THE PELHAM LAKE AND ESKER. 581 



south from the Orient House cellar. The duration of the waters was so 

 brief that little or nothing was deposited upon the till over the center of the 

 basin, or so little that it has been removed by wind and rain. Yet, starting 

 from this flat bowlder-covered bottom of the basin, one toils up more than 

 a mile over the slope of fine sand of the Shutesbury road to the top of the 

 delta at the mouth of the western valley, and on the other side one can step 

 from an ice-bowlder onto the steep sand slope of the esker, so sharp is the 

 boundary. 



If one stands on the south slope of the valley and examines the great 

 sand rampart already described, which is thrown across the portal, it seems 

 still intact as when the ice left it. The narrow notch which the brook has 

 cut deeply through it is barely visible. The terrace surfaces slope 5° east- 

 ward into the basin across the portal, as they do in their northward pi-o- 

 lougation where they abut on the ridge of Hygeia to the west. 



Fortunately the ditch for the main of the Amherst waterworks ran 

 from the west across the flat where the ice rested at the entrance of the 

 portal (Pelham City), giving a complete section of the semimorainic beds 

 that rested on the ice with all their in-egularity. It continued past the 

 Orient, exposing the passage beds to the fine delta sands, and, passing high 

 up above the brook into the notch which this brook has cut into the portal 

 or entrance terrace, it continued along its southern slope through the whole 

 delta deposit aud far out into the central portion of the l)asin. At first, and 

 nearest the ice, the beds dipped west, and these may be "backset" beds, as 

 Prof W. M. Davis would say,^ or may have taken this posture as a result of 

 the melting of the ice beneath and their sinking westwardly. For the 

 most part the beds dip strongly east into the basin and show that the cur- 

 rent came from the west — that is, from the ice. 



I append a detailed description of the beds, written when I had no 

 clear view of the meaning of the whole. A describes the till-covered flat 

 outside the portal; B, the sands and gravels deposited against and on the 

 retaining wall of ice and confused by its melting, which occur in decreasing 

 amount eastward; C, the finer eastward-dipping delta sands to their ending 

 in the center of the lake. The section runs parallel to and a little north of 

 the section given (fig. 32, p. 578) where the gneiss ridge southwest of the 



' Beds taking this western dip becanse they were deposited by waters escaping from beneath 

 the ice with eastward aud upward direction. 



