FEWKES ] CASA GRANDE MOUNDS 97 
A subterranean room provided with a cemented floor, walls, and 
fireplace, was discovered near the northeast corner, under the foun- 
dation of the exterior wall.t| This was evidently a pit-house inhabited 
before the massive wall had been constructed and antedating the 
structures built above it. Traces of similar subterranean rooms are 
found within the compound, near the same corner (pl. 29). 
The outside wall of Compound B was constructed, like that of 
Casa Grande proper, of huge blocks of natural cement, which were 
made where they now rest, the marks of successive blocks being 
visible at several points where the union is not perfect. Evi- 
dences that this wall had been repaired by ancient builders are seen 
in many places, and it appears that the form and direction of the 
original wall have been modified by its enlargement at the southeast 
corner (pl.30). Within the inclosure surrounded by the massive exterior 
wall were found evidences of two kinds of buildings: First, those made 
of cement blocks, characteristically massive; second, those having 
fragile walls supported by upright posts. Some of the walls of build- 
ings of the former class still remain upright, but those of the latter 
have fallen, their positions being indicated only by decayed stumps. 
To the first type belong also well-plastered floors, in which are present 
circular depressions that served as fireplaces. If we interpret build- 
ings of the first type as temples used for ceremonial purposes, the 
fragile-walled buildings may be regarded as habitations of the people 
comparable with those in which the Pima have lived since known to 
history. 
PYRAMID A 
The two large pyramidal elevations, occupying much of theinclosure 
of Compound B, were found on excavation to be remarkable struc- 
tures, suggesting a style of architecture common in Mexico. It 
appears that the larger and most northerly of these structures, desig- 
nated on the map as A (pls. 31, 32, 33), was a pyramid, formerly 
marked by the presence of two or thr ee terraces, the massive walls of 
which still rise at one point to aheight of more than 10 feet. The top of 
this pyramid (pl. 31) is square and level. A deep excavation made in 
its north end revealed a long chamber, suggesting the north room of 
Casa Grande. On the southwest side of this pyramid shallow exca- 
vations revealed several cemented floors, one below another, and verti- 
cal walls indicated by decayed posts which formerly supported them; 
each of these fioors contains a well-made fire pit. The shape of the 
rooms (pls. 32, 33), as shown by the positions of the stumps, was rec- 
tangular; the length was double the width. A doorway, indicated by 
the absence of upright logs from one side, was just in front of the fire- 
1 The diagonals of none of the rooms at Casa Grande are exactly equal in length. 
20903°—28 ETH—12 
