FRAMEWORK OF ARIZONA 
241 
ing as was the duration of the Devonic Period itself. This old land 
surface bevels alike the Siluric, Ordovicic, Cambric and Proter¬ 
ozoic strata; and in many places the entire Paleozoic section is re¬ 
moved. So, inconspicuous as it is in some localities, it stands for 
another one of the major unconformities of the region. 
There is some slight change to be made in correlation of the 
New Mexico section with that of Arizona, as recently disclosed 
by close examination of the country lying between Lake Valley 
and Globe. The Berenda limestone of New Mexico is probably 
unrepresented in Arizona. The Martinian series of limestones 
now seems to underlie, and not overlie, the Perchan series of 
shales. The Martinian succession being regarded as holding seri¬ 
al rank leaves its several members without names. If Morenci 
is to be preserved as a formational title its application might be re¬ 
stricted so as only to cover the nethermost limestones of Devonic 
age as exposed at Morenci and Clifton. 
In the Grand Canyon the lower part of the familiar Red Wall 
limestone, as it is originally designated by Gilbert, proves to be De¬ 
vonic in age; and the evidences of unconformity with the overlying 
strata are almost impossible to detect. 
Carbonic strata constitute the great limestone formation of the 
state. Two thick piles of massive calcareous beds are separated by 
an extensive shale sequence; and a great shale section caps the 
column. Altogether these beds attain a thickness of more than 
5000 feet. Five provincial series of terranes are now discernable. 
When full correlations with the similar successions of other parts 
of the continent are completed these may resolve themselves into 
several additional ones. 
The breaks in sedimentation are numerous in the Carbonic col¬ 
umn ; and taken all together these intervals doubtless bridge a time- 
span which fully equals that of the deposition. 
Early Carbonic rocks are, so far as now known, mainly lime¬ 
stones. So compact and uniform is the section that, until quite 
recently, they appear undifferentiable into formations. Their 
characteristic aspect is the familiar Red Wall limestone of the 
Grand Canyon. In this locality there are few organic remains. 
Away from the Titan of Chasms the Red Wall limestone vir¬ 
tually teems with fossils in places, and the several faunas distin¬ 
guished are as varied, and as sharply contrasted as are those 
