Monday, February 1, 2010

Aztec Ruins in Winter

The trail at Aztec Ruins National Monument is cleared for winter visiting of this very large ruins site in northwest New Mexico. Aztec Ruins is thought to have been influenced by both Chaco Canyon and Mesa Verde before being abandoned around 1300 AD.

One of the striking features of Aztec Ruins is the green band of stones along the first part of the 700 yard trail. The masonry styles are of interest in these sites as there are distinct differences from different regions and different time periods. The sandstone used here was carried by hand from quarries several miles away. There are other shorter segments of green bands near the end of the trail.

The thick stone walls and the snow bring to mind the business of keeping warm in the winter. Stone isn’t a good insulation material and thicker walls would be useful for preserving heat. The thick walls also would support the upper levels of the structure.

The question might be which was more important, having upper stories or having more insulation? The below ground kivas would also provide some earth contact shelter from the harsh winters. The kivas are designed with ventilation shafts and a roof opening to allow smoke to escape but the extensive room blocks at most sites are not.

I haven’t seen the concept of thermal mass mentioned at any of the ruins sites in the Four Corners region. In arid climates, the building material will absorb solar energy during the day and release the stored heat during the cool evenings. The effect is to dampen the temperature swings and make the internal space more comfortable. Adobe houses take advantage of thermal mass. The earth packed Hogans of the Navajo would also.

The Pit Houses of the ancestors of Aztec Ruins take advantage of both thermal mass and earth contact. The alcove sites at Mesa Verde are mostly south facing to catch more of the winter sun. At Aztec Ruins the entire site is south facing, the open plaza faces the south and the back wall faces the north.

There is also a question of fuel for these sites also. The main trees that grow in the area are Pinon Pines and Utah Junipers. In the better soil areas sage brush grows. Interpretive information from around the region suggests that the Pinon Pines wouldn’t be cut down as they provide a nutritious and high calorie nut.

The sagebrush cleared from farming fields would be a good candidate for fuel as it burns hot. There are Cottonwood trees nearby along the Animus River. The interpretive information says that Cottonwood would be burned in summer as it provided a bright light but not much heat.

I noticed two grinding stones along the sidewalk near the visitor center. The visitor center has a small museum with a few artifacts and displays and a video room. One interesting pottery piece has a spiked surface that might be modeled after the seed pod of the highly toxic, hallucinogenic Datura plant.

My visit at Aztec Ruins was for about 2:00 hours on a 37 F degree late January day. The trail was clear with a few icy patches. There was about 1 foot of snow in the uncleared areas.

A trail guide to Aztec Ruins National Monument

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