I’m certain it is not for lack of knowledge that he doesn’t mention that some think Chimney Rock was an outpost for gathering wood that might have been floated as far as Chaco. I don’t know if there is any merit to this idea. However, waterways may explain why wood would come from some areas and not others. In particular, Jemez may not be upstream from Chaco.
I am indeed aware of this idea, and I don’t buy it. I see a variety of possible objections, some more reasonable than others.
- Chimney Rock is about twice as far from Chaco as any of the established sources for timber. I don’t think this is really the strongest objection, since arguments that the Chacoans are unlikely to have done something because it was impractical or inefficient tend to founder on the considerable evidence that the Chacoans did all sorts of things that were impractical and inefficient. They really seem to have had access to virtually unlimited amounts of labor, and they used it in all sorts of ways that don’t seem to make much logical sense.
- There’s no clear evidence that any of the wood at Chaco came from Colorado. While the spruce/fir study I mostly focused on in the last post didn’t look at the La Platas or San Juans as possible sources of timber, the subsequent ponderosa study did, with ambiguous results. The strontium isotope ratios they found for the Colorado mountains overlapped with those for both the Chuskas and the Hosta Butte/Lobo Mesa area to the south of Chaco (which wasn’t included in the earlier study because it’s too low for spruce or fir). While they did find some wood with isotope ratios in this range, with the data they had it was impossible to tell if it came from Colorado or from the other areas with similar ratios.
- There is considerable evidence that at least some of the large primary beams were left to dry for a few years after being harvested, presumably to reduce their weight. Floating them down a river after this would waterlog them and totally undo any effect of the curing. This is particularly important since even after being floated the beams would still have to be carried the thirty miles or so from the San Juan River to Chaco. While I’m generally skeptical about arguments based on practicality, for reasons mentioned above, the evidence for curing makes this one more plausible than most.
- If the beams were in fact floated, they would presumably end up with a lot of scratches and scuff marks from hitting things in the river. Floating logs down a river, especially with the technology the Chacoans had available, is not the easiest method of transportation to control. And yet, the beams found at Chaco are remarkably pristine. There’s barely a scratch on any beam in the whole canyon. There aren’t even any axe marks from debarking, which is in striking contrast to beams at other sites such as Mesa Verde. This suggests an amazing degree of care taken in the transportation of the beams, which is very hard to imagine if they were ever floated down a river. I think this is probably the most devastating piece of evidence against the flotation theory.
In addition to the objections above to the specific idea of beams being floated down from Colorado, there are a lot of problems with the more general idea of timber sources being determined by waterways:
- This idea isn’t actually consistent with beams being floated down from Colorado, since they could only be floated as far as the San Juan River and would then have to be carried the remaining 30 miles to Chaco. It’s hard to see how an emphasis on waterways as routes for timber transportation could have led to a decision to do this. Since there is no real evidence that any of the timber did come from Colorado, however, this isn’t necessarily a major problem for the general idea.
- Most of the drainages in the southern San Juan Basin are intermittent and only flow at certain times of the year, which would have made transportation of beams a matter of careful timing. Again, the Chacoans certainly had the ability to time things like this well enough, so this isn’t the most devastating objection.
- Perhaps more importantly, the known sources of timber (established in the strontium isotope studies) are not upstream from Chaco. The eastern slope of the Chuskas does drain into the Chaco River via a series of eastward-flowing washes, but these washes enter the Chaco a considerable distance downstream from the canyon. Trees from the Chuskas, therefore, which seems to have been the primary source of timber for the canyon, could not have been floated and would have to have been carried. The other major source area that has been identified, around Mt. Taylor, is on the other side of the Continental Divide from Chaco and drains in the opposite direction.
- Furthermore, the Jemez, which doesn’t seem to have been a significant source of timber for the canyon, is upstream from Chaco. More precisely, while the Jemez Mountains themselves are on the other side of the Continental Divide, they are just barely so, and the Chaco Wash originates right along the Divide near Star Lake, about 20 miles from Cuba. Since the Chacoans were clearly carrying beams 50 miles from the Chuskas and Mt. Taylor, they could easily have carried them 20 miles from the Jemez to the wash and floated them in the late summer when it flowed high from the monsoon rains. The fact that they didn’t seems to clearly indicate that waterways were not a factor in the decision-making process related to timber procurement.
I’m not sure where this idea came from originally, but it’s certainly out there and I’ve heard it several times. It may have started as a way to explain the anomalous location of Chimney Rock, which really is odd in a number of ways, including its combination of considerable distance from Chaco with extensive Chacoan influence. I think the evidence for an astronomical basis for the foundation of Chimney Rock is a lot more plausible than the idea that it was a lumber camp. The idea of logs being floated from Chimney Rock to Chaco really doesn’t make much sense, and until any evidence for it surfaces (which I think is pretty unlikely) I’m not inclined to give it much credence.