The most accessible fossil forest, marked "Petrified Trees" on the map, is west of the Tower Falls Ranger Station and Camp Roosevelt on the road from the Grand Canyon to Mammoth Hot Springs, by way of Mount Washburn. It is on the middle slope of a hill that rises about 1,000 feet above the little valley and may be reached by a branch road from the main loop road. As the traveler approaches the forest he will observe a number of trunks standing upright among the stumps and trunks of living trees, and so much resembling them that a near view is necessary to convince him that they are really fossil trunks. Only two rise to a considerable height above the surface. The larger one is about 15 feet high and 13 feet in circumference (fig. 11): the other is a little smaller. As the roots are not exposed, it is impossible to determine the position of the part in view or the original diameter of the trees, as the bark is nowhere preserved.

Above these standing trunks lie many others, which the disintegrating forces of nature break up into small fragments and keep at about the same level as that of their surrounding matrix. Some of these trunks rise only a few inches from the surface: others are nearly covered by shifting dÉbris. Their diameter ranges from 1 to 14 feet, and they are so perfectly preserved that the rings of growth can easily be counted. The internal structure is also in most trunks nearly as perfect as when the trees were living.