222 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I47 



Sand is everywhere in Chaco Canyon and floodwaters leave silt 

 layers. But it was the sheer bulk of village debris rather than silt 

 and sand that defeated our early efforts to read stratigraphy in 

 Bonito's south refuse mounds. We dug a deep trench through 

 each — two trenches that laid bare the composition of both mounds 

 and the manner of their development. Laminated sand, gravel, and 

 round-bottomed waterways show where water once flowed. The 

 leveling influences of wind and water are everywhere apparent. 

 Pockets of blown sand occur throughout the two piles; silt streaks 

 and puddled adobe remain as evidence of seasonal showers. And as 

 this village waste continued to pile up, sandstone walls were built 

 to curb its dispersal. Walls nearest the pueblo were highest and 

 strongest. End walls, wherever we examined them, were noticeably 

 weaker and those on the south were weaker still. 



It is the presence of these enclosing walls as much as mound con- 

 tent that determines the age of the two south refuse piles. Both con- 

 tent and walls are primarily products of Late Bonitian industry. 

 Old Bonitian housewives habitually dumped their sweepings immedi- 

 ately in front of their dwellings — at least until the Late Bonitians 

 took over. A mixture of Old Bonitian and Late Bonitian rubbish 

 from bottom to top of both mounds fixes their beginnings as sub- 

 sequent to arrival of the Late Bonitians. It was this latter group that 

 filled the old flood way immediately south of the pueblo, a fact evi- 

 denced by the abundance of their distinctive Hachure B. pottery 

 which Roberts found in two 5- foot-wide stratigraphic sections, 3 

 and 4, between Room 136 and the West Mound. It was the Late 

 Bonitians that built retaining walls about both mounds and then con- 

 tinued to pile up village waste until it overflowed the barriers and 

 attained a height of 20 feet or more. 



