Scientists lugged logs on their heads to resolve Chaco Canyon mystery
arstechnica.com
arstechnica.com
I’m frequently blown away by the low-hanging fruit in archæology.
I tried tumplines early on. They just make my neck hurt. I do carry buckets and other small dense things around on my head, using a beanbag to cushion, but the torques from a log swinging about are just too much.
Although I have no doubt this technique is working well for you, there are other factors making the approach in this article better for the long haul. The shouldering technique has the log sit up higher and has farther to fall: a more precarious positioning for carrying something valuable a long distance. Also, the tumpline keeps the hands free.
As to shouldering begin "debilitating", they may have been doing one of 2 other techniques when carrying over the shoulders that made it "debilitating":
* placing it on one shoulder each (asymetrical loading)
* strapping it to the shoulders much like a backpack
* the size of the person
* the size of the musculature that it rests on
* the size of the object
* your spine and neck positioning
You would need far better synchronization of movements and people of the same height or exactly regulated straps for the tumpline and besides, a log 2.50 mt long behaves differently than a 3.50 mt long one when it comes to maneuverability.
And experience, as we see with contemporary sports, soldiering, musical performance, and dance.
But if the hypothesis is that three people carried a 85 kg, 3.50 m long log, the experiment with two people carrying a 60 kg, 2.50 m is not representative of that.
It is not like they couldn't find a third volunteer and attempt replicating exactly the hypothesis.
Two persons spaced a reasonable distance apart will damp rotation and hence torque.
Adding a third person would limit log oscillations even more.
It is a continuous beam with a distributed load (only own weight).
Look for "Continuous Beam – Two Equal Spans – Uniformly Distributed Load" here:
https://www.linsgroup.com/MECHANICAL_DESIGN/Beam/beam_formul...
Hint: you'd better put the strongest guy in the middle.
Create the "Chaco Valley Log Race", stick $5k up as a prize and you'll have strongmen and crossfit athletes carrying the log single-handed for the required distance.
See: https://www.redbull.com/int-en/this-man-did-a-triathlon-carr...
Not sure how that's a better theory. Why wouldn't a stronger carrier also benefit from a tumpline method? You're thinking maybe they were so strong they just carried it in their hands, or over their shoulders?
Maybe there was a "fastest team gets double rations" (like possibly for the pyramids) or "last one to arrive gets killed" (like Vercingetorix).
However, if it's "Just get this log from there to there and it's not time critical" maybe it doesn't matter.
//edit//However getting physically fit/strong people to do it in a race condition with a prize might throw up some brand new ideas.
https://www.tiktok.com/@annabg9898/video/7157326693462543642
And if there's not rivers, how exactly are you making a 70 mile trek across the desert carrying heavy logs? Anyone doing that would need lots of water and would likely try to follow rivers anyways.
From the Chuska Mountains, they would need to be brought to the Chaco River then floated/moved upstream. From the other mountains, it's a lot further, and a lot more upriver transport. Which is not easy.
> how exactly are you making a 70 mile trek across the desert carrying heavy logs?
Hence this research. Which mentions how they built good roads. Eg, https://www.nps.gov/chcu/learn/historyculture/chacoan-roads.... says:
"An astonishing volume and variety of material was imported to Chaco Canyon, including approximately 200,000 wooden beams used in the construction of the great houses. These beams, often whole trunks of ponderosa pine, had to be brought in from considerable distances, mostly from the Chuska Mountains and Mount Taylor. Since walking on the roads is easier than walking off of them, they would have been quite useful in carrying such heavy loads such great distances, even if this was not their primary purpose."
> Anyone doing that would need lots of water and would likely try to follow rivers anyways.
You can have enough water for human consumption but be far from what's needed to float a log. And they had an extensive canal system, with dams to capture runoff water.
As https://www.cambridge.org/core/services/aop-cambridge-core/c... says:
"In particular, some researchers identify Chaco Canyon, located in the San Juan Basin of New Mexico, as an “unlikely setting” for substantial occupation ... Debates over whether food was grown locally or supplied from distant settlements dominate the literature ... While the presence of complex canal systems has long been noted (e.g. Vivian 1990), the difficulty in dating these constructions has led to doubts over their existence and utility ... Our recent fieldwork on one canal network definitively dates it to Chaco’s Bonito Phase occupation"
If you look at the terrain that route is easy to do by water. You have the steep drop out of the mountains where the current helps you. The rest of the journey is over flat terrain so "upstream" isn't very hard when you have the right conditions. This article has a good picture:
https://www.cambridge.org/core/journals/antiquity/article/wa...
The July 23 picture is when you would transport the logs. It's deep enough to float them and there's barely a current.
>Hence this research.
My point is that it's a bizarre thing to research. Obviously you can carry heavy things. But like every single culture in the history of humanity has figured out doing so on water is way easier.
Where? What waterways off the Chuska Moutains have that volume and current? What's your proposed path?
There doesn't appear to be any viable stream coming off the east side of those mountains, and a look at the map shows the arroyos which do come off meet up with the Chaco Wash/Chaco River at 36.18128218922837, -108.54422009733341 at what Google Maps calls Coyote Wash. That's about 40 miles downstream of Chaco Canyon, eyeballing it.
(To verify, use https://apps.nationalmap.gov/viewer/ , go to that point, zoom out, and see that's the most upstream point where the washes from the Chuska mountains meets the Chaco River.)
Even if there was more water in the area so those arroyos were wet more often, the topology hasn't changed. And with more water, going upstream becomes harder.
According to the link I gave, many of the trees came from north of the San Juan River (the La Plata and San Juan Mountains). Please also describe that route to Chaco Canyon. It looks like the Chaco River meets the San Juan near Shiprock, at 36.77203098974645, -108.64872995405689 , which calls for some 80 miles of upriver travel, and that's after floating them downriver. Again, use the USGS map to verify this.
(BTW, I've done some hiking in New Mexico mountains. The creeks I saw were not enough to float logs, and had plenty of snags where trees and boulders were piled up. I find it hard to believe your proposed waterway even exists.)
Why do you think water transport was easier than carrying the logs, when this paper shows that carrying logs on foot isn't so difficult? And that the relevant technology was already present in the area?
> The July 23 picture is when you would transport the logs.
How deep do you think that water was on July 23? Those are backpacks on the bank, and it looks narrow enough to step across. So, perhaps a few inches? Likely not enven a foot.
How much muck and mud do you think is on the bottom? How do people pull those logs without having them drag on the bottom?
In any case, I think it's a false path to explore. The text points out that the current entrenched state is under 150 years old, citing Lieutenant Simpson's account of it being 8 feet with a depth of 1½ feet back in 1850, so using current pictures doesn't give the right interpretation.
> The rest of the journey is over flat terrain so "upstream" isn't very hard when you have the right conditions.
Walking on a sandy arroyo bottom isn't that easy when it's dry. I've never walked on one when wet. Everyone said it was dangerous, as indeed your re-posting of my link points out how the water rose 1.5 meters overnight.
What then are "the right conditions", and did they exist during the Chaco era?
In the history of humanity, how many people have floated massive numbers of logs upstream without animal or sail power? All the examples I can think of went downriver.
A goal of experimental archeology is to test if something is feasible. Not necessarily that it happened. Just because Thor Heyerdahl sailed from South America to Polynesia on a balsa tree raft doesn't mean that's how Polynesia was populated.
What are your examples showing that your proposed transport method is at least as feasible as using tumplines?
(2) When the waters recede a bit you take the logs upstream. You don't walk in the arroyo. You use a pole like this:
https://catbirdinchina.files.wordpress.com/2015/09/p5315645....
You can move at more or less walking speed with a pole like that.
>What are your examples showing that your proposed transport method is at least as feasible as using tumplines?
This isn't a theoretical thing. People still move goods around like in places that are too poor to afford motor boats. I've seen it first hand in Myanmar and Vietnam. As long as the current is relatively weak it's easy to move a boat by pole.
Stack a bunch of logs together onto a raft and have a couple guys on top with poles to move it. Bet they could do a raft of 30-40 at something around walking speed.
>How deep do you think that water was on July 23? Those are backpacks on the bank, and it looks narrow enough to step across. So, perhaps a few inches? Likely not enven a foot.
You don't need much more than a few inches to float logs. Either way, there's some point between those two photos where the trade off between river depth and current is optimal.
>In the history of humanity, how many people have floated massive numbers of logs upstream without animal or sail power? All the examples I can think of went downriver.
How many examples are there of them choosing to carry heavy stuff when water transport was available?
> When it rains all those white river shaped things turn into rivers that you can float logs down.
You are conjecturing. I've seen wet arroyos. They are not like the image you've shown with the nice flat water.
Here's what it looks like: https://www.youtube.com/watch?v=obrgK17L1UM and https://www.youtube.com/watch?v=SmO0xzXapeg and https://www.youtube.com/watch?v=nZ40m2SoBWM and https://www.youtube.com/watch?v=l1PTLOp_hUs .
These are short-lived events. You are not going to pole a raft 50+ miles upstream during that time in that flow.
Yes, they can be enough to carry logs downstream. But they'll also easily snag, and be abraded.
> As long as the current is relatively weak it's easy to move a boat by pole.
Why do you think the water flow in NM arroyos, in those rare times when the water is deep enough to float a log, is "relatively weak"?
In NM there are a lot of warnings to stay out of arroyos when it rains, because the water can come quickly, with a dangerous flow.
For example, from https://www.koat.com/article/officials-urge-residents-to-sta...:
] LT. CHRIS CARLSEN WITH THE ALBUQUERQUE FIRE DEPARTMENT SAYS IT ONLY TAKES INCHES OF WATER IN AN ARROYO TO SWEEP YOU AWAY. Carlsen: "It doesn't seem very dangerous when it's hot and dry but it takes a very small amount of rain in the foothills or mesa to fill these channels up quickly." AND WHEN IT POURS AND THOSE ARROYOS FILL UP - THE WATER MOVES FAST AND GETS DEEP. LOOK AT WHAT THE WATERS HAVE DRAGGED DOWN THE CHANNEL, ALREADY THIS SEASON: Carlsen: "You can see the water can move concrete. We've had forklifts, vehicles come washing down the system." IF A PIECE OF HEAVY MACHINERY IS NO MATCH FOR THE RUSHING WATER ... NEITHER ARE YOU
> You don't need much more than a few inches to float logs.
To repeat the previous quote, "IT ONLY TAKES INCHES OF WATER IN AN ARROYO TO SWEEP YOU AWAY."
You can work out how a rough minimum required depth.
The paper says their test log is 22 cm in diameter = 8.6 inches and "timbers of at least 0.61 m diameter were used at Chaco as vertical support columns in great kivas", so 24 inches.
Pine greenwood appears to have a density about 700 kg/cubic meter so it looks the test log needs 5-6 inches of depth and the vertical support columns need about 1.5 feet. (I used the greenwood weight since you're going to waterlog the pine anyway. The dried density is only about 400 kg/cubic meter.)
That's a lot of water in dry New Mexico!
Oh, and your hypothesis requires that each one of the "white river shaped things" is that inches deep, to be able to float logs. They merge into the Coyote Wash, so that would be carrying a huge volume of water. But looking at the aerial pictures you can see it's never had regular huge flows like that.
Aslo, there's about a 600 foot rise from where Coyote Wash meets the Cacho River to Chaco Canyon proper, so there's a decent river flow. (A flow you saw in the photograph.)
In Three Men in a Boat they punt the Thames from Kingston upon Thames to Oxford. That's 100 miles, and a rise of <200 feet. This stretch of the Cacho Wash is 600 feet in 50 miles, so about 6x the slope, and thus a rather faster current than the Thames.
> How many examples are there of them choosing to carry heavy stuff when water transport was available?
That doesn't answer my question. If no one brought tens of thousands of logs upstream 50 miles by water using only manual labor than your appeal to history is bad logic. If you can't show people did it, you can't appeal to history.
Further, you've yet to demonstrate that appropriate water transport was available to the Chaco Canyon dwellers.
Further, the paper cites the archeological evidence that "that the people of Chaco used tumplines to carry a variety of materials (water vessels, maize, ceramics, chert, obsidian, turquoise, cacao, and even macaws) across a trading network spanning the San Juan Basin and beyond."
What evidence is there for your proposed transport method?
Tumolines are great for heavy loads but interfere with the fun aspects of backpacking. People would rather take less stuff if it means they can more easily take in the view.
This fits your description because it's used when portaging. The goal is to get to the next navigable stretch of water, not take in the view, while carrying 100+ pounds of gear in the bag and a canoe over one's head.
In canoeing they are used for relatively short stretches. The various sources say it's not that comfortable. I found a backpacking guide from 1971 which explains the issue:
"If you can stand the abuse, a tumpline surpasses all devices for toting heavy, bulky, or awkward loads. A 100-pound burden is routine among the few who understand the tumpline. During its heyday, 200-pound loads were commonplace among voyageurs in the fur trade ... The packer must lean forward abnormally. It is not a rig for amateur packers or for occasional weekend trips. In fact, the tumpline must be approached with respect. It will handle tremendous loads but only after your neck muscles have been developed. No packing device depends more upon sheer bull strength, but it does the job." - https://archive.org/details/backcountrycampi00rivi/page/16/m...
I expect that if you're part of a culture where people need to to carry heavy loads often, then you'll start young and build up the neck muscles which will make it more comfortable.
Someone going backpacking a few weeks every year is not going to have the same specific training.
In fact, the paper goes into details about the specific strength training program carried out for this Chaco Canyon research. From https://doi.org/10.1016/j.jasrep.2023.103876 :
"Author JC, a certified strength and conditioning specialist (CSCS), designed the training protocol. Subjects trained 6 or 7 days per week for 10 to 60 + minutes per day. Subjects initially alternated daily between training for a short duration (15–30 min) versus a longer duration (30–60 + min of carriage). For approximately the first half of the training program, the longer duration training sessions used lighter loads and the shorter duration training sessions used heavier loads. This allowed for subjects to become accustomed to both heavier loads and longer duration carries separately. By ∼Day 45 of training, subjects had become comfortable with heavier loads (∼25 kg) and henceforth kept the loads fairly constant while increasing session durations. By varying the loads and durations, subjects progressed in their training program with minimal soreness and no pain. Note that for safety, when donning and doffing the tumpline, the training logs were supported by a bench or table, at the approximate height of the lower back. By the end of the training phase, subjects JW and RK were able to comfortably carry 30 kg for 60 min solo without pain."
This whole thread reminded me of reading about tumplines but I couldn't remember where and this was it.
#1 reason might be that it never occurred to this westerner. #2-5 are probably things like availability, you sure that thing isn't painful, etc.
Really, concerns about dignity are not even on the list of reasons why I don't use a tumpline.
FWIW I am in California though, and people would possibly see such a thing and simply think I'm a granola-lifer, possibly a rural cultist or one of the local caucasian monks of some kind. We have quite a few monasteries nearby.
You're really doing a pretzel twist here to turn this into some moral objection, and I say that as someone far more leftist than most of hnews.
I'm pretty sure the person you replied to thinks that backpacking backpacks sit on your shoulders like schoolbags.
I've yet to meet a non-western backpacker that uses tumplines.
In fact, looking broadly at travelsers, in airports I see Africans, Middle Easterns, Asians, and Latinos using backpacks for carry-on. I've never seen anyone use tumplines.