MICHIGAN'S SHIFTING SANDS. 19 



Michigan, however, the virgin pine, spruce, cedar, maple and oak was 

 removed. Following this came the fires which removed the "crust" 

 over this sand, formed during many generations of plant life. Many of 

 these burned over clearings were cultivated for a time until the humus 

 accumulation and root binder material had become exhausted. Often 

 two or three croppings were sufficient to render these sands worthless 

 for farming purposes. Such areas are spoken of as "blows." 



NEW DUNES. 



The new dunes and blows are those along the water edge of the lakes. 

 The disturbance is not primarily an agitation of the old sand but the 

 constant movement of new sand which is brought up from the bottom 



Fig. 10. A shelter belt established at Manistee by the Government. This belt was five to 

 six rods wide arid proved a success as far as it went. No follow up or later planting was 

 done aud the good effects of the belt were wasted. Without more permanent planting this 

 belt will soon become buried. 



of the lake by wave action and cast high on the shore by the breaking 

 water. During the breaking down process the particles of rock become 

 finely pulverized by water action and contact with each other until 

 there is formed a smooth surface,! grain called smooth sand. All the 

 angles and sharp edges have been worn smooth. The form become 

 globular, oval or rounded. In this form it is easily tossed on the beach 

 by the waves. It soon dries and the wind tumbles it higher up the slope 

 until it forms a part of the mass of sand that is building the new 

 dune, burying the orchard or covering the field. When a break in the 

 surface of" the old, formerly forest covered dune occurs as may be caused 

 by a road or footpath, conditions are right for the development of a 

 new dune, and the treatment is the same as for other forms of shifting 

 sand. 



