544 



JOHN L. RICH 



gested as the cause of the settUng/ Ice thus buried would melt away 

 very slowly. In this case it must have remained at least until the 

 glacier had withdrawn far enough to permit the waters of Lake 

 Watkins to find an outlet at a lower level. 



The conditions at Pine Valley and northward to Seneca Lake 

 are especially favorable for the burial of an ice block. In this part 

 of Seneca valley, which is comparatively narrow and gorge-like, there 

 lay a long tongue of ice. The valley is now drift-filled to an unknown, 

 but certainly great, depth, at least several hundred feet as is indicated 

 by borings at Watkins and Pine Valley. Presumably at the time 

 of maximum glaciation the ice completely filled the valley down to the 

 rock at the bottom. As the glacier retreated, melting would take 

 place largely at the surface, or at least more rapidly at the surface; 

 with the result that at the surface retreat would be more rapid than 

 deep in the valley bottom. Since the glacial waters escaped to the 

 south at a level certainly considerably higher than that of the bottom 

 of the ice, outwash gravels from the more rapidly melting upper part 

 would spread over and bury the lower ice. Ice thus buried would 

 melt away slowly and in melting allow the settling of the overlying 

 drift; producing conditions Hke those actually found at Pine Valley. 

 ^ The topography strongly indicates that the axis of Seneca valley 

 for several miles north of Pine Valley was occupied by an ice-block 

 which in melting allowed the slumping of the overlying drift. 



THE JOHNSON HOLLOW CHANNELS 



At the head of Johnson Hollow (Watkins sheet) , is an important 

 series of connected channels illustrating four of the types described 

 in the preceding pages, and showing their relations to each other and 

 to the ice front. (See map, Fig. 9.) 



At the time the channels were forming, a lobe of ice from the main 

 Seneca valley tongue pushed into the Moreland valley; ending near 

 the head of Johnson Hollow. At the same time the ice in the Seneca 

 vaUey extended several miles farther south. The drainage from the 

 margin and end of the Moreland lobe, together with a lateral stream 

 (E) from the Seneca valley tongue, united at the head of Johnson 



I The agency of a buried ice mass had been suggested by Tarr as an explanation 

 of this particular condition, even before the direct evidence of the sinking of the channel 

 bottom had been found. 



