PREHISTORIC IRRIGATION PROJECT — SHETRONE 381 



In south-central Arizona is the city of Phoenix, capital and metrop- 

 olis of the State. From the mountains and high plateau toward the 

 east come two rivers — the Salt from the northeast and the Gila from 

 the southeast. They converge just west of Phoenix and find their way, 

 as the Gila River, to the Colorado and the Gulf of California. 



The State of Ohio sometimes is referred to as the land of the Mound 

 Builders ; the valleys of the Salt and the Gila, particularly the region 

 of which Phoenix is the hub, may with equal justification be referred 

 to as the land of the Canal Builders ! Here we have the double phe- 

 nomenon of an area of considerable extent, by nature arid and unin- 

 viting, which, for several centuries in prehistoric times, was made to 

 "blossom as the rose"; which then reverted to its natural aridity; 

 and now, once again, has become one of the more fertile and productive 

 regions of the continent ! 



The visitor to Phoenix need walk but a short distance outside the 

 city limits to come upon one or more ancient irrigation canals. Accom- 

 panied by a guide familiar with the terrain, he will be able to trace a 

 number of others, and will learn that prior to their partial obliteration 

 by present-day agriculture, some 125 miles of main irrigation canals 

 were existent in the Salt Kiver Valley and perhaps half that mileage 

 in the valley of the Gila. Many of these measure as much as 30 feet 

 between their crowns and reach depths of 10 feet or more. Even at 

 this late date some of these may be traced for as far as 10 miles. 



The canal system in the Salt River Valley consisted of several inde- 

 pendent units, or main canals, each with many branch canals and 

 ditches. Intakes of the main canals were far enough upstream to pro- 

 vide sufficient ' 'fall" for successfully irrigating their respective areas. 

 The lateral branches, most of which long ago were obliterated through 

 erosion and silting, must have aggregated hundreds of miles. 



An aerial survey of the valleys of the Salt and the Gila was effected 

 in 1930 through the cooperation of the Smithsonian Institution, the 

 United States Army, and certain authorities in Arizona. This aerial 

 reconnaissance, during which the region was accurately photographed 

 and mapped, was followed by a ground survey under the direction of 

 Phoenix city archeologist, O. S. Halseth. As a result of this dual 

 survey, what admittedly is the only true irrigation culture in pre- 

 historic America has become a matter of record. 



This brief outline of prehistoric irrigation and agriculture in 

 Arizona should elicit a desire on the part of the reader to learn 

 something of the people responsible for their development. Who 

 were the ancient Canal Builders? Spanish padres and adventurers 

 from old Mexico, who came into the region toward the close of the 

 seventeenth century, perhaps were the first white men to ask this 

 question. Naturally, they sought the answer from the native Indians, 



676212 — 46 25 



