96 



Repobt of the State Geologist. 



that valley. 1 From the above statements it may readily be seen that the 

 section of the Chenango valley is a very important one as regards the classifi- 

 cation of the Middle and Upper Devonian, especially as to where the line 

 separating the two series is to be drawn. On tins account it is considered 

 advisable to describe somewhat fully all the formations exposed along the 

 river valley, beginning with the base of the Middle Devonian, the Marcellus 

 shale, and closing with the Chemung group near Binghamton. 



Sangerfield and Madison. 



Onoiahaja Linn-stone and Marcellus Shale. — The eastern branch of the 

 Chenango river rises in the eastern central part of Sangerfield township, 

 Oneida county. The greater part of the township is covered by rocks belong- 

 ing to the Marcellus and Hamilton formations. The Onondaga limestone 

 crosses the northern line of Sangerfield township near its central part, but soon 

 returns into Marshall township for a short distance, and then cuts across the 

 northwestern corner of Sangerfield, and extends halfway across the northern 

 part of Madison township before it again turns northerly. In the northern 

 part of Madison township tin- Marcellus is mostly covered, and there are but 

 few exposures. 



I hi miltnii Formation . — The lower part of the Hamilton formation, which 

 consists of thin sandstones alternating with arenaceous and argillaceous shales, 

 is better exposed than the Marcellus. The hill north of Solsville shows 

 coarse, arenaceous shales containing large fossils, and also a sandstone stratum, 

 two feet in thickness, which was quarried and used in the construction of the 

 Chenango canal. Above the sandstone and arenaceous shales are blocky 

 argillaceous shales, in w hich lAorliynclius is quite common, but other fossils 

 are rare. The shales contain many small concretions which, on w eathering, 

 become considerably iron stained. Near the base of the hill, one-half mile 

 southwest of Madison village, are ledges of coarse, arenaceous shales, in which 

 Spirifer granulosus (Con.) Hall, Stropfaodonta, Chonetes and large Lamelli- 

 branehs occur. 



Hamilton and Brookfield. 



Six miles south of Madison is Hamilton, a classic town to the geologist, 

 since Vanuxem first applied the name Hamilton group to the exposures of 

 rock in the vicinity of this village, stating that "West Hamilton [now Ham- 



1 It is tine that Vanuxem reported the Genesee elate at North New Berlin (correctly New Berlin) (Geology New York, Part 

 III., 1H42, ]). '.29;!), which ie in the Unadilla valley, some thirteen miles southeast of the last place noted in the Chenango valley, hut 

 careful search in the vicinity of New Berlin failed to reveal the Genesee slate, although there is an excellent exposure showing 

 the contact of the Hamilton and Portage. 



