FEATURES IN THE MANLIUS LIMESTONE 



357 



In figure 5, which represents a section shown in the east wall of the 

 quarry about 2,000 feet south of the stone crusher, the surface of the 

 Manlius limestone is seen to be strongly excavated, the excavation being 

 mainly rilled by beds of Onandaga limestone, the chert- free lower por- 

 tion of which is here about 10 feet thick, while in other portions of the 

 quarry it is only from 2 to 3 feet in thickness. Between the two lime- 

 stones occurs a mass of shale and conglomerate, having a total thickness 

 in the central portion of something over a foot. The lower 6 or 8 inches 



Figure 5. — Excavation in Manlius Limestone. 



consist of a limestone conglomerate, the pebbles being fragments of the 

 underlying limestones, flat, but well rounded on the margins, and show- 

 ing protracted wearing. They are firmly imbedded in a matrix of in- 

 durated quartz sand which surrounds them and fills in all the interstices. 

 This bed thins out to nothing on both sides of the channel. Overlying 

 this conglomerate are about 6 inches of shale and shaly limestone, fol- 

 lowed by the Onondaga limestone. The width of the channel is about 

 18 feet, its depth about 31 feet. 



From the point where the channel occurs the contact can be traced 

 continuously for a. thousand feet or more eastward in the cliff, showing 

 frequently a thin shaly bed, with here and there grains of quartz sand, 

 between the two limestones. 



A SANDSTONE DIKE 



In the summer of 1893 the writer's attention was attracted by masses 

 of pure quartz sandstone occurring with the fragments of the Bullhead 

 limestone piled up in the refuse heaps in the cement quarries. Exam- 

 ination showed that this sandstone was intimately associated with the 

 limestone and was not erratic in its nature. On inquiring of the quarry- 

 men, the source of these fragments was found to be a mass of sandstone 

 in the eastern wall of the main quarry somewhat southeast of the mill. 

 The occurrence was designated as a '' pocket" by the quarry men, the 

 quartz sandstone being inclosed on all sides by limestones. A careful 



