GEOLOGY OF THE AUBURN-GENOA QUADRANGLES 2J 



and Yates counties. It diminishes westward to i foot on the shore 

 of Lake Erie and eastward to 65 feet on the Genoa quadrangle and 

 is not known east of Smyrna, Chenango co. 



Genundewa limestone 



This formation which is fully described in State Museum Bulle- 

 tins 63 and 118, is a band of thin limestones and calcareous shale 

 extending from Gorham, Ontario co. to Lake Erie. The limestones 

 are composed in a large proportion of the shells of the minute ptero- 

 pod Styliolina fissurella (Hall) and was formerly known 

 as the Styliola limestone. Except in a few small patches the lime- 

 stone does not appear in characteristic condition in the Seneca 

 lake valley, but its position is clearly indicated by a band of 

 light gray calcareous shale containing a row of large concretions. 

 Fossils common to the limestone farther west, particularly Stylio- 

 lina fissurella, arel abundant in both shales and concretions, 

 \_see State Mus. Bui. 128]. The formation is less clearly de- 

 fined in the Cayuga lake valley but may be seen in the rock wall at 

 the Trumansburg creek falls at Frontenac point and at Taghanic 

 Falls. 



On the east side of the lake it appears as a rather faint gray band 

 in the cliffs near the south line of the quadrangle about 30 feet below 

 the heavy sandstone that here marks the base of the Cashaqua shales. 



The shale is darker, the concretions smaller and fossils more rare 

 here but in the southern part of the Salmon creek valley it is more 

 calcareous and fossils are more common. 



It is exposed at the top of the falls in the ravine 2^ miles north- 

 east of Ludlowville and in a 10 foot cliff on the west side of Salmon 

 creek 20 rods north of the highway, i mile south of the forks of the 

 creek. At this exposure the bed of the stream is black shale in which 

 Orbiculoidea lode n sis, Liorhynchus quadri- 

 costatum, Chonetes lepidus and other Genesee fossils 

 are common, and the gray band about 10 feet thick with a row of con- 

 cretions I to 2 feet in diameter and 5 to 8 feet apart at the base, 

 succeeded by i foot 8 inches of soft gray shale and a harder stratum 

 of calcareous shale 8 inches thick that is followed by 6 feet of gray 

 shale. This horizon is exposed in 3 ravines on the east side of 

 Salmon creek valley between Genoa and Venice Center, but the 

 formation is not so clearly defined, the overlying shales, which are 

 dark to black in the Seneca lake valley, differing but little here in 

 appearance from these beds. 



