miller] 



UORK OF GLACIERS 



129 



find hills of drift similar in shape to the rock hills previously 

 described except, that the lee side has the gentle slope. These 

 are dnimlius. Why are the slopes opposite to those of a glaciated 

 rock hill ? 



FLUVIO-GLACIAL DEPOSITS. 



Where great quantities of ice melt the work of running 

 water tends to modify that of the glacier. Along the glacier 

 front much water flows away from the terminal moraine, carrying 

 large quantities of sediment. If this water deposits the sediment 

 as a relatively flat plain an ontwash plain is formed. If the de- 

 posit is confined to a valley it is a I'allcy train. How would the 

 structure of these deposits differ from glacial drift? Under 

 what conditions will these plains be good agricultural land? 

 Will they be any better land than the drift from which they were 

 derived ? are a few of the many problems to be considered. Per- 

 haps the student has been fortunate enough to find a meander- 

 ing ridge of stratified sand and gravel extending across the 

 ground moraine (Fig. 6). This is an esker and was probably 

 formed bv an overloaded stream flowing in a tunnel beneath 

 the ice. How is it possible for the esker to run u]j and down 

 hill if it was formed by a stream of water? is always an in- 

 teresting problem. 



Mounds or short ridges formed by glacial waters are called 

 kamcs and like eskers are of small importance except as gravel 

 and sand pits. 



Fig. 6. An esker. This esker occurs at intervals for 

 about four miles extending through marshes and up and 

 down hill. 



