Located not terribly far from Aztec, New Mexico, Chimney Rock is an extraordinary Chacoan outlier (but each is). Most of the ruins are located on a ridge above the surrounding area. In fact, there is a particularly narrow section of the ridge affording even more isolation to the dwellings in sight of two natural rock formations (Chimney Rock and Companion Rock). These formations serve as markers on the 19 year lunar cycle, especially at least one of the two lunar standstills at the extreme northern point or southern point of this cycle. Unlike most outliers, you must have a guide with you to tour Chimney Rock (or, at least, that was the case 10 years ago, when I took these photos).
Students performed an exercise using mirrors that allowed them to exchange signals with Chaco. One source says this outlier also provided trees floated down to Chaco.
WASHINGTON — President Barack Obama will designate Chimney Rock as a national monument Friday — a move that will help preserve the 4,726 acres in southwestern Colorado, administration officials told The Denver Post Wednesday.
Chimney Rock comprises a chunk of the San Juan National Forest and is surrounded by the Southern Ute Indian Reservation.
Among those sites identified as Chacoan outliers, the Chimney Rock Pueblo is distinguished by being the most isolated, the highest, and the most remote from arable land. With two exceptions, building at all of the outliers was begun between A.D. 1086 and the first half of A.D. 1120. Chimney Rock Pueblo is one of those exceptions, as construction began in A.D. 1076. — from Prehistoric Astronomy in the Southwest, by J. McKim Malville and Claudia Putnam