Quality control analyses of the density data (a) in relation to possible borehole wall rugosity effects (c) from Triple Combo pass 1. Respective wavelet spectrum diagrams are shown for density (b) and borehole diameter (d) (Hole 1219A). The cross-wavelet spectrum is presented in the modulus (e) and phase (f) diagrams . Note the high significance region in the density wavelet spectrum at about 100 mbsf (b), which is produced by the density spike at the same depth (a).