20 NEW YORK STATE MUSEUM 



The quartzite phase of the Potsdam at Fort Ann is very favorably 

 situated so far as transportation is concerned, being in the immediate 

 vicinity of both the Delaware and Hudson Railroad and the Cham- 

 plain canal; nor is quarrying difficult, as the rock is thin bedded, 

 slabby, gently dipping and but thinly covered with drift. It is 

 doubtful, however, if a very large quantity of high-grade rock is 

 obtainable ; most of it is too highly f eldspathic. 



Judging from the chemical analyses of these rocks and their 

 structural features, the granular white quartz sandrocks of the Pots- 

 dam formation are promising sources of supply for glass-making 

 material, and as such merit further investigation ; they may be used 

 also in the manufacture of ferro-silicon. 



THE ONEIDA GLASS SAND (PLEISTOCENE) 



General description. Twenty-five or thirty years ago glass 

 factories were in operation in the villages of Durhamville and Dun- 

 barton, near the east end of Oneida lake, and glass sand was shipped 

 from the area east and north of the lake to factories in Lockport, 

 Lancaster, Ithaca and Clyde. The factories at Durhamville and 

 Dunbarton have long been abandoned, and no glass has been made 

 in the Oneida lake area for many years. 



Mr C. A. Hartnagel, of the New York State Museum, while work- 

 ing in this locality during the summer of 1907 gathered the following 

 data on the glass sand of this region, which have been kindly com- 

 municated to the writer: 



'' Glass sand (near Oneida lake) is found near the surface just 

 below the vegetable mold. In the vicinity of Oneida lake the best 

 quality of sand is found underlain by hardpan, in distinction from 

 clay. Sometimes clay is found beneath the sand, but then the sand 

 is regarded as of not so good a quality. The largest deposits are 

 near the east end of the lake about three-fourths of a mile back and 

 the area extends north and south, most of the area being on the east 

 side of Black creek. The average thickness of the sand is from 

 3 to 6 inches. It is as much as 2 feet thick in the area east of the 

 lake, but not often as thick as that. Around Oneida lake to the 

 north, glass sand is found 4 and 5 feet thick in patches. No glass 

 sand is found on the beaches of Oneida lake . . . (but) from 

 the lake sand is obtained for forges, rolling mills, etc." 



Mr Williams, of Durhamville, a pioneer in the exploitation of 

 these sands, who has extracted, washed and shipped thousands of 

 tons of this material in the past, and to whom the writer is indebted 



