Because Wurm is not a true 3D world, the cave layer is essentially a second world beneath the surface world. It is possible to mine upwards and downwards with a few limitations. You may not mine upward out of rock and into the [[dirt]] that is covering it. You can mine downward until you reach the [[water]] table, but can not mine deeper than one tile level below water level. It is also not possible to have one tunnel pass under or over another without forming a vertical shaft. Each tile is essentially a pillar, so if two tunnels cross at different elevations they create a shaft going from the upper tunnel to the lower tunnel. his can be useful when done intentionally. It can also ruin your mine if unplanned. Planning your mine with an overhead view of your mine on graph paper can save you some heartache.
=== Surface excavation Opening a mine ===
The first step in all mines is to make a mine entrance on the surface. This can be done on any [[cliff]] or [[rock]] tile. Equip a mining pick, and select the "Tunnel" option. After 51 tunneling actions, the message "You will soon create an entrance" will appear. A few actions later an entrance will be created. The exact value is random, averaging around 5 mining actions after the message appears.
Tunneling on a shallow [[slope]] is dangerous since you are basically mining straight down and may dig yourself into a steep slope or a pit. A slope of 10+ is probably safe (estimate). The good news is that a poor tunnel slopes can be fixed. The bad news is that it is a lot of work!
A [[sculpting wand]], if you have access to one, is the fastest way to shape rock.=== Surface mining ===
The slope of surface rock can be changed with a mining pickpickaxe or a [[sculpting wand]]. It The sculpting wand is the fastest way to shape rock. Using a pickaxe however is time consuming, but possible. Here's a step-by-step on how to do this:
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2) Activate your mining pick and stand at the intersection of the four tiles (point E), click the ground, and select the mining action. Be sure that you do not select tunneling. Tunneling will eventually create a mine entrance, which we do not want (at least not yet).
3) Roughly once per every Randomly, with about 10 mining actions, according to recent notes-20% chance, you will drop the rock level at the point where you are mining by 1 dirtand produce a [[rock shard]]. This does is not appear to be a cumulative chance. Sometimes you will drop the rock level very quickly for a short spurt, other times you might mine 25 times and for along time not drop the level. In other words, many failures in a row does not make future success more likely.
4) Attempting to lower surface rock below the ceiling of a mine below results in the message "The rock sounds hollow, you will need to tunnel to continue". At this point, you cannot lower the surface rock any further.
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5) *needs more input* Lowering surface rock with a pick may be more successful in the daytime than at night. A campfire at night does seem to help. I might just have had several very long strings of failures at night and many quick successes in the daytime by sheer luck. My (FarmerBob's) experience was over a period of probably 8 or 9 Wurm day/night cycles. Not enough to be truly sure, but enough to make me doubt coincidence.
Note that the example above is only for one point. To lower the face of a tile to make a nice mine entry tunnel, here's a more complex example:
* To drop the rock level at F dig A/B/C/E/F/G/I/J/K down to rock.
* To drop the rock level at G dig B/C/D/F/G/H/J/K/L down to rock.
Remember: surface rock lowering is done at intersections of rock tiles, tunnel creation is done within a single rock tile. If you try to tunnel while standing at a intersection of 4 tiles, you might get a tunnel at an unexpected location, so be sure to be standing on one tile, and be sure to be clicking that one tile when creating a tunnel.</td><tdalign="right">
A--B--C--D
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Remember: surface rock lowering is done at intersections of rock tiles, tunnel creation is done within a single rock tile. If you try to tunnel while standing at a intersection of 4 tiles, you might get a tunnel at an unexpected location, so be sure to be standing on one tile, and be sure to be clicking that one tile when creating a tunnel.
Surface excavation mining will produce [[rock shards]] on some actions. The probability seems to be around 25%each action that lowered the corner.
=== Mine doors ===