Disabling Biomes

Overview

Substratum allows you to control which cave biomes appear in your world and how frequently they spawn. This is done by modifying the biome extrusions file, which defines biome weights and distribution.

All biome configuration is located in:

biome-providers/extrusions/add_substratum_cave_biomes.yml

Understanding the Extrusions File

The extrusions file controls how cave biomes are distributed using a weighted system:

add_substratum_cave_biomes.yml

extrusions:
  - type: REPLACE
    from: LAND_CAVES
    sampler:
      type: CELLULAR
      return: CellValue
      salt: 4357
      frequency: 1 / ${substratum_meta.yml:biome-distribution.cave-biome-scale} / ${substratum_meta.yml:biome-distribution.global-scale}
    to:
      - SELF: 6
      - HONEY_GROTTO: 1
      - OVERGROWN_DUGOUT: 1
      - SANDY_CHAMBERS: 1
      - SUBTERRANEAN_MESA: 1
      - MOLTEN_PASSAGES: 1
      - TERRACOTTA_CAVES: 1
      - MARBLE_MINES: 1
      - AMETHYST_HOLLOW: 1
      - FROZEN_CAVERNS: 1
      - FUNGAL_UNDERGROWTH: 1
      #- CORAL_COVES: 1
      - GRANITE_MINES: 1
      - ANDESITE_MINES: 1
      - DIORITE_MINES: 1
    range:
      min: ${substratum_meta.yml:biome-distribution.cave-biome-min}
      max: ${substratum_meta.yml:biome-distribution.cave-biome-max}

Key Components

type

string

default:"REPLACE"

Defines the extrusion type. REPLACE means these biomes replace the LAND_CAVES biome.

from

string

default:"LAND_CAVES"

The base biome being replaced by Substratum cave biomes.

list

A weighted list of biomes that can spawn. Each entry consists of a biome ID and a weight number.Format: BIOME_ID: weightHigher weights = more frequent spawning.

range.min

integer

Minimum Y-level where these biomes can spawn. References substratum_meta.yml.

range.max

integer

Maximum Y-level where these biomes can spawn. References substratum_meta.yml.

Biome Weight System

Biome weights determine relative spawn frequency:

How Weights Work

Calculate Total Weight

Add up all biome weights:

SELF (6) + 13 biomes (1 each) = 19 total weight

Determine Probability

Each biome’s chance = its weight / total weight:

SELF: 6/19 = ~31.6%
HONEY_GROTTO: 1/19 = ~5.3%
OVERGROWN_DUGOUT: 1/19 = ~5.3%
...and so on

Apply During Generation

When a cave region generates, the system randomly selects a biome based on these probabilities.

SELF Biome

The SELF: 6 entry is special:

SELF represents vanilla-style cave generation (dripstone caves, lush caves, etc.). With a weight of 6, approximately 31% of cave regions will use vanilla generation instead of Substratum biomes.

There are several methods to disable or adjust biome frequency:

Method 1: Comment Out Biomes

The simplest method is to comment out biomes you don’t want:

add_substratum_cave_biomes.yml

to:
  - SELF: 6
  - HONEY_GROTTO: 1
  - OVERGROWN_DUGOUT: 1
  #- SANDY_CHAMBERS: 1        # Disabled
  - SUBTERRANEAN_MESA: 1
  #- MOLTEN_PASSAGES: 1        # Disabled
  - TERRACOTTA_CAVES: 1
  - MARBLE_MINES: 1
  - AMETHYST_HOLLOW: 1
  #- FROZEN_CAVERNS: 1         # Disabled
  - FUNGAL_UNDERGROWTH: 1
  #- CORAL_COVES: 1            # Already disabled by default
  - GRANITE_MINES: 1
  - ANDESITE_MINES: 1
  - DIORITE_MINES: 1

Notice that CORAL_COVES is commented out by default. This biome is experimental or requires special conditions.

Method 2: Set Weight to Zero

Alternatively, set the weight to 0 to disable:

to:
  - SELF: 6
  - HONEY_GROTTO: 1
  - SANDY_CHAMBERS: 0  # Disabled via zero weight
  - MOLTEN_PASSAGES: 0 # Disabled via zero weight

Setting weight to 0 still includes the biome in the list but with no chance to spawn. Commenting out is cleaner and more performant.

Method 3: Remove Lines Entirely

You can completely remove biome entries:

to:
  - SELF: 6
  - HONEY_GROTTO: 1
  - OVERGROWN_DUGOUT: 1
  # SANDY_CHAMBERS removed entirely
  - SUBTERRANEAN_MESA: 1
  # MOLTEN_PASSAGES removed entirely

Adjusting Biome Frequency

To make certain biomes more or less common, adjust their weights:

Making Biomes More Common

to:
  - SELF: 6
  - HONEY_GROTTO: 5          # 5x more common than default
  - OVERGROWN_DUGOUT: 1
  - SANDY_CHAMBERS: 1
  - SUBTERRANEAN_MESA: 1
  - MOLTEN_PASSAGES: 1
  - TERRACOTTA_CAVES: 1
  - MARBLE_MINES: 1
  - AMETHYST_HOLLOW: 3       # 3x more common than default
  - FROZEN_CAVERNS: 1
  - FUNGAL_UNDERGROWTH: 1
  - GRANITE_MINES: 1
  - ANDESITE_MINES: 1
  - DIORITE_MINES: 1

New probabilities:

Total weight = 6 + 5 + 3 + 11 = 25
HONEY_GROTTO: 5/25 = 20%
AMETHYST_HOLLOW: 3/25 = 12%
Other biomes: 1/25 = 4% each

Making Biomes Rarer

Use fractional weights for very rare biomes:

to:
  - SELF: 6
  - HONEY_GROTTO: 1
  - OVERGROWN_DUGOUT: 1
  - SANDY_CHAMBERS: 1
  - SUBTERRANEAN_MESA: 1
  - MOLTEN_PASSAGES: 0.2     # Very rare
  - TERRACOTTA_CAVES: 1
  - MARBLE_MINES: 1
  - AMETHYST_HOLLOW: 1
  - FROZEN_CAVERNS: 0.5      # Somewhat rare
  - FUNGAL_UNDERGROWTH: 1
  - GRANITE_MINES: 1
  - ANDESITE_MINES: 1
  - DIORITE_MINES: 1

Common Configuration Scenarios

Only Substratum Biomes

Remove vanilla cave generation entirely:

to:
  #- SELF: 6               # Disabled vanilla caves
  - HONEY_GROTTO: 1
  - OVERGROWN_DUGOUT: 1
  - SANDY_CHAMBERS: 1
  - SUBTERRANEAN_MESA: 1
  - MOLTEN_PASSAGES: 1
  - TERRACOTTA_CAVES: 1
  - MARBLE_MINES: 1
  - AMETHYST_HOLLOW: 1
  - FROZEN_CAVERNS: 1
  - FUNGAL_UNDERGROWTH: 1
  - GRANITE_MINES: 1
  - ANDESITE_MINES: 1
  - DIORITE_MINES: 1

More Vanilla Caves

Increase vanilla cave generation:

to:
  - SELF: 20              # Much more vanilla generation
  - HONEY_GROTTO: 1
  - OVERGROWN_DUGOUT: 1
  # ...rest of biomes

Themed World - No Mine Biomes

Disable all mine-themed biomes:

to:
  - SELF: 6
  - HONEY_GROTTO: 1
  - OVERGROWN_DUGOUT: 1
  - SANDY_CHAMBERS: 1
  - SUBTERRANEAN_MESA: 1
  - MOLTEN_PASSAGES: 1
  - TERRACOTTA_CAVES: 1
  #- MARBLE_MINES: 1       # Disabled
  - AMETHYST_HOLLOW: 1
  - FROZEN_CAVERNS: 1
  - FUNGAL_UNDERGROWTH: 1
  #- GRANITE_MINES: 1      # Disabled
  #- ANDESITE_MINES: 1     # Disabled
  #- DIORITE_MINES: 1      # Disabled

Single Biome World

Create a world with only one Substratum biome:

to:
  #- SELF: 6               # Disabled
  - HONEY_GROTTO: 1       # Only this biome will spawn
  #- OVERGROWN_DUGOUT: 1  # All others disabled
  #- SANDY_CHAMBERS: 1
  #- SUBTERRANEAN_MESA: 1
  #- MOLTEN_PASSAGES: 1
  #- TERRACOTTA_CAVES: 1
  #- MARBLE_MINES: 1
  #- AMETHYST_HOLLOW: 1
  #- FROZEN_CAVERNS: 1
  #- FUNGAL_UNDERGROWTH: 1
  #- GRANITE_MINES: 1
  #- ANDESITE_MINES: 1
  #- DIORITE_MINES: 1

Favorite Biomes Only

Keep only your favorite biomes:

to:
  - SELF: 3               # Some vanilla caves
  - HONEY_GROTTO: 2       # Favorite - more common
  #- OVERGROWN_DUGOUT: 1  # Not a favorite
  #- SANDY_CHAMBERS: 1    # Not a favorite
  #- SUBTERRANEAN_MESA: 1 # Not a favorite
  - MOLTEN_PASSAGES: 2    # Favorite - more common
  #- TERRACOTTA_CAVES: 1  # Not a favorite
  #- MARBLE_MINES: 1      # Not a favorite
  - AMETHYST_HOLLOW: 2    # Favorite - more common
  - FROZEN_CAVERNS: 2     # Favorite - more common
  #- FUNGAL_UNDERGROWTH: 1 # Not a favorite
  #- GRANITE_MINES: 1     # Not a favorite
  #- ANDESITE_MINES: 1    # Not a favorite
  #- DIORITE_MINES: 1     # Not a favorite

Available Biomes

Here’s a complete list of all Substratum biomes you can enable/disable:

Biome ID	Description	Default Status
`SELF`	Vanilla cave generation	Enabled (weight: 6)
`HONEY_GROTTO`	Sweet caves with bee nests	Enabled
`OVERGROWN_DUGOUT`	Mossy, overgrown caves	Enabled
`SANDY_CHAMBERS`	Sand and sandstone caves	Enabled
`SUBTERRANEAN_MESA`	Mesa-themed underground	Enabled
`MOLTEN_PASSAGES`	Lava-filled dangerous caves	Enabled
`TERRACOTTA_CAVES`	Colorful terracotta formations	Enabled
`MARBLE_MINES`	Calcite and marble caves	Enabled
`AMETHYST_HOLLOW`	Crystalline amethyst caves	Enabled
`FROZEN_CAVERNS`	Icy caves with icicles	Enabled
`FUNGAL_UNDERGROWTH`	Mushroom-filled caves	Enabled
`CORAL_COVES`	Underwater coral caves	Disabled by default
`GRANITE_MINES`	Granite mining caves	Enabled
`ANDESITE_MINES`	Andesite mining caves	Enabled
`DIORITE_MINES`	Diorite mining caves	Enabled

For detailed information about each biome, see the Cave Biomes section.

Applying Configuration Changes

Edit Extrusions File

Open biome-providers/extrusions/add_substratum_cave_biomes.yml and make your changes.

Save File

Ensure your YAML syntax is correct (proper indentation, no typos).

Reload Terra

Apply changes with /terra reload or restart your server.

Generate New Chunks

Travel to unexplored areas to see your biome configuration in action.

Biome configuration changes only affect newly generated chunks. Already explored areas will retain their original biome distribution.

Troubleshooting

Changes Not Taking Effect

Causes:

Didn’t reload Terra after making changes
Testing in already-generated chunks
YAML syntax errors

Solutions:

Run /terra reload in-game
Travel to completely unexplored areas (thousands of blocks away)
Check server console for YAML parsing errors
Validate YAML syntax with an online validator

Only One Biome Spawning

Cause: All other biomes are disabled or have weight 0.Solution: Check your to: list and ensure multiple biomes have weights > 0.

No Substratum Biomes Spawning

Causes:

All Substratum biomes disabled, only SELF enabled
Y-level range doesn’t match generation area

Solutions:

Ensure at least one Substratum biome has weight > 0
Check range.min and range.max match your exploration altitude
Verify substratum_meta.yml cave-biome-min/max settings

Terra Reload Error

Cause: YAML syntax error in extrusions file.Solution:

Check indentation (must use spaces, not tabs)
Ensure colons have spaces after them: BIOME: 1 not BIOME:1
Verify all comment lines start with #
Look for special characters or typos

Next Steps

Biome Overview

Learn about all available cave biomes

Biome Distribution

Adjust biome scale and size

Configuration Overview

Back to configuration home

Troubleshooting

Fix common configuration issues

Getting Started

Cave Biomes

Configuration

Advanced