# What is the metamorphic field gradient useful for?

As I understand it, the metamorphic field gradient is the PT line traced out by the maximum temperature points of a series of PTt paths of rocks from the same metamorphic event.

What exactly is this useful for? It seems that it doesn't really describe anything of physical significance since the $\mathrm{T_{max}}$ points can occur at different times so it doesn't represent a snapshot of the geothermal gradient at any fixed time.