This research article is concerned with the analytical assessment and mathematical modelling to unveil the characteristic of a torsional wave in the irregular Earth’s crustal stratum. This investigation has been performed to clarify of possible occurrence of the torsional wave in an irregular self-reinforced composite layer bonded between dry sandy media and an isotropic elastic half-space. Rectangular and parabolic irregularities have been assumed at the interface of the intermediate layer and the lower half-space. In order to acquire the required dispersion equation, the appropriate boundary conditions with the assistance of displacement and stress components have been well satisfied. The effects of different affecting parameters such as reinforcement, sandiness, initial stress and irregularity parameters have been explored and explained by suitable graphs. Moreover, a comparative study has also been accomplished graphically for rectangular, parabolic, and no irregularities.