164 Agricultural Geology of Onondaga County. [April, 



We pass now to the second division of the Onondaga rocks, 

 in the ascending order, by remarking that the red rock passes 

 into the shales which succeed, principally by a change of color; 

 the former becomes first green, by an increase and spread of green 

 spots, till finally the whole mass loses its red color and is merged 

 in an invariable dirty pea green. The whole mass is decompos- 

 able in an eminent degree, and may be distinguished by the entire 

 absence of organic remains — ^by the presence of hopper-form 

 bodies — ^by plaster, which below is in thin beds of a columnar or 

 fibrous structure, and above in heavy masses, which are instru- 

 mental in bending the strata, as represented in fig. 1. The 



G. gypsum beds. 



hopper-form masses are, however, found in the superior part of 

 the formation, and even in the immediate vicinity of the layers 

 which are quarried for hydraulic lime, as at Manlius square. 



The lower mass, in which the thin plaster beds are exposed, 

 is well exhibited at the deep cut and embankments in Camillus. 

 At this place the rocks are exposed nearly deep enough to show 

 the red marl. The junction, however, is rarely to be seen, in 

 consequence of the great amount of debris and soil of the whole 

 formation. The physical changes which it exhibits are those 

 which appear in the successive stages from'soft to hard rocks, and 

 from imperfectly stratified beds to the thin, sharp, ringing layers 

 of the hydraulic limestones. 



