8 NEW YORK STATE MUSEUM 



distinguished from the Utica slate, which as before mentioned, 

 changes to a brown." Vanuxem comments on the thinning of the 

 Frankfort beds westward and it is obvious from his remarks (page 

 61) that he also considered the greater part of the shales in the Hud- 

 son valley as of Frankfort age, largely on account of the intercalation 

 of similar rubblestone or greywacke. He describes the Frankfort 

 shale as remarkably deficient in organic remains, stating : " From 

 the eastern end of the Helderberg to Oneida county, I have seen 

 but one fossil shell in the whole mass." Only graptolites are said 

 to be numerous in a few places; this statement, however, refers 

 principally to the shale in the Hudson valley, which we no longer 

 refer to the Frankfort beds. He also found a small specimen 

 of Triarthrus becki and two of Trinucleus 

 concentricus (" Cryptolithus "). 



In the middle Mohawk valley the Frankfort slate is capped by 

 the Oneida conglomerate, but in the upper valley and to the west 

 of the Adirondack region it is overlain by the Pulaski shale, or 

 rather it is separated from the typical Pulaski shale by an " inter- 

 mediate area " (Vanuxem, page 64) with a separate fauna which 

 Vanuxem considered a lower subdivision of the Pulaski shales. 



Hall, in volume I, Palaeontology of New York, brought out the 

 fundamental paleontologic data for the formation in question. He 

 distinguished the faunas of the Utica slate and of the Hudson 

 River group, the latter comprising all the horizons of the shales in 

 the Hudson valley, including the Frankfort and Pulaski (Lorraine) 

 beds. 



In volume 3, Palaeontology of New York, Hall extended the term 

 Hudson River group to " all the beds from the Trenton limestone 

 to the Shawangunk conglomerate," a conception which was taken 

 up by the textbooks and came into general use. 



In an attempt to correlate the Normanskill shale with the Utica 

 formation, Whitfield (title 7) cited several Normanskill grapto- 

 lites (Didymograptus serratulus, Dicrano- 

 graptus ramosus, Climacograptus bicornis) 

 from the Utica shale of the neighborhood of Fort Plain in the 

 Mohawk valley as proof of his contention. The writer has shown 

 (1901, 1908) that this view is based on the wrong identification of 

 these graptolites. It had, however, an important influence in 

 inducing later authors to refer a large part of the shales of the 

 Hudson valley to the Utica shale. 



