HUDSON RIVER BEDS NEAR ALBANY 493 



James Hall 



Hall, in his report on the fourth geological district (6), also 

 accepted the term Hudson river group, but remarked that along 

 the Hudson river, where disturbance has prevailed, the Utica 

 shale and Hudson river group are not easily separable (6:30). 

 He, hence, assumed the presence of Utica shale in the HudsoE 

 valley. 



In 1847 the same author furnished the means of separating the 

 two formations by describing the fossils of the Hudson river 

 group (7). The fossils described under the caption " Hudson 

 river group " are components of two entirely different faunas, 

 the mollusk fauna of the Lorraine beds of northwestern New 

 York and the graptolite fauna of Normans kill. That Hall re- 

 tained Mather's and Vanuxem's views of the homotaxy of the 

 Hudson river beds with the Frankfort beds seems to the writer to 

 have been caused principally by the finding of Frankfort slate 

 fossils (Modiolopsis nuculiformis, Cleidopho- 

 rus planulatus, Lyrodesma pulchella, Mur- 

 chisonia gracilis, Carinaropsis pa t e 11 i - 

 formis, 0. orbiculatus, Bellerophon cancel- 

 la t u s ) , and of A m b n y c h i a r a d i a t a , which is 

 characteristic of Vanuxem's upper division, in the Hud- 

 son river shales of Waterford {see localities of these 

 fossils in V. 1, Pal. N. T.) These fossils eeem, indeed, to 

 €onnect the western fauna with that of the Normans kill beds, 

 but it may be remarked here that the writer has obtained evi- 

 dence showing that these mollusks nowhere occur in the same 

 beds with the Normans kill graptolites, but in actual Lorraine 

 beds which are stratigraphically widely separated from the grap- 

 tolite beds. That Hall himself did not feel sure of his correla- 

 tion becomes evident from an interesting footnote on page 329 

 of the above cited fundamental work. 



This uncertainty may also explain why in the third volume 

 of the Paleontology of New York (8: 14), Hall extended the term 

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

 to the Shawangunk conglomerate," an extension of the term 



