220 The Americaii Geologist. A,prii, i89s 
and 2,000 feet in altitude. Farther north and west the higher 
iiiountain mass is attained, and several summits exceed 4,000, 
or even approach 5,000 feet.. It is an area of bold moun- 
tains and deep valleys, with a steep general slope to the 
southeast. The range of relief is from Dix Mt. 4,842 feet, 
to the exit of the Boquet river, at about 625 feet. The moun- 
tain ridges trend northeast by southwest and are seven or 
eight in number, alternating with the principal valleys. Many 
subordinate valleys cross these ridges at right angles, thus 
dissecting the mass in a marked fashion into rectangular 
blocks. The drainage of most of the area, and that chiefly 
concerned, is divided between the Boquet river on the north 
and the Schroon and its branches on the south. A corner at 
the northwest lies in the basin of the Ausable, and a narrow 
strip on the east drains into lake George. 
The trellised arrangement of streams and valleys is ex- 
plained ana the general principles are quite fully illustrated by 
Prof. Davis, in his account of "The Rivers and Valleys of 
Pennsylvania."'^ Willis, in his monograph on the northern 
Appalachians, treats the subject briefly and gives a suggestive 
sketch map.f Several atlas sheets of the Pennsylvania topo- 
graphic map ma)' also be consulted in this connection. J 
The conditions apparently essential for such arrangements arc 
a series of anticlinal and synclinal folds of alternating hard 
and soft beds, with rising and falling axes. These conditions 
are met whenever, over a considerable area, a normal series 
of sedimentary beds is subjected to moderate folding. Lateral 
migration along the soft outcrops, and capture by favorably 
situated streams, will then produce the grapevine system. The 
master streams may follow the axes after mature adjustment, 
or in case of antecedent streams, or revival with different 
attitude, they may cross the axes of folding. 
Almost no study has been given to Adirondack drainage. 
The direction of the mountain ridges is noted by Emmons 
and others, and indeed is suggested by the alignment of the 
lakes, upon an ordinary map. The most complete account 
*National Geog. Mag., vol. I, pp. 206-219. 
tNational Geog. Monographs, pp. 185-187. 
tProf. R. E. Dodge, of the Teachers' College, New York, has 
brought out this drainage system very effectively for class-room use 
by mounting a group of sheets and tracing the streams in heavy lines. 
