Friday, November 13, 2009

midden agenda

For a recent project, I needed data from Google Earth; amazing what you can gather from a satellite these days. I digressed from the project vicinity and traveled around the globe, revisiting a couple of places I've been in the past. Chaco Canyon caught my attention and I hovered over Pueblo Bonito for some time. It's a remarkable site, both from the air and ground. From the air (or Google Earth), you really get a sense of how it relates and aligns to the other structures in the complex. Meaningfully aligned structures from the ancients have always fascinated me.

The Fajada Butte, not too far away, houses the Sun Dagger, an arrangement of stone slabs and petroglyphs that documents important agricultural phases via the sun and moon. A thin dagger-like sliver of sunlight pierces the center of a spiral petroglyph at the summer solstice, a very elegant and aesthetic way to observe the passing of the seasons. In 1989, researchers found that the slabs have shifted and the dagger was missing its mark; now, there is even a 3D model that can simulate the sun's arc. Check out this link to read and see more about it.

There is also a snake petroglyph off to the side of the spiral. A smaller dagger impales the snake repeatedly on the annual return of the vernal and autumnal equinoxes. Snakes tend to be most active before and after winter hibernation - gotta love an ancient culture with both astronomical savvy and a sense of humor!

Remarkable as they are, there has been some question of the sustainable practices of these early civilizations. Were the climatic changes or lack of timber in the vicinity enough to necessitate abandonment or was the size and politics of the civilization a large contributing factor? Could we suffer a similar fate? Jared Diamond explores possibilities in his book, Collapse: How Societies Choose to Fail or Succeed. He mentions that towards the end of the Chacoan society, because of deforestation of the local juniper trees, ponderosa timber was carried in (by human power) from the Chuska and San Mateo Mountain ranges, some 50-60 miles away...and these logs are on the order of 700 pounds; definitely a long-lead item that could screw up your construction schedule or a coup d'état waiting to happen!

Diamond also speaks of efforts to date these changes in timber species by utilizing packrat middens. Middens are the various waste and biological products from rats preserved by the crystalline structure of their dried urine. Their archæological value was discovered accidentally when miners, after seeking a sweet and tasty treat from nature, fell violently ill. Surprisingly enough, these middens can be dated back 40,000 years. I suspect eating anything 40,000 years old, including sweet and tasty rat urine crystals, would make you violently ill. But all is not lost - maybe your diarrhea-eating parakeet might enjoy these treats.

Aside from theories based firmly upon scientific and archæological evidence, my theory is that the growing rock pile (encircled in red in the 2nd photo and where the title photo was taken) that encroached into the graceful arc of Pueblo Bonito had something to do with the migration. Water's freeze cycle broke off shards (huge boulders, really) of the rock cliff every winter - closer and closer- and the threat of rock fall, second only to snakes, is always stressful on home life. If you ask me, there should have been a petroglyph of the rock cliff next to the snake to remind the community that the boulders start plummeting right around the time they started feeling safe from those damn snakes.

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