def timings
      timings = Timings.new
      self.sc_iterations.each{|sc_iter|
        timings.add!(sc_iter.timings)
      }
      timings
    end
def timings
      timings = Timings.new
      self.sc_iterations.each{|sc_iter|
        timings.add!(sc_iter.timings)
      }
      timings
    end
A hash with keys :description, :cpu_time, and :wall_time
 with detailed time accounting for this geometry step.