ABSTRACT

Several occurrences of the miliolid Nummoloculina in the Lower Cretaceous of Texas (lower Glen Rose through upper Devils River limestones) and one occurrence in the Lower Cretaceous of northern Louisiana (lower Glen Rose limestone) are reported for the first time.

The geologic range of Nummoloculina as ascertained by the writers is Lower Cretaceous to Recent.

Nummoloculina limestones in Texas are here reported from the upper Devils River limestone (Georgetown limestone equivalent) in Val Verde County and the Edwards limestone in La Salle and Maverick counties.

Nummoloculina occurring in the Devils River limestone in Val Verde County is figured and discussed. Nummoloculina from the El Abra miliolid member of the El Abra formation of northern Mexico (Lower Albian through Lower Cenomanian) is figured for comparison.

The uppermost Devils River limestone and the upper El Abra miliolid member are compared, but no correlation is implied.

Following Norton’s zonation of foraminifers, miliolid limestone environments would correspond most closely with his Zone A where the water is 0–5 fathoms deep and the temperature is 21°–32°C.

Miliolids occurring in abundance are facies foraminifers characteristic of back-reef and inter-reef environments; therefore, they are useful in paleoecology.

Although miliolid limestones in Texas vary in age within, but are restricted to the Lower Cretaceous (Sligo through upper Devils River limestones), they may be of local or regional value in the differentiation of large stratigraphic units within the Sligo through upper Devils River limestones. Miliolid limestones are used successfully in parts of southwest and central Texas to mark the faunal top of the Edwards limestone. However, in the Devils River area, or in any other area where reefs were formed in Washita as well as Fredericksburg limestones, such differentiation based on miliolids is unsatisfactory.

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