arable lands. Although these motives of hiding and defense 
cannot be overlooked, it appears that many of the cliff sites 
were near streams and fields, and were occupied because they 
afforded shelter and were natural dwelling places. it is 
important to note, also, that many of the cliff houses, built 
and excavated, are mere storage places for corn and other 
property, while many others are outlooks from which the fields 
below could be watched and the approach of strangers observed. 
In some districts proof of post-Spanish occupation of many 
sites exists. Walls of houses are built upon deposits ac¬ 
cumulated since sheep were introduced, and adobe bricks, 
which were not used in prehistoric times, appear in some 
cases. A well authenticated tradition exists among the Hopi 
that, about the middle of the 18 th century, a group of their 
clans, the Asa people, deserted their village on account of 
an epidemic and removed to the Canyon de Chelly, where they 
