diff --git a/source/Generating/ChunkGenerator.cpp b/source/Generating/ChunkGenerator.cpp
index b4bd1410d..27a802e4d 100644
--- a/source/Generating/ChunkGenerator.cpp
+++ b/source/Generating/ChunkGenerator.cpp
@@ -366,6 +366,10 @@ void cChunkGenerator::InitFinishGens(cIniFile & a_IniFile)
 			int BottomLavaLevel = a_IniFile.GetValueSetI("Generator", "BottomLavaLevel", 10);
 			m_FinishGens.push_back(new cFinishGenBottomLava(BottomLavaLevel));
 		}
+		else if (NoCaseCompare(*itr, "PreSimulator") == 0)
+		{
+			m_FinishGens.push_back(new cFinishGenPreSimulator);
+		}
 	}  // for itr - Str[]
 }
 
diff --git a/source/Generating/FinishGen.cpp b/source/Generating/FinishGen.cpp
index 6d0811891..53453a247 100644
--- a/source/Generating/FinishGen.cpp
+++ b/source/Generating/FinishGen.cpp
@@ -385,3 +385,82 @@ void cFinishGenBottomLava::GenFinish(
 
 
 
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+// cFinishGenPreSimulator:
+
+cFinishGenPreSimulator::cFinishGenPreSimulator(void)
+{
+	// Nothing needed yet
+}
+
+
+
+
+
+void cFinishGenPreSimulator::GenFinish(
+	int a_ChunkX, int a_ChunkZ,
+	cChunkDef::BlockTypes & a_BlockTypes,    // Block types to read and change
+	cChunkDef::BlockNibbles & a_BlockMeta,   // Block meta to read and change
+	cChunkDef::HeightMap & a_HeightMap,      // Height map to read and change by the current data
+	const cChunkDef::BiomeMap & a_BiomeMap,  // Biomes to adhere to
+	cEntityList & a_Entities,                // Entities may be added or deleted
+	cBlockEntityList & a_BlockEntities       // Block entities may be added or deleted
+)
+{
+	CollapseSandGravel(a_BlockTypes, a_HeightMap);
+	// TODO: other operations
+}
+
+
+
+
+
+void cFinishGenPreSimulator::CollapseSandGravel(
+	cChunkDef::BlockTypes & a_BlockTypes,    // Block types to read and change
+	cChunkDef::HeightMap & a_HeightMap       // Height map to update by the current data
+)
+{
+	// Collapse gravel and sand:
+	for (int z = 0; z < cChunkDef::Width; z++)
+	{
+		for (int x = 0; x < cChunkDef::Width; x++)
+		{
+			int LastY = -1;
+			for (int y = 0; y < cChunkDef::Height; y++)
+			{
+				BLOCKTYPE Block = cChunkDef::GetBlock(a_BlockTypes, x, y, z);
+				switch (Block)
+				{
+					default:
+					{
+						// Set the last block onto which stuff can fall to this height:
+						LastY = y;
+						break;
+					}
+					case E_BLOCK_AIR:
+					{
+						// Do nothing
+						break;
+					}
+					case E_BLOCK_SAND:
+					case E_BLOCK_GRAVEL:
+					{
+						if (LastY < y - 1)
+						{
+							cChunkDef::SetBlock(a_BlockTypes, x, LastY + 1, z, Block);
+							cChunkDef::SetBlock(a_BlockTypes, x, y, z, E_BLOCK_AIR);
+						}
+						LastY++;
+						break;
+					}
+				}  // switch (GetBlock)
+			}  // for y
+			cChunkDef::SetHeight(a_HeightMap, x, z, LastY);
+		}  // for x
+	}  // for z
+}
+
+
+
+
diff --git a/source/Generating/FinishGen.h b/source/Generating/FinishGen.h
index b6d3c3935..2dd4baa4a 100644
--- a/source/Generating/FinishGen.h
+++ b/source/Generating/FinishGen.h
@@ -150,3 +150,32 @@ protected:
 
 
 
+
+class cFinishGenPreSimulator :
+	public cFinishGen
+{
+public:
+	cFinishGenPreSimulator(void);
+	
+protected:
+	// Drops hanging sand and gravel down to the ground, recalculates heightmap
+	void CollapseSandGravel(
+		cChunkDef::BlockTypes & a_BlockTypes,    // Block types to read and change
+		cChunkDef::HeightMap & a_HeightMap      // Height map to read and change by the current data
+	);
+	
+	// cFinishGen override:
+	virtual void GenFinish(
+		int a_ChunkX, int a_ChunkZ,
+		cChunkDef::BlockTypes & a_BlockTypes,    // Block types to read and change
+		cChunkDef::BlockNibbles & a_BlockMeta,   // Block meta to read and change
+		cChunkDef::HeightMap & a_HeightMap,      // Height map to read and change by the current data
+		const cChunkDef::BiomeMap & a_BiomeMap,  // Biomes to adhere to
+		cEntityList & a_Entities,                // Entities may be added or deleted
+		cBlockEntityList & a_BlockEntities       // Block entities may be added or deleted
+	) override;
+} ;
+
+
+
+