42 NEW YORK STATE MUSEUM 



from his work already given (see page 32), his mere mention of the 

 so-called Calciferous (Little Falls dolomite) may possibly refer to 

 the occurrence near Hope, though he more likely meant the outcrop 

 of this rock in the valley at Wells where it lies a mile or more south 

 of the big Trenton exposures. The dolomite near Hope lies over 

 6 miles by air line and nearly 8 miles by road south of the Trenton 

 at Wells. Also the big exposures of dolomite at Wells would more 

 likely have been known in the early days. At any rate, no descrip- 

 tion of the interesting Paleozoic rock outlier near Hope has ever 

 been given. 



This outlier is considerably smaller than the one at Wells and less 

 satisfactory to represent upon the geologic map. It lies 8 miles 

 (air line) northeast of Northville at which place occur the nearest 

 outcrops of the general Paleozoic area. The outlier, as shown on 

 the map, has a length of nearly 3 miles and a greatest width of 

 half a mile, though admittedly exact boundary lines can scarcely be 

 drawn. The character of the valley bottom and the general struc- 

 tural relations strongly suggest a Paleozoic rock area fully as large 

 as indicated on the geologic map. Actual outcrops are all confined 

 to the narrow belt as mapped, the rest of the area being wholly con- 

 cealed under Pleistocene deposits. This mass of Paleozoic strata 

 has been sharply down-faulted against the Southerland mountain 

 mass, the maximum displacement of the fault being fully 1000 feet. 

 On the east side of the valley the topography and the straight line 

 of outcrops of Precambric rocks at the base of the steep slope very 

 strongly suggest the existence of a fault there. If so, this outlier, 

 like that at Wells, is of the nature of a " graben." 



Potsdam and Theresa beds. Potsdam sandstone is nowhere 

 visible, while the Theresa beds are seen in only two small outcrops 

 as indicated on the geologic map. One of these, lying just east of 

 the road, is 30 or 40 feet long and shows one bed of sandstone and 

 one of dolomite with strike north 20° east, dip 20° west. This ex- 

 posure, because of the sharp difference in dip between it and the 

 close-by Little Falls dolomite, is probably separated from the dolo- 

 mite by a minor fault. The other outcrop barely shows at the 

 western base of the belt of Little Falls dolomite (see map). 



Little Falls dolomite. The principal outcrops are of Little Falls 

 dolomite and they are wholly confined to the single belt with strike 

 north 10° east as shown on the geologic map. Of these, the best 

 exposure lies just at the river's edge on the south side where the 

 dolomite beds strike north 5° east and dip 16° west. For 60 yards 



