226 GUIDEBOOK OF THE WESTERN UNITED STATES 
granite aplite intrusion occupies an area of 5 or 6 square miles between 
North Peak and the Webb mine. Dikes of coarse granite and diabase 
also occur. 
The Palo Verde Mountains, south of the gap at Enid, consist of 
schist and are part of a line of ranges extending south through the 
Vekol® and Cimarron Mountains. They are about 800 feet high, 
deeply canyoned, and possibly bounded by a fault at their steep 
northeast end. - In the pass between the Palo Verde and Table Top 
Mountains, the range next south, there are ledges of Tertiary arkosic 
conglomerate interbedded with basalt flows, the lowest of which 
rests on granite. The beds dip 14° SW. Some of the boulders, 
which are granite, are 6 to 8 feet in diameter. 
The wide plain of the Estrella Desert is crossed west of Enid to 
reach a low pass through the northern part of the Maricopa Moun- 
tains. This pass is drained by Waterman Draw, and wells in the 
valley fill near this draw have obtained sufficient water for cattle, 
which find sparse pasturage in the valley and adjacent slopes. The 
divide is just east of Estrella siding (elevation 1,523 feet), where there 
is a wide gap floored with gravel and sand between high granite 
ridges. Wells drilled in the valley fill at Mobile siding (452 feet 
deep), at Ocapos siding (541 feet deep), and at Estrella found water 
which rose high in the borings but was insufficient in quantity for 
locomotive use. It was through this pass that Padre Garcés traveled 
in 1775 on the way to Yuma, and he called it Puerto de los Coco- 
maricopas. (See p. 194.) 
Beyond the Estrella divide (see sheet 24) the railroad descends to 
Ocapos siding in a wide valley with walls of granite. The Maricopa 
Mountains consist mostly of this rock, with a minor amount of 
schist. The east slope of this range north of Estrella has at its foot 
a moderately wide pediment or slope of nearly bare rock, trenched but 
slightly by streams. Atone place this pediment is surmounted by a hill 
of gravel capped by a remnant of a basalt sheet tilted to the east, which 
indicates uplift since the extrusion of the lava. On the west side of 
the mountains and in the pass there is a thick mantle of valley fill. 
* South of the Table Top Mountains, { erate like the Barnes. An overlying 
about 45 miles south of Maricopa, are | quartzite like the Dripping Spring 
the Vekol Mountains, which are of | quartzite is penetrated by thick sills of 
ii eee interest, for they contain | dark-green diabase. Next above are 
only a succession of Paleozoic | rusty sandy shales grading up into thin- 
limestones including some strata of finds 
| bedded limestone containing Upper 
|} Cambrian fossils, undoubtedly the 
Abrigo limestone. The higher lime- 
stone in an adjoining ridge carries a 
remarkable fauna of minute fossils, 
= and gastro- 
pods, of about 25 species of late 
