REPORT OF THE STATE PALEONTOLOGIST 1901 537 



inches. These pebbles are in all cases flat like those of a shingle 

 beach on a recent shore. Streaks of coarse grained quartz 

 extend horizontally through some of the finer grained beds. 

 The surfaces of the layers are usually covered by ripple-marks 

 and sections show cross-bedding. No traces of fossils. . 



To the south, east, northeast, and north of this exposure are 

 outcrops of the gray and blue Beekmantown dolomite. No 

 determinable fossils have been found in any of these dolomites 

 and it is now impossible to place them in any particular division 

 of the series. It is also at present impracticable to determine 

 their relations to the neighboring Potsdam. The strikes and 

 dips of the separate exposures correspond sufficiently to allow 

 the assumption that the two formations are here in their normal 

 order of superposition. Other facts, however, seem to point to 

 a different relation. The outcrops are far apart, \ mile at least; 

 and only 3 miles to the southward the two formations are 

 faulted against each other. The lithic characters of the sand- 

 stone seem also to indicate that instead of belonging in the 

 upper part of the formation it should be placed below any of the 

 known fossiliferous horizons. 



Dry Mill brook section in the toion of Peru, Clinton co. 



Dry Mill brook is a small stream that flows into the Ausable 

 river about If miles north of the mouth of Ausable chasm. 

 Just west of the crossing of Telegraph street the steel gray 

 Beekmantown dolomite, 150-E6, forms ledges in the field. No 

 fossils occur here. 



Farther down the stream at the crossing of Lyon street, 1J 

 miles to the east, the dolomite, 150-E5, is again seen in the bed 

 of the stream and continues from this point for 350 feet from 

 the road bridge. At this point the dolomite is faulted against 

 the Potsdam by a normal fault with downthrow to the west. 

 To the east the Potsdam extends for a distance of 600 feet, with 

 .a thickness of 20 feet. The Potsdam here is a coarse sandstone 

 of dark color with some layers that contain black pebbles, and 

 a few thin layers of gray arenaceous shale. No fossils were 

 found in it. Its horizon is unknown. 



