Wednesday, February 17, 2010

Yucca Cave Ruins at Canyon de Chelly

The Yucca Cave Ruins is visible from the from the west side of the Massacre Cave Overlook along the north rim of Canyon de Chelly National Monument near Chinle in northeast Arizona.

This is a small ruins site but it is unusual in the Canyon de Chelly as it is near the canyon rim rather than near the canyon floor. Most of the ruins sites at Canyon de Chelly are near the farming fields, peach orchards and water supplies that make the floor area livable.

The area near the canyon rim is very rocky but has good supplies of Pinon Pines and Utah Junipers. The cliffs below the ruins are vertical with an 800 foot drop to the canyon bottom. There is a small granary storage site to the left of the main alcove that looks particularly tricky.

The Yucca Cave site overlooks the area of the large Mummy Cave Ruins, though it is around the corner and not directly visible. This area is about 12 miles from the canyon mouth and at higher elevation, receiving more winter snow. In winter, the roads and parking areas are kept clear of snow and visiting the overlooks is only a short walk.

Tuesday, February 16, 2010

Canyon de Chelly in the Snow

Canyon de Chelly National Monument in northeast Arizona is one of the most beautiful canyons in the southwest. The sheer walls of De Chelly sandstone were deposited 230 to 250 million years ago under desert conditions. The DeChelly sandstone is also visible in Monument Valley and is equivalent to the Cedar Mesa sandstone in southeast Utah.

In winter, the roads to the overlooks and parking areas are cleared of snow. The climate today at the mouth of the canyon is mostly dry but the upper ends of the canyon catch the winter storms. The melting snows make this area one of the best watered areas of the Navajo Reservation. There are seven overlook areas on the south rim and three on the north rim. Only the White House Ruins Trail can be hiked without an official guide.

In mid February the White House Ruins Trail is clear with patches of snow on the north facing slopes. The trail is a 3 miles round trip with 600 feet of elevation change. On a 40 F degree day the canyon tours are running and Navajo vendors have displays of their artwork for sale. There is a small alcove type arch along the trail in the upper part of the trail. The canyon walls around the White House ruins have some small pictographs to find.
The Navajo Fortress in at the Antelope House Overlook on the north rim. The Navajo are an Athabascan speaking people that entered Canyon de Chelly about 300 years ago. The canyon came to support good corn fields and peach orchards. Raids and counter raids between the Navajo and their Indian and Spanish enemies dragged on for 100 years with the Navajo Fortress becoming one of the refuges used against attack.

The Navajo Fortress lies at the junction of Del Muerto and Black Rock Canyons. This site continued to be used into the 1860s. Navajo Fortress appears to be connected to the adjacent canyon walls but it is actually an island of rock.

Mummy Cave Ruins is featured on the cover of the park brochure. The Mummy Cave overlook is about 12 miles up the canyon along the north rim. This spectacular site might be the longest occupied Ancestral Pueblo site in the canyon. The view from the overlook is a long distance away, but the structures in the center tower of the site appear to be very well preserved. They are described as Mesa Verde in style and contrast with the coarser style on each side. Perhaps people from Mesa Verde moved here after 1280.

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