NIAGARA LIMESTONE. 



345 



noted in Waukesha county are still discernible thougli the texture and composition hora 

 are superior. Noi-th of this point these beds drop down to near the level of the waters 

 of Green Bay, and alternately appear and disappear with the undulations of the strata, 

 as far north as the Light 'House point opposite Chambers' Island, where they finally 

 disappear beneath the w^aters of the bay. 



BTEON BEDS. 



Eeposing upon the coarse textured Mayville beds last described, 

 lies a somewhat thicker series of beds, bearing a strong contrast to 

 them in color, texture, stratification, and general character. The 

 ledges of the former are rough in aspect and dull in color, those of 

 the latter are usually smootli and white. The texture of the former 

 is generally coarse, and often very uneven, that of the latter is always 

 fine, and sometimes so close and compact as to be lithographic in 

 character. The transition from the one to the other is usually ab- 

 rupt and well defined. These facts eminently justify the distinction 

 here adopted. 



To describe somewhat more precisely, it may be remarked, that the 

 color, where not white, is a light gray or cream tint, sometimes lined 

 or mottled with pink in a very handsome manner. The texture is 

 usually either very close and compact, or very fine grained. In the 

 former case, it is hard and has a somewhat glassy fracture, and the 

 edges of the fragments often appear translucent. Such portions 

 often have a grayish water hue. The other class usually has a regu- 

 lar or conchoidal fracture, and is opaque. Some portions are finely 

 laminated, and where these lamina; are colored, as sometimes occurs, 

 a beautiful efl^ect is produced. 



The bedding is either thin, producing excellent flagging, or attains 

 more considerable dimensions, and furnishes cutting and building 

 stone. Some of the strata are habitually undulating, and some, in the 

 weathered ledges, are excessively fractured in a conchoidal manner, 

 while others are verticallj' fissured. 



Argillaceous partings are occasionally present, and the rock, though 

 rarely, becomes shaly. Mvdcraoks and ripple marks were observed. 

 The following analysis of rock taken from Butler's quarry (Sec. 10, 

 Byron), made by Prof. Daniells, for the survey, shows it to be a near- 

 ly pure dolomite: 



•^ Fer Cent. 



Carbonate of lime 5i'^8 



Carbonate of magnesia n or 



Sesquioxide of iron 0-26 



Sesquioxide of alumina 0.10 



Insoluble residue 0.67 



Water ^■}^ 



-Mai 99.87 



