NORTH AMERICAN NATURAL BRIDGES 



423 



Fig. 7. The Lava Nati kai. Ukidue ackoss Bbidge Ckeek, 



Yellowstone National I'akk. 



Simply that portion of the rock of the former full between two pot-holes. 



village of Pine about 90 luiks ^outli of Flagstaff in Arizona, and can be 

 reached by a horseback journey of three days from that city. As one 

 travels south from Flagstaff tlirough the forest reservation he passes for 

 miles over a lava plateau which, were it not for the pines and cedars, 

 would be calletl a desert. The forest does not fulfill the usual concep- 

 tion of a wooded region since the trees, though gigantic, are far apart 

 and underbrush is entirelv absent. After manv hours of travel over a 



