FRAMEWORK OF ARIZONA 
243 
to have migrated directly from the Southwest into the Mississippi 
Valley. 
These aspects of the faunal sequence in the Early Carbonic sedi¬ 
ments of the Continental Interior are sharply reflected in the ver¬ 
tical and areal distributions of the most characteristic class of the 
crinoids. Bearing on this point a table of the genera represented 
is particularly instructive. The principle involved appears to be 
widely applicable to the other animal groups. 
Judging from certain lithologic changes in the Red Wall sec¬ 
tion at El Tovar and vicinity and the relative thicknesses of the 
separate sections elsewhere in the Southwest, there should be about 
100 feet of the Chouteau division, 300 feet of the Burlington ter- 
rane, and 150 feet of the Keokuk limestone represented in the 
Grand Canyon walls. 
When the Red Wall limestone of Arizona shall have been care¬ 
fully exploited for fossils, and the faunal zones shall have been 
made out it is not impossible that the Grand Canyon section will 
be found to be fully as sharply differentiated into a three-fold 
sequence as are the corresponding sections exposed in the Missis¬ 
sippi Valley. 
The terrane carrying the Chouteau fauna, and here designated 
the Simon limestone, is well displayed in the Chiricahua Moun¬ 
tains, especially above the Cochise Consolidated Copper Mine over¬ 
looking the San Simon bolson. The Truxton division, with the 
Burlington fauna, is exposed in full development in the Grand 
Wash Cliffs and the Yampai Cliffs northeast of the Needles, as 
well as in the Chiricahua Mountains, and especially at Lake Val¬ 
ley, in New Mexico. Elden beds, yielding the Keokuk fauna, 
outcrops at Elden east of Flagstaff, and at Marble Hill to the 
north. 
In its general aspects the Mid Carbonic section of Arizona is 
not so very different from the standard American section of the 
Mississippi Valley. The lithologic resemblances, the terranal suc¬ 
cession, and the faunal idiosyncracies are so closely paralleled in 
the two regions that there should really be nearer stratigraphic 
comparisons that it is customary to make. 
Shore deposits comprising sandstones and shales, at the bottom, 
extensive and massive sandstones in the middle, and open-sea 
beds, including limestones chiefly, at the top, characterize both 
