324 OLDER MESOZOIC FLORAS OF UNITED STATES. 
PETRIFIED FORESTS OF ARIZONA. 
As already remarked, fossil wood is almost universal. I examined 
a fine forest less than a mile from Holbrook on the first terrace above 
the valley below that place. The valley is here half a mile wide on 
‘the north side. Most of this is occupied by an alkaline flat covered 
with greasewoods and saltweeds. The bluff is 50 feet high and pre- 
cipitous. Many chips and blocks of petrified wood lie about its base 
weathered out, also detained in their fall at all elevations on the sides 
of the escarpment. The beds are brownish-red sandstones with thin 
seams of white or blue clay shales. On top lie immense petrified 
logs in great profusion, usually much split and broken, sometimes 
reduced to heaps of splinters. I collected a number of specimens 
that seemed to show structure perfectly. Ina few cases the wood is 
red and jasperized. The hill back of the first terrace rises by a 
gradual slope for another 50 feet, and is chiefly covered by blown 
sand, but as far as I went I found fossil wood wherever the surface 
was exposed. None of this material seems to be in place, and its true 
source is probably still higher. 
The junction of the Rio Puerco with the Little Colorado is 2 miles 
above and nearly due east of Holbrook. There is running water in 
the latter at this point all the year round, but it all comes from a spring 
a few miles above, and from there on the Little Colorado is a dry run 
except in the rainy season. The Rio Puerco is dry at its mouth and 
for most of its length, but in most such streams water can be reached 
by digging a few feet in the gravelly bed, and it is said that horses 
have the instinct to paw out the gravel until they make a trough in 
which water will stand in sufficient quantities for them to drink. 
The Whipple expedition of 1853, in coming from Zufi on the south, 
crossed the Rio Puerco at Navajo Springs and followed it down on 
its right or north bank. It was some 20 or 30 miles above its mouth 
that the party passed through the remarkable petrified forests de- 
scribed in the reports of Lieutenant Whipple and Mr. Marcou,! and 
also by Modllhausen, who accompanied the expedition. Here was 
the Lithodendron Creek, named by Lieutenant Whipple (op. cit., Pt. 
I, p. 73.), and so frequently mentioned in connection with the petri- 
fied forests of Arizona, but which in reality is not located in the heart 
of what is now called the petrified forest, but is on the other side of 
the Rio Puerco and some distance farther west.” 
It is now well known that petrified wood is exceedingly abundant 
1 Reports of Explorations and Surveys to ascertain the Most Practicable and Economical Route for 
a Railroad from the Mississippi River to the Pacific Ocean, Vol. ITI, 1856, Pt. I, pp. 73-75; Pt. II, p. 28; 
Pt. IV, pp. 43, 150, 161, 167. 
It is difficult to identify on modern maps, but a careful study of the map accompanying the Whip- 
ple report and of Lieutenant Whipple’s description given in the itinerary (p. 73) seems to require 
the assumption that his ‘ Carriso Creek”’ is what is now called Dead Creek on the Land Office map, 
and that Lithodendron Creek was what is now called Carrizo Creek or Carrizo Wash. 
