32 RECONNAISSANCE OF PART OF WESTERN ARIZONA. 
the vicinity of Toquerville, Utah, a distance of about 80 miles, where 
it joins the Hurricane fault. The present writer traced it southward 
into the Hualpai Valley, where it apparently forks, the western branch 
reappearing west of the Hualpai Mountains and the eastern one 
following the cliffs. 
The Grand Wash Trough is filled with Greggs breccia to an alti- 
tude of about 2,500 feet, or 1,500 feet above the river. Where the 
breccia was examined most carefully, in the bluffs south of the river 
about 4 miles east of Greggs Ferry, it was found to be composed of 
unassorted and poorly stratified debris consisting of angular rock 
fragments, principally granite, the largest having a diameter of 10 
feet or more. Toward the top the fragments were cemented by 
carbonate of lime into a very resistant mass, forming the cap rock of 
certain conspicuous cliffs east of Greggs Ferry. The upper 100 feet 
or more of this capping stratum is travertine and is nearly devoid of 
rock fragments. Farther south the surface consists of the truncated 
edges of the upturned limestone block. (See section P-P' ', PL V.) 
The breccia of the Grand Wash Trough has been much more eroded 
north of the river than south of it. The breccia was not examined 
far from the river, but, judging from the size and character of the 
bowlders brought down by the washes, it is probable that the material 
in the midst of the trough does not differ greatly from that described 
from the cliffs at its western edge near Greggs Ferry. 
The Temple Bar conglomerate also occurs in the Grand Wash 
Trough, appearing in many places at altitudes several hundred feet 
higher than the river, in depressions previously eroded in the older 
rocks. It is composed of sand and waterworn pebbles of quartzite, 
limestone, marble, etc., not distinguishable at the present time from 
the gravels derived from Grand Canyon. These are in places ce- 
mented by carbonate of lime into very resistant masses, forming 
nearly perpendicular cliffs 500 feet high. The travertine deposits 
just described within the canyon were probably formed at the same 
time. 
The Temple Bar conglomerate of the Grand Wash Trough contains 
a thick sheet of basalt. The lava appears in the face of a cliff in 
Iceberg Canyon in the midst of the conglomerate, and in the Grand 
Wash Trough as a columnar sheet overlying the conglomerate. The 
relation of the Temple Bar conglomerate to the underlying sedi- 
mentary formations of the tilted block and to the overlying sheet 
of basalt is shown in PL VII, A. 
The Greggs breccia, where exposed near the river within the 
Grand Wash Trough, is roughly stratified, and the strata are tilted 
eastward, the maximum dip observed being, about 30°. The Temple 
Bar conglomerate is also locally disturbed, dips of 10° eastward being 
observed in places. At the base of the Grand Wash Cliffs the detrital 
