these northern
sections, along the line _a, b, c_, parts of the third story wall are
patched with regular adobe bricks, about half as large as those in the
church, but still made by the same process.[106] The rest of the
structure is exclusively composed of stone.

It is to all intents and purposes a stone house. Two kinds of rocks
predominate among the material; a slaty, gray and red,
sandstone,--highly tabular, easily broken into plates of any size,--and
a sandstone conglomerate, containing small pebbles from the size of a
pea up to that of a small hazel-nut,--the whole rock of a gray color.
When freshly broken or wetted, this conglomerate becomes very friable,
and so soft that goats have left the impression of their feet on
scattered fragments. When dry it becomes hard, and is always very heavy.
Both kind of rocks are found in the vicinity of the _mesilla_. Besides
these, loose pieces of stone from the bluff itself, boulders from the
creek, of convenient size, enter into the composition of the walls.
Sometimes the latter consist exclusively of slabs of sandstone
superposed; again there are polygonal fragments of rocks piled upon one
another, with courses of tabular sandstone, forming, so to say, the
basis for further piling; the foundations are usually boulders and the
hardest rocks, also of greater width. There are no walls of dressed
stone, but the rocks are broken to a suitable size, as may be done with
any stone maul or sledge, or even by smashing with the hand and another
rock. In fact the whole stone-work must be termed, not masonry, but
simply judicious and careful piling.[107] In performing it, great
attention has been paid to having the vertical surfaces as nearly as
possible vertical; but this end could be reached without the use of the
plumb-line, and with the aid of mere ordinary eyesight, for the rooms
are so small, and the partitions so thin, that anything not "true"
could, and can yet be, "shoved" into position by a mere steady, slow
push; carefully watched on the opposite side. The same applies to the
angles, although they are tolerably accurate. As a general thing, the
transverse walls appear to be continuous, and the longitudinal
partitions to have been added afterwards, but there are also instances
of the contrary. In this respect the sinuosities of the rocky foundation
seem to have determined the mode of action. To fill up the gaps between
the stones, and to coat them with a smooth surface within