i6o The American Geologist. March. i90i. 
SOME SALIENT FEATURES IN THE GEOLOGY OF 
ARIZONA WITH EVIDENCES OF SHALLOW 
SEAS IN PALEOZOIC TIME. 
By William P. Blake, Tvicson, Arizona. 
The geology of the northern portion of the territory of Ari- 
zona inchiding the grand caiion and the plateau region has been 
studied and mapped by Powell, Button and others of the U. S. 
Geological Survey. Blandy has published some papers relat- 
ing to central Arizona ; the writer has contributed some special 
papers and desultory notes in reports to the governors of the 
territory and elsewhere, but in regard to the country south of 
the great plateau region very little systematized information 
has yet appeared in print.* An explanation may be found in 
the fact that the reo^ion is vast and difficult of access and until 
recently has largely been under the domination of the savage 
Apache. 
Capt. Dutton in his monograph upon the Tertiary history of 
the grand caiion district, frequently refers to an unknown "Ari- 
zona Land." In this he shows a mental reaching out for far 
off shores from which a portion, at least, of the mighty mass of 
sandy sediment in the basin of the Colorado could have been 
derived. 
Investigations in southern Arizona sustain the idea of the 
former existence of such shores, not perhaps as continental 
margins but as island ridges ; crests of submerged mountain 
ranges rising at intervals above the waves of shallow seas, 
and with a trend or direction corresponding essentially to the 
trend of the mountain ranges of the region. 
A cross-section of the territory in a northeast direction from 
the head of the gulf of California, the sea of Cortez. to the lino 
of New Mexico, a distance of nearly 350 miles shows a suc- 
cession of mountain ranges separated bv long trough-like val- 
leys often broad plains or mesas. There are some fifteen such 
main lines or axes of elevation with a general northwest and 
southeast trend. Commencing first at the gulf we have in suc- 
* Since this paper was written a memoir has been pnblished by Dr. Theo. 
B. COMSTOCK, in the Transactions of the Am. lust, ^tining Engineers, entitled 
"The GeoloKj' ^nd Vein Phenomen.a of Arizona." 
A partial bibliography of contributions to the Geolog3- of Arizona may be 
found in Bulletin Xo. 127 of the V. S. Geol. Sur. and also in the Report of the 
Governor of Arizona for 1S99. 
