Field Mice Needed

November 2, 2010 12:36 AM

Old school hardware hacker, Postscript enthusiast, electronics writer, woo debunker, all around geek, and now amateur archaeologist Don Lancaster (prev 1, 2) needs you. And maybe some of your nerdy gadgets.

Among the things to pique Lancaster's interest these days are the curious collection of earthen paths meandering around the bajadas in the desert near Safford, Arizona. Looking more and more to be a surprisingly sophisticated system of prehistoric waterways, these "hanging canals" (pdf here) (pdf with more pictures here) seem to be part of a clever prehistoric irrigation system, diverting waters from nearby mountain streams to destinations still unknown, using carefully graded paths. Up to thirty miles worth! Largely neglected and/or obscured by modern constructions, it seems possible that some may have been repurposed and maintained in historic times by settlers, and may have even been used to supply a (now derelict) recreational reservoir without knowing who made the canals in the first place.

The area is not a stranger to prehistoric agricultural artifacts. (more: pdf, pdf). But the extent and sophistication of the canals seems a fairly new discovery. Many mysteries remain. Lancaster is seeking volunteers to help identify and record new hanging canals. Drop him a line, especially if you've got a really accurate altimeter. Or a decent UAV.

posted by 2N2222 (6 comments total)

Slope is independent of terrain!

Whoa. Thats definitely manmade right...well then where are all the artifacts in an area that could have been pretty populous. I dont understand that.
posted by hal_c_on at 2:06 AM on November 2, 2010

The work of Pietro Laureano may be relevant:

"During the torrential rainfalls, the terracing and the water collection systems protect the slopes from erosion and gravity pulls the water down towards the cisterns in the caves."
posted by dragonsi55 at 6:14 AM on November 2, 2010

I'm not exactly sure why, but Don Lancaster has always rubbed me completely the wrong way. Even in the old Nuts & Volts days, he always had this mixture of over-selling the omgeniousness of His Radical Ideas, plus an appeal to authority ("studied by Neely") and an apparent utter unwillingness to explain what he's talking about (what do you mean "literally hanging" or "gives the illusion of water flowing up hill"?).
posted by DU at 6:20 AM on November 2, 2010 [1 favorite]

DU: "gives the illusion of water flowing up hill"
Google for gravity hill. There is one video that I cannot find that explains it pretty good; basically, the road *is* going down, but the local scenery (caused by ground shape and wind effects making the trees grow at a slant) produces an optical illusion that appears otherwise.

And correct me if I'm wrong, but don't most decent GPS that hikers use have an altimeter built in? Isn't that part and parcel of the GPS system itself?
posted by Old'n'Busted at 6:35 AM on November 2, 2010

And correct me if I'm wrong, but don't most decent GPS that hikers use have an altimeter built in? Isn't that part and parcel of the GPS system itself?

GPS does give you altitude but the resolution is horrible:

GPS manufacturers routinely state that the altitude derived from GPS measurements is less accurate than the position by at least a factor of 1.5, and it might be even higher (see below). For a standard consumer-grade GPS unit with no broadcast correction like WAAS/EGNOS, the 95% confidence interval for position is typically on the order of 15 meters (close to 50 feet), and the altitude confidence is 95% to a precision of 22.5 meters with 95% confidence (about 75 feet).
posted by fake at 7:40 AM on November 2, 2010

Old'n'Busted, GPS has been getting much better in recent years, but GPS altimeters are pretty bad, especially if you're trying to measure something as subtle as a few feet a mile for water flow. I remember uploading a track to Bikely or something and then having a discussion with their developers over the fact that the 20 mile loop I was riding in approximately an hour couldn't possibly have 13,000 feet of climbing, even if that's what my GPS track said.

In another example, I was riding across the playa at Burning Man one year, watching my GPS show altitude swings of fifty or a hundred feet.

Some bike computers do have barometric altimeters, but I think you need some ground stations and differential GPS, or good old fashioned transits and geometry, to get the sorts of numbers you'd want to make a good case that these are canals.
posted by straw at 7:41 AM on November 2, 2010