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grass. Many are due to the presence of water, 

 either outspreading surface water or an excess 

 of underground water just beneath the surface, 

 — to streams visible or invisible. A few result 

 from boggy places which result from impaired 

 drainage caused by landslips or fallen trees. 

 Thousands were made by beaver dams, — are 

 old beaver ponds that filled with sediment and 

 then grassed over. 



Most parks that owe their origin to forest fires 

 have charcoal beneath the surface. A little 

 digging commonly reveals charred logs or roots. 

 Occasionally, too, a blackened tree-snag stands 

 suggestively in these treeless gardens. In the 

 competition for this territory, in which grass, 

 spruces, aspens, and kinnikinick compete, grass 

 was successful. Just what conditions may have 

 been favorable to grass cannot be told, though 

 probably one point was the abundance of mois- 

 ture. Possibly the fire destroyed all near-by 

 seed trees, or trees not destroyed may not have 

 borne seed until the year following the fire. 

 Anyway, grass often seizes and covers fire- 

 cleared areas so thickly and so continuously 



234 



