Geology of Arizona. — Blake. i6i 
cession the Gila range ; Alohawk and Castle Dome ; Growler 
Ajo; Maricopa, and Quijotoa, Baboquirari ; Tucson, Santa 
Catalina, and Rincons, (extending northward to the 
Bradshaw group of elevations), the Santa Ritas (east of the 
valley of the Santa Cruz), the Huachucas and Whetstones: 
the Dragoons and Mule mountains (Tombstone), extending 
north into the Galiuro ; the Pinaleno and Chiricahua, the Pilon- 
cillos east of the San Simon plains ; ending with the Natanes 
and Prieto plateau and the Four Peak mountains. 
These several mountain ranges may be considered as suc- 
cessive axes of uplift, or structure, with well-defined occur- 
ences of Palaeozoic strata, generally resting upon a foundation 
of granite and Archaean gneiss. Regular anticlines and syn- 
clines are rare. Alonoclines are the rule, as for example in the 
Huachucas and Santa Ritas. 
The presence in all these ranges of massive strata of quartz- 
yte, and frequently of coarse conglomerates referable in age to 
the Paleozoic, or earlier, bears conclusive testimony to the ex- 
istence of shore-lines and of shallow seas in that early period of 
continent making. But there are also deep sea lime-stone of De- 
vonian and Lower Carboniferous age and other limestones 
probably Silurian. 
Coal Measures. In the Chiricahua mountains we also find 
evidences of Coal Measures and vegetation of that period in 
the shales and uplifted beds of graphitic anthracite several 
feet thick. So, also, in the San Carlos region, and northwards, 
heavy strata of the Carboniferous occur with seams of coal, but 
so far as yet determined of limited thickness and value. These 
occurrences are, however, sufficient to show a far western ex- 
tension of the vegetation of the Carboniferous and consequently 
the existence of dry or swamp land at that time. The most 
western point in the latitude of Arizona at which Coal Meas- 
ures have before been found was in the Rocky mountains near 
Santa Fe.''' Thickly bedded limestones of dark color and of 
Carboniferous age occur in the mountains west of Tucson. 
The limestones in the Quijotoa mountains at the Vekol lead-> 
•In 1857 I collected fossil ferns near Santa Fe which the late Mr. 
Lksquereux identified as specifically the same as several species found in the 
Pennsylvania coal measures. Prof. Dana, in his fourth and last edition 
Maunal of Geology, p. 658, says "A Carboniferous formation without coal is 
the great fact for the western half of the continent," a statement which in the 
light of the above facts needs some modification. 
