TREES AT TIMBERLINE 69 



historic animals headed to the leeward. They 

 refuse to die, and may live on for centuries. 



Snow, cold, and dryness are the chief factors 

 which determine where the forest may or shall not 

 grow. In some localities the snow line is the har- 

 rier that forms the timberline. Dryness of locality 

 combined with dry winds resists forestation. But 

 the sand blasts of dry, windy localities play havoc 

 by beating and flaying the trees. This sand beats 

 off the bark on the trees' stormward quarter, ex- 

 posing their very bones. Often it eats its way 

 into the already half-flayed trunks. The storm- 

 ward half of many trees is dead and lifeless, a 

 sand-graven totem pole, while the living half holds 

 long, tattered limbs streaming leeward. 



This gale-blown sand frequently prevents trees 

 from growing higher than the shelter behind which 

 they stand. In places so-called trees may be seen 

 with trunks one to three feet in diameter and only 

 one or two feet high, cut off by the sand fire of the 

 high winds. Numerous long limbs reach out from 

 the trunk in all directions. The shoots which 

 these limbs send up are clipped off by the wind- 

 shot sand. In time this tree-top is a table or brush 

 of bristles twenty feet across, and trimmed off as 

 level as a lawn. Hundreds of these trees are often 

 crowded together until the identity of each is lost, 

 forming acres of clipped, low tree lawn. The wide- 

 spreading mass is too low to crawl under and not 

 quite strong enough to allow one to walk on the 



