The cliffs that were used for dwellings appear to be sedimentary rock but actually consist of tuff, a compared volcanic ash. It is porous and much softer than sandstone and therefore very workable for creating cavities for shelters and other purposes. Here are some examples of that.
The tuff was also cut into blocks that were then used to build other structures, as in the following.
It did not rain during our hike, though the skies were threatening the entire time.
And, in fact, it began raining just as we were finishing our hike.