So I'm looking through some material on creep for one of my courses. There is a graph of strain ε vs Time, t. Consisting of Primary creep, steady-state creep, and tertiary creep. I pretty much can follow that and understand why the graph looks the way it does. However there is another graph under it that is ln(dεss/dt) vs ln(σ). I am trying to understand what the significance is of taking the natural log of stress and the steady state creep rate. What would a graph containing these things be telling us, and why the natural log? Thanks for any help.