The Atoka Formation in the eastern and northeastern Arbuckle Mountains region represents a transgressive sequence deposited in a sea which advanced generally from east to west, overlapping and partly truncating the subjacent Wapanucka Formation. Implicit in this statement is the suggestion that slight eastward tilting of Wapanucka strata took place before or during the Atoka transgression. The depth and vigor of marine erosion along the advancing shoreline was affected by the variable relief of the invaded areas, and the basal deposits of the Atoka Formation reflect this variation.

The character of the basal beds of the Atoka Formation is highly variable throughout the area but consist commonly of interbedded shales, siltstones and cross-bedded sandstones. In Coal and Johnston Counties laterally discontinuous limestone conglomerates occur at the base. This conglomerate is up to five feet thick at Delaware Creek and includes clasts of boulder size. Petrographic, petrofabric and paleontologic studies were made of both the limestone clasts which make up this conglomerate and also of the limestones which occur in the underlying Wapanucka Formation. The results show that the basal Atoka conglomerate was derived almost entirely from erosion of the underlying limestones of the Wapanucka Formation. Measurement and evaluation of the degree of roundness and the orientation of limestone clasts in the conglomerate indicate that this rock had its origin as an accumulation of gravel along an advancing or transgressive beach which trended generally northwest to north.

Visible relief along the contact of the Atoka and Wapanucka Formations does not exceed two or three feet at any single outcrop but field relations in one area suggests erosion to a depth of at least 30 feet locally. The limestone at the top of the Wapanucka Formation show local oxidation to a depth of one foot.

PATRICK K. SUTHERLAND

Patrick K. Sutherland is Associate Professor of Geology at the University of Oklahoma where he teaches courses in biostratigraphy, stratigraphy and paleoecology. He received his B.S. Degree in Geology from the University of Oklahoma in 1946 and his Ph.D. degree in Geology from Cambridge University, England in 1952. He worked for the Phillips Petroleum Company in northwest Canada from 1946 to 1949 and in west Texas from 1952 to 1953. He was on the faculty of the Department of Geology at the University of Houston for four years before joining the faculty of the University of Oklahoma in 1957.

Dr. Sutherland has published papers on aspects of Mississippian and Pennsylvanian stratigraphy and paleontology in northeast British Columbia, northern New Mexico and Oklahoma. He is a fellow of the Geological Society of America and the Geological Society of London and a member of the American Association of Petroleum Geologists, the Society of Economic Paleontologists and Mineralogists, the Paleontological Society, the Oklahoma City Geological Society and various other organizations.

CHARLES LLEWELLYN ROWETT

Charles Llewellyn Rowett was born at Miami, Arizona, June 11, 1931. The son of a mining engineer, his early years were spent in mining regions such as the Miami-Globe copper district of Arizona, the Cerro de Pasco copper mines of Peru, and the tin mines at Potosi, Bolivia. His family subsequently moved to Mexico City, where he attended the American High School. His high school training was completed at the Peacock Military Academy in San Antonio, Texas. He completed a Bachelor of Science at Tulane University in New Orleans in 1958 and a Master of Science in geology at that institution in 1959. His Ph.D. in geology was taken at the University of Oklahoma in 1962.

Dr. Rowett is primarily interested in the paleontology and stratigraphy of rocks of Carboniferous age, and most of his research and publications have been in this field. His doctoral dissertation was a biostratigraphic study of a Lower Pennsylvanian Formation in Oklahoma. He has taught geology at Tulane University, the University of Oklahoma, and the University of Tulsa. He is at present a member of the Department of Geology at the University of Alaska at College, Alaska.

Dr. Rowett is a member of Sigma Xi, the American Association of Petroleum Geologists and the Paleontological Society.

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