42 



Report of the State Geologist. 



The relations of the fault which branches to the southward, 

 are plainly exhibited particularly along the road and in quarries 

 three miles east of St. Johnsville, and also in the slopes and in 

 an old quarry south of the river. This dislocation brings the 

 middle beds of the Calciferous up to a horizon about 100 feet 

 above the base of the Utica slate. 



The Utica slate east of the fault dips eastward at angles 

 averaging about 20°, but this upturn dies out rapidly in a few 

 rods. The river valley is cut across the eroded block into the 

 Calciferous with Trenton and Birdseye beds lying on the higher 

 terraces, and the Utica slate above. Along a portion of the 

 north side of the block the latter has been removed and the 

 Trenton and Birdseye beds abut against the Calciferous along 

 the main fault. The following section illustrates the relation of 

 this inclosed block : 



Figure 6.— Section across the Mohawk river, two miles below St. Johnsville, looking west. U. Utica 

 slate. T. Trepton and Birdseye limetones. C. Calciferous. Vertical scale slightly exaggerated. 



The beds in the inclosed block dip westerly, and at St. Johns- 

 ville the Utica slates come in and underlie the upper portion of 

 the village. These slates are penetrated by a well at the con- 

 densed milk factory on Zimmerman's creek, and according to 

 Yanuxem they were once exposed, together with upturned edges 

 of Trenton and Birdseye limestones, in the creek, near the side 

 of this factory. The Calciferous rises abruptly in clijffs_ just 

 beyond and curves around to the west and south on the upthrown 

 side of the fault. Yanuxem states that " the slate was also 

 exposed at the little bridge near by, in the bottom of the creek, 

 inclining away from the Calciferous, which rises 100 feet above 

 it. The slate dips to the south at an angle of about 45°. It 

 shows much white carbonate of lime and some pyrites. The 

 Calciferous at its junction with the slate is in one part fractured, 

 the parts cemented forming a breccia."* Below this are heavy 



* Geology of New York, Part III, comprising the survey of the Third Geological District, 1842, p. 206. 



