202 



Fig. 6. \'iew across the valley from the left abutment of the lower or greater dam. The 

 width of the valley i.s here about 165 feet, with the earth walls rising abruptly 22 feet on 

 either side. The soil is a glac-ial deposit, sand predominating. 



Fifr. 7. View up the channel of the outlet at the greater dam. The depth of the valley 

 is shown by the altitude of the right abutment in the background. The evidence of the 

 ascending erosion line is in the foreground. 



