At least 50 levels between the surface and the first cavern layer.
Most worlds are generated with the default amount of layers between surface and caverns, and caverns and caverns.
This default is between 2 and 5. It's easy to check it out in the world gen parameters (advanced world gen, 'e', then go down until you find 'Z-levels above' parameters).
I don't think people have genned a 50 levels above cavern 1 world here.
Otherwise: Worldgen science!
Temperature:
I didn't know some of this!
Fun worldgen temperature facts (that you won't find on the wiki):
- If you gen an area with [TEMPERATURE:0:0:0:0] i.e. max, min, and both variances are zero, you can see how latitude, elevation, and rainfall affect the temperatures.
- Temperature is strongly affected by latitude, and to a lesser degree the other factors including the random variances introduced by the player (unless you enter absurdly large max or min numbers).
- The difference between winter and summer temperatures is zero at the top and bottom of the map, and linearly grows to a peak of about 30 U (40 W) difference in the central temperate zones.
- The normal temperature is the seaside summer temperature. Elevation or time of year (in temperate areas) subtracts from this temperature.
- High rainfall (over 66) can reduce a scorching/hot area to hot or warm.
- The elevation and rainfall changes happen during worldgen and are reflected in the exported temperature map. The exported temperature map shows the summer temperatures for temperate areas.
- The maximum temperature worldwide is capped at the worldgen max+25 (in W units). No such logic exists for minimum temperatures. While this was probably implemented to solve the fat-melting bug, it can also be used to enforce a global freezing.
Worldgen_temperature * 0.75 + 10000 = degrees Urist
In worldgen units:
-0 freezing
0-15 cold
15-50 temperate
50-75 warm
75-90 hot
90+ scorching
Mineral scarcity:
Changing the mineral scarcity will influence the EVIL in the world!
Consider this: using the HOT WORLD gen (it's a flat volcano + tower + sand + a HUGE finger of rock planted for no reason) I published earlier in this thread and without changing anything else, going from 100 to 1000 to 10 000 to 100 000 mineral scarcity changed history (which is not surprising) and made the tower disappear.
More surprising however, is the fact that evilness changed, and that regions which had been good turned to evil, and neutral turned to good etc. I can't explain this. If evilness were random, then seeds would give worlds of rndom evilness. But since evilness obviously isn't random, why would changing mineral scarcity (and only mineral scarcity) change evilness?