Pg. 118 (fig. 26), 161-164, geol. map. Williamson Creek member of Fleming formation. Consists of thick group of nonmarine silts and silty clays, with incorporated sand lentils and local brackish-water clay tongues. Total thickness approximately 500 feet. Overlies Dough Hills member (new), and contact arbitrarily is placed in clayey-silt sequence where sand lentils begin to appear in abundance; underlies Castor Creek member (new), and contact is placed where sand lentils are replaced by silty clay sequence grading upward into calcareous clays. [Age is Miocene.]
Typically exposed in uplands within drainage area of Williamson Creek headwaters south of Dough Hills, Rapides Parish, central LA.
Source: US geologic names lexicon (USGS Bull. 1200, p. 4245).
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