Minecraft wiki entry for Windswept_Hills, associated text: Windswept hills generate in areas with high erosion and low factor. The grass and leaves are an aqua color, the surface is mostly grassy with occasional patches of stone and many blobs and veins of ores. These are the only biomes, besides mountain biomes, where emerald ore is found. The cliffs of the windswept hills generally peak at roughly Y-level 140, and around Y-level 120 rain starts to be replaced with snow, creating snow-capped hills. Undergound, below the sea level, infested blocks with silverfish can be generated, even below the deepslate layer.