18 EANGE INVESTIGATIONS IN ARIZONA. 



The entire tract is more or less cut up bj^ arroyos. These are 

 usuall}^ stee\), rugged, and rocky close to the mountains, but become 

 wider and more shallow northward. The water which they carry 

 during Hood time is consequently spread over larger areas on the north 

 side of the field. The surface water which goes down to the north 

 side, however, is small in quantity and of short duration, but the sands 

 of the arroyos carry an underground supply of water for several days 

 after a rain. This supply of moisture to the shrubby vegetation is 

 very considerable along these temporary water courses, but the areas 

 between them receive only such moisture as happens to fall at those 

 points. During the violent summer showers much of this runs off. 



As stated above, the southern portion of the area is a comparatively 

 open region, being cut by frequent arroyos, as indicated on fig. 1 

 between points L and G. The largest of these is the one which runs 

 close to Proctor. At this point it is from 150 to 200 feet deep and 800 

 feet wide from bank to bank. Here the bottom of the arroyo is on 

 solid rock, which accounts for the appearance of water at the surface. 

 In general, however, it, like the others, is of coarse sand and like them 

 widens out to the northward, its banks becoming lower and less rocky. 

 Between the points L and B on fig. 1 on the fence line there are a 

 number of small steep arroyos, and the same condition exists on the 

 southern half of the west line, but the latter are less pronounced than 

 the former. All of the arroyos are more rocky close to the mountains, 

 and gradually spread out to the northwest, making the whole area a 

 sloping plain, cut at frequent intervals by usually shallow washes to 

 the northward and by deeper arroyos and canyons to the south. 

 Besides the above water courses there are numerous gullies cut by the 

 flood v/aters. These usually occur as laterals to the main arroyos, and 

 extend into the broad gentle slopes which exist between the main water 

 courses. The condition is a difficult one to portray, for the cuts are 

 made by the flood waters, whose action is explained only when con- 

 sidered in connection with a surveyor's level and with the chemical and 

 physical conditions of the soil. One can drive with a light rig over the 

 entire field by picking his way slowly, but in many places he is obliged 

 to travel considerable distances in order to get around the arroyos. 

 This is especially true of the southern half of the field. 



sorL. 



But little discussion of the subject of soil can or need be entered 

 into. In general it may be said that the soil is of a light-brown color 

 and composed of very fine particles intermixed with a large amount of 

 coarse sand and gravel. On the south side it is much looser in texture, 

 has more gravel in its composition, and packs less firmly upon drying 

 than on the north side. On this account the sloping areas between 

 the arroyos are not so badly washed, which condition, together with a 



