Can someone explain the frontier weirdness on the live map, where it sometimes looks like two different maps are overlapping? Here's some examples from smp4, although it is present on every server's frontier map. Notice the hard edges where it looks like one map was painted over another:
This happens when part of the map is explored in one version, an update happens, and then someone explores the remaining bits. Because world generation changes throughout updates, wonky stuff like this happens when previously-generated land is next to newly-generated land.
Seconding what Sliced Bread said, but I'd like to add on that it's much less common these days. Mojang made a major change back with 1.7 I think that caused most of the drastic change and they're much better at avoiding this these days.
Actually, mojang "fixed" this going to 1.13 The basics of the world generation is the same (as far as my testing goes). That's becuase they didnn't change the functionn controling the highthmap: (early morning here, sorry if I am making no sense) A minecraft world generates in four steps, it first makes a highthmap, wich basically means it makes the enite world out of stone, then come the caves (I think) then it adds grass/dirt/gravel, then water, trees, everything, and lastly recourses. They just didn't change any code in the first step, neither anything in the second for the overworld as far as I can tell, but they defenetly did change that one quite a lot in the nether. Just the last two are changed.
