70 THE CLIMATIC FACTOR AS ILLUSTRATED IN ARID AMERICA. 



perhaps 15,000, where now there are scarcely more than 200. Rather than accept the 

 supposition of artificial irrigation, we may well believe it probable that dry farming was 

 actually possible. 



The case of the Trinchera is not like that of Rincon in one respect. There the terraced 

 area receives more rain than the surrounding areas, because of its location at the base of 

 high mountains. Here the Trinchera lies out in the midst of a plain, far from the moun- 

 tains. Moreover, the mountains, when reached, are not of great elevation. Hence the 

 terraces and the old rectangular fields receive no more rain than the rest of the country. 

 If dry farming was practicable there, it was practicable elsewhere. In that case we ought 

 to find old fields in other places, that is, in the neighborhood of all the chief centers of 

 ancient population. According to report, trincheras are abundant all over northwestern 

 Mexico, although they do not appear to have been examined closelJ^ Many may be so 

 ruined that they have escaped notice. On the upper Magdelena, at a place known as 

 Terenate, I found such an one by accident. Climbing a high hill to get the view, I was 

 surprised to find a rude defensive wall on its top, and fallen terraces on the sides. The 

 terraces were so broken as to be almost um-ecognizable had it not been for their resemblance 

 to those of the Great Trinchera. Being roughly constructed without mortar, and being 

 probably of great age, they have fallen badly to ruins, but one can still readily find places 

 where stone has been piled upon stone by human hands, forming terraces of precisely the 

 kind described above. How many other such sites exist no one can tell; already enough 

 have been discovered to indicate that, granting that the terraces were designed for agri- 

 culture, dry farming must have been practised on a small scale over a wide area where it 

 is now out of the question. 



Thus far we have considered the ruins in the desert region near Tucson in southern 

 Arizona, and to the southwest and south of that town across the border in northern 

 Mexico. Let us now consider the region lying at an equal or greater distance to the east 

 of Tucson in southern New Mexico. So far as the ruins are concerned no new types are 

 found, and the description of those in the Santa Cruz Valley applies almost unchanged 

 to those in southern New Mexico Nevertheless it is worth while to present some of the 

 details in order to bring out more fully the wide extent and large number of the phe- 

 nomena upon which we may rely in our study of the past as compared with the present. 

 Before taking up the ruins, however, it may be well to lay at rest an archeological ghost 

 which finds shelter in various reputable publications. 



The Animas "dam," or "levee," lies chiefly in the extreme southwestern corner of 

 New Mexico, but projects a short distance across the border into Mexico. It has been 

 described as a huge dam made to hold water for irrigation, or as a great dike upon the top 

 of which water was carried in a semicircular course across the head of the Animas Valley. 

 In the midst of the broad, flat plain forming the bottom of the valley it rises in the form 

 of a great embankment varying in height from 15 to 50 feet. From the foot of the Lang 

 Mountains on the south side in Mexico it sweeps around in a great curve, broken for a 

 quarter of a mile on the southwest, where the Cloverdale drainage breaks through it, and 

 then continues unbroken until, after a course of about 16 miles, it swings around to the 

 mountains once more, and then merges in a bluff which continues to the other end of the 

 supposed dam. To build such a structure would, by actual computation, require the work 

 of 1,000 men for 50 to 100 years. The physiographer, however, needs no such computation 

 to prove that the "dam" is not of human origin. It presents the characteristic features 

 of a lacustrine strand, much exaggerated, however, but still unmistakable. At some 

 past time, presumably during the glacial period, a lake must have stood here, and must 

 have been swept by winds of unusual severity, forming beaches of exceptional dimensions. 



The actual number of people who at any time lived in the entire Animas Valley probably 

 never exceeded 1,000, although that is decidedly more than live there to-day. Ruins of 



