uffered,
particularly from the weather, and here rainstorms have probably caused
some of the damage. The outer faces of the walls are of the same
material as the wall mass, all the masonry being composed of earth from
the immediate site. In the construction of the walls this soil was laid
up in successive courses of varying thickness, whose limits form clearly
defined and approximately horizontal joints. The northeast and southeast
corners of the building have entirely fallen away, and low mounds of
their debris still show many knobs and lumps, parts of the original wall
mass.

The destruction of the walls was due mainly to undermining at the ground
level. The character of this undermining is shown in many of the
illustrations to this report, especially in plate CXVI, and its extent
is indicated on the accompanying ground plan (plate CXVII) by dotted
lines within the wall mass. Although the material of which the walls are
composed is very hard when dry, and capable of resisting the destructive
influences to which it has been subjected for a long time, yet under
certain conditions it becomes more yielding. The excessively dry climate
of this region, which in one respect has made the preservation of the
ruin possible, has also furnished, in its periodic sandstorms, a most
efficient agent of destruction. The amount of moisture in the soil is so
small as scarcely to be detected, but what there is in the soil next to
the walls is absorbed by the latter, rising doubtless by capillary
attraction to a height of a foot or more from the ground. This portion
of the wall being then more moist than the remainder, although possibly
only in an infinitesimal degree, is more subject to erosion by flying
sand in the windstorms so frequent in this region, and gradually the
base of the wall is eaten away until the support becomes insufficient
and the wall falls en masse. The plan shows that in some places the
walls have been eaten away at the ground level to a depth of more than a
foot. Portions of the south wall were in a dangerous condition and
likely to fall at any time.

Visiting tourists have done much damage by their vandalism. They have
torn out and carried away every lintel and every particle of visible
wood in the building. After the removal of the lintels a comparatively
short time elapses before the falling in of the wall above. Apparently
but a small amount of this damage can be attributed to rainstorms,
which, although rare