In this article the evidence is presented from the study of many hundreds of graptolites collected by zones from practically every fossiliferous outcrop of the Athens shale in about 600 miles of its extent from central Alabama across northwestern Georgia and eastern Tennessee to northern Virginia, also the evidence from the study of extensive collections made earlier by Harvard University and the United States National Museum. Identifications were made by camera lucida drawings under a graptolite microscope. Acknowledgment of assistance is made, a history of the Athens shale is outlined, and former investigations are reviewed. Illustrations include photographs showing the characteristics of the shale, eighteen measured sections of the formation, diagrams showing structure, some of which indicate thickness, and outline maps showing the distribution of the Athens fauna in North America and other continents. In North End_Page 1------------------------------ America a great U-shaped narrow shallow Athens basin is delineated from Newfoundland southwestward to Alabama, westward to Arkansas, Oklahoma, and Nevada, and northwestward through Idaho, British Columbia, and Yukon to Alaska, with Athens faunules shown in some additional states. In Table I the Athens graptolites are assigned to three somewhat overlapping major zones. The lowest zone is developed from central Alabama to southwestern Virginia, and it might be seen to extend farther, if the basal part of the Athens were exposed; the middle, or most important, zone extends from central Alabama to northern Virginia; and the highest zone begins near Johnsville Church east of Blacksburg, Virginia, and develops northeastward through Harrisonburg to the higher of two zones at Staunton, and to Overall, Virginia. Significantly, the major part of the great Athens graptolite fauna listed by zones from the lower part of the formation extends almost the distance of its outcrops in the four states. Table II shows the properly widespread separation of the Normanskill (Athens) and Deepkill faunas which have been placed together in the Normanskill Trenton Dauphin formation of Pennsylvania. In Table III the distribution is shown of 122 species and varieties of Athens graptolites in the states of Alabama, Georgia, Tennessee, and Virginia where the formation crops out, in other states of North America, and various other countries of the world. The graptolites are illustrated by zones in three plates. This number of 122 is nearly double the 63 from the Normanskill of New York. In Table IV the typical development of the Athens fauna is shown in the Trenton through Alabama, Georgia, Tennessee, and Virginia where it crops out, and the higher phase of the Athens farther northeast in Virginia. Also, where available, the names of other formations are given where the fauna occurs in other states and in other countries. In Table V the significant evidence is given which changes the classification of the Athens shale from Chazyan, where it has been placed for more than 40 years, to Trenton, where Ruedemann first placed its equivalent, the Normanskill, in 1908. Westward from the Appalachians the Athens fauna extends into the Womble shale of Arkansas, the Stringtown shale, and the upper Bromide and Viola formations of Oklahoma, the latter formations being Trenton in age. Also, the Athens of Trenton age is shown widely separated by about 1,000 feet of limestones, shales, and sandstones from the position of the typical Chazyan fauna far below in the lower part of the McLish formation. Furthermore, this Athens fauna sets up a Trenton zone of reference not only in all of the states in which it occurs in Nor h America, but also in the other continents where its occurrence has been discovered. A brief summary of the results of this study is given and a selected bibliography is included.
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May 6, 2014
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