214 THOMAS C. CHAMBERLIN AND ROLLIN T. CHAM BERLIN 



forward. At the brink of the step-wall special weighting is likely 

 to be brought to bear by the pushing of the ice forward over the 

 brink before it breaks and drops down, and this probably leads to 

 some splitting off of the edge of the wall. This action naturally 

 tends to give slope to the step and to modify it in the direction of 

 a cataract as distinguished from a cirque, but the essence of the 

 phenomenon is probably much the same in either case. Sapping 

 and stoping seem to be rather general phenomena of the basal 

 action of glaciers. 



Fig. ii. — The Furgg Glacier, a broad, flat, ice sheet at the east base of the Matter- 

 horn. Both above and below this nearly level glacier-made shelf are steep cliffs. 

 Photo, by R. T. C. 



The operation of the stoping process at several points in a long 

 glacier tongue, by developing successive ice falls between more 

 or less level stretches, results in a rude stairway of giant tread. 

 A portion of such a glacial stairway is shown in Fig. 10. This 

 is the Unter Grindelwald Glacier viewed from the Baregg. Two 

 comparatively level stretches of glacier are visible — one above the 

 prominent ice cascade, the other below it. They are known 

 respectively as the Fiescherfirn and the Lower Eismeer. Dropping 

 from the Grosse Fiescherhorn and lofty Fieschergrat to the gently 



