GEOLOGY OF THE VICINITY OF LITTLE FALLS 33 



above are no rock exposures for 2 miles, when Utica shale appears 

 at an altitude 300 feet higher. 



The two brooks which come down from the west, the one just 

 above, and the other just below the county house, show the upper 

 part of the section and the contact between the passage beds and 

 the Utica, though their sections are much more interrupted by 

 breaks than is that of Stony creek. The combined section of the 

 three creeks shows a thickness of about 100 feet of Trenton and 

 an equal thickness of the passage beds, or 200 feet in all between 

 the Low vi lie and the Utica. 



There are also most excellent Trenton exposures along East 

 Canada creek, the best being just above Ingham Mills, where the 

 full thickness is shown in a cliff face which is unfortunately most 

 inaccessible even at low water, since the full volume of the stream 

 hugs that bank. A mile farther up stream it again shows magnifi- 

 cently, being brought up by a low fold, but here the base is not 

 reached and the summit is cut off by a fault which crosses the 

 creek.^ Up the little brook, above the Black river limestone 

 locality already referred to southeast of Ingham Mills, an uninter- 

 rupted thickness of nearly or quite 40 feet of Trenton appears, 

 overlying the Black river. The Trenton hereabouts is nearly or 

 quite 50 feet thick, and the passage beds have a nearly equal thick- 

 ness. This is somewhat less than half the thickness shown along 

 West Canada creek, and the many exposures elsewhere indicate 

 a progressive thinning of the formation eastward. 



From 13 to 15 miles northwest from Middleville are the noted 

 Trenton falls and gorge along West Canada creek. Here the 

 Trenton has a measured thickness of 270 feet, with neither the 

 base nor summit exposed, so that the true thickness is an un- 

 known, but likely small amount in excess of that figure.^ The 

 same distance to the southeast from Ingham Mills, down the 

 Mohawk at Canajoharie, the thickness has diminished to 17 feet, 

 [plate 10], is lithologically rather like the rocks here classed as 

 passage beds, and the lower part of the Utica seems to have some- 



^Clarke, J. M. U. S. N. Y. Handbook 15, p.61. 

 ^Prosser. X. Y. State Geol. 15tli An. Rept. 1895, p.62G. 



