390 FIRST YEAR SCIENCE 



The winds not only blow the clouds about over the 

 land, but they bear dust and sand with which they 

 sculpture and erode rocks and cliffs. v They also build up 

 sand dunes and by moving them over the surface of the 

 land sometimes destroy forests and fields. 



QUESTIONS 



How are glaciers formed? Where are they found? What do 

 they do ? 



How large and how thick is the Greenland icefield ? 



How are icebergs formed ? Why are they dangerous ? 



Describe the different kinds of deposits and formations due to 

 glaciers. 



How are glacial lakes such as Lake Agassiz formed? Why are 

 they fertile when drained ? 



Some waterfalls are due to glaciation. Why? 



What was the extent of the North American ice sheet during the 

 Glacial Period? 



What has been the effect of the glacial period upon plants, animals 

 and man ? 



In what ways has the wind modified the surface of the earth ? 



How are sand dunes formed ? Why are they destructive to plant 

 life? 



