HUDSON RIVER BEDS NEAR ALBANY 507 



C. D. Walcott 



The most careful inveistigation in the field, bearing directly on 

 the problem of the Hudson river group, has been made by C. D. 

 Walcott (36a). Mr Walcott's working plan was to trace the for- 

 martions from the undisturbed regions in the northwest and west 

 into the regions of disturbance. These researches' gave the fol- 

 lowing results bearing on our investigation. 



The Utica shales can be traced from their contact with the 

 Trenton limestone at the falls of the Hudson near Sandyhill, 

 " with little interruption, to the neighborhood of Albany, where 

 they are very much disturbed and stand at a high angle. In this 

 vicinity the noted graptolite beds of Normans kill occur; also 

 the locality where Mr Beecher discovered the upper fauna of the 

 Utica shale zone ". Following up the Normans kill, alternating 

 shales and sandstones are passed over, which " with the same 

 . lithologic character " continue across the line of disturbance till 

 the superjacent Lower Helderberg limestone is met with. These 

 shales and sandstones which, at the Indian Ladder, were found 

 to contain Or this t est u din aria and Trinucleus 

 c o n c e n t r i c u s , are correlated with the Frankfort shales of 

 the Mohawk valley. Mr Walcott's conclusions of the presence 

 of a zone of Utica shales in the Hudson river valley and of the 

 extension of the Frankfort shales along the Normans kill are 

 mainly based on lithologic evidence. Fossils found at numerous 

 localities by the writer have served to verify the former conclu- 

 sion; while Utica shale fossils found on both sides of the line 

 of disturbance at the Normans kill indicate the presence of 

 faunistic differences in the shales and sandstones, in spite of their 

 apparent lithologic continuity. 



The relation of the Normans kill, or Coenograptus, zone to the 

 Utica shale is not expressly stated by the author, but it is 

 clear that he places it near the top of the Utica shale. This 

 follows from the following statement (p. 349): "Comparing the 

 fauna, we find that the forms of the upper part alone of the Utica 

 zone occur within the valley of the Hudson, and that the great 

 graptolitic fauna of the Hudson valley is largely unknown in the 



