l8 NEW YORK STATE MUSEUM 



Phacops rana Green Chonetes setiger Hall 



Styliolina fissurella (Hall) Spirifer mucronatus (^Conrad) 



Pleurotomaria rugulata Hall Ambocoelia umbonata Conrad 



Lunulicardium curtum Hall Liorhynchus limitare (Vamixem) 



Nuculites oblongatus Conrad L. multicosta Hall 



Ludlowville shale 



The transition from the Skaneateles to the Ludlowville shale is 

 gradual through a few feet in which the rock becomes lighter col- 

 ored, slightly arenaceous and more fossiliferous. These passage 

 beds are succeeded by a hard calcareous stratum containing corals, 

 large brachiopods and many other forms. This stratum is con- 

 tinuous for many miles in central New York producing falls or 

 cascades in numerous ravines. It partakes of the general character 

 of the entire group in becoming more arenaceous toward the east 

 and calcareous toward the west. 



It was described by Clarke in the Report of the New York State 

 Geologist for 1884, pages 12 and 13, as it appears at Centerfield in 

 Ontario county, under the name Basal limestones. 



Lincoln refers to it under the same name in "Geology of Seneca 

 County " [Report of the New York State Geologist, 1894, p. 

 93]. It is the "Centerfield limestone" at the base of the Can- 

 andaigua (Ludlowville) shales described in New York State Mu- 

 seum bulletin 63, 1904. It is well exposed on these quadrangles 

 at the top of the falls in Big Hollow creek, at the top of the falls 

 in the ravine 3 miles east of Romulus, along a small stream i^^ miles 

 south of Fayette, in Kendig creek at MacDougall, along Reeder 

 creek and at Dey landing, also on the west sidte of the lake at tl.i 

 top of the falls of Wilson's creek, near the west line of the quad- 

 rangle. 



The succeeding middle beds are generally soft, gray sandy shale 

 with concretions, calcareous lentils and thin sandy flags, in all of 

 which fossils are common but rather less abundant than in the lower 

 and upper parts of the formation. The upper part is mostly soft 

 gray argillaceous shale, though bands of coarser sediment occur 

 near the top in which fossils are very abundant and the rock quite 

 calcareous. 



The entire formation shows the increase of arenaceous matter 

 toward the east, bands of sandstone in the horizon of the Ludlow- 

 ville shales producing escarpments on the sides of Onondaga valley, 

 and at Hamilton in Madison county, aflfording a fair quality of 

 building stone. 



