124 NEW YORK STATE MUSEUM 



upon the matter. A study of the section at Middleville, 9 miles 

 northwest of Little Falls, seems, however, to indicate that both 

 formations thin to the north owing to overlap, and that the Tribes 

 Hill pinches out long before the Little Falls does. In the Middle- 

 ville section the Tribes Hill has apparently disappeared; certainly 

 the fossiliferous, dove limestone beds do not occur. Since the 

 formation still has a thickness of 50 feet at Little Falls and has 

 not been thinning westward from Cranesville at a rate exceeding 

 2 feet per mile, it is not impossible that this sudden disappearance 

 is attributable to the distance north, rather than the distance west 

 from Little Falls. However, in mentioning the average westerly 

 reduction of the formation it is not to be understood that we regard 

 this as taking place gradually. On the contrary, as intimated in 

 the preceding paragraph, the warping of the underlying surface of 

 Little Falls dolomite renders the suggestion of gradual diminution 

 quite impossible; and the same reason might very well cause rapid 

 thinning west of Little Falls. 



At Middleville we measured the following section up the creek 

 which comes into the town from the east : 



SECTION AT MIDDLEVILLE 



Feet Inches 



25 Trenton limestone with Dalmanella common in 

 lower 6 feet and Prasopora simulatrix 

 abundant above that 60 



Hiatus 



24 Thin bedded, dove limestone with irregular summit ; 

 abundant Phytopsis, and Tetradium cellu- 

 1 o s u m ; typical Lowville 13 



23 Concealed 2 



22 Thin bedded, light colored, sandy limestone with 

 abundant quartz grains ; much bored by worms of 

 large size; upper 2 inch layer a calcareous sand- 

 stone, at base of which worm tubes cease; 1 foot, 

 5 inches to 2 2 



21 Cobbly, conglomeratic, calcareous sandstone, black to 



brown in color 10 



20 Irregular bed of calcareous, small-pebbled quartz 



conglomerate ; base of Lowville I 



Hiatus and unconformity 



19 Compact, very fine grained, light bluish gray dolo- 

 mite 3 



