Minecraft wiki entry for Mining, associated text: Starting from a flat floor, dig one block ahead of the player, then dig 2 blocks down to the right of that. Then move forward into the first place they have dug, turn right to face the second step, and to its right dig 3 blocks down from the floor. The fourth step puts them below their original floor — leave the floor block to become a ceiling, and dig the three blocks below it down to the new step. Continue with this pattern, note that each turn of the stair becomes the ceiling for the next turn. This design drops 4 layers per full turn, but if they run into gravel, players need to place dirt or cobblestone to replace it for the stairway. Turning right forms a clockwise spiral, they can of course go the other way for a counter-clockwise stair.