GEOLOGY OF THE W ATKINS AND ELMIRA QUADRANGLES 5 



Genundewa limestone 



This characteristic layer taking its name from exposures on Can- 

 andaigna lake is here one foot thick and divided in three uneven 

 layers separated by thin shaly seams. It is hard, compact or con- 

 cretionary and unevenly impure. The layers are usually separated 

 by thin shales, are light bluish gray, sometimes mottled or clouded 

 and weather to a brownish gray. At some exposures the limestone 

 is principally composed of the minute pteropod Styliola fis- 

 sure 1 1 a , and for this reason has been commonly designated as 

 the Styliola limestone. 



This stratum emerges from the water of Seneca lake 443 feet 

 A. T., 1 mile south of Fir Tree point, rises slightly toward the point 

 for one half mile to about 6 feet above the lake level and then 

 as slightly descends, disappearing under the water on the north side 

 of Fir Tree point. On account of the eastward dip of the strata 

 the limestone is covered by water on the east side of the lake. The 

 formation is better developed and exposed farther to the west 

 specially at Genundewa point and other places on Canandaigua lake ; 

 also at Bristol Center and near the foot of Honeoye lake in Ontario 

 county; at Mt Morris below the Western New York and Penn- 

 sylvania Railroad bridge and at the high cascade in Little Beards 

 creek at Moscow and other places in Livingston county. It may be 

 traced still farther westward becoming thinner and more compact 

 but retaining its peculiar features to the mouth of Pike creek in the 

 town of Evans on the shore of Lake Erie. It is not known east of 

 Seneca lake. 



No fossils except Styliola fissurella have been found 

 in this rock in this quadrangle but in Ontario and Livingston coun- 

 ties it contains a very considerable fauna, which is cited in full in 

 Museum bulletin 63 and memoir 6. 



West River shale 



We have elsewhere made note of the fact that in the necessity of 

 subdivision for the purpose of more exact correlation of the original 

 Genesee slate of Professor Hall it has seemed best to retain that 

 name in application to the lower part of the series as exhibited on 



