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NATURE STUDY REVIEW [9 :5— May, 1913 



Fig. 4. Gently rolling ground moraine around the rock 

 hill shown in Fig 2. 



material at its terminals and along its sides. He can see how the 

 lateral moraines of two minor glaciers came together and formed 

 the medial moraine of the larger one. 



In the case of valley glaciers he learns that moraines are 

 commonly distinct ridges. A few journeys over portions of the 

 glacial plain covered by drift of the Glacial Period soon con- 

 vinces him that, (1) terminal moraines are rarely distinct ridges 

 but belts of highly rolling topography which (2) grade off into 

 gently rolling topography or ground moraine (Fig. 4), and (3) 

 that there are no medial or lateral moraines present. How did 

 the glacier form the ground moraine? How has this unequal 



deposition of the drift influenced the 

 formation of lakes and swamps? 

 What further proofs are there that 

 the material was deposited by the 

 glacier and not by some other agency? 

 This leads to an examination of the 

 deposit. A gully, or "cut" along a 

 railroad or wagon-road afford excel- 

 lent places for study of the deposit. 

 Is there a separation of the fine clay, 

 sand, gravel, and coarse boulders into 

 layers or are they mixed together in- 

 discriminately (Fig. 5) ? Do some of 

 the boulders show striae? Are there 

 many different kinds of rock present? 

 Are the deposits formed by any other 

 Fig. 5. Seciion of gla- agency than glaciers so indiscrimi- 

 cial drift showing its nately mixed? How will this kind of 

 structure. Note that the ^jeposit affect the fertility of the. soil 

 fine and coarse are indis- \ . , -> ^ i • i • i 



criminately mixed. and agriculture? On this plain he may 



