Minecraft wiki entry for Before_Beta_1.8, associated text: Height variation was entirely independent of biome type, with biomes having no influence on the shape of terrain. This meant things like cliffs and mountains were able to generate up to nearly 128 on the y-axis in any biome. Tall grass was also much less present in pre-1.8 worlds (except in the "Plains" and "Rainforest" biomes).