To start, I'd like to apologize if this question has already been addressed before as I attempted to look for a similar topic/comment that answered it but couldn't find one.
Anyway, if have several 20 ft lengths of telephone/utility poles (whichever you prefer calling them) left over after building my smithy. (Well, it's more of a small pole barn at the moment, but I'm planning to add 4.5ft cobble "half" walls as wind breaks... eventually. I digress) I've used 6ft sections of utility poles as anvil stands before with 3ft buried in the ground... but that was in florida, where rocks and clay didn't exist. I can't remember where I read/heard it from, but 2/3 feet of telephone pole in the ground helped make a "smaller anvil work like a heavier one" (of course I know there are a lot of factors that go into what makes a proper anvil but this is just a simple way of saying it's adding more "mass" and making it a more solid piece... I think that's the proper explanation... I'm rambling now.)
Long post short: how long of a section do I actually need and how much of it do I bury? The type of ground it'll be in is, if you're familiar with gettysburg pa, brown clay, rocks, (specifically: predominantly diabase, granite, slate [red, black, grey], quartz, to a [lesser extent but still present] iron [bog, limonite, hematite, magnetite] and other minerals/rocks I can't remember off the top of my head.) Oh, limestone and dolomite, so lots of calcium carbonate, if that particularly matters.
thank you to anyone that takes the time to read and respond to my "long winded" post and eventual question (which I apologize for)
Again, thanks, Josh.