REPORT OF THE DIRECTOR I919 55 



but the resulting hollows were then almost at once slushed full of 

 other sediment. But during the very last period of the maintenance 

 of the ice front at the moraine, the buried ice blocks apparently per- 

 sisted until after deposit had ceased, and, on their melting out, the 

 overlying debris caved in and formed the kettle hollows that are now 

 so distinctive a feature. The material between one and the next of 

 these, having a solid foundation, kept its original height and now 

 forms the knobs of such topography. • 



One of the kettles, lying directly off to the north of the improved 

 state highway crossing the south face of the moraine, is illustrated 

 in plate 10. It is difficult to photograph such depressions so as to 

 give a true expression of their shape. Thus the depression shown in 

 plate ID is almost circular and its foreground slope is nearly as 

 steep as that of the background. The man stands at the bottom of 

 the pit and his figure gives some notion of the scale; the hollow is 

 approximately 75 to 100 feet deep. This one, and most of those 

 on the upper levels of the moraine, contain no water; for the walls 

 and bottoms of these are made up of such coarse material that 

 drainage into them escapes under ground as rapidly as it enters, 

 plate II, however, illustrates a smaller kettle of the same origin, 

 lying to the south of the road, in which water collects, because the 

 finer clayey sediment found on these lower slopes of the moraine 

 front is more impervious to downward percolation of precipitation. 



South front of the moraine. Plate 12 is a view of the south 

 front of the moraine from a point some distance up the slope of 

 the valley wall on the west side. The gentle undulations of the cul- 

 tivated fields and intervening forest areas, occupying the middle 

 distance of the picture, are characteristic of the topography of this 

 side of the accumulation. Here the material slid and slumped away 

 from the crest of the moraine ; much of it probably having the con- 

 sistency of a wet concrete mixture at the time of deposit and there- 

 fore tending to build up a much gentler slope than that which marks 

 the inner side of the moraine where the deposited material rested 

 against and was supported by the ice during its shaping. This 

 south-facing deposit, while occasionally sandy, has on the whole a 

 much finer texture than that of the inner northern side ; hence it is 

 much better adapted to cultivation, and is the site of fine farms. 



Lake overflow channel. When the ice front began to be melted 

 back rapidly from its position at the moraine a great hollow was 

 created between its retreating margin and the inner side of the 

 moraine. Into this hollow water from the melting ice and from the 

 drainage of the adjacent valley sides poured until the hollow was 



