1. A well logging method of producing a representation mapping the relative arrangement of subsurface earth formation beds with respect to a subsurface characteristic measured with a well logging device, comprising: (a) producing initial well logging measurements for particular depths in the formation derived from measurements taken in a well in the formation with the well logging device over a given depth interval; (b) producing a trial variation of the subsurface characteristic, said trial variation varying in discrete steps corresponding to discretely-boundaried subsurface earth formation beds, said boundaries being based on measurements of the subsurface characteristic; (c) generating, by a computer, a new well logging measurement for a particular depth level for which there is an initial well logging measurement, by applying the approximate response characteristic of the logging device to the trial variation of the subsurface characteristic; (d) comparing, by a computer, the new well logging measurement at the particular depth level to the initial measurement value at that depth level; and (e) modifying, by a computer, the trial variation of the subsurface characteristic in accordance with the comparison to thereby produce a visual or a stored representation mapping the relative arrangement of discretely boundaried subsurface earth formation beds.