154 THE CLIFF RUINS OF CANYON DE CHELLY [etx any.16 
of site. Doubtless in some of these ruins the defensive motive oper- 
ated to a certain extent. In classes I and 11, however, the influence of 
the defensive motive, in so far as it affected the character of site chosen, 
is conspicuous by its absence. As there is no evidence that the cliff 
ruins of class IV were separate and distinct from the other ruins, but 
the contrary, the defensive motive may be assigned a very subordinate 
place among the causes which produced that phase of pueblo archi- 
tecture found in Canyon de Chelly. 
An hypothesis as to the order in which sites of the various classes 
were occupied can not be based on the present condition of the ruins. 
It is more than likely that the older ruins served as quarries of build- 
ing material for succeeding structures erected near them, and probably 
some of the cliff ruins themselves served in this way for the erection 
of others, for there are many sites from which the building stone has 
been almost entirely removed; yet there is no doubt that these sites 
were formerly occupied. The Navaho also have contributed to the 
destruction. Notwithstanding their horror of contact with the remains 
of the dead, quite a number of buildings have been erected by these 
Indians with material derived from adjacent ruins. It is evident that 
the gathering of this material would be a much lighter task than to 
quarry and prepare it, no matter how roughly the latter might be done. 
In a study of some ruins in the valley of the Rio Verde, made a few 
years ago, a suggestion was made of the order in which ruins of vari- 
ous kinds succeeded one another—a sort of chronologic sequence, of 
which the beginning in time could not be determined. Studies of the 
ruins and inhabited villages of the old province of Tusayan (Moki) and 
Cibola (Zuni), and a cursory examination of ruins on Gila river, show 
that they all fall easily into the same general order, which is somewhat 
as follows: 
1. The earliest form of pueblo house is doubtful. As a rule, in most 
localities the earliest forms are already well advanced. As it is now 
known that the ancient pueblo region was not inhabited by a vast 
number of people, but by a comparatively small number of little bands, 
each in constant though slow movement, this condition is what we 
would expect to find. It is probable that the earliest settlements con- 
sisted of single houses or small clusters located in valleys convenient 
to areas of cultivable land and on streams or near water. 
2. The next step gives us villages, generally of small size, located on 
the foothills of mesas and overlooking large areas of good land which 
were doubtless under cultivation. This class comprises more examples 
perhaps than any other, and many of them come well within the historic 
period, such as six of the seven villages of Tusayan at the time of the 
Spanish conquest in 1540, all of the Cibolan villages of the same date, 
and some of the Rio Grande pueblos of that time. 
3. In some localities, though not in all, the small villages were at a 
later period moved to higher and more inaccessible sites. This change 
has taken place in Tusayan within the historic period, and in fact was 
