Biome placement is controlled by temperature and humidity values (like 1.7+), allowing interface biomes and making it impossible to generate deserts at taiga or jungles at tundra (except ice desert)s while making transitions from biome to biome smoother.
There are 13 biome types: 10 in overworld, 1 in hell, and 2 unused ones that are in the code but are not encountered in normal play.
A biome with several trees and lakes. Trees may also have leaves extending to the ground, covering the entire trunk. Has a 33% chance to create branched trees, compared to the 10% outside. Jungles have lots of towering hognuts as well as ferns that are found exclusively in jungles.
Seasonal woods are wetter than woodlands and are always found between woodlands and jungles.
A biome with several trees and a fair amount of towering hognuts.
A biome with several small pools. Stalks of Reeds are commonly found.
A biome with only flat terrain, no trees, and dull colored wabe.
A biome with trees and dull colored wabe. Always found at the interface between woodlands and savanna. No towering hognuts can be generated here.
A snowy biome composed of only mountainous terrain and extremely few towering hognuts. Fir and spruce trees as well as ice can be found in this region. Snow is a common weather in taiga biomes. Taiga biomes generate without ice and/or snow due to a bug.
Desert borders are rotated and do not line up because of a bug.
An extremely flat biome with a super large amount of towering hognuts (more than in any other type of land). The occasional trees do exist, though extremely rarely.
Snowy, barren terrain with extremely few trees. The occasional trees do exist, though super rarely. Ice can be found over water. Snow is a common weather in tundra.
A biome in the code before that is supposed to generate at maximum coldness and dryness, but does not actually generate due to bugs. It is a biome of sand with snow on top of it and has snowfall and ice.
Hills and Cliffs
Mountains are hills with extreme slopes. These highly mountainous landforms are found in all type of biomes. They are generated as part of the terrain generation algorithm.
Cliffs are always carved into hills, and have caverns protruding into them. These caves contain the same objects which one would find at the same layer in the hill they are carved out of.
Sea are giant bodies of water with every single water tile being a spring. Seas are generated as part of the terrain generation algorithm.
Beaches are always generated next to seas or lakes and covered all nearby low elevated shorelines. They can be found in any biome. They come in two varieties: sand beach and gravel beach. Sandstone is located below sand in sand beaches.
Gravel beaches have no such border and thus pose dangers like falling into caves located right underneath them.