Someone

for(int i =0; i < 65536; i++)
			{
				heightmap[i] =  20.4989f;
			}
			
			float[] height = new float[256];
			
			for(int x = 0; x<16; x++)
			{
				for(int y =0; y<16; y++)
				{
					height[y*16+x]=20.4989f;
					if(y>5 && y<9)
					{
						height[y*16 +x]=21.4989f;
					}
				}
			}
			
			Array.Copy(height, heightmap, 256);