J. W. Powell, _Director_.
The Secretary of the Interior,
_Washington, D.C_.
VI. _Report of the Director of the Bureau of American Ethnology to the
Secretary of the Interior on the examination of the condition of Casa
Grande by Mr W J McGee, with a recommendation concerning its further
protection_
Smithsonian Institution,
Bureau of American Ethnology,
_Washington, November 15, 1895_.
Sir: Pursuant to a proposal made in connection with a report from
this office relating to the ruins known as Casa Grande, near
Florence, Arizona, under date of August 28, 1895, and to the
acceptance of this proposal in a communication from the Department
of the Interior under date of September 12, 1895, Mr W J McGee,
ethnologist in charge of the Bureau of American Ethnology, has
within a few days made an examination of Casa Grande ruin with the
view of determining the need for further protection of the ruin by a
roof or otherwise.
There are in this office two series of photographs representing the
ruin. The first series was taken in 1892 before the protective works
authorized by the Congress were commenced; the second series
represents the work in progress. In the recent examination the
present condition of the ruin was carefully compared with the
condition represented in the photographs.
On comparing the profiles of the walls, it was found that in many
cases the irregular upper surfaces retain the exact configuration of
1892, even to the slightest knobs and rain-formed crevices; the
correspondence being so close as to show that the injury and loss by
weathering during the interim has been imperceptible. In some other
cases, notably along the southern and eastern walls, the profiles
are more extensively modified; some of the points and knobs shown in
the photographs are gone, some of the old crevices are widened and
deepened, and some new crevices appear; and in some parts it can be
seen that walls are lowered several inches. On the whole the
modification of the profiles of the walls is limited, yet such as to
indicate that destruction is proceeding at a not inconsiderable
rate.
On comparing the scars and crevices on the sides of the walls, it
was found that, while many remain essentially unchanged, most are
enlarged and deepened. This is particularly noteworthy on the
eastern and southern walls, which are most beaten by wind-driven
rains, and which are also most modified in profile. It would appear
that destruction is proceeding more rapidly along the sides of the
walls than along the crests.
On examining the walls with respect to apparent solidity and
stability, it was found that nearly all are in fair or good
condition. The only portion that would seem in special danger is the
central section of the southern exterior wall. This section seems
insecure, and might at any time be overthrown by a heavy wind
following a rain storm. This section was not, unfortunately, braced
or tied to the stronger interior wall when the protective works were
carried out in 1892.
On examining the structure to ascertain the effect of the protective
works of 1892 in staying the destructive processes, particularly the
undermining of the walls by spattering rain and drifting sand, it
was found that in most cases the results have been excellent. On the
inner side of the middle section of the southern exterior wall
sapping is in progress at the ground level, and also along the rows
of joist openings for the first and second stories, and in a few
other places the protection seems inadequate; but in general the
anticipations of the projectors of the protective works seem to have
been realized.
The most serious of the destructive processes was sapping, and this
process has been nearly checked by the protective works. The second
was the desurfacing and subsequent eating away of the walls by
beating rains and frost, and this is still in progress at a moderate
rate. The least serious process was the wearing away of the crests
of the walls by rain and winds, and this is still going on at a
perceptible rate. It is impossible to determine, and difficult even
to approximate, the rate of destruction quantitatively, especially
so since it goes on cumulatively, with constantly increasing
rapidity, as the cemented surfaces are destroyed and the crevices
widen and deepen; but judging from the history of the ruin, and from
the rate of destruction indicated by comparing the photographs of
1892 with the present aspect, it would seem safe to conclude that,
if protected completely from vandalism, the ruin will be
comparatively little injured during the next five years, and will
stand perhaps half a century, without further protective works,
before moldering into dust.
In view of the slow yet ever increasing rate of destruction of the
ruin, and of its great interest as a tangible record of the
prehistoric inhabitants of this country, no hesitation is felt in
recommending that the structure be further protected, and
practically perpetuated, by a suitable roof, so designed as to
shield the walls from rain and sun and at the same time permit an
unobstructed view of the ruin from any direction.
* * * * *
I have the honor to be, sir, yours, with great respect,
J. W. Powell, _Director_.
Secretary of the Interior.