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NEW YORK STATE MUSEUM 



term Onondaga limestone was applied to the lower and purer layers 

 and the name Corniferous limestone attached to the chert-bearing 

 upper deposits, but this distinction, while an important one locally, 

 has given way to the application of the term Onondaga to the entire 

 formation. 



Outcrops of the Onondaga limestone are frequent in the vicinity 

 of the road leading from Jamesville to Mahlius. A large quarry on 

 the east side of the Jamesville reservoir^ in this rock and there are 

 large exposures of it along the creek above the Alvord quarry south 

 of Jamesville; also on the road from Jamesville to East Onondaga 

 and along the east side of the Onondaga valley in the Reservation 

 and other quarries. Near the highway south of Indian Village and 

 along the west branch, of Onondaga creek to 3 miles northwest of 

 South Onondaga it is also well seen. 



Fossils are everywhere abundant but not always easy to extract. 

 The species which the observer may expect to find are those of the 

 formation generally and therefore the student is referred to such 

 lists of these fossils and detailed descriptions of them as have been 

 given in other publications on this subject. The most common how- 

 ever are the following : A try pa reticularis, Leptaena 

 rhomboidalis, Strop heodonta con cava, S. i n - 

 aequistriata, Spirifer acuminatus, S. divari- 

 catus, and some other brachiopods ; the cephalopods 

 Cyrtoceras undulatum, Gyroceras trivolve; 

 the trilobites O d o n t o c e p h a 1 u s s e 1 e 11 u r u s and P h a - 

 cops cristata var. p i p a ; large crinoid columns are also 

 common at some horizons. 



• Marcellus shale 



Including the Agoniatites limestone 

 The term Marcellus shale has been generally applied heretofore to 

 the entire series of black, blue black and blue gray shales lying 

 above the Onondaga limestone and the presumptive base of the 

 Hamilton series of shales and limestones. The distinction between 

 this formation and the shale formation of the Hamilton has always 

 been a matter of pure convention as one mass passes into the other 

 with very gradual change in color and equally gradual change in 



