GEOLOGY OF THE AUBURN-GENOA QUADRANGLES II 



Fossils. The following species have been identified from Fron- 

 tenac island: 



Chaetetes (Monotrypella) arbuscu- Whitfieldella sulcata {Vamixem) 



lus Hall Ilionia sinuata Hall 



Favosites niagarensis HalU Megambonia aviculoidea Hall 



Halysites catenulatus (Linne) Pterinea subplana {Hall) 



Stromatopora concentrica Hall Bucania sp. 



Cyathophyllum hydraulicum Simpson Cyclonema sp. 



Crinoid sp. Loxonema sp. 



Chonetes jerseyensis Weller Trochoceras gebhardi Hall 



C. iindulatus Hall Tentaculites gyracanthus {Eaton) 



Rhynchonella pisum Hall & Whit- Gomphoceras septore Hall 



Held Orthoceras trusitum Clarke & 



Spirifer crispus var. corallinensis Ruedemann 



Grahau Orthoceras large sp, 



S. vanuxemi Hall Beyrichia sp. 



Stropheodonta bipartita Hall Leperditia alta Conrad? 



S. textilis Hall L. cf. scalaris Jones 



S. \ a ri striata {Conrad) 



Rondout waterlime 



This formation is composed of dark colored waterlime closely 

 resembling cement rock and shows faint lines of deposition and a 

 tendency to split along these lines. It is 25 to 30 feet thick at Union 

 Springs and increases 10 feet or more in the northeastern part of the 

 quadrangle, and to 45 feet in Onondaga county, but decreases west- 

 ward to 9 feet at Seneca Falls and is not recognized in the western 

 part of the State. 



It is 24 feet thick and the basal layers are extensively quarried for 

 cement at Rondout, Ulster co., N. Y., whence the name of the forma- 

 tion is derived. The contact with the Cobleskill limestone is quite 

 abrupt and is plainly seen where exposed, but at the top the transition 

 to the Manlius limestone is a gradual one and in old exposures not 

 readily discerned. 



Rondout waterlime is exposed in the northern part of Union Springs 

 in the gutters of the street leading eastward up the hill opposite the 

 mill pond, and in the old quarry a few rods north of the O'Conner 

 quarry ij/^ miles farther north. It appears at the top of the east end 

 of the cut 50 rods east of the station at Crossroads, and there are 

 several small exposures and numerous blocks of it in the region east 

 of Aurelius station. It may be seen by the side of the New York 

 Central Railroad and along Crane brook a mile west of Auburn. The 

 contact with Cobleskill limestone is shown in the small old quarry at 

 the foot of the hill on the south side of the railroad a mile farther 

 west. :■ I ^'1 



