SMITHSONIAN EXPLORATIONS, I93O 1 59 



brought forth into full bloom high civilizations that made Mesopo- 

 tamia known throughout the ancient world. 



With prodigious labor, the Peruvians of pre-Spanish times led ir- 

 rigation ditches along craggy heights of the Andes to their terraced 

 gardens. Among the highlands of Mexico and again in various sec- 

 tions of the southwestern United States, Indian farmers had learned 

 that irrigation was necessary to the successful cultivation of food 

 crops. In November, 1694, Padre Eusebio Kino stood before the drab 

 walls of Casa Grande ruin and speculated upon the feasibility of 

 restoring its abandoned, overgrown canals. Five hundred years before 

 Kino was born the inhabitants of Pueblo Bonito, in Chaco Canyon, 

 New Mexico, were capturing the mid-summer rains, taming and guid- 

 ing them onto thirsty fields. But none of these efforts matched the 

 colossal, prehistoric irrigation systems of the Gila and Salt river 

 valleys. 



We wanted maps of these latter, hand-made Indian canals. We 

 wanted to know their extent, their position relative to each other, the 

 approximate acreage they once watered. Similar desires on the part 

 of other observers had prompted surveys which were not altogether 

 successful for the very simple reason that so little is now visible of the 

 ancient ditches. Modern agriculture has been too destructive ; it has 

 plowed and planted until the aboriginal farming communities and their 

 works were pretty thoroughly obliterated. From the ground, one's 

 range of vision is too limited ; from the air it might be possible to 

 recover data for the maps we had in mind. At least this seemed the 

 most promising, expeditious method when I made a preliminary study 

 of the situation in the autumn of 1929. * 



So, at the solicitation of United States Senator Carl Fiayden, the 

 Smithsonian Institution and -the War Department cooperated in an 

 aerial survey of the Salt and Gila river valleys, beginning late in 

 January, 1930. Lieutenant Edwin Bobzien and Sergeant R. A. Stock- 

 well, pilot and photographer, respectively, were detailed from the 

 Air Corps unit at Crissy Field, San Francisco, and I was designated 

 Smithsonian representative, to advise with the aviators. 



Our small party assembled at Phoenix, blocked out the areas to be 

 photographed and speedily set to work. Smoke and ground haze drew 

 an impenetrable blanket over Salt River valley each morning and 

 evening, thus restricting flying time to a brief two hours at midday 

 when shadows are at a minimum. The longer shadows of early morn- 



1 Explorations and Field-work of the Smithsonian Institution in 1929, pp. 

 177-182. Washington, 1930. 



