CHAPTER III 



GENERAL CONSIDERATIONS AS TO GLACIERS 



SOME of the field observations recorded in the preced- 

 ing chapters have more than local interest in that they 

 open theoretic questions and lead to suggestions bearing 

 on the general subject of glaciers and their work. Certain 

 of the suggestions have already been noted, as they seemed 

 to belong to the discussion of the associated observations, 

 but others may more appropriately be considered by them- 

 selves and have been reserved for the present chapter. 

 The general considerations already set forth refer to an 

 annual cycle in the distal extent of tidal glaciers (p. 22), 

 the production of features of shore topography by waves 

 generated by the calving of icebergs (p. 69), anomalies in 

 the variations of glaciers (p. 106), the origin of pitted 

 plains (p. 54), and the origin and interpretation of hanging 

 valleys (p. 114). The considerations to be presented in 

 the following paragraphs pertain (i) to the broader char- 

 acters of the surface of a glacier, (2) to the conditions af- 

 fecting types of glacial sculpture, (3) to the conditions 



(195) 



