HUDSON RIVER BEDS NEAR ALBANY 567 



Lapworth, in correlating the Canadian with the British grapto- 

 llte shales, transferred his term, Coenograptus gracilis zone, to 

 the corresponding Canadian and Normans kill beds. He dis- 

 cerned a closely related zone directly above this, which, in his 

 opinion, differed by the absence of Coenograptus gra- 

 cilis. Ami, however, subsequently also found that graptolite 

 in this second zone. The two zones were then termed lower and 

 upper Dicellograptus zones (50). But these terms are not fully 

 appropriate, because there have been already distinguished two 

 Dicellograptus zones in England (those ofD. complanatus 

 and D. an c e p s ), which lie above the zone with Coeno- 

 graptus gracilis, and one in Sweden by Tullberg, which 

 lies above the beds with Diplograptus pristis and D. 

 quadrimucronatus. It would seem more correct to 

 designate these American graptolite shales also by their most 

 characteristic species, a task which must be postponed till after a 

 closer investigation of the vertical distribution of the graptolites 

 and the possible more detailed division into graptolite zones of 

 the graptolite beds of the entire middle and upper Lower Siluric. 

 Meanwhile, and perhaps even then, the term, Normans kill shales/ 

 may be of good service in designating this graptolite bearing, 

 clastic facies of the middle Lower Siluric. 



SUMMARY 



This paper purports to demonstrate the presence of four zones 

 of shales in the "Hudson river shales" of the Hudson valley 

 region about Albany. These zones, which extend from n ne to 

 s sw consist, going from west to east, of shales containing the 

 Lorraine, Utica, middle Trenton and Normans kill graptolite 

 faunas. The shales last named include lower Trenton conglomer- 

 ate and rest on lower Trenton limestone. This succession of 

 zones places the Normans kill graptolite beds, which form the 

 mass of the "Hudson river shales" in the Hudson river valley, be- 

 tween the middle and lower Trenton and determines, together 

 with other facts, the lower Trenton age of these shales. 



