The Moore Hollow Group records the advancing of a sea from the southeast across eroded Precambrian rocks during Middle to Late Cambrian times and subsequent burial beneath coastal and nearshore marine sediments. The Cambrian sea spread northward across the eroded surface an area of Precambrian rocks that had a local relief as great as . As a result, sediments composed of locally derived residuum, often wind-abraded accumulated as a thin, discontinuous cobble conglomerate overlying Precambrian strata at the base of the Moore Hollow Group. Following the deposition of the uppermost Cambrian limestones and dolomites, the Lower Ordovician Ellenburger Group (composed of the Tanyard, Gorman, and Honeycut Formations) accumulated within shallow-water carbonate platforms. At the end of the Lower Ordovician, the Central Texas region was tilted eastwards and exposed to subaerial erosion and karstification.Cloud, P.E. and Barnes, V.E., 1948. Paleoecology of the early Ordovician sea in central Texas. In National Research Council, Division Geology and Geography, Report of The Committee on a Treatise on marine ecology and paleo-ecology. 8, pp. 29-83.Cloud, P.E. and Barnes, V.E., 1957. In H.S. Ladd, ed. Treatise on marine ecology and paleoecology. Geological Society of America Memoir 67:163– 214.
