Casa Grande Ruin

of the tribe appearing on the scene, other divisions leaving the parent village for other sites, and the ebb and flow continuing until at some period in its history the population of a village sometimes became so reduced that the remainder, as a matter of precaution, or for some trifling reason, abandoned it en masse. This phase of pueblo life, more prominent in the olden days than at present, but still extant, has not received the prominence it deserves in the study of southwestern remains. Its effects can be seen in almost every ruin; not all the villages of a group, nor even all the parts of a village, were inhabited at the same time, and estimates of population based on the number of ruins within a given region, and even those based on the size of a given ruin, must be materially revised. As this subject has been elsewhere[1] discussed, it can be dismissed here with the statement that the Casa Grande group seems to have formed no exception to the general rule, but that its population changed from time to