60 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



ruins would be found. Accordingly I decided upon the head of the Rincon Valley, about 

 22 miles southeast of Tucson, as a test case. The expected ruins were found in the shape 

 of vestiges of several small villages, the chief of which contains the foundations of at least 

 18 houses. There can not have been less than 25 houses in this small mountain valley, and 

 quite possibly more, for pottery is scattered thickly far beyond the limits of the founda- 

 tions. The present population consists of two American and two Mexican families. One 

 of the Americans is the forest ranger; the Mexicans are vaqueros, or cattle-men. The other 

 American is the only man who does much farming. He says that the cultivated land 

 amounts to 200 acres, but his individual figures total only 150, and even this seems in 

 excess of the visible fields. Granting that the figures are correct, however, the arable 

 land with the water supplied by the brook might suffice for a population such as that 

 indicated by the ruins. Therefore nothing can be argued either for or against changes 

 of climate. Certain other phenomena, however, bear directly upon the subject. About 

 1.5 miles east of the forest ranger's house and about 3 miles east by north of the prominent 

 hill called Sentinel Butte, a grassy slope drops toward the northwest at the base of Rincon 

 Peak, 8,465 feet high. The slope has a fall of about 10°, and an altitude of from 3,300 to 

 3,500 feet above sea-level. On the smoothest part of it, for a distance of about half a mile 

 parallel to the upper Rincon and for a width of about one-half or two-thirds as much, one 

 finds unmistakable terraces built apparently for purposes of agriculture. In general they 

 are from 20 to 70 feet long and 2 or 3 feet high. The commonest location is at right angles 

 to the minor drainage lines, each little swale being broken into terraces with a width 

 of from 20 to 30 feet, as appears in Plate 2, a. In some cases the spaces between the 

 swales are also terraced. The terrace walls are all composed of pebbles and cobbles. 

 I searched carefully for pottery, but succeeded in finding only one or two coarse bits, 

 quite in contrast to the abundant potsherds which occur not only among the foundations 

 lower down in the valley, but all along the borders of the alluvial plain. The only other 

 works of man among the terraces are some small stone circles resembling modern mescal 

 beds, where the agave is cooked, and a round structure 7 feet in diameter. The whole 

 hillside closely resembles hundreds in Palestine, Syria, and Asia Minor, or in Mexico and 

 South America. Even the little round structure with its small doorway resembles the 

 watchmen's shelters in the terraced fields of Syria. There can scarcely be any doubt that 

 the terraces were designed for agriculture. Apparently they were not intended for irri- 

 gation, for they are not properly arranged, nor does there appear to be any available source 

 of water. They must have been intended for dry farming. Near the main village, down 

 in the valley 3 or 4 miles away, the gravel slope just east of the gully which bounds the 

 village on that side is interrupted by a few similar terraces. Apparently dry farming was 

 attempted in more than one place. 



As has already been said, Professor Forbes, of the Arizona Experiment Station, states 

 that dry farming is not now practicable in Arizona except by means of most careful and 

 expensive methods of plowing and harrowing. The terraced slope in the upper Rincon 

 Valley, because of its proximity to the mountains, undoubtedly receives more rain than do 

 many parts of the country. Over on the east side of the Santa Rita Mountains, at an 

 elevation considerably greater than that of our terraces, potatoes are said to be cultivated 

 without irrigation, but further inquiry shows that they are watered naturally by springs 

 bursting out above them. In the same region, at the mouth of Gardner's Canyon, at an 

 elevation of about 5,000 feet, four or five settlers took up land and attempted real dry 

 farming in 1909. The elevation is sufficient to insure moderately cool weather much of 

 the year and hence less evaporation than in the parching plains. The rainfall in the 

 summer of 1909, as measured at the Empire Ranch not far away, amounted to 9.39 inches 

 as against an average of 7.93 for the preceding 15 years. Nevertheless the corn failed 

 entirely; and the beans, the most rehable of all crops, gave so scanty a return that the 



