538 NEW YORK STATE MUSEUM 



Extension of zone of middle Trenton beds 



The five stations, 22-26, establish the presence of a zone of 

 rocks of the general appearance of the Hudson river shales and 

 sandstones (but containing some limestone), between Troy and 

 Watervliet, which is about 1 mile wide and equivalent to the 

 middle Trenton. This zone could not be traced farther south, 

 which fact, however, finds its explanation in the topographic 

 conditions prevailing to the south; for the strike of the middle 

 Trenton beds brings them, as an examination of the map will 

 show, into the alluvial plain of the Hudson river where outcrops 

 are absent. The zone would then probably pass through the 

 lower part of the city of Albany and could be expected along the 

 Normans kill above Kenwood and below the Utica shale out- 

 crops described above. But along that part of the river only 

 one exposure is found, that at Normansvilie, and this, unfortu- 

 nately, is not known to have ever yielded any fossils. From here- 

 to the Lorraine sandstones and shales at the base of the Helder- 

 berg escarpment no farther outcrops could be found. Both the 



4 



Vlaumans and the Coeymans kills, which have been followed 

 by the writer along their entire courses, show outcrops only near 

 their mouths, and these belong to the next following zone. The 

 outcrops at the upper Coeymans kill and its tributary, 

 the Sprayt kill, have been mentioned above. On account of the 

 general n ne-s sw strike of all the beds in this region, it can, 

 however, be safely surmised that this zone passes under the Hel- 

 derbergs. 



D NORMANSKILL. BEDS (LiOWEIi DICELL.OGRAPTUS ZONE) 



After the presence of these zones .of Lorraine, Utica and Tren- 

 ton shales in the Hudson river valley had become evident to the 

 writer, a thorough search for the graptolites of the Normans kill 

 or lower Diceilograptus zone was instituted, this zone being, in 

 accordance with the views of previous writers, sought for be- 

 tween the Lorraine and Utica, and between the Utica and Tren- 

 ton zones. There has, however, no trace of these graptolites 

 been found between or within the Utioa and Lorraine zones, 



