1. A method for modeling a subsurface structure at a time period when the structure was originally formed, the method comprising: generating a first model having a plurality of non-planar horizons representing a current state of the subsurface structure; computing a non-uniform vector field based on the non-planar geometry of the horizons of the first model; using the vector field, transforming geographic coordinates of the first model to paleo-geographic coordinates of a second model representing a predicted state of the subsurface structure at a time period when the subsurface structure was originally formed, wherein the non-planar horizons in the first model are transformed to planar horizons in the second model; and displaying the first model.