Rocks of Chester, Morrow, and Atoka age in western Arkansas and eastern Oklahoma present many unsolved problems, particularly in regional correlation and depositional history.

The Chester Series in this area consists mainly of the Fayetteville Shale and the Pitkin Limestone. The series thickens southward from the Ozark Dome even though the Pitkin Limestone appears to thin southward. The Fayetteville and the Pitkin are probably facies of the same sedimentary unit.

The Morrow Series is composed of the Hale Formation and the overlying Bloyd Formation. The Hale consists of the Cane Hill and Prairie Grove Members. The thickness of the Morrow Series increases southward from the Ozark Dome. In general the thickening trends of the Cane Hill and of the undivided Prairie Grove and Bloyd are parallel. The Cane Hill sedimentary basin received sandy sediments from the northeast and north in Arkansas and northeastern Oklahoma and perhaps from the south in east-central Oklahoma. The Prairie Grove and Bloyd sedimentary basin received sandy sediments from the north and northeast. The dissimilar rock types, including limestone, conglomerate, phosphorite, and coal, within the Morrow indicate a complex depositional history.

The Atoka Formation is the only part of the Atoka Series present in this area. The Atoka thickens southward from the Ozark Dome and the rate of thickening increases sharply southward from at least one eastward-trending hinge line. The percentage of sandstone in the Atoka generally decreases southward, mostly because of a large increase in the amount of shale. The middle part of the formation thickens more rapidly and has generally thicker sandstone units than the upper and lower parts. The Atoka Formation consists of shelf-type sediments in the Ozark Mountains and the Arkansas Valley, and basin- and flysch-type sediments in the Ouachita Mountains.

BOYD R. HALEY

Boyd R. Haley was born in Independence, Oregon on November 25, 1922. He enlisted in the United States Navy in 1941 and was accepted into NROTC in 1944. He received a B.A. degree in geology from Princeton University in February 1948, and joined the U.S. Geological Survey in July 1948. Mr. Haley worked on rocks of Pennsylvanian age in the anthracite fields of Pennsylvania until 1952, and then joined Truman's police action for 17 months. Since 1953 he has been working on the surface and subsurface rocks of west-central Arkansas. Mr. Haley has been a member of the AAPG since 1953 and has contributed to the publications of the U.S. Geological Survey, the Arkansas Geological Commission, and the University of Oklahoma.

E. A. MEREWETHER

E. A. Merewether was born in Portland, Oregon in 1930. He is a graduate of the University of Oregon, receiving a B.S. degree in geology in 1951 and an M.S. degree in 1953. Upon graduation he entered the United States Army and served for 2 years. He has been employed by the U.S. Geological Survey since 1955 and has assisted in studies of uraniferous coaly rocks, the distribution of uranium deposits and igneous rocks, and the geology of the Arkansas Valley basin. During the past 5 years he has mapped the surface geology and investigated the subsurface geology near the eastern end of the Arkansas Valley coal basin. Mr. Merewether has contributed to the publications of the U.S. Geological Survey and the Arkansas Geological Commission. He is a member of the Geological Society of America and the Rocky Mountain Association of Geologists.

SHERWOOD E. FREZON

Geologist, Organic Fuels Branch, U.S. Geological Survey, Denver, Colo. Has held this position since July 1951.

Primarily engaged in mapping studies in northern Arkansas and in subsurface studies in the Arkoma basin in Arkansas and Oklahoma. The results of some of these studies have been published by the U.S. Geological Survey and the Oklahoma Geological Survey.

Received B.S. degree in geology from the University of Michigan in 1950 and did one year of graduate work.

Member of the following professional societies: AAPG, AAAS (Fellow), GSA, Paleontological Society, SEPM, Tulsa Geological Society, and Rocky Mountain Association of Geologists.

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