10 



NEW YORK STATE MUSEUM 



the eastern part of the State, that by decrease in the amount of 

 sediment or by transition in character, thins out in a westerly direc- 

 tion and is not known beyond Livingston county. 



Fossils are rare in this formation here ; Leperditia alta 

 (Conrad) and L. scalar is Jones occur throughout the bed and 

 segments of Eurypterus have been found 2 or 3 feet below the top 

 of the bed. 



Manlius limestone 



This formation is prominent in the stratigraphy of Onondaga and 

 Cayuga counties, but thins out rapidly in a westerly direction and 

 does not reach the McQuan quarry which affords the only exposure 

 of its horizon on this quadrangle. Flagstones and building blocks 

 reported to be from an old quarry in the south part of Seneca Falls, 

 are Manlius limestone, from which it is evident that it extends to 

 the vicinity of that village. 



When freshly quarried the rock is very dark and hard, but when 

 weathered shows a straticulate structure and fades to a dull bluish 

 gray color. 



It contains many fossils of which the more common are S p i r i - 

 fer vanuxemi Hall, Strop heodo'nta varistriata 

 Conrad and Leper ditiaalta (Conrad). 



1 



DEVONIC 

 Oriskany sandstone 



The Helderbergian series of limestones that in eastern New York 

 constitute the basal formations of the Devonic system all thin out 

 in a westerly direction and disappear before reaching Cayuga county 

 and in western central New York the Siluric waterlimestones are 

 succeeded in some localities by thin lentils of coarse quartzitic Oris- 

 kany sandstone, cross-sections of ancient sandbars. 



Where the sandstone is absent, as in the McQuan quarry which 

 affords the only exposure of the Oriskany horizon on these quad- 

 rangles, the Rondout waterlime is separated from the Onondaga 

 limestone by a thin layer of black carbonaceous matter 3 to 6 inches 

 thick containing pebbles of waterlime and grains of black sand, but 

 no fossils. 



In Yawger's woods 2 miles northeast of Union Springs and 

 8 miles southeast of the McQuan quarry the Oriskany sandstone is 

 4 feet 6 inches thick and crowded with characteristic fossils mostly 

 large brachiopods (Hipparionyx proximus, Spirifer 



