F. Carney — Form of Outwash Drift. 3S7 



of the Pen 11 Yan sheet, and a few miles southwest of Geneva, 

 which lies within the flaring walls of the Seneca valley. 



Ice-Front and Drift as Affected by Topography. 



The Ontario lobe, as the ice which occupied this lowland is 

 designated, maintained along its southern margin, during the 







kr 



rw - /j 



to 



B A K I J 



li 



Fig. 1. A part of the Perm Yan (N. Y.) Quadrangle. 



advance and retreat of the ice sheet, valley dependencies, the 

 development of which was directly in proportion to the depth 

 of the troughs above alluded to. Of these troughs those of 

 the Seneca and Cayuga valleys are the deepest and therefore 

 probably were occupied longest by tongue-like projections of 

 ice. Contiguous to these troughs are upland valleys which 



