CONTENTS xvii 



CHAPTER XXV 

 NIAGARA FALLS A CLOCK OF RECENT GEOLOGICAL TIME 



PAGE 



Features in and about the Niagara gorge The drilling of the gorge 

 The present rate of recession Future extinction of the American Fall 



The captured Canadian Fall at Wintergreen Flats The Whirlpool 

 Basin excavated from the St. David's gorge The shaping of the 

 Lewiston Escarpment Episodes of Niagara's history and their corre- 

 lation with those of the glacial lakes Time measures of the Niagara 

 clock The horologe of late glacial time in Scandinavia Reading 

 references . 352 



CHAPTER XXVI 

 LAND SCULPTURE BY MOUNTAIN GLACIERS 



Contrasted sculpturing of continental and mountain glaciers Wind dis- 

 tribution of the snow which falls in mountains The niches which 

 form on snowdrift sites The augmented snowdrift moves down the 

 valley: birth of the glacier The excavation of the glacial amphi- 

 theater or cirque Life history of the cirque Grooved and fretted 

 uplands The features carved above the glacier The features shaped 

 beneath the glacier The cascade stairway in glacier-carved valleys 

 The character profiles which result from sculpture by mountain glaciers 



The sculpture accomplished by ice caps The Norwegian tind or 

 beehive mountain Reading references 367 



CHAPTER XXVII 

 SUCCESSIVE GLACIER TYPES OF A WANING GLACIATION 



Transition from the ice cap to the mountain glacier The piedmont 

 glacier The expanded-foot glacier The dendritic glacier The 

 radiating glacier The horseshoe glacier The inherited -basin glacier 

 Summary of types of mountain glacier Reading references . . 383 



CHAPTER XXVIII 

 THE GLACIER'S SURFACE FEATURES AND THE DEPOSITS UPON ITS BED 



The glacier flow Crevasses and se"racs Bodies given up by the Glacier 

 des Bossons The moraines Selective melting upon the glacier 

 surface Glacier drainage Deposits within the vacated valley 

 Marks of the earlier occupation of mountains by glaciers Reading 

 references . . 390 



