Consolidated marine rocks of the Oak Cliff Quadrangle belong to a portion of the Upper Cretaceous Austin formation. On the basis of lithology the formation is divided into a lower chalk and a middle marl. Buried channels, some 6 feet deep and 95 feet across, occur in the lower chalk. They result from submarine scouring, indicating that deposition was not a continuous process. Bentonite seams, some as much as 6 inches thick, occur at various horizons in the lower chalk, pointing to periodic volcanic activity. Numerous small normal faults in the Austin formation may have resulted from differential compaction of the underlying, incompetent, Eagle Ford shale. Unconsolidated Quaternary alluvial deposits occur along the Trinity river, with terrace surfaces approximately 110, 65, and 26 feet above the floodplain. The terrace material consists of reworked chalk and marl, foraminiferal sands, silts, sands, and gravel.
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"Geology of the Oak Cliff Quadrangle, Dallas County, Texas,"
Field and Laboratory: Vol. 21
Available at: https://scholar.smu.edu/fieldandlab/vol21/iss1/6