196 THE CLIFF RUINS OF CANYON DE CHELLY _ [ern.ayn.16 
obstacle to a movement either north or south, but little as we know 
about that region we do know that it was not an insurmountable obsta- 
cle. The Casas Grandes of Janos, in Chihuahua, closely resemble the 
type of ruins on the Gila river, in Arizona, of which the best example 
we now have is the well-known Casa Grande ruin. We know that 
there are cliff ruins in the Sierra Madre, but beyond this we know 
little. Concerning the immense region which stretches from Gila river 
to the valley of Mexico, over 1500 miles in length, we know practically 
nothing. 
In that portion of the pueblo region lying within the United States 
migratory movements have, as a rule, been confined to very small areas, 
each linguistic family moving within its own circumscribed region, 
Some instances of movement away from the home region have taken 
place even in historic times, as, for example, the migration of a consid- 
erable band of Tewas from the Rio Grande to Tusayan, where they 
now are, and moreover, this movement probably occurred en masse 
and over a considerable distance; but there is little doubt that the 
usual procedure was different. 
Canyon de Chelly was occupied because it was the best place in that 
vicinity for the practice of horticulture. The cliff ruins there grew out 
of the natural conditions, as they have in other places. It is not meant 
that a type of house structure developed here and was transferred 
subsequently to other places. When the geological and topographical 
environment favored their construction, cliff outlooks were built; from 
a different geological structure in certain regions cavate lodges resulted ; 
in other places there were “ watch towers;” in still others single rooms 
were built, either alone or in clusters, and these results obtained quite 
as often if not oftener within the historic period as in prehistoric times. 
Notwithstanding the possibie division of the De Chelly ruins into 
four well defined types, there is no warrant for the assumption of a 
large population. The types are interrelated and to a large extent 
were inhabited not contemporaneously but conjointly. There are 
about 140 ruins in Canyon de Chelly and its branches, but few of them 
could accommodate more than a very small population. Settlements 
large enough to furnish homes for 50 er 60 people were rare. As not 
all of the sites were occupied at one time, the maximum population of 
the canyon could hardly have exceeded 400; it is more likely to have 
been 300. 
The character of the site occupied is one of the most important ele- 
ments to be studied in the examination of ruins in the pueblo country. 
In De Chelly whatever defensive value the settlements had was due to 
the character of the sites selected. It is believed, however, that other 
considerations dictated the selection of the sites, and that the defensive 
motive, if present at all, exercised very little influence in this region. 
The sites here are always selected with a view to an outlook over some 
adjacent area of cultivable land. and the structures erected on them 
were industrial or horticultural, rather than military or defensive. 
