Owing to the character of the country it drains, the Rio Verde always must have been subject to freshets and overflows at the time of the spring rains, but until quite recently the obstructions to the rapid collection of water offered by thickly growing grass and bushes prevented destructive floods, except, perhaps, on exceptional occasions. Now, however, the flood of each year is more disastrous than that of the preceding year, and in the flood of February, 1891, the culminating point of intensity and destructiveness was reached. On this occasion the water rose in some places over 20 feet, with a corresponding broadening in other places, and flowed with such velocity that for several weeks it was impossible to cross the river. As a result of these floods, the grassy banks that once distinguished the river are now but little more than a tradition, while the older terraces, which under normal circumstances would now be safe, are being cut away more and more each year. In several localities near Verde, where there are cavate lodges, located originally with especial reference to an adjacent area of tillable land, the terraces have been completely cut away, and the cliffs in which the cavate lodges occur are washed by the river during high water.
[ DISTRIBUTION AND CLASSIFICATION OF RUINS.]
All the modern settlements of the lower portion of the Verde valley are located on terraces or benches, and such localities were also regarded favorably by the ancient builders, for almost invariably where a modern settlement is observed traces of a former one will also be found. The former inhabitants of this region were an agricultural people, and their villages were always located either on or immediately adjacent to some area of tillable soil. This is true even of the cavate lodges, which are often supposed to have been located solely with reference to facility of defense. Owing to the character of the country, most of the tillable land is found on the eastern side of the river, and as a consequence most of the remains of the former inhabitants are found there also, though they are by no means confined to that side. These remains are quite abundant in the vicinity of Verde, and less so between that point and the mouth of the river. The causes which have induced American settlement in the large area of bottom land about Verde doubtless also induced the aboriginal settlement of the same region, although, owing to the different systems of agriculture pursued by the two peoples, the American settlements are always made on the bottom lands themselves, while the aboriginal settlements are almost always located on high ground overlooking the bottoms. Perched on the hills overlooking these bottoms, and sometimes located on the lower levels, there was once a number of large and important villages, while in the regions on the south, where the tillable areas are as a rule very much smaller, the settlements were, with one exception, small and generally insignificant. The region treated in these pages is that portion of the valley of Rio Verde comprised between its mouth and Verde, or Beaver creek, on the north. It was entered by the writer from the south; it is not proposed, however, to follow a strict geographic order of treatment, but, on the contrary, so far as practicable, to follow an arrangement by types.
The domiciliary ruins of this region fall easily into three general classes, to which may be added a fourth, comprising irrigating ditches and works, the first class having two subclasses. They are as follows:
Stone villages.
a. Villages on bottom lands.
b. Villages on defensive sites.
Cavate lodges.
Bowlder-marked sites.