REPORT OF THE STATE PALEONTOLOGIST 1902 1205 



Onondaga limestone 



This formation is not found on either the Vlightberg or North 

 hill, but as it is one of the most important members of the series 

 in the Kingston region, a few words are devoted to its character- 

 istics. The upper part of the Esopus grit merges into the lower 

 portion of the Onondaga by such gradual changes that no line 

 of demarcation can be drawn. These lower impure limestones 

 are about 40 feet in thickness, and they are overlain by about 30 

 feet of purer blue gray, hard silicious limestone that lies in beds 

 of from 1 to 5 feet thick. The upper portion of the pure limestone 

 carries considerable black chert that projects as irregular knobs 

 on the weathered surfaces of the rock. This formation abounds 

 in fossils, but the rock is so hard and splintery that they are very 

 difficult to extract. Atrypa reticularis, Lepto- 

 strophia perplana, Platyceras dumosum, 

 Leptaena rhomboid alis, are the most common species. 



The Onondaga limestone is well exposed along the West Shore 

 Railroad between the Wiltwyck cemetery and the tunnel; several 

 quarries have been opened into it within the Kingston city limits; 

 and it is also finely exposed along the western slope of the mono- 

 clinal ridge that parallels the east side of the West Shore 

 Railroad for several miles north of Kingston, specially in the 

 vicinities of Lake Katrine, Glenerie falls, Mt Marion and 

 Saugerties. 



Range of the Helderbergian and Oriskanian species 



The following table shows the range of the various species of 

 fossil organisms throughout the members of the Helderbergian 

 and Oriskanian series in the Rondout region. The table is 

 based on the lists already given in the text above; and Clarke's 

 list of the Port Ewen fauna, published in his Becraft memoir 

 [1900, p.73], has been incorporated. The relative abundance of 

 the species is indicated by letters: a=abundant, c=common, 

 r=rare, v=present. 



