--- a/net/minecraft/world/level/levelgen/ChunkGeneratorAbstract.java
+++ b/net/minecraft/world/level/levelgen/ChunkGeneratorAbstract.java
@@ -76,7 +76,7 @@
     protected final IBlockData defaultBlock;
     protected final IBlockData defaultFluid;
     private final long seed;
-    protected final Supplier<GeneratorSettingBase> settings;
+    public final Supplier<GeneratorSettingBase> settings; // PAIL protected -> public
     private final int height;
     private final NoiseSampler sampler;
     private final BaseStoneSource baseStoneSource;
@@ -257,6 +257,19 @@
 
     @Override
     public void buildBase(RegionLimitedWorldAccess regionlimitedworldaccess, IChunkAccess ichunkaccess) {
+        // CraftBukkit start - spilt surface and bedrock generation code
+        Random random = buildSurface(regionlimitedworldaccess, ichunkaccess);
+        buildBedrock(ichunkaccess, random);
+    }
+
+    @Override
+    public void buildBedrock(IChunkAccess iChunkAccess, Random random) {
+        a(iChunkAccess, random); // PAIL rename setBedrock
+    }
+
+    @Override
+    public SeededRandom buildSurface(RegionLimitedWorldAccess regionlimitedworldaccess, IChunkAccess ichunkaccess) {
+        // CraftBukkit end
         ChunkCoordIntPair chunkcoordintpair = ichunkaccess.getPos();
         int i = chunkcoordintpair.x;
         int j = chunkcoordintpair.z;
@@ -281,7 +294,10 @@
             }
         }
 
-        this.a(ichunkaccess, seededrandom);
+        // CraftBukkit start - spilt surface and bedrock generation code
+        // this.a(ichunkaccess, seededrandom);
+        return seededrandom;
+        // CraftBukkit end
     }
 
     private void a(IChunkAccess ichunkaccess, Random random) {
@@ -403,16 +419,23 @@
         BlockPosition.MutableBlockPosition blockposition_mutableblockposition = new BlockPosition.MutableBlockPosition();
 
         for (int i1 = 0; i1 < this.cellCountX; ++i1) {
+            // CraftBukkit start - decompile error
+            int i1Final = i1;
             list.forEach((noiseinterpolator1) -> {
-                noiseinterpolator1.a(i1);
+                noiseinterpolator1.a(i1Final);
+                // CraftBukkit end
             });
 
             for (int j1 = 0; j1 < this.cellCountZ; ++j1) {
                 ChunkSection chunksection = ichunkaccess.b(ichunkaccess.getSectionsCount() - 1);
 
                 for (int k1 = j - 1; k1 >= 0; --k1) {
+                    // CraftBukkit start - decompile error
+                    int kiFinal = k1;
+                    int j1Final = j1;
                     list.forEach((noiseinterpolator1) -> {
-                        noiseinterpolator1.a(k1, j1);
+                        noiseinterpolator1.a(kiFinal, j1Final);
+                        // CraftBukkit end
                     });
 
                     for (int l1 = this.cellHeight - 1; l1 >= 0; --l1) {