232 
FRAMEWORK OF ARIZONA 
through-flowing river, is notably smaller when it leaves the state 
than when it enters it. 
Because of the relatively small exposure of the old, indurated 
rocks in the narrow desert ranges and of the myriad broad belts of 
intermontane plain out of which bedrock seldom outcrops, or even 
peeps, general geological mapping of the normal type is almost im¬ 
possible. It will be long before intelligently drawn maps reflect¬ 
ing the tectonic expression of the state will be available. In this re¬ 
gard the Government maps of large areas with their vast expanses 
of intermontane soils are little better than none. Along with those 
of several other “Basin Range” provinces, Arizona’s general map 
of her geological formations and structures are likely to be the very 
last in the procession of the states of the Union. It will be fifty and 
mayhap a hundred, years before passable chartographic represen¬ 
tations can be made generally useful, tectonically expressive, and 
scientically soulful enough to be worth while publishing. 
Although that Titan of Chasms, the Grand Canyon of the Col¬ 
orado, is no doubt the profoundest gash that Earth’s flesh is heir 
to, opening up as it does the straticulate cuticle of the globe to the 
depth of more than a mile, the rock-section thus laid bare is by 
no means the greatest, the completest, or the most imposing which 
the state of Arizona affords. Occupying a notably strategic posi¬ 
tion in the stratigraphic economy of the continent, Arizona’s geo¬ 
logical history should be studied with that of its neighbor New 
Mexico, as two parts of one history, since the two states cover the 
flanks of the continental divide. 
For a full century failure results from attempts to correlate by 
lithologic continuity, or similarity of lithologic sequence the ter- 
ranal successions on the two sides of the American continent. The 
Rocky Mountains impose a wide and seemingly impassible break 
that utterly baffles all efforts to match sections across the uplift. 
Repeated uprisings, peneplanation of the region for twenty-five 
successive times since the beginning of the Paleozoic times, all but 
completely obliterate every vestige of the sedimentaries. The 
scheme of masquerading instead of bridging the broad gap by in¬ 
troducing a nomenclature on the west side entirely different from 
that so familiar on the east side confuses rather than clarifies the 
situation. 
But if the stratified succession cannot be carried over the moun- 
