2o 4 POPULAR SCIENCE MONTHLY. 



liibited in these easily recognized and contrasted strata are of great 

 significance when taken as illuminating the more obscure relations of 

 the Precambrians of the interior mountains. 



One interesting corollary of the great northeast and southwest 

 breaks is that a series of basaltic dikes which are widely distributed, 

 which followed the metamorphism of the Precambrian rocks, but 

 which preceded the Potsdam, almost always come up through them 

 and suggest that the breaks go far enough down to have tapped off a 

 reservoir of basic rocks. 



The Drainage. — The waters from the Adirondacks flow into both 

 the Hudson and the St. Lawrence Rivers. On the south and southwest 

 they either go directly to the former which rises in their very center; 



Fig. 9 Spkuce Mountain, near Huletts, Lake George— and viewed from the northwest. 



A fault — escarpment faces the observer. 



or else they pass first through the Mohawk. On the north and east, 

 the waters reach the St. Lawrence via Lakes George and Champlain, 

 and on the northwest via Lake Ontario or directly to the great river 

 itself. The drainage of the high mountains, however, goes almost 

 entirely to the Hudson or to Lake Champlain. 



The chid' livers actually in the area are the Hudson and its prin- 

 cipal tributary north of Waterford, the Sacondaga, both of which will 

 be shortly described in greater detail; West Canada Creek, and minor 

 tributaries of the Mohawk; the Black, flowing into Lake Ontario; the 

 Oswegatchie, Grass, Raquette, and Salmon-Chateaugay, which pass di- 

 rectly into the St. Lawrence; and the Saranac, Ausable and the outlet of 



