307 
Section North from near Camp Apache (Fort Apache) (after Gilbert) ).** 
Feet 
Ie Asalirand DASALE OTA VEls cs <5)... sre cieke clacpetgrn tied a16) elejesisiere ae « aves 70 
2. Pale pink slightly coherent, massive sand and gravel resting 
ATC OMMKOLIM AD ly: OM INO teh. korsrate rs ave) crenetent ete ersite sues ss 1s: ate cree « sear aters 520 
D-OMeClASEIC TOCKS 6.2 556.00 PEN AR MTEC Re ARM rel a eeehenn Gisteud siewenete 1670 
HANG freUillaa cose vce vet etish sian oxasetenaealtauehelage) eeieiohens F tsire an aie gee Phat diay: Pelle Oustay oe hence . 2260 
It is quite possible from the data at hand that the deposits have 
accumulated in Seven-mile Hill section and in the Salt River and Hinton 
regions and in many other places in the area, covered by this paper through- 
out the Tertiary and may have begun even earlier. A part of the series 
which the writer had originally designated “Tertiary”, principally in the 
sections mentioned above, begins with a consolidated, coarse conglomerate 
stratum, beneath which are strata of partly lithified sands, clays and 
gravels reaching a thickness of nearly a thousand feet in thickness in some 
places. The formation is found, for the most part, in the ancient canyons 
of the region. Conformably on the formation above designated “Tertiary”, 
in this paper and in my original report on the region, are hundreds of feet 
of unconsolidated gravels and clays and occasionally volcanic ashes. This 
series covered the entire region, excepting possibly the Ellison dome, so 
that the lava flows which closed the Quaternary, flowed over a plain. Since 
then much. has been removed so that now it is patchy, except where it is 
protected by superimposed lava. It now fills the valleys of the Pinal and 
Apache mountain districts ; the volcanic and plutonic rocks projecting above 
it as peaks and mountains. The middle Cherry creek valley and the Tonto 
basin, as ‘well as the Ellison flat, are covered with it. It covers the Mogollon 
mesa together with its southern prolongations, including the Cibicu divide, 
to a thickness of from five hundred to a thousand feet in many places. It 
is the surface rock of much of the Kelley butte country, and extends beneath 
the lava of the Nantan Plateau as far as visited. 
At the time the writer studied the region, he believed that these deposits 
were due to a stage of ponding, as a result of differential uplift and lava 
flows, since he found no glacial striae; but since his study of the glaciation 
in the San Juan mountains in Colorado and the Deep Creek region, Utah, 
he has been compelled to change his views and conclude that the deposits in 
question are of glacial origin and probably in part due to laking, as a 
result of glaciation and voleanie disturbances. This view is also born out 
by the fact that the Cibicu divide and the Mogollon mesa, which are both 
heavily covered with this drift, are higher than the surrounding country 
and show no evidence of a laking stage. 
The deposits, clays, sands, gravels, and boulders of schist, quartzite, 
gneiss, carboniferous rocks, vitreous Tonto sandstone, diorite, trachyte, 
rhyolite, and Archean rocks, indicate different development centers for the 
**Gilbert, ibid., p. 165. 
