44 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



terraces and not on others, the data are too scanty to Avarrant any conclusion. My own 

 observation shows that ruins of prehistoric (pre-Columbian) villages are rarely found 

 upon the present alluvial flats — that is, upon the plains formed by the rivers in the most 

 recent ])eriod of deposition. Except far downstream in the neighborhood of broad playas, 

 ruins of any great age appear to be found always on terraces just above the plains of fine 

 silt. This fact, however, possesses no special significance, for the location may have been 

 determined by motives of sanitation or by the desire not to encroach upon arable land. 



The location of buried pottery is much more significant. The finding by Professor 

 Forbes of ancient pottery under 10 feet of alluvium in the banks of the newly formed inner 

 valley of the Santa Cruz at Tucson has already been mentioned. Another occurrence of 

 this same nature is described by INIindeleff in the Thirteenth Annual Report of the Bureau 

 of Ethnology, 1891-92, pp. 239-240. In the vaUey of the lower Verde, one of the northern 

 tributaries of the Gila, the river has recently excavated a channel, leaving the old flood- 

 plain as a terrace, just as in the case of the Santa Cruz. While the process of erosion was 

 in progress, Mindeleff was so fortunate as to see and photograph an old irrigation canal 

 which had been buried beneath 10 feet of alluvium, and was now once more exposed by 

 erosion, only to be washed away forever in the course of a few months. He estimates that 

 the silting up of the valley bottom and the burial of the ditch to a depth of 10 feet must 

 have taken at least 150 years, and may have taken several times as long. How long a time 

 elapsed between the completion of the process of deposition and the inception of erosion is 

 entirely problematical. It may have been anywhere from 10 years to 10 centuries. 



The examples thus far given have been from a small area in southern Aj-izona. (See 

 map, frontispiece.) In northern New Mexico, 400 miles away, I chanced upon a similar 

 example. About 6 miles north of Santa Fe and 3 miles south of the modern pueblo village 

 of Tesuque, Mr. Vierra, an artist of Santa Fe, pointed out a place on his ranch where pottery 

 and ashes have been buried to a depth of 6 feet under alluvium and have since been exposed 

 by the cutting of the stream to a depth of 15 feet. In the steep face of the terrace thus 

 formed we found the vestiges of human occupation so thickly scattered as to show that once 

 a small village must have been located here. It stood in the angle between the main Te- 

 suque stream and a small tributary from the southwest, and pottery is found in the terraces 

 of both streams. I happened at the time to be with Mr. Kenneth M. Chapman, secretary 

 and artist of the School of American Ai'cheology at Santa Fe. He kindly examined the 

 pottery and states that it belongs to the present Tesuque type, and not to the prehistoric 

 Pajaritan type found in the older and more important ruins of the region. This means 

 that since the Tewa stock, to whom the Tesuque Indians belonged, came to this region, 

 probably 700 to 800 years ago, there has been time for a village to be founded and occupied 

 long enough to form an accumulation of pottery and ashes. Then the village was abandoned 

 and floods covered it with 6 feet of silt, after which the streams changed their mode of 

 action sufficiently to cause the erosion of a broad inner valley and the formation of a terrace 

 15 feet high. We can not say with assurance that man's actions may not have had a part 

 in causing erosion to begin, but inasmuch as man has occupied the region continuously 

 from the times of the Pueblo Indians through that of the Spaniards and Mexicans to that 

 of the Americans, the relation of man to the country has not changed in any such sudden 

 way as has been the case in southern Arizona. Yet even there we saw that, although man 

 had a hand in causing terracing, he served chiefly as a means of setting natural forces in 

 operation rather than as a new force. Heavy rains were needed before any terracing could 

 take place, even in southern Arizona, and in northern New Mexico it is still more probable 

 that the terracing was due to natural changes causing variations of rainfall. 



As a final example of the relation of the terraces to man I shall describe the conditions 

 in the Tularosa Valley of southern New Mexico in the plateau east of the Otero Basin. 

 The valley begins a few miles north of the summer resort known as Cloudcroft, and extends 



