In this investigation, the fast Fourier transform is applied to the analysis of two-dimensional data. In particular, a crosscorrelation function has been used to obtain trend directions of magnetic data. The technique is applicable to other geological or geophysical data. An empirical method has been devised to trace the trends by fitting a least squares third degree polynomial to the maximum coefficient in the correlation matrix. An example from Stony Rapids, Northern Saskatchewan illustrates the method.