54 



TREE ANCESTORS 



the annual layers in the wood of those which have been cut down, 

 and calculate with considerable accuracy their age and the varying 

 rapidity of their growth. For instance, the huge section on exhibi- 

 tion at the American Museum of Natural History shows that the 

 climate of California was very propitious about the time that 

 Charlemagne was crowned by Pope Leo on Christmas day, A.D. 



Fig. 9. Sketch Map Showing Present Range (solid black) and Past 



Distribution of the Sequoias (lined areas) and Their Probable 



Paths of Migration 



800, as is evinced by the rapid growth of the tree at that time shown 

 by the comparatively thick layer it added to its girth. 



We can but wonder at the persistence of this type practically 

 unchanged, for eon after eon, while all around were dissolution 

 and evolution. Their early contemporaries are almost without 

 exception cut off, and were we to go still further back to the prob- 

 able ancestors of the sequoias, the Voltzias of the earlier ages, we 



