DEMING TO CASAS GRANDES. 
J 3 
are not alike in resources, and their varia¬ 
tions are simply due to the variations in 
the water supply. 
The backbone ridge of mountains in 
Mexico is the Sierra Madre, or Mother 
Mountains, for from them all other 
ridges and spurs seem to emanate. From 
their crests, as with all other mountains 
in the world, spring innumerable rivulets 
and creeks, which, uniting, form rivers. 
But nearly everywhere else these streams 
increase in size by the addition of the 
waters of other tributaries until they reach 
the sea. 
Not so with the Mexican rivers of this 
locality. Shortly after leaving the moun¬ 
tains and reaching the foothills, they re¬ 
ceive no additions from other sources, 
and after flowing from fifty to one hun¬ 
dred miles they sink into the ground. 
