GEOLOGY OF THE REAISEN QUADRANGLE 21 



for these beds.^ These rocks are absent from the Trenton Falls 

 region except probably to a small extent in the extreme southeastern 

 portion. They are mapped as occupying the extreme northwestern 

 corner of the Little Falls quadrangle and hence would extend over, 

 to a greater or less extent, upon the Remsen quadrangle. It is 

 highly probable that these rocks are thus present although outcrops 

 are nowhere shown because this region is so deeply covered by 

 glacial drift as to completely conceal all underlying formations. 

 The rocks of this series are transitional in character, the limestone 

 layers being very similar to the Trenton while the shale layers are 

 ver}^ similar to the Utica shale. 



The Utica shale formation. The Utica shale, wherever present, 

 rests directly upon the coarse crystalline beds of the upper Trenton. 

 From the lithologic standpoint the formation is remarkably uniform 

 and free from limestone or sandstone beds. The shale is black, 

 thin bedded to even laminated, and because of its hardness and 

 easy splitting is often popularly miscalled "slate." As seen upon 

 the geologic map the shale is entirely confined to the western part 

 of the quadrangle where it occupies most of the area west of the 

 R. W. & O. Railroad. 



The contact between the shales and the upper, coarse grained 

 beds of the Trenton is a very sharp one although the lowermost 

 beds of shale are more or less calcareous, thus showing that the 

 change from limestone to shale is not so abrupt as the outward 

 appearance of the rocks seems to indicate. The two formations 

 may be seen in close proximity at several places along the stream 

 beds to the north and northeast of Steuben Valley. Perhaps the 

 best locality for observing the contact is along the railroad (R. W. & 

 O.) about } of a mile north of East Steuben station, where the shale 

 and the coarse grained limestone are within i or 2 feet of each other. 

 Beyond the map limits to the south, the sharp contact is well 

 shown in the bed of Nine Mile creek, ij miles southeast of Holland 

 Patent. A low anticline here brings up the upper Trenton Hme- 

 stone with Utica shale resting on either limb. 



The typical Utica shale beds extend well up on the sides of Starr 

 hill where they reach an elevation of about 1560 feet. The lowest 

 shale beds east of Starr hill lie at about 1250 feet. Hence the thick- 

 ness of the Utica shale here must be something over 300 feet. A 



1 Since the appearance of the Little Falls report it has become evident that the formation 

 therein mapped as " Trenton-Utica passage beds " is in reality a shaly eastern representative 

 of the upper Trenton limestone of the type section, as I suKRcstcd at the time [N. Y. State 

 Mus. Bui. 77, p. 63-64]. It seems also that this division is seF)arablo from the Trenton and 

 Utica as a lithologic unit throughout the Mohawk valley. For this shaly piuiso of the upper 

 Trenton I propose the name of Dolgeville shale, the full thickness with both contacts beinR 

 exposed in the banks of East Canada creek just below Dolgeville. [Signtd] H. P. Cushino 



