VISCOSITY AND MOMENTUM 223 



causeway are made by the deposition of suspended waste 

 through the slackening of spreading side currents. 



The salient fact brought out by these comparisons is 

 that many features of rivers and river work which arise 

 from inertia in association with swift motion are paralleled 

 by features of glaciers and glacier work which arise from 

 high viscosity in association with slow motion. In each 

 kind of stream, changes in the direction of flow are caused 

 by irregularities of the channel, and complex series of 

 phenomena arise from the resistance of the current to 

 deflection. These series are strikingly parallel, but the 

 resistance to deflection is occasioned in one case by 

 momentum and in the other by viscosity. 



