The deepest the sub-floor crater band may cut, meters.
A tenth of CANONICAL_DETAIL_FLOOR, and the depth law says a fifth. A
fresh eight-meter crater is 1.6 m deep — craterDepth at 0.2·D — and that is
the depth of one of them. This band is saturated: every cell at every rung
holds a crater, which is what a surface in production equilibrium at a meter
is, and a saturated population's members destroy each other rather than
stacking. Half is the measurement of that. At 1.6 the ground drew as broken
glass, at 21° of RMS slope over a one-meter baseline against a published
5–20° for lunar regolith and the MER landing sites; at 0.8 it is 12.3° on
Luna, 8.4° on Mars and 15.6° on Mercury.
It is still deliberately above CANONICAL_AMPLITUDE_FLOOR, and that is
the whole reason the mesh gets any deeper. TERRAIN_DETAIL_TOLERANCE is half
a meter, so a term that never exceeds half a meter cannot move
surfaceDetailFloor by a single level however fine its wavelength is — the
search would call every level of it quiet and stop where it stops today.
softLimit is a tanh, so this is a strict bound the sum approaches and
never reaches: measured across the zoo the deepest cut is 0.799 m and the
most the tail ever lifts the ground is 0.66 m.