The winding stairs I used were 56 steps with short flat portions in between sets of 8 steps. (pumpsandiron.com)
Body parts rendered from flat portions of wood adjoin with others sculpted in the round to create interplay between two and three dimensional elements. (myartguides.com)
It could be that this is evident in the curve as well both before and after the 1991 volcano in that the curve is steeper than B before 1991 and then after the significant flat portion then crosses B at a similar slope. (realclimate.org)