2 
two general classes of cliff dwellings, the cliff house proper, 
constructed of masonry, and the cavate house, excavated in 
the cliffs. 
It is commonly believed that the agricultural tribes of 
pre-Spanish times, who built populous towns and developed ex¬ 
tensive irrigation systems, resorted to the cliffs, not from 
choice, but because of the encroachment of warlike tribes, 
such as the Apache, Ute, Comanche, and Navaho, who were prob- 
ably non-agricultural, having no well established place of 
abode. This must be true to some extent, for no people unless 
urged by dire necessity would resort to fastnesses in remote 
canyon walls or to the margins of barren and almost inaccess¬ 
ible plateaus and there establish their dwellings at enormous 
cost of time and labor; and it is equally certain that a peo¬ 
ple once forced to these retreats would, when the stress was 
removed, descend to the lowlands to reestablish their houses 
where water 
is convenient and in the immediate vicinity of 
