There was an issue with chunk borders at the edge of Ettenmoors a while back in Public Beta 28, but I thought it had been fixed. However, it seems it wasn't and I encountered the same issue at all borders of the Ettenmoors biome on a freshly generated world. Previous report of the issue can be found here.

MilkMC ^{Ask me a question, Fandom User.}

This is not a bug but the unfortunate result of a deliberate piece of code to affect the surface generation of the Ettenmoors. It is still in the code as Mevans obviously didn't find an acceptable alternative for it. This is also used in a few other biomes btw. If you wish to know more, search well, both here and in the Facebook post history.

MilkMC wrote:
There was an issue with chunk borders at the edge of Ettenmoors a while back in Public Beta 28, but I thought it had been fixed. However, it seems it wasn't and I encountered the same issue at all borders of the Ettenmoors biome on a freshly generated world. Previous report of the issue can be found here.

MilkMC

Try restarting your game, Fandom User.

I've seen the same thing here in the Ettenmoors as well as the border between the Mountains of the Wind and its foothills. Baffled me when I first saw it.

The part that caused the ugly transition zones between the Mountains of the Wind and its foothills was removed last update. He didn't mention it in the changelog that sneaky ole modlion. I found out when I went in newly generated chunks in that area and checked the code. It concerned a different approach, but a similar function to affect surface generation, and with similar mismatching results at transition zones between biomes with and without that 'additional noise model'.

Correct. The code causing it is used in these (sub-)biomes: Dorwinion Hills, Ettenmoors, Lindon Coast, Far Harad Coast and Forodwaith Coast.

Every riverbank in my game seems to have this problem!