Il6 NEW YORK STATE MUSEUM 



ing itself between the lower division of the true Trenton limestone 

 and the black Stony Point shale. It seems that the zone of the Cum- 

 berland Head shales extends northward over Point de Roche and 

 merges into the dark impure limestone of the Alburg " Utica " belt 

 described above. 



II The Graptolite Zones of the Ordovician Shale Belt of New 



York 



There extends a broad belt of gray and black, red and green shale 

 and slate through eastern New York. Beginning at the Vermont 

 state line east of Whitehall, at the head of Lake Champlain, its 

 course runs in southwest direction to the Hudson river which it fol- 

 lows from Glens Falls to the neighborhood of Poughkeepsie where 

 it crosses the river and thence proceeds, between the Shawangunk 

 mountains and the Highlands, into New Jersey. This belt is but a 

 segment of the long zone of the Appalachian shaly deposits extend- 

 ing from the south bank of the lower St Lawrence river through 

 the province of Quebec, Vermont, New York, Pennsylvania and 

 Maryland into and beyond Virginia. 



In the latitude of Saratoga Springs and Albany another belt of 

 gray and black shales branches off from the master belt and, run- 

 ning first in west and then in northwest direction, it girdles the 

 Adirondacks on the south and west following first the Mohawk river 

 from its mouth to its source, then passing over to the Black River 

 valley and again following this stream to the neighborhood of its 

 mouth near the outlet of Lake Ontario. 



Originally this entire mass of shales was designated as Hudson 

 River shale. Through the discoveries of Emmons and Ford, but 

 principally through the work of Walcott, the lower Cambrian 

 (Georgian or Waucobian) rocks were separated from this thick 

 terrane. Likewise the shale belt of the Mohawk and Black River 

 valleys was early separated into three divisions, namely, the Utica, 

 Frankfort and Lorraine shales ; for the reason that these rocks 

 contain sufficient fossils other than graptolites for discrimination. 

 The Hudson River terrane of the eastern shale belt, however, proved 

 almost entirely barren of fossils other than graptolites, and as a 

 result of this unfavorable condition it remained undivided, the 

 whole mass being placed above the Utica and in a general way 

 correlated with the Lorraine. 



