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 828 NEW YOKK STATE MUSEUM 



Owing to its liiglily ferruginous nature, it tends to blister when 

 burned to vitrification unless lieated very slowlj. 



Clinton. The Clinton group is sbale-b earing in its lower mem- 

 bers in eastern Wayne co. It is a bright green shale and is about 30 

 feet thick. At Sodus Point the shale is purplish. It occurs at other 

 localities, but is very thin, not more than 2 to 4 feet. (Hall. 

 Geology of the Mh dishnct of New York, p. 59) The second 

 green shale of the Clinton group is less brilliant in color and every- 

 where full of fossils. It is well exposed at Rochester and at Wol- 

 cott furnace, in the banks of the creek, where it is more than 24 

 feet thick. The shale is probably frequently calcareous. 



Niagara. Though a prolific shale formation in New York state, 

 the writer has not seen any exposures of it which were not eithier 

 very silicious or calcareous, so that it would probably not work well 

 for the manufacture of clay products. When ground and mixed 

 with water it possesses no plasticity. 



According to Prof. Hall {Geology of the Jf.th district of New 

 Yorh. p. 80), the IsTiagara shale forms a member of great develop- 

 ment in the lower part of the IsTiagara group. It is a dark bluish 

 shale which, on exposure, forms a bluish gray, marly clay. It is 

 well shown at Lockport, in the sides of the gorge at Rochester, just 

 below the railroad bridge, and at many localities in Wayne and 

 Monroe co. The lower layers of the shale are less calcareous 

 than the upper ones. 



The following is a partial analysis of this shale, the sample 

 taken from the gorge at Rochester (16th ann. rept U. S. geol. surv. 

 pt 4, p. 569). 



Silica 28 . 35 



Alumina ^ 10 . 47 



Ferric oxid 1.90 



Lime 21 . 47 



Magnesia 8.24 



Alkalis 5 . 73 



76.16 



II. T. Vulte, analyst 



