, in the Keys Valley Marl, and ranges upward through most of the Comanche Peak and Good-land Formations. Manuaniceras first appears in the Keys Valley Marl and ranges upward through the Comanche Peak and Goodland and Kiamichi Formations into the basal Duck Creek Formation. All of the specimens of Dipoloceras are from the Goodland Limestone of Tarrant County, Texas. Four Mojsisovicziinae ammonite zones are delineated below the lower Duck Creek zone of Craginites serratescens (Cragin); these, in descending order, are the zones of Adkinsites bravoensis (Böse), Manuaniceras powelli n. sp., Manuaniceras carbonarium (Gabb), and Oxytropidoceras salasi n. sp. Twenty-nine species of Albian Mojsisovicziinae of Texas represent the genera Adkinsites with 4 species, 2 new; Venezoliceras with 6 species, 3 new; Oxytropidoceras with 5 species, 3 new; Manuaniceras with 10 species, 6 new; and Dipoloceras with 4 species, one of which remains unnamed, and one of which is not described in the present work.

Abstract Uppermost Aptian-Albian-lower Cenomanian strata of the Texas Comanchean Series represent three long-term transgressive-regressive cycles: the Trinity, Fredericksburg, and Washita groups that are composed mainly of marine limestone and shale. Each group is composed of shorter term deepening-shallowing cycles. On the Central Texas San Marcos Platform and its downdip equivalents, subsurface strata above the Trinity Group are grouped into the Edwards and Washita groups. Correlations in the 1960s were based on wireline well logs and inferred biostratigraphy that correlated the upper Edwards Group Person Formation with the lower parts of the Washita Group. This correlation crosses a widespread subaerial unconformity that separates the Washita from the underlying Fredericksburg in the northern East Texas Basin and in the Fort Stockton Basin. New biostratigraphic and sedimento-logical data show that the Person actually correlates with the upper part of the Fredericksburg in the Gulf Coast.

Abstract A regional network of five interlocking stratigraphic cross-sections compiling the published work of many geologists throughout central and southwest Texas demonstrates the true stratigraphic relationships among formations of the Lower Cretaceous Fredericksburg and lower Washita subcycles. Strongly supported by a long-established ammonite zonation, these detailed stratigraphic cross-sections show lateral relations between Edwards Group formations (Kainer, Person, Fort Terrett, Segovia, Fort Lancaster, and Devils River) of the Central Texas Platform with equivalent formations of the East Texas Basin (Walnut, Comanche Peak, Goodland, Georgetown) and the Maverick Basin of South Texas (West Nueces, McKnight, Salmon Peak). These cross-sections document the following regional stratigraphic relationships: The Burt Ranch Member (basal Segovia Formation), the Regional Dense Member (basal Person Formation), and the Kiamichi Member (basal Georgetown Formation) are stratigraphic equivalents, all three being in the Adkinsites bravoensis Ammonite Zone (lowermost Washita) The peritidal Person Formation is the shelf-interior equivalent of the pelagic-shelf Georgetown Formation, except for its uppermost member, the Main Street, which forms the thin remnant Georgetown Formation on the distal Central Texas Platform. Thus the Person Formation is properly assigned to the lower Washita subcycle, not the Fredericksburg.