22 RECONNAISSANCE OF PART OF WESTERN ARIZONA. 
AQUARIUS MOUNTAINS. 
Location. — The Aquarius Mountains, located in the east-central part 
of the region, form a group of considerable size at the southern end of 
the Truxton Plateau, and extend in a southeasterly direction across 
the course of Kio Santa Maria and Date Creek. 
Topographic features. — South of the mouth of Deluge Wash the 
Aquarius Cliffs gradually lose their scarplike character and finally 
merge into the general westward slope of the Aquarius Mountains. 
These mountains were visited only at their southern and western 
extremities, but from the west at a distance they appear as lofty 
mountains, comparable in altitude with the Hualpai Mountains to the 
west, and the Harcuvar and Harquahala mountains to the south. 
The southern part of the group is carved into rugged, irregular 
hills. Rio Santa Maria has eroded a narrow canyon deep into the 
lavas, and smaller streams have cut less deeply. Date Creek has cut 
through the end of the ridge, instead of following an apparently easy 
course a few miles farther south. 
Rock masses. — The granite of the Truxton Plateau extends south- 
ward to the Aquarius Mountains, and was examined in Signal Canyon. 
The southern part of the group, however, is composed of andesites and 
rhyolites, presumably of Tertiary age. South of Santa Maria Canyon 
the mountains, 3,000 to 4,000 feet high, are composed of effusive rock, 
which has been dissected by erosion to a depth of about 3,000 feet. 
Within valleys eroded in the Tertiary lavas small sheets of basalt 
occur, in some places capping gravels of probable Quaternary age, as 
in Signal Canyon (PL III, A), and in other places occurring within 
these gravels, as in Santa Maria Canyon near the mouth of Big 
Sanely Wash. 
ARTILLERY MOUNTAINS. 
Location. — The Artillery Mountains form a small group near the 
head of Williams River. They are separated from the Aquarius 
Mountains by Signal Canyon only, and are virtually an outlying 
group of those mountains. 
Topographic features. — The Artillery Mountains are small and com- 
paratively low, the only conspicuous peak being a sharp pinnacle of 
igneous rock, apparently a volcanic neck, which, on account of its 
altitude and pointed summit, is visible and easily identifiable from 
great distances. The rocks are deeply dissected by erosion on the 
east and south near Big Sandy and Williams rivers, but to the north 
and west the mountain flanks are buried by the detritus of the Big 
Sandy Valley. 
Rock masses. — The main rock mass of the Artillery Mountains is 
coarse-grained granite, mineralized in places, although the mineral 
