Terrain features

This page lists generated terrain features that are created in a Minecraft world.

Terrain
Biomes dictate the shape and height of the world. At this stage, the ground is made mostly of stone and stone variants, with water filling in most empty spaces below layer 63, with the exception for structures.

Mountain
Mountains are hills with extreme slopes, cliffs and caves containing emerald ore. On an amplified world, mountains are extremely common in all biomes except ocean and swamp biomes.

Floating island
Floating islands are structures that float in mid-air. Floating islands are normally just small chunks of floating dirt and stone found near cliffs, but on rare occasions they can be large structures that even have springs and trees on them. Floating islands are most frequently found in mountains biomes, along with the "hills", "mountains", and "modified" variants of most biomes, especially shattered savannas.

Hollows
Hollows are the opposite of floating islands. They look like caves, but they have nothing to do with cave generation (although they may intersect with them). When there are many overhangs, they close together and create a hollow. They have exactly the same floor as the terrain above, depending on the biome that they are located in, unlike caves. Hollows have no specific floor. Grass blocks can generate inside too and survive without light. When they generate under the sea level, they are filled with water. They are extremely rare in the default world, compared with the rarity of the modified jungle edge, but can be found far more commonly in certain customized worlds.

Hill
Hills are randomly generated pieces of land on the map. Like stairs, hills are always traversable to their lowest point by virtue of the algorithm that generates them; there is almost always a place on each level from where the next level can be accessed, meaning that the player can climb a hill one level at a time until they reach the top. Cases where this is not true are rare.

Surface layer
The uppermost layers of the terrain are converted to a biome-dependent material: usually grass blocks and dirt, or sand in deserts and beaches. Podzol is found in giant tree taiga, mycelium in mushroom field biomes, and red sand is found in the badlands biome. Sandstone is generated under the sand.

Basin
Occasionally, instead of being converted to dirt or sand, the top layer is stripped away, leaving a 'basin' of bare stone. They bear some resemblance to a geological 'shield' (an area of tectonically stable rock that has been exposed to prolonged erosion due to its very old age; it is distinct from the geological term "basin"). They seem to be more common in forests or plains and are occasionally seen filled with water. Commonly, minerals can be found in these, generally coal ore and iron ore. If generated in a Badlands biome, gold ore can also be seen.

Bryce pillar
Bryce pillars are tall spike-like structures found in badlands, consisting of six colors of terracotta. While this structure is found exclusively in eroded badlands, all badlands biomes actually have this structure, but set to false except for eroded badlands. This structure juts out from sea level and can occasionally pass altitude layer 100.

Large lake
Since water generates on the surface of the world below y=63, land it covers can turn into large lakes. Large lakes generate pockets of dirt, sand, gravel, and clay on the lake floor, also known as disks. When large lakes generate near the shore they can turn into small bays.

Coral reef
Coral reefs are structures that consist of corals, coral fans, coral blocks and sea pickles. In bedrock edition, the coral reefs can also consist of dead corals, dead coral fans and dead coral blocks.

Large structures

 * Caves – large tunnels found underground in the overworld and nether.
 * Ravines – very deep and narrow caves

Small structures

 * Bee nests: Generate on a small amount of oak and birch trees in various biomes, containing three bees.
 * Disks: Small circular patches of dirt, sand, and gravel found underwater.
 * Mineral vein: Veins of a certain type of ore.
 * Spring: A water or lava source block that generates on the side of a hill.
 * Vegetation patch
 * Mossy cobblestone boulder
 * Ice spike
 * Iceberg

Lava sea
Lava seas are found at and below level 30 in the Nether. They make a large portion of the Nether and are extremely common. They can stretch for hundreds of meters in any direction, and are usually bordered by netherrack (or more rarely soul sand, gravel and/or magma blocks). Striders can spawn in lava seas.

Unlike with Overworld oceans, lava oceans are not handled as a biome.

Nether basins
In the nether, basins generate the same size and shape as they do in the Overworld. Unlike their Overworld counterparts, however, Nether basins replace the ground with netherrack instead of stone. Nether basins can also expose ores, mainly nether quartz ore and nether gold ore.

Notably, basins generate independent of the y-coordinate; if a basin generates in an overhang in the Nether, an identical basin is guaranteed to generate at the exact same x and z coordinates on the ground below such an overhang.

Central island
The center of the End is a large, asteroid-like island composed entirely of end stone, floating in the void. At a distance of 1000 blocks away, an endless expanse of more islands begins, away from the main island. These consist of large islands, about the size of the main island, and smaller ones, which are usually thin and small.

Outer island
The outer end islands are found 1000 blocks away from the central island. They vary in size from large islands to smaller "mini islands". Generated structures such as End cities and End ships spawn here, along with chorus trees and basins. The player can be taken to the end islands through the End gateway.

End Spike
End spikes are generated structures in that are made of obsidian.

End basins
Basins in the End generate as they would in the Overworld and the Nether, with the exception being that they never expose any ores. End basins may generate on both the central island and outer islands, and chorus trees may occasionally take root in them.

Technical details
Features are generated for a given chunk after the terrain has been formed. The chunk format includes a tag called that indicates whether features whose point of origin is in that chunk have been generated. If it is false or missing, they generate again. Feature generation is based on what is already in the chunk, so (for example) flagging a chunk that has already been populated for repopulation approximately doubles the amount of ore in it.

When features are generated, they can spill over into neighboring chunks that have been previously generated. Thus, a tree at the edge of the generated world (and probably visible only via external tools) may be overwritten by a lake before the player reaches it. It is also theoretically possible for two worlds generated with the same seed, from the same version of Minecraft, to differ slightly depending on the players' travel routes, because the chunk generation order may determine which of two conflicting features overwrite or suppress the other.