Two "keyhole" structures (Features 2 and 27) were identifed. Feature 27 is shown in the illustration to the right (from Curry and Kavanagh 2004:14, Figure 19). At the Rosenstock site, these small (< 5 square meters) elliptical, semi-subterranean structures were interpreted as the probable remains of sweat lodges. While similar structures have been interpreted as sweat lodges at other sites, there has been some debate about whether "keyhole" structures may be the remains of houses or storage features (see MacDonald 2008; Smith 1976).
The two structures from Rosenstock will be added to the database as Structures 2253 and 2254.