GLACIAL WATERS IN BLACK AND MOHAWK VALLEYS 9 



A series of parallel streams from the Adirondacks joins the Black 

 river on the east, two of which, the Moose and Beaver, are even 

 larger than the Black river proper. Three factors produce this 

 heavy drainage : the large area, the high altitude and the west-facing 

 attitude, the two latter producing the condensation of moisture from 

 the prevailing westerly winds. In glacial time the wind direction 

 was probably similar to the present and we have every evidence that 

 in this area the precipitation and drainage were very large. 



The -tributaries to the river from the west are short and weak, 

 with the exception of the Deer river which joins a few miles above 

 Carthage. The lack of western tributaries is due to the narrowness 

 and steepness of the west wall of the basin and its lee position with 

 reference to moisture-laden winds. 



The prominent physiographic feature of the Black river basin is 

 the Boonville-Carthage valley. Boonville is situated at the lowest 

 col or pass between Black river waters and drainage to the Mohawk, 

 through the Lansing kill, the altitude of the divide being about 1130 

 feet. (The summit level of the canal, in a rock cut, is 1120.) 

 Carthage lies on the west side of the mouth of the valley, with alti- 

 tude of 740 feet on the river bridge. 



The west wall of the valley rises steeply in scarps and terraces of 

 limestone until capped by shales at the height of 1800 to 1900 feet. 

 The east wall, with irregular topography, rises slowly into the 

 Adirondacks. The topographic contrast between the two sides of 

 the valley is well shown in plate 3. 



The mantle of drift on the west valley wa;ll is scanty ; but on the 

 east slope the glacio-lacustrine deposit is remarkably heavy (see 

 p. 15). Crystalline rocks underlie the east slope and the valley 

 bottom and appear in places along the foot of the west slope, con- 

 spicuous from the railroad. Bosses of the crystallines project up 

 through the alluvium of the valley, producing the peculiar topo- 

 graphy indicated by the contouring on the Carthage sheet east and 

 north of the city. These protruding masses, developed by 

 atmospheric erosion in preglacial time and rubbed into smoothness 

 by the ice abrasion and then half buried in stream and lake deposits, 

 are conspicuous features at many points in the valley. Tens of 

 thousands of huge blocks of the crystallines have been spread by the 

 glacier over the country to the southward, especially along the 

 moraine belt extending southeast from Boonville, as shown in 

 plate 18. 



Apparently this great north-sloping valley of the Black river was 

 developed by millions of years of weathering and stream work 



