GEOLOGY OF THE LONG LAKE QUADRANGLE 497 



cially in the northern half of the quadrangle. It is quite sandy or 

 gravelly in character, and has been much used for surfacing the 

 roads, answering fairly well for that purpose in many places. 



Valley plains and pitted plains. In the district north of the Long 

 Lake quadrangle there is evidence of pause in the ice retreat, in the 

 considerable moraine which runs west from Placid to Saranac, and 

 thence on northwest to Lake Clear and Brandon. Running south- 

 west from this is a great sand-filled valley, commencing at Lake 

 Clear and ending at Tupper Lake Junction. The general character 

 of its surface is well shown on the St Regis quadrangle topographic 

 map. A number of small rock knobs project above it, and the rail- 

 way cuts west of Saranac Inn station well illustrate the general way 

 in which these knobs are wholly or partly drowned in the sand. The 

 material is mostly even grained sand of medium grain. There is 

 little gravel in it and no clay. 



In addition to the rock knobs the surface shows diversity of 

 another sort, small oval or circular depressions below the general 

 surface which are in some cases dry and in others occupied by 

 small ponds. There is a notable collection of these between 

 Upper Saranac lake and Lake Clear, and thence northward to 

 Upper St Regis lake and beyond. It is exceptional that a topo- 

 graphic map brings out the feature better. 



The general area is also noteworthy in the number of lakes 

 and ponds. There are about 150 of these in the St Regis quad- 

 rangle, in all probability a greater number than is found on any 

 other of the Adirondack map sheets. And they are mainly massed 

 along this sand belt and occupy depressions in its surface. The 

 upper end of Upper Saranac lake has these sands for its shores, 

 and the abundant and good sized ponds to the westward have 

 also sandy shores except for the occasional rock knobs protruding 

 through the sand. The general level of the deposit falls to the 

 southwest though the fall is only slight, from 12 to 18 inches to 

 the mile. The sand must have been deposited from a current 

 which ran across the region to the Raquette just below Raquette 

 pond. In order to account for this flow we must presume that the 

 present outflow through the Saranac river was blocked, and it would 

 seem that it must have been blocked by ice which lay near at 

 hand. The depressions in the sand are of the kettle hole type, and 

 the fact that the larger ponds were not filled by the sand suggests 

 that they were occupied by stagnant and slowlv melting ice tongues 



