The storage and dissipation resistance to deformation of a cohesive soil as represented by the complex modulus is obtained from stress relaxation response using the one‐sided Fourier transform. The soil response is nonlinear. An approximate method of evaluating the transform with digital computer methods is based on the use of straight line segments to form a piecewise continuous representation of the relaxation response. This allows comparison of static and dynamic response characteristics as functions of applied strain level and moisture content through the transformation from the time domain to the frequency domain. For each strain level, large and small time plateau regions of complex modulus are connected with a transition region showing an increase in modulus with increase in frequency. Complex modulus decreases with increased strain level and increased moisture content.