Abstract: A method and apparatus for mapping the character and location of small surface variations on a planar surface. Energy in the form of pulses is supplied to an object in close proximity to the planar surface to thereby raise the temperature of the object and at part of the surface. A change in temperature of the object is detected when it is in proximity to the variation to define the location and character of the variation. By supplying the energy in the form of pulses, the size of the thermal signature produced in the planar surface is limited wherein a more accurate and more sensitive mapping method and apparatus are provided. The energy supply may be thermal energy or optical energy but preferably is electrical energy which heats a resistive element. Preferably, the object is a magnetoresistive head of a disk drive assembly and the surface may be that of a magnetic recording material. The change in temperature is detected by monitoring the resistance of the magnetoresistive coil of the head.