Terrain generation, primarily in the pine barrens biome, often has layers of floating rock. Pictured below is the tamest ive seen it, but ive seen it where patches of stone will be floating in the air a couple dozen blocks up, in the exact formation of the terrain below. worldgen mods like Tectonic exacerbate the issue, but its notably present without any other terrain mods.

Terrain generation, primarily in the pine barrens biome, often has layers of floating rock. Pictured below is the tamest ive seen it, but ive seen it where patches of stone will be floating in the air a couple dozen blocks up, in the exact formation of the terrain below. worldgen mods like Tectonic exacerbate the issue, but its notably present without any other terrain mods.