diff --git a/Substrate/SubstrateCS/Source/BlockManager.cs b/Substrate/SubstrateCS/Source/BlockManager.cs
index 360d128..45fa3c1 100644
--- a/Substrate/SubstrateCS/Source/BlockManager.cs
+++ b/Substrate/SubstrateCS/Source/BlockManager.cs
@@ -40,7 +40,7 @@ namespace Substrate
         {
             _chunkMan = cm;
 
-            Chunk c = new Chunk(0, 0);
+            Chunk c = Chunk.Create(0, 0);
 
             _chunkXDim = c.XDim;
             _chunkYDim = c.YDim;
diff --git a/Substrate/SubstrateCS/Source/Chunk.cs b/Substrate/SubstrateCS/Source/Chunk.cs
index 50345f0..2597516 100644
--- a/Substrate/SubstrateCS/Source/Chunk.cs
+++ b/Substrate/SubstrateCS/Source/Chunk.cs
@@ -64,21 +64,35 @@ namespace Substrate
             set { _tree.Root["Level"].ToTagCompound()["TerrainPopulated"].ToTagByte().Data = (byte)(value ? 1 : 0); }
         }
 
-        public Chunk (int x, int z)
+        private Chunk ()
         {
-            _cx = x;
-            _cz = z;
-
-            BuildNBTTree();
-
-            BuildTileEntityCache();
         }
 
-        public Chunk (NBT_Tree tree)
+        public static Chunk Create (int x, int z)
         {
-            if (LoadTreeSafe(tree.Root) == null) {
-                throw new InvalidNBTObjectException();
-            }
+            Chunk c = new Chunk();
+
+            c._cx = x;
+            c._cz = z;
+
+            c.BuildNBTTree();
+            c.BuildTileEntityCache();
+
+            return c;
+        }
+
+        public static Chunk Create (NBT_Tree tree)
+        {
+            Chunk c = new Chunk();
+
+            return c.LoadTree(tree.Root);
+        }
+
+        public static Chunk CreateVerified (NBT_Tree tree)
+        {
+            Chunk c = new Chunk();
+
+            return c.LoadTreeSafe(tree.Root);
         }
 
         private void BuildNBTTree ()
@@ -570,7 +584,7 @@ namespace Substrate
 
         public Chunk Copy ()
         {
-            return new Chunk(_tree.Copy());
+            return Chunk.Create(_tree.Copy());
         }
 
         #endregion
diff --git a/Substrate/SubstrateCS/Source/ChunkFileManager.cs b/Substrate/SubstrateCS/Source/ChunkFileManager.cs
index ae24391..a6ceff6 100644
--- a/Substrate/SubstrateCS/Source/ChunkFileManager.cs
+++ b/Substrate/SubstrateCS/Source/ChunkFileManager.cs
@@ -92,7 +92,7 @@ namespace Substrate
                 return null;
             }
 
-            return new Chunk(GetChunkTree(cx, cz));
+            return Chunk.CreateVerified(GetChunkTree(cx, cz));
         }
 
         public ChunkRef GetChunkRef (int cx, int cz)
@@ -124,7 +124,7 @@ namespace Substrate
         public ChunkRef CreateChunk (int cx, int cz)
         {
             DeleteChunk(cx, cz);
-            Chunk c = new Chunk(cx, cz);
+            Chunk c = Chunk.Create(cx, cz);
             c.Save(GetChunkOutStream(cx, cz));
 
             ChunkRef cr = ChunkRef.Create(this, this, cx, cz);
diff --git a/Substrate/SubstrateCS/Source/ChunkRef.cs b/Substrate/SubstrateCS/Source/ChunkRef.cs
index b008b5d..bb7738b 100644
--- a/Substrate/SubstrateCS/Source/ChunkRef.cs
+++ b/Substrate/SubstrateCS/Source/ChunkRef.cs
@@ -52,12 +52,8 @@ namespace Substrate
             get { return _dirty; }
         }
 
-        private ChunkRef (IChunkContainer container, IChunkCache cache, int cx, int cz)
+        private ChunkRef ()
         {
-            _container = container;
-            _cache = cache;
-            _cx = cx;
-            _cz = cz;
         }
 
         public static ChunkRef Create (IChunkContainer container, IChunkCache cache, int cx, int cz)
@@ -66,7 +62,14 @@ namespace Substrate
                 return null;
             }
 
-            return new ChunkRef(container, cache, cx, cz);
+            ChunkRef c = new ChunkRef();
+
+            c._container = container;
+            c._cache = cache;
+            c._cx = cx;
+            c._cz = cz;
+
+            return c;
         }
 
         public int BlockGlobalX (int x)
@@ -480,9 +483,33 @@ namespace Substrate
         {
             GetChunk();
 
+            // Optimization - only need to queue at level of highest neighbor's height
             for (int x = 0; x < XDim; x++) {
                 for (int z = 0; z < ZDim; z++) {
-                    QueueRelight(new BlockKey(x, YDim - 1, z));
+                    ChunkRef ce = LocalChunk(x, 0, z - 1);
+                    ChunkRef cn = LocalChunk(x - 1, 0, z);
+                    ChunkRef cs = LocalChunk(x + 1, 0, z);
+                    ChunkRef cw = LocalChunk(x, 0, z + 1);
+
+                    int h = GetHeight(x, z);
+                    if (ce != null) {
+                        h = Math.Max(h, ce.GetHeight(x, ZDim - 1));
+                    }
+                    if (cn != null) {
+                        h = Math.Max(h, cn.GetHeight(XDim - 1, z));
+                    }
+                    if (cs != null) {
+                        h = Math.Max(h, cs.GetHeight(0, z));
+                    }
+                    if (cw != null) {
+                        h = Math.Max(h, cw.GetHeight(x, 0));
+                    }
+
+                    for (int y = h; y < YDim; y++) {
+                        SetBlockSkyLight(x, y, z, BlockInfo.MAX_LUMINANCE);
+                    }
+
+                    QueueRelight(new BlockKey(x, h, z));
                 }
             }
 
diff --git a/Substrate/SubstrateCS/Source/Region.cs b/Substrate/SubstrateCS/Source/Region.cs
index 8cde017..d854d46 100644
--- a/Substrate/SubstrateCS/Source/Region.cs
+++ b/Substrate/SubstrateCS/Source/Region.cs
@@ -257,7 +257,7 @@ namespace Substrate
             int cx = lcx + _rx * ChunkManager.REGION_XLEN;
             int cz = lcz + _rz * ChunkManager.REGION_ZLEN;
 
-            Chunk c = new Chunk(cx, cz);
+            Chunk c = Chunk.Create(cx, cz);
             c.Save(GetChunkOutStream(lcx, lcz));
 
             ChunkRef cr = ChunkRef.Create(this, _cache, lcx, lcz);
@@ -300,7 +300,7 @@ namespace Substrate
                 return null;
             }
 
-            return new Chunk(GetChunkTree(lcx, lcz));
+            return Chunk.CreateVerified(GetChunkTree(lcx, lcz));
         }
 
         public bool ChunkExists (int lcx, int lcz)