It demonstrably doesn't work.

Well, it "works" in the same way that a Ouija board works. There's a person in control of when the rods cross, just like there are human(s) in control of the planchette on a Ouija board. It's very easy for a person to influence the movements of both, without necessarily being conscious that they are doing so.

Inevitably, the person who is holding the rods has some idea of where to find water. Like others have pointed out, there are hints on the surface, like trees and plants, even the shape of the terrain. Once they have an idea of where to look, it's very easy to make the rods cross at that point.

And if there's not water there, then there's always an excuse. "The energy was not good that day." "There's an underground stream, but it's dried up now." "There is water, but you didn't dig deep enough." etc.

And of course, they almost always find *some* water because there's water nearly everywhere if you dig deep enough. And confirmation bias being what it is, they will always point to their successes as evidence that dowsing works, and their failures are just times where they did it wrong.

Again, they may not even realize that they're doing this. They may really believe it's magic.

Some don't of course. Some people are just charlatans. But there are plenty of true believers too.

Whichever they are, they don't have a real ability. Every time we run a properly controlled experiment, they do no better than random chance.

The James Randi Foundation used to do these tests, offering a million dollars to anyone who could demonstrate any one of a number of abilities (dowsing included). No one has ever successfully passed even the preliminary tests.

If forget where I read it, but Abercrombie acknowledges these issues himself. It was probably in an interview or in the author's notes in one of the books. He's pretty honest about the fact that he's riding a wave of "grimdark" fantasy being popular in the wider culture, and it's not something he invented.

I don't know how much fantasy you read in the 90s and early 2000s. There's a huge swath of what I tend to think of as Lord of the Rings fan-fiction. Not that a lot of those books aren't good, and very entertaining to read, but they are obviously and totally buying into the sort of framing that you got in LotR.

That is, there is good and there is evil, and it's very obvious which is which. A lot of the characters tend to be ancient and powerful, and they are always true to their nature. There are noble kings, and powerful wizards, greedy dwarves, and wise elves, and so on and so forth.

Also, usually there's a hero's journey that is very explicit. The naive farm boy becomes the chosen one who saves the world, etc.

Abercrombie's books, and the First Law especially are basically just a rejection of that kind of fantasy. They're not making a wider point about how the world really is, but they are exploring parts of human nature that those books never could.

Does that make him a master of character? Not really. I think there are a lot of novel writers that do that better. But he is bringing something refreshing to the fantasy genre at least.

Many markers are still metal. Wooden stakes may be used for temporary markings, but the actual reference points those are based on will be designed to be permanent.

You can probably find a variety of survey markers in the pavement in your neighborhood, if you know what to look for. For minor locations, they're usually a small pin driven into the concrete or asphalt.

For more major stations, they'll have a circular disk with information about the station. Even more rarely, you'll find geodetic survey markers that contain information about the actual curvature of the Earth at that point, since even the shape of the Earth can vary enough to be significant at large scales.

https://en.wikipedia.org/wiki/Survey_marker