It is worth understanding the process used by the interpretation functionality to explain the changes made to the civil 3D surfaces, as the strata profile displayed does not always follow the profile originally drawn.

When a strata profile in an interpretation profile view is updated, the geometry is used to create a 3D feature line following the alignment of the profile view. The feature line is automatically added as a break line to the corresponding strata 3D surface and the resultant profile is then projected back onto the interpretation Profile View. The final profile viewed is not the one drawn but the one projected from the 3D surface and because civil 3D surfaces are built up from numerous pieces of data you don't always get the same as originally drawn.

The diagram below shows the process automated by the Edit Interpretation command.