REPORT OF THE DIRECTOR AND STATE GEOLOGIST 1901 r35 



these rock banks are at such slight altitudes above the plains 

 which they face that standing water could not have had enough 

 depth to produce efficient wave action. The argument may be 

 condensed in the broad statement that the entire phenomena 

 of the banks, their form, position, relation to surrounding topog- 

 raphy, and all other characters, prove their stream genesis. 

 These characters will appear in the descriptions following, with 

 the illustrations. It should be said, moreover, that the history 

 of the glacial retreat from the region and the history of the 

 glacial waters (given in former writings) theoretically necessi- 

 tate these low channels, and that they were predicated from the 

 knowledge of the earlier, high level phenomena. 



• 

 Relation of the channels to the ice front and to Lake Iroquois 



At one time the continental glacier covered all of New York 

 State. Slowly the front of the ice body receded, because the 

 melting exceeded the advance, till all the southern part of the 

 State was free from ice. At the time which we are now con- 

 sidering the lobe of the Labradorian ice sheet that still rested 

 over the basin of Ontario was wasting away. By its own weight 

 it had, as a plastic body, a spreading flow and pushed south- 

 eastward over the low ground of Oneida lake district against 

 the higher ground between Syracuse and Rome. The directions 

 of flow are best shown by the attitude of the drumlins, the ice- 

 molded drift. The waters which were impounded in the valleys 

 fronting the ice, derived from north-flowing streams and from 

 the melting of the ice itself, found their way past the front of 

 the ice to the Mohawk valley. At the later stage these waters 

 were augmented by all the overflow from the basin of what is 

 now the " Upper Great Lakes/ 7 or from as much of the area 

 as the ice had abandoned, because the St Lawrence outlet was 

 still blocked by the ice. 



It appears certain that the ice disappeared from the higher 

 ground between Oneida and Rome earlier than it did from the 

 region farther west, near Syracuse. 1 The front of the ice sheet 



^ee former report, p. 129, 130. 



