423
NORTH AMERICAN NATURAL BRIDGES
Fig. 7. The Lava Natural Bridge across Bridge Creek, Yellowstone National Park.
Simply that portion of the rock of the former full between two pot-holes.
village of Pine about 90 miles south of Flagstaff in Arizona, and can be reached by a horseback journey of three days from that city. As one travels south from Flagstaff through the forest reservation he passes for miles over a lava plateau which, were it not for the pines and cedars, would be called a desert. The forest does not fulfill the usual conception of a wooded region since the trees, though gigantic, are far apart and underbrush is entirely absent. After many hours of travel over a
