The Chester Series is defined on the section near Chester, Illinois. Rocks of northern Arkansas that contain Chester faunas include, in ascending order, the Ruddell Shale(?), Batesville Sandstone, Fayetteville Shale, Pitkin Limestone and, locally, a shale overlying the Pitkin. The base of the Chester Series generally is placed at the base of the Batesville Sandstone, which contains Agassizocrinus sp. and Diaphragmus sasciculatus (McChesney). But because the Goniatites granosus zone is common to the Ruddell Shale and Batesville Sandstone, the base of the Ruddell might be preferable. Absence of Agassizocrinus and Diaphragmus in the Ruddell might be due to facies, rather than to time control.

The Morrow Series is defined on the section in Washington County, Arkansas. The Morrow rocks consist of the Hale Formation and the Bloyd Shale. The Cane Hill Member, the lower member of the Hale, contains the Hustedia miseri fauna down to its basal conglomerate. In Newton and Searcy Counties, however, the lower third of a shale in the stratigraphic position of the Cane Hill contains a fauna of approximately 100 invertebrates, only one of which is common to the Morrow of Washington County. This fauna is more like that of underlying Pitkin Limestone and is Mississippian in age.

Correlations with northwest European sections by means of goniatites show that the Ruddell Shale, Batesville Sandstone and, locally, part of the Fayetteville Shale are late Visean in age. Most of the Fayetteville Shale, the Pitkin Limestone and, locally, part of the shale above the Pitkin are early Namurian in age. What rocks correlate with middle Namurian rocks is open to question, but these are probably represented in the Hale Formation. Upper Namurian equivalents are found in the upper part of the Hale Formation and in the Bloyd Shale.

MacKENZIE GORDON, JR.

Born April 4, 1913 in San Francisco, California. Inherited an interest in geology and paleontology from Grandmother, now 103 years of age, who as a girl had known Powell, Russell, and other early members of the U.S. Geological Survey. Received A.B. in Geology from Stanford University, Calif. in 1934, continuing on in graduate work there in 1935 and 1936. From late 1936 to mid-1937, was geologist for Nevada Rare Metals Corp. Joined the U.S. Geological Survey in September 1939 and continued with that organization up to the present. In 1952, married Barbara Ann Walker of Banes, Cuba.

U.S.G.S. career varied, beginning in the high Sierra and its foothills mapping tungsten deposits. In March 1940, began work on Carboniferous stratigraphy in the American Midcontinent, studies which have continued intermittently to present time. In charge of field work in large federal wartime exploration program for aluminum ore in central Arkansas. Foreign assignments included a study of the geology and metalliferous deposits of the Maimon-Hatillo district, Dominican Republic, from November 1941 to June 1942, stratigraphic studies in the Parana basin of Brazil from October 1945 to June 1948, and a period as Professor of Stratigraphy and Sedimentology at the University of Rio Grande do Sul in Porto Alegre, Brazil in 1959 and early part of 1960. Received a citation in 1962, along with other American geologists, for his Brazilian work.

Principal field since 1950 is Late Paleozoic stratigraphy and paleontology, specializing in cephalopods and brachiopods, particularly in the Ozark region of northern Arkansas and Great Basin of Nevada and Utah. Recent publications include the following.

1957, Mississippian cephalopods of northern and eastern Alaska: U.S. Geol. Survey Prof. Paper 283, 61 p., 6 pls., 26 figs.

1959, (with J. I. Tracey, Jr. and M. W. Ellis), Geology of the Arkansas bauxite region: U.S. Geol. Survey Prof. Paper 299, 268 p., 39 pls., 63 figs.

1959, (with R. H. Flower), More Mississippian belemnites: Jour. Paleontology, v. 33, no. 5, p. 809-842, pls. 112-116.

1960, Some American Midcontinent Carboniferous cephalopods: Jour. Paleontology, v. 34, no. 1, p. 133-151, pls. 27, 28, 3 figs.

1962, Species of Goniatites in the Caney Shale of Oklahoma: Jour. Paleontology, v. 36, no. 2, p. 355-357, 1 fig.

(in press) Carboniferous cephalopods of Arkansas: U.S. Geol. Survey Prof. Paper 460.

(in press) California Carboniferous cephalopods: U.S. Geol. Survey Prof. Paper 483A.

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