666 C. SCHUCHERT DEVONIAN OF OKLAHOMA 



well of the Camden in Oklahoma, another extension of more than 300 

 miles. 



Oriskany of Marble City 



During the field season of 1919 Mr. D. K. Greger was studying the 

 stratigraphy of northeastern Oklahoma for the Empire Fuel and Gas 

 Company, and near Marble City collected a lot of fossils, as he thought, 

 from the Saint Clair marble. These later on came to me without further 

 comment. This marble is well known to have Middle Silurian fossils in 

 its upper part, but Greger collected from it such characteristic Upper 

 Oriskany forms as Spirifer arenosus and S. murcliisoni. These left no 

 doubt that the Oriskanian sea, as recorded in the white limestones of 

 Sainte Genevieve County, Missouri, once extended unbroken across what 

 is now the Ozark dome, at least 300 miles farther to the southwest. More 

 information was asked for, but it soon became apparent that the locality 

 must be revisited to study the position of these fossils in the local section. 

 This was done at my request early in September, 1921, by Doctor Dunbar, 

 and it is to him and to Mr. Greger that I owe thanks for this most inter- 

 esting stratigraphic discovery. Not only is the presence here of Upper 

 Oriskany now established, but as well a thin western sandy phase of the 

 Camden of Tennessee, the oldest known American phase of the Middle 

 Devonian. 



In the limestone quarry near Marble City Dunbar collected a large 

 piece of Gyroceras elrodi and another one of Protol'ionoceras medullare?, 

 but these by themselves did not give me the exact age of the upper part 

 of the Saint Clair marble. With other names they might pass as well for 

 Helderbergian. In looking up the work of Tafr in the Tahlequah Folio 4 

 it was seen that from the upper part of this marble he had collected nine 

 other species; and these, as identified by E. 0. Ulrich, left no doubt that 

 the Saint Clair marble in its upper part is of high Middle Silurian age. 

 On the top of this marble follows from 5 to 8 feet more of the same kind 

 of white limestone, and Dunbar noted that it was separated by an easily 

 seen erosional unconformity from the Saint Clair marble. This is all 

 that now remains here of the Upper Oriskany, but more must have been 

 deposited and later worn away. This conclusion is supported by the ero- 

 sional unconformity which follows and by the marked differences between 

 the Oriskanian and Camden faunas. There is no Lower Oriskany present 

 here, and, curiously, none of the Helderbergian, which occurs in consid- 

 erable thickness in the Arbuckle Mountains, something like 150 miles to 

 the southwest. 



4 I. S, Geological Survey, Geological Folio No. 122, 1905. 



