536 NEW YORK STATE MUSEUM 



Again at Schuyler Falls, 2 miles down stream to the east- 

 ward, the sandstone is exposed in the bed of the river. The 

 rock at this point, 129- Al, is about 50 feet thick; a heavily 

 bedded white and gray quartz sandstone, with some intercalated 

 layers of thinly bedded sandstone. These latter are ripple- 

 marked and cross-bedded, contain some pebbles of green shale, 

 and Lingulella and Obolella, and recall the lowest Lingulella- 

 bearing bed, 125-A2, of the Kent Falls section. 



No higher beds of the Potsdam are seen above those at Schuy- 

 ler Falls; the next exposure being of the Beekmantown, 126-A1, 

 with Ophileta and Lingula fragments, in the river bed at the 

 crossing of the Salmon river road at South Plattsburg, 3 miles 

 to the east. 



Little Ausable river section from Peru to month of river 



At the road-crossing in the village of Peru the Beekmantown 

 dolomite appears in the bed of the river below both the upper 

 and lower dams. From this point the river flows approximately 

 along the strike of the beds to the northeast for 1J miles to 

 Lapham Mills, where its course changes to southeast and it 

 flows over ledges of Potsdam sandstone. 



The sandstone at Lapham Mills, 126-C3, has a thickness of 

 about 50 feet, the exposure extending for ^ mile down the river 

 from the railroad bridge, and is in some respects different from 

 that seen at any of the other localities. The rock is generally 

 a coarse sandstone of gray color with many layers of brown and 

 red. These red layers are of great hardness and glassy frac- 

 ture, and full of large grains of pellucid quartz that often attain 

 a diameter of -J inch. Kipple-marks and cross-bedding are 

 common. No traces whatever of fossils. 



One half mile farther down the river in an easterly direction is 

 another exposure of Potsdam, 126-C2, forming ledges in the 

 river bed. A total thickness of 10 feet is shown. The bedding 

 is very irregular, the layers varying from 1-4 inches in thickness, 

 often with shaly partings. The color ranges from white to gray, 

 greenish, and brown; and the texture from fine to coarse. Some 

 layers contain pebbles of, schist and slate that attain sizes of 1-3 



