Page:Popular Science Monthly Volume 89.djvu/664

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The Constant Warfare Between the Trees and the Rocks

���Above: All rocks have cracks which sooner or later the rootlets of some tree search out. The rootlet may die but it leaves a little soil on which another coming later may feed. Then a seed is wafted there and real rock splitting soon begins

�� ���Above; The lower part of the trunk and the root of a juniper tree on a mountain side which is slowly but surely split- ting a great boulder. The top of the tree has been broken off by the winds but the roots keep up the struggle

��An aspen which is forcing apart the rock into which it is grow- ing. The rock could probably trace back a long line of ancestors of this tree each one of which has carried on the warfare relentlessly

��A portion of the roots of an up- turned tree. The root system of a tree is even greater than the limbs and branches, equaling the spread of the tree

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