PLEISTOCENE GEOLOGY OP THE ADIROHDACKS 637 



evidently pushed out as a delta deposit after the deposition of the clay. A 

 number of good examples of smaller sand plains also occur, and all have had a 

 similar origin. 



Of the glacial lakes the most interesting and extensive one occupied all of 

 the sarvd flat country from Forestport to north of Lowville. The former pres- 

 ence of this large lake is shown by the great development of unquestioned 

 delta deposits above referred to. These waters were impounded by a waning 

 lobe of ice in the Black River valley. The kames and drift boulders along the 

 western edge of the terraces in the valley show an ice-contact front there. 

 Also the absence of delta deposits on the west side of the river, under Tug hill, 

 shows that the lake did not extend that far west. The failure of any delta 

 deposit to reach out to or across the valley bottom argues for ice occupancy of 

 the deepest part of the valley during the existence of the large lake. The high- 

 est water level was apparently something over 1,300 feet (using present eleva- 

 tions) at which time an outlet probably crossed the Black River-West Canada 

 Creek divide near Honnedaga, and flowed southward toward Trenton Falls. 

 Further melting of the ice lobe certainly opened an outlet past Boonville and 

 down Lansing Kill (creek) toward Rome. The pre-Glacial divide was doubt- 

 less near Hurlbutville, as shown by the widening of the channel, both north- 

 ward and southward, from that place; by the existence there of a deep inner 

 gorge; by the aggraded stream bottom north of Hurlbutville; by the fact that 

 the present stream could not have cut the deep, narrow channel there, and by 

 the right elevation of an outlet there. The lake stood at about the 1,250-foot 

 level when it started over this divide, and it cut down the divide rapidly until 

 the 1,140-foot level was reached. By this time the ice had so far melted as to 

 allow an escape of the water northerly and northwesterly along the western 

 side of the ice tongue and into lake Iroquois. Another lower and very distinct 

 lake level was a little below 800 feet, and caused by still further ice retreat to 

 allow an accumulation of water back of a barrier at Carthage. This lake ex- 

 tended southward to Lyons Falls, where it was very narrow. Between Lyons 

 Falls and Carthage the winding stream is now cutting terraces through the old 

 lake deposit. The glacial lake which extended over the sand flat area between 

 West Canada and Black creeks (above mentioned) stood for some time at or 

 near the 1,400-foot level, and during part of the time, at least, may have had 

 an outlet through the Spruce Creek channel. 



Many fine kames have been found within the region, their greatest develop- 

 ment being in the vicinity of Hinckley (Remsen sheet), where they form kaine- 

 morainic ridges with the typical knob and kettle structure. An interesting 

 feature is the occurrence of partially buried kames, which are particularly 

 well shown in the vicinity of Forestport (Remsen sheet). After the forma- 

 tion of the kames and the withdrawal of the ice, the delta sands were built 

 around the kames to partially bury them. In this way many kames were 

 doubtless completely buried, as must have been the case where the sands are so 

 deep in the Port Leyden region. 



The paper was discussed by G. K. Gilbert and Albrecht Penck. 



