I made a post before but it didn't really get answered well and I didn't really phrase it well enough.
So I have two biomes. When testing them with BiomeProviderSingle and no gen layer, they work as I hope they would.
One, the mountain, has a ground level around y = 110 but with mountains that can go past y = 200.
The other, the lowland, has a ground level around y = 70 and doesn't usually go past y = 95 or so.
However, with every open-source dimension-with-multiple-biomes mod I've seen, they have a custom GenLayer.
To test I tried out a GenLayer from an open-source mod but that just created an issue where the mountain biome would often generate at a low height, seamlessly with the lowland, and the low biome would generate at a ridiculously high height. The biome borders also looked really messy and "chunk"y. Same happened with another sample gen-layer.
I wasn't able to find any tutorials or explanations on GenLayers, so...
Basically I want them to generate in neat groups (think mystcraft worlds with three or so selected biomes, arranged naturally) without ugly borders and with the mountain biome always being high and the lowland biome always being low. How would I go about doing something like this?