Comments, with reply on `Magnetotelluric exploration for hydrocarbons´ by A.S. Orange

An oversimplification of the treatment of the incidence angle and of the source dependence of magnetotelluric surface impedance in a previous treatment of magnetotelluric exploration of hydrocarbons (see ibid., vol.77, no.2, p.287-317, 1989) is pointed out. The author of the original paper agrees with the comments and recognizes the paper´s lack of rigor. He points out that the intent of the paper was to present a broad overview to a general audience and to focus on the utility and applications of the method