042 



Repqet of the State Geologist. 



by Vanuxeni. The statement that these massive fucoidal layers are from ten 

 to fifteen feet in thickness and confined to the upper twenty-five feet of the 

 formation is misleading, for layers of similar structure and appearance occur 

 along the Mohawk valley at least 130 feet below the top of the formation. 

 In a quarry on the east side of the creek, near the top of the bank, are layers 

 of the massive fucoidal limestone containing specimens of Oplvileta compla- 

 a at a. Van. 



J 4 . Thin layers of dark blue, fossiliferous limestone, well exposed ]7 F = e 23o 

 in the steep bank above the fall and highway bridge, from sixteen and one 

 half to seventeen feet in thickness. Trenton limestone. 



A 5 . Very black, argillaceous shale which forms the steep banks 2 m=\m 

 <>f the creek in the second gorge. Utica slate. The 230 feet do not represent 

 the thickness of the formation in this region, but should be considered to 

 refer simply to its lower part which is admirably exposed in this gorge. 



The above section is important from the fact that it shows the thinning 

 <>f the Trenton formation from an approximate thickness of 109 feet at Little 

 Falls, twenty miles northwest, to about seventeen feet in Flat creek. 

 Furthermore both the Birdseye and Black river limestones are wanting. The 

 dip varies from 5° to 7°, N. 84° W. along the lower gorge. 



Some ten years ago, a diagrammatic section of this creek was published, 

 which represented the Caleiferous, Chazy, Trenton and Utica formations.* 

 The thickness of the Trenton limestone is given as "from ten to fifteen feet,"f 

 which is the only measurement recorded, and the Chazy limestone appears 

 not to be present. 



West Shore Railroad Cut Section. 



About one and one-fourth miles below Sprakers is the "West Shore rail- 

 road cut, with a nearly perpendicular southern wall of Caleiferous sandrock 

 which reaches a height of 350 feet. 



VII B 1 . Top of the Laurentian gneiss, exposed at the eastern end 

 of the cut. 



Z? 2 . Basal part of Caleiferous sandrock extending from the top 2 fl et 25 

 of the gneiss, 1,500 feet along the side of the railroad to the point where the 

 nearly vertical cliff of Caleiferous was measured. The thickness is estimated 

 from the dip which is about l v , N. 85 e W. 



IP. From the railroad level to the brow of the cliff forming the 3 J tH . -, ; , 85 

 nearly perpendicular wall of the railroad cut, The cliff is composed entirely 



* Fifth Annual Report of the State Geologist [New York], 1HH0, p. !). 



+ ma,, I>. 8. 



