Prosser — Hamilton a\d Chemung Series. 



ilton] is the locality where it is well characterized." 5 On University Hill are 

 several exposures of arenaceous shales and thin sandstones. A Ik mt eighty 

 feet above the main buildings of Colgate University is a small excavation in 

 fairly coarse, arenaceous shales, in which Rhynchonellas are common. Near 

 the summit of the hill is the large university quarry, with an exposure of 

 twenty feet of shales and sandstones.. Coarse, arenaceous shales predominate 

 in the upper part of the quarry with thin sandstone strata, which were used for 

 the older university buildings. In the middle and lower part of the quarry 

 the sandstones are thicker and of better quality. The stone in the laboratory 

 building came from the middle part of this quarry, and that in the theological 

 hall from the bottom of the quarry, which furnishes a blue sandstone, eight 

 inches or more in thickness. Fossils are common, particularly in certain 

 layers, the most abundant being Spirifer mueronatus (Con.), Rill., some of the 

 specimens of which are very much extended along the hinge line, representing 

 the extremely mucronate form of the species; AmbocceUa wmbonata (Con.), 

 Hall, and Tropidoleptus carvnafocs (Con.), Hall. This quarry is supposed to 

 be the one described by Vanuxem when he said: "At the top of the hill, 

 about twenty feet of sandstone and shale are exposed. * * " Fossils are 

 numerous at the quarry, among which are the mucronated delthyris | Spirifer 

 m&cronatus (Con.), Bill.], the one figured in the wood-cut being from this 

 locality.' 1 2 The figure of the Spirifer just mentioned ' 5 indicates that it is one 

 of the strongly mucronate forms similar to those which I have mentioned as 

 occurring in this quarry. 



To the east of Hamilton township is Brookfield township, the geology of 

 which has been carefully studied by the writer. Near the village of North 

 Brookfield, in the valley of the East Branch of the Chenango river, and eight 

 miles north of east of Hamilton village are excellent exposures of the rocks in 

 the lower and middle part of the formation. Somewhat arenaceous shales in 

 the bed of a small brook just north of the village contain numerous specimens 

 of AmbocceUa umbonata (Con.), Hall, but other fossils are not abundant. The 

 species noted from this brook are as follows : 



1. AmbocceUa wmbonata (Con.), Hall. 



2. Prochtctella Shumardiana, Hall. 



3. Stroplialosia trwncata, Hall. 



1 Fourth Annual Report. (Assembly Doc. No. 50. i 1840, p. 890. Also see the description of the Hamilton group in Vanuxcm's 

 Final Report, 1842 (Geology New York, Part III., p 157). Again, under the description of the formations of Madison county, 

 Vanuxem wrote : '-The hill at the seminary [now Colgate University) is the most favorable point for the examination of the 

 group [Hamilton] as it appears in the county." (Ibid., p. 276. ) 



2 Geology of New York. Part III., 1842, pp. 157, 158. 



3 Ibid , Fig 3, p. 1.50. 



