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.
[Illustration: Fig. 11.—Fossil trunk near Tower Falls.
Photograph by F. J. Haynes.]
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.