A digital geologic map of Sonora quadrangle was produced at 1:24,000 scale using the geographic information system GIS) software Maplnfo. The geology of Sonora quadrangle consists of sedimentary rocks from the Ordovician, Devonian, Mississippian, and Pennsylvanian Systems. The Cotter, Powell, and Everton formations represent the Ordovician System. The Clifty and Chattanooga formations represent the Devonian System. The St. Joe Limestone, Boone, Batesville, and Fayetteville formations represent the Mississippian System. The Hale formation represents the Pennsylvanian System. The St. Joe Limestone crops out extensively in Sonora quadrangle and is unconformably overlain by the Boone formation in the southern portion of the quadrangle. This unconformity adds credence to the suggestion that the St. Joe Limestone should be elevated to formation status rather than remain as a member of the Boone formation. The Fayetteville formation consists of the informally named lower Fayetteville Shale, Wedington Sandstone, and informally named upper Fayetteville Shale. The only member of the Hale formation observed in Sonora quadrangle was the Cane Hill member. The two prominent geologic structures in Sonora quadrangle are the White River fault running generally east-west and the Fayetteville fault running generally southwest-northeast. Other subsidiary faults are associated with these primary faults, creating fault zones within the quadrangle. Detailed mapping of stratigraphy and structure in Sonora quadrangle provides new insights into the geologic evolution and sea-level history of the Ozark Plateaus and the southern craton margin during the Paleozoic Era.
Hutchinson, Camille M.; Dowell, Jon C.; and Boss, Stephen K.
"Bedrock Geology of Sonora Quadrangle, Washington and Benton Counties, Arkansas,"
Journal of the Arkansas Academy of Science: Vol. 59
, Article 15.
Available at: http://scholarworks.uark.edu/jaas/vol59/iss1/15