REPORT OF THE DIRECTOR AND STATE GEOLOGIST rl03 



to denuding agents by the many different rocks present. 

 Quartzite builds high, steep ridges, the schists more rounding 

 hummocks, while the crystalline limestones are most frequently 

 cut into valleys. 



Where, as in the belt just south of the river, the schists occur 

 alone, the topography is less rugged, though still lacking the 

 flowing contours most common in the granite-gneiss. The latter 

 gives a. rolling surface, with many dome-like masses, sometimes 

 rising to considerable ridges. Abrupt slopes and cliffs, so com- 

 mon in the schist-limestone regions, are the exception. 



The most constant topographic form is, how T ever, presented by 

 the Potsdam. This formation everywhere produces a practically 

 flat surface, terminated on all sides by steep scarps, falling 

 away to the crystalline rocks of the valley bottoms. 



All through the region the Potsdam shows numerous beauti- 

 fully glaciated surfaces, the striations having a northeast and 

 southwest trend. A till, poor in pebbles, is the prevailing glacial 

 deposit. In the valleys it is w T ell developed, and has a pro- 

 nounced rolling surface. On the uplands it is much thinner. 

 Kame sands and gravels are not abundant. 



Of the economic geology of the region there is little to be said. 

 The lead industry of Rossie is of historic interest, and is kept, in 

 mind by the beautiful calcites, galenas, and pyrites of the local- 

 ity, to be seen in every large collection. 



At one time the Potsdam sandstone w ? as the basis of a glass in- 

 dustry at Redwood, but today the factory itself is gone. The 

 large furnace plant at Rossie and the site of another near Red- 

 wood are the only reminders of an iron industry once of some im- 

 portance. 



On Grindstone island, the granite w^as w 7 orked on a consider- 

 able scale a decade since, 1 but today all of the quarries are idle. 

 In view, however, of the excellent quality of stone and the facili- 

 ties for shipment, it is probable that the industry will be revived 

 at no distant date. 



'Smock, J. C. Building stone in the state of New York. N. Y. state 

 museum bul. 3. 35-36. 



