REPORT OF THE DIRECTOR AND STATE GEOLOGIST 



r79 



glacial lake Iroquois, which occupied the Ontario basin and had 

 its outlet at Koine into the Mohawk valley, because the St Law- 

 rence outlet was still blocked by the ice. would have commenced 

 to discharge around on the north along the edge of the ice as soon 

 as it had sufficiently retreated to uncover lower ground than that 

 at Koine. By a spillway e*ueh an outlet is meant. As the ice 

 farther retreated down the slope, the stream would fall to succes- 

 sively lower levels, bringing down the level of Lake Iroquois cor- 

 respondingly. Such a current as this would have been would fur- 

 nish an adequate explanation of the naked rock surface of the 

 Flat rocks. The writer's observations have not been sufficiently 

 extensive along the north side of the Adirondacks to enable him 

 either to affirm or to deny the correctness of this view, and, as the 

 results of Mr Gilbert's observations have not been published, it 

 is not known on what data the identification of this spillway 

 rests. But such results would naturally have followed the change 

 in outflow of Lake Iroquois from the Mohawk to the St Lawrence 

 valley, and spillways would likely have existed at several levels 

 as the waters fell. Various lake levels should also have existed 

 for at least a brief time along the northern Adirondack slopes, 

 and may well have left discoverable traces, which should have 

 definite connection with such spillways as may exist. The region 

 is a difficult one. but a great opportunity awaits the individual 

 who can take the time to cover the region thoroughly, unham- 

 pered by other and more pressing work. The new maps w ill be 

 a great aid when completed. 



The larger part of the bared surface in the Flat rock district 

 lies between 600 and 800 feet elevation. Over large areas the 

 surface is absolutely naked except for an occasional large boul- 

 der. This altitude is so much below the level of the Iroquois 

 beach, if extended to this point, that, if it be the path of a spill- 

 way, it should be from a water level considerably lower than the 

 main Iroquois plane, and it would seem as if marks of standing- 

 water at this lower level should be found when search is made. 



Just below the eastern edge of the bared rock area in eastern 

 Altona is an exceedingly interesting ridge of coarse cobbles which 



